Superior lateral brachial cutaneous nerve. Peripheral nervous system

Anatomy and etiology of long thoracic nerve compression. The long thoracic nerve is a purely motor nerve that arises from the ventral rami of the spinal nerves C5, C6, and C7. It passes along with other components of the brachial plexus under the clavicle, then descends down the anterolateral wall chest to the serratus anterior muscle. This large muscle attaches the scapula to the chest wall, providing overall stability to the shoulder when moving the arm. Damage to the long thoracic nerve can occur due to trauma or severe physical activity, involving the shoulder girdle in movement. Long thoracic nerve neuropathy may be due to idiopathic brachial plexus plexopathy.

Clinical picture of the long thoracic nerve long thoracic nerve mononeuropathy involves pain and weakness in shoulder joint. Patients experience difficulty abducting the arm or raising it above the head. In the patient's position with arms extended forward and emphasis on the wall, the phenomenon of the “pterygoid scapula” appears. The shoulder blade rises above the chest because the weakened serratus muscle cannot support it.

Long thoracic nerve diagnosis established on the basis of the above-mentioned clinical signs and the detection of fibrillation potentials on EMG affecting only the serratus anterior muscle. Determining the velocity of potential conduction along the long thoracic nerve (LPNV) is technically difficult; LPNVs of other nerves are normal.

Suprascapular nerve. Compression of the suprascapular nerve.

Anatomy and etiology of suprascapular nerve compression. The suprascapular nerve is a purely motor nerve that arises from the superior cord of the brachial plexus and passes through the suprascapular notch along the superior edge of the scapula to the supraspinatus and cavitary muscles. The suprascapular nerve is most often injured in injuries associated with excessive anterior flexion of the shoulder joint.

He may get involved in pathological process with idiopathic brachial plexus plexopathy.

Clinical picture consists of pain in the back of the shoulder joint and weakness of the supraspinatus and infraspinatus muscles. The supraspinatus muscle provides abduction of the arm, while the infraspinatus muscle is responsible for external rotation of the arm.

Diagnosis established on the basis of anamnesis, clinic, physical data and EDI. Conventional studies of the SPNV are normal, but a study of the SPNV of the motor nerves with recording from the supraspinatus muscle may reveal a decrease in amplitude or prolongation of the latency period compared with the healthy side.

Posterior scapular nerve

Anatomy and etiology of posterior scapular nerve compression. The posterior scapular nerve (PSN) is a purely motor nerve that originates from the superior fascicle of the brachial plexus and passes through the middle scalene muscle to the rhomboid and levator scapulae muscles. PLN lesions are relatively rare.

Clinical picture of compression of the posterior scapular nerve includes pain in the scapula region and weakness of the rhomboid and levator scapulae muscles.

Diagnosis of posterior scapular nerve compression established on the basis of clinical signs and EMG data identifying fibrillation potentials related to the muscles innervated by the ON. For PLN, there are no satisfactory methods for assessing PNV.

Brachial plexus(plexus brachialis) formed by the anterior branches of the 4 lower cervical spinal nerves and the anterior branch of the 1st thoracic spinal nerve. In the plexus in relation to the clavicle, two parts are distinguished: supraclavicular (pars supraclaviculars) and subclavian (pars infraclavicularis). The first is located within the lateral triangle of the neck, the second - in the axillary cavity.

From supraclavicular part plexuses begin with short branches (Fig. 254).

Subclavian part plexus is represented by three bundles: lateral (fasc. lateralis), rear (fasc. posterior) and medial (fasc. medialis). Long nerves originate from the subclavian plexus upper limb. The musculocutaneous nerve and the lateral root of the median nerve begin from the lateral fascicle; from the medial - the medial root of the median nerve, the ulnar and medial cutaneous nerves of the shoulder and forearm; from the posterior - the radial and axillary nerves.

Short branches:

1. Dorsal nerve of the scapula(n. dorsalis scapulae) innervates the levator scapulae muscle, major and minor rhomboid muscles.

2. Long thoracic nerve(n. thoracicus longus) innervates the serratus anterior muscle.

3. Subclavian nerve(n. subclavius) innervates the muscle of the same name.

4. Suprascapular nerve(n. suprascapularis) innervates the supraspinatus and infraspinatus muscles, the capsule of the shoulder joint.

Rice. 254. Brachial plexus:

1 - anterior branches of the spinal nerves from C 5 to Th 1; 2 - medial plexus bundle; 3 - rear beam; 4 - lateral bundle; 5 - ulnar nerve; 6 - median nerve; 7 - radial nerve; 8 - axillary nerve; 9 - musculocutaneous nerve; 10 - 1st rib

5. Subscapular nerve(n. subscapularis) innervates the subscapularis, teres major and vastus dorsi muscles.

6. Thoracic nerves- medial And lateral(nn. pectorales medialis et lateralis)- innervate the major and minor pectoral muscles.

7. Axillary nerve(n. axillaris) innervates the deltoid muscle, minor teres muscle, the capsule of the shoulder joint and the skin of the outer surface of the shoulder.

Long branches (Fig. 255, 256):

1. Musculocutaneous nerve(n. musculocutaneus) innervates the anterior muscle group of the shoulder. The continuation of this nerve is called lateral cutaneous nerve of the forearm(n. cutaneus antebrachii lateralis). It innervates the skin of the anterolateral surface of the forearm.

2. Median nerve(n. medianus) there are no branches on the shoulder. In the forearm, the nerve gives off branches to the anterior group of muscles, with the exception of the flexor carpi ulnaris and the medial half of the flexor digitorum profundus, which are innervated by the ulnar nerve. In the hand, the median nerve is divided into 3 common palmar digital nerve(nn. digitales palmares communes), which in turn are divided into the palmar digital nerves (nn. digitales palmares proprii), going to the skin of I, II, III and the outer surface of the IV fingers.

From the first common digital nerve, muscle branches arise to the muscles of the eminence of the thumb, with the exception of the adductor pollicis muscle and the deep head of the flexor pollicis brevis muscle. The branches of this nerve also go to the I and II lumbrical muscles.

3. Ulnar nerve(n. ulnaris) there are no branches on the shoulder. On the forearm it gives branches to the elbow joint, flexor carpi ulnaris and part of the flexor digitorum profundus. Innervates the skin of the medial surface of the IV and V fingers, the muscles of the eminence of the little finger, the interosseous muscles, the III and IV lumbrical muscles, the adductor pollicis muscle and the deep head of the flexor pollicis brevis muscle.

4. Medial cutaneous nerve of the shoulder(n. cutaneus brachii medialis) innervates the skin of the medial surface of the shoulder.

5. Medial cutaneous nerve of the forearm(n. cutaneus antebrahii medialis) innervates the skin of the medial surface of the forearm.

6. Radial nerve(n. radialis) innervates the posterior muscle groups of the shoulder and forearm, the skin of the posterior and inferolateral surface of the shoulder, the skin back surface forearm, skin of the dorsal surface of I, II and the outer side of III fingers (Fig. 257).

Rice. 255. Long branches of the brachial plexus, view from the anteromedial side. The pectoralis major and minor muscles are cut and removed:

1 - lateral bundle; 2 - rear beam; 3 - medial bundle; 4 - axillary artery; 5 - subscapular nerve; 6 - subscapularis muscle; 7 - subscapular artery; 8 - artery circumflexing the scapula; 9 - thoracodorsal nerve; 10 - thoracodorsal artery;

1 - latissimus dorsi muscle; 12 - medial cutaneous nerve of the shoulder; 13 - radial nerve; 14 - deep artery of the shoulder; 15 - triceps shoulder; 16 - ulnar nerve; 17 - medial cutaneous nerve of the forearm; 18 - medial epicondyle; 19 - lateral cutaneous nerve of the forearm; 20 - biceps brachii; 21 - superior ulnar collateral; 22 - median nerve; 23 - brachial artery; 24 - coracobrachialis muscle; 25 - pectoralis major muscle; 26 - axillary nerve; 27 - musculocutaneous nerve; 28 - deltoid muscle; 29 - pectoralis minor muscle; 30 - deltoid branch (from the thoracoacromial artery); 31 - thoracoacromial artery

Rice. 256. Nerves of the hand. Palm side, front view:

1 - ulnar nerve; 2 - tendon retinaculum; 3 - muscle that abducts the little finger; 4 - muscle that flexes the little finger; 5 - common palmar digital nerves (from the ulnar nerve); 6 - muscle opposing the little finger; 7 - tendons of the muscles - long flexor fingers; 8 - own palmar digital nerves (from the ulnar nerve); 9 - own palmar digital nerves (from the median nerve); 10 - muscle that adducts the thumb (transverse head);

11 - common palmar digital nerves (from the median nerve); 12 - short muscle flexing the thumb; 13 - short muscle, abductor pollicis; 14 - median nerve (palmar branch)

Rice. 257. Nerves of the upper limb (photo from the specimen):

A - shoulder girdle: 1 - lateral bundle of the brachial plexus; 2 - posterior bundle of the plexus; 3 - medial bundle; 4 - pectoralis minor muscle (cut); 5 - musculocutaneous nerve; 6 - axillary nerve; 7, 9 - branches of the brachial plexus, forming the median nerve (10); 8 - radial nerve; 11 - medial cutaneous nerve of the shoulder; 12 - ulnar nerve; 13 - medial cutaneous nerve of the forearm; 14 - biceps brachii; 15 - deltoid muscle

Rice. 257. Continuation:

b - shoulder: 1, 3 - branches of the medial cutaneous nerve of the forearm; 2 - medial saphenous vein of the arm; 4 - ulnar nerve; 5 - median nerve; 6 - biceps brachii; 7 - lateral saphenous vein of the arm; 8 - lateral cutaneous nerve of the forearm

Rice. 257. Continuation:

c - hands (palmar surface): 1 - median nerve, splitting into common palmar digital nerves; 2 - superficial palmar arterial arch; 3 - branch of the ulnar nerve to the muscles of the hand; 4 - ulnar artery and nerve

The somatic peripheral nervous system includes spinal nerve roots, spinal nodes, nerve plexuses, spinal and cranial nerves. Even within the spinal canal, the anterior (motor) and posterior (sensitive) roots gradually come closer together, then merge and form the radicular nerve along the spinal nodes, and then the spinal nerve. Therefore, the spinal nerves are mixed, since they contain motor (efferent) fibers from the cells of the anterior horns, sensory (afferent) fibers from the cells of the spinal ganglia and autonomic fibers from the cells of the lateral horns and nodes of the sympathetic trunk.

After leaving the central canal through the intervertebral foramina, the spinal nerves divide into anterior branches ( rr. anteriores), innervating the skin, muscles of the limbs and the anterior surface of the body; posterior branches ( rr. posteriores), innervating the skin and muscles of the posterior surface of the body; meningeal branches ( rr. meningei), heading to the dura mater of the spinal cord, and connecting branches ( rr. communicantes), containing sympathetic preganglionic fibers that follow the nodes of the sympathetic trunk ( gangl. trunci sympathici). The anterior branches of the cervical, lumbar and sacral spinal nerves form bundles of corresponding plexuses, from which the peripheral nerves arise.

Nerve fiber (axon) is the main structural element of the peripheral nerve. There are myelinated and unmyelinated nerve fibers. Myelinated nerve fibers are divided into thick, which conduct pulses at a speed of 40–70 m/s, and thin, conducting pulses at a speed of 10–20 m/s. The speed of impulse conduction along unmyelinated nerve fibers is 0.7–1.5 m/s. Fibers with a thick myelin sheath provide complex and deep types of sensitivity (two-dimensional spatial sense, discriminatory sense, stereognosis, joint-muscular sense, etc.), fibers with a thin myelin sheath - pain, temperature and tactile, and non-myelinated fibers - only pain sensitivity. In this case, fibers with a thin myelin sheath are involved in the formation of the sensation of localized pain, without myelin - diffuse pain. Myelinated axons predominate in somatic (spinal and cranial) nerves, non-myelinated axons predominate in the visceral nerves of the sympathetic part of the autonomic nervous system; the nerves of its parasympathetic part (vagus, oculomotor nerve root, etc.) mainly consist of myelinated nerve fibers.

Nerve fibers are grouped into separate bundles of various calibers, delimited from other formations of the nerve trunk by the perineural sheath. On a cross section of human nerves, connective tissue sheaths (epineurium, perineurium) occupy significantly more space (67–84%) than bundles of nerve fibers. The bundles in the nerve trunks can be located relatively rarely, with intervals of 170–250 μm, and more often, the distance between the bundles is less than 85–170 μm.

The epineurium of nerves with a large number of bundles is replete with small-caliber blood vessels. In nerves with a small number of bundles, the vessels are single, but larger. The thickness of the bundles depends not only on the number, but also on the type of nerve fibers that make them up. More powerful bundles are formed by myelin fibers. Due to the fact that nerve fibers pass from one bundle to another, complex intra-stem plexuses are formed. This partly explains the absence of clear zones of impairment of motor, sensory and autonomic functions with partial nerve damage.

Cervical plexus (plexus cervicalis) (Fig. 24). The plexus is formed by the anterior branches of the four upper cervical spinal nerves (C 1 -C 4) and is located lateral to the transverse processes on the anterior surface of the middle scalene muscle and the levator scapula muscle, under the sternocleidomastoid muscle. Cutaneous and muscular branches emerge from it to the deep muscles of the neck, which are involved in the innervation of the scalp, ear, neck, diaphragm and shoulder girdle. When damaged, pain and sensitivity disorders occur in the innervation zone.

The cervical plexus forms the following nerves.

Lesser occipital nerve (n. occipitalis minor) is formed from the anterior branches of the C 1 - C 3 cervical spinal nerves. It innervates the skin of the lateral part of the occipital region and partially the auricle. When the nerve is irritated, occipital neuralgia occurs, and with compression-ischemic lesions, paresthesia occurs in the external occipital region.

Rice. 24. Cervical plexus:

1 – suboccipital nerve; 2 – greater occipital nerve; 3 – lesser occipital nerve; 4 – great auricular nerve; 5 – transverse nerve of the neck; 6 – supraclavicular nerves; 7 – phrenic nerve; 8 – neck loop; 9 – upper cervical node; 10 – hypoglossal nerve

Greater auricular nerve (n. auricularis magnus) is formed from the anterior branches of the C 3 -C 4 cervical spinal nerves and provides innervation to the earlobe, auricle and external auditory canal.

Transverse cervical nerve (n. transversus colli) is formed from the anterior branches of the C 2 -C 3 cervical spinal nerves and innervates the skin of the lateral and anterior regions of the neck.

Supraclavicular nerves (nn. supraclavicularis) are formed from fibers of the anterior branches of the C 3 -C 4 cervical spinal nerves and innervate the skin of the supraclavicular, subclavian, suprascapular regions and the upper outer part of the shoulder.

Damage to the supraclavicular nerves is accompanied by pain in the innervation zone, which intensifies when the head is tilted to the sides. Intense pain is usually accompanied by tonic tension of the neck muscles, leading to a forced position of the head (in such cases, differential diagnosis with meningeal syndrome is necessary). In addition, there are disorders of surface sensitivity in the area of ​​innervation and pain points along the posterior edge of the sternocleidomastoid muscle.

Phrenic nerve (n. phrenicus) is formed from C 3 -C 5 cervical spinal nerves, is mixed. It innervates the diaphragm, pleura, pericardium, peritoneum and liver ligaments. When the nerve is damaged, paralysis of the same half of the diaphragm occurs (it manifests itself in paradoxical breathing: when inhaling, the epigastric region sinks, when exhaling, it protrudes), and when irritated, hiccups, shortness of breath and pain in the hypochondrium, shoulder girdle and neck can be observed. Most often, the nerve is affected by infectious diseases (diphtheria, influenza, scarlet fever, etc.), intoxication, tumor metastases in the cervical vertebrae, etc.

Brachial plexus (plexus brachialis) (see Fig. 25 on color incl.). The plexus is formed by the connection of the anterior branches of the four lower cervical (C 5 -C 8) and two upper thoracic (Th 1 -Th 2) spinal nerves. Nerve fibers form primary bundles - upper, middle and lower, and then secondary bundles (lateral, medial and posterior). The upper bundle is formed from the fusion of the anterior branches of the C 5 -C 6 spinal nerves, the middle – C 7 and the lower – C 8 -Th 2. The brachial plexus is divided into supraclavicular and subclavian parts. The supraclavicular part of the brachial plexus is located in the supraclavicular fossa. The following nerves are formed from it.

Anterior thoracic nerves (rr. anteriores nn. thoracici) innervate the pectoral muscles: major (adducts and rotates the shoulder inward) and minor (pulls the scapula forward and downward). Isolated damage to these nerves is rare. Paresis or paralysis of these muscles is manifested by difficulty in bringing the upper limb to the chest.

Dorsal nerve of the scapula (n. dorsalis scapulae) innervates the rhomboid major and minor muscles and the levator scapulae muscle.

Long thoracic nerve (n. thoracicus longus) innervates the serratus anterior muscle, which brings the scapula closer to the chest.

Subclavian nerve (n. subclavius) innervates the subclavian muscle, which pulls the clavicle down and medially.

Suprascapular nerve (n. suprascapularis). The sensory part supplies the ligaments and capsule of the shoulder joint, the motor part supplies the supraspinatus and infraspinatus muscles (shoulder abduction at an angle of 15° and external rotation of the shoulder) (see color on, Fig. 25).

Thoracospinal nerve (n. thoracodorsalis) innervates latissimus muscle backs. Its defeat is accompanied by a violation of the movement of the arm back behind the back and to the midline, i.e., inward rotation.

Infraclavicular part of the brachial plexus located in the armpit and innervates the arm. There are three bundles in it: lateral, formed by the anterior branches of the C 5 -C 7 nerves; medial – anterior branches of the C 8 and Th 1 nerves; posterior - posterior branches of the three primary bundles. The musculocutaneous nerve is formed from the lateral fascicle ( n. musculocutaneus) and lateral root of the median nerve ( n. medianus); from the medial - ulnar nerve ( n. ulnaris), medial cutaneous nerve of the shoulder ( n. cutaneus brachii medialis) and forearms ( ), medial root of the median nerve; from the posterior - axillary nerve ( n. axillaris) and radial nerve ( n. radialis).

Median nerve (n. medianus) contains motor, sensory and a large number of vegetative fibers. Innervates the muscles of the anterior surface of the forearm; flexors of the hand and I–II fingers, pronators of the forearm and hand, the muscle opposing the thumb and I–II lumbrical muscles; the skin of the palmar surface of the radial edge of the hand, I–III and half of the IV fingers, the dorsal surface of the terminal phalanges of the I–II and partially IV fingers. When the median nerve is damaged, the flexion of the hand and fingers I–III, opposition of the thumb and pronation (it is difficult to grasp objects), flexion of the proximal phalanges and extension of the remaining phalanges of the II–III fingers are impaired. The muscles of the forearm and the eminence of the thumb atrophy, a “monkey hand” is formed, and vegetative-trophic disorders (regional pain syndrome, causalgia) may appear. Deep sensitivity is lost in the terminal interphalangeal joint of the second finger.

The nerve is often damaged in natural anatomical tunnels. In this case, a distinction is made between the supracondylar-ulnar groove syndrome (provoked by extension of the forearm and pronation in combination with forced flexion of the fingers and is accompanied by pain, paresthesia in the innervation zone of the median nerve, weakness of the flexors of the hand and fingers); pronator teres syndrome (symptoms of loss of function of the median nerve increase with pressure in the area of ​​the pronator teres); carpal tunnel syndrome (the main symptom is paresthesia and pain in the fingers, aggravated by the wrist flexion test and tapping along the projection of the median nerve at the level of the wrist).

Ulnar nerve (n. ulnaris) innervates the flexors of the IV and V fingers, all interosseous, III and IV lumbrical muscles, the muscle that adducts the first finger and the abductor V finger. Provides sensitive innervation to the palmar surface of the 5th and half of the 4th, as well as the dorsal surface of the 5th, 4th and half of the 3rd fingers.

When the nerve is damaged, flexion of the little finger, abduction and adduction of the fingers (the patient cannot grasp and hold objects between the fingers), flexion of the proximal and extension of the remaining phalanges of the fourth and fifth fingers are impaired. Partial atrophy of the forearm muscles occurs, the interosseous spaces of the hand recede, and the elevation of the little finger (“clawed paw”) becomes flattened. Sensory disorders spread to the ulnar part of the hand from the palm and back, the area of ​​the V and ulnar side of the IV fingers. Deep sensitivity is impaired in the joints of the fifth finger.

The following are distinguished: ulnar nerve tunnel syndromes: cubital syndrome (with rheumatoid arthritis, prolonged sitting at a desk, paresthesia and numbness first appear in the area of ​​innervation of the ulnar nerve, and later weakness and atrophy of the hand muscles); wrist syndrome (paresthesia inner surface hands, weakness in flexion and adduction of the fifth finger, aggravated by finger pressure and tapping on the wrist).

Medial cutaneous nerve of the shoulder (n. cutaneus brachii medialis) innervates the skin of the inner surface of the shoulder. It is affected by prolonged walking on crutches or scarring in the upper third of the shoulder.

Medial cutaneous nerve of the forearm (n. cutaneus antebrachii medialis) innervates the skin of the inner surface of the forearm. It is affected by scar processes along the medial surface of the middle and lower third of the shoulder.

Clinical signs of damage to these nerves are paresthesia, pain, and numbness in the innervation zone.

Axillary nerve (n. axillaris) innervates the deltoid muscle, which abducts the shoulder to a horizontal level, and is also involved in flexion and extension of the shoulder (movement of the shoulder forward and backward), rotation of the shoulder outward (teres minor muscle) and provides sensitive innervation of the skin in the area of ​​the shoulder joint and the outer surface of the shoulder in its upper third. Nerve damage is manifested by pain in the shoulder joint, impaired abduction of the upper limb to the side, lifting it forward and backward, hypotrophy deltoid muscle(differential diagnosis must be made with glenohumeral periarthrosis and cervicothoracic radiculopathy).

Radial nerve (n. radialis) innervates the triceps brachii muscle, extensors of the hand and fingers, supinator of the forearm, brachioradialis muscle and abductor muscle of the first finger of the hand. Provides sensitive innervation to the posterior region of the shoulder and forearm, the radial part of the dorsum of the I, II and partially III fingers. If the radial nerve is damaged, the extension of the forearm, hand and fingers, and the abduction of the first finger are disrupted. The triceps brachii muscle atrophies (“dangling hand”, Fig. 26). The extensor-elbow and carporadial reflexes decrease or disappear, and sensitivity in the innervation zone is disrupted.

There are lesions of the radial nerve in the axilla (for fractures humerus), at the level of the intermuscular septum of the shoulder (“sleep paralysis”), in the area elbow joint and upper part of the forearm (lipomas, fibromas of this area, bursitis, synovitis of the elbow joint, etc.), supinator syndrome, Turner syndrome (compression of the radial nerve due to a fracture of the lower end of the radius).

Clinical symptoms of brachial plexus lesions depends on the location and extent of the pathological process. Thus, when the upper primary bundle is damaged (with injuries, prolonged throwing of hands behind the head during surgery, tumor metastases, etc.) upper Erb-Duchenne palsy, characterized by damage to the proximal part of the upper limb while the function of the hand and fingers is preserved. The hand hangs like a whip. The reflex from the biceps brachii muscle disappears, and the carporadial one decreases. The sensitivity of the radicular type (C 5 -C 6) on the outer surface of the shoulder and forearm is upset. One of the clinical forms of compression-ischemic damage to the superior bundle of the brachial plexus is Personage-Turner neuralgic amyotrophy, which begins with increasing pain in the area of ​​the shoulder girdle, shoulder and scapula and gradually turns into deep paresis of the proximal parts of the arm with distinct atrophy of the serratus anterior, deltoid and parascapular muscles.

Rice. 26.“Dangling hand” with damage to the radial nerve

Damage to the primary inferior bundle of the plexus causes Dejerine-Klumpke lower palsy, in which distal paralysis occurs with predominant damage and atrophy small muscles and flexors of the fingers and hand. Sometimes, with high damage, Horner's syndrome occurs. Sensitivity is impaired in a radicular manner (C 8 -Th 2) on the inner surface of the hand, forearm and shoulder.

With total damage to the brachial plexus (with gunshot wounds of the supra- and subclavian areas, with a fracture of the clavicle, the 1st rib, with a dislocation of the humerus, tumors or metastases of this localization, etc.), peripheral paralysis of the arm and shoulder girdle occurs with sensitivity disorder and pain syndrome in the neck, scapula, arm, with loss of the extensor-elbow, flexion-elbow and carporadial reflexes. The brachial plexus is most often affected in muscular-tonic syndromes cervical osteochondrosis(for example, Naffziger anterior scalene syndrome; scalenus syndrome; pectoralis minor syndrome - Wright-Mendlovich hyperabduction syndrome; Steinbrocker shoulder-hand syndrome; Paget-Schroetter syndrome with subclavian vein thrombosis).

Thoracic nerves (nn. thoracici) are mixed, formed from Th 2 -Th 12 roots. The anterior branches of the thoracic nerves are intercostal. The first six intercostal nerves innervate the muscles and skin of the anterior and lateral parts of the chest, the lower six innervate the muscles and skin of the anterior abdominal wall. The posterior branches of the thoracic nerves innervate the muscles and skin of the back. When the intercostal nerves are damaged, girdling and constricting pain occurs and sensitivity in the corresponding zones is disrupted, reflexes are lost, and muscle paresis develops. abdominals. When spinal nodes are involved in the pathological process (ganglioneuritis), a rash in the form of vesicles is observed ( herpes zoster).

Lumbar plexus (plexus lumbalis) (Fig. 27, A) is formed from the anterior branches of the lumbar (L 1 -L 4) spinal nerves and partially the anterior branches of the 12th thoracic nerve. Located anterior to the transverse processes of the lumbar vertebrae on the anterior surface quadratus muscle loins, large in thickness psoas muscle.

The following nerves emerge from the plexus: iliohypogastric, ilioinguinal, femorogenital, femoral, obturator, lateral cutaneous nerve of the thigh. Damage to the entire plexus is rare (with fractures of the spine and pelvic bones; with compression by tumors, hematoma, pregnant uterus; with inflammatory processes in the retroperitoneal space); individual trunks are much more often affected. The clinical picture of lumbar plexopathy is characterized by pain in the lower abdomen, lumbar region, and pelvic bones; reduction of all types of skin sensitivity pelvic girdle and hips; movement disorder in lumbar region spine, hip and knee joints.

Iliohypogastric nerve (n. iliohypogastricus) is formed from the anterior branches of the Th 12 and L 1 spinal nerves. Innervates the transverse, rectus and oblique abdominal muscles, the skin of the suprapubic region and the upper lateral region of the thigh. It is usually damaged during operations on the abdominal or pelvic organs (especially during hernia repair).

Ilioinguinal nerve (n. ilioinguinalis) is formed from the anterior branch of L 1. Innervates the lower sections of the transverse, internal and external oblique abdominal muscles, the skin of the upper section of the inner thigh, genitals and groin area. Usually damaged during operations for hernia repair, appendectomy, nephrectomy; The development of compression-ischemic (tunnel) neuropathy is also possible. Nerve damage is manifested by pain and paresthesia in the groin area, antalgic posture when walking and limited extension, internal rotation and abduction of the hip.

Femorogenital nerve (n. genitofemoralis) is formed from the anterior branches of the L 1 -L 2 spinal nerves. Motor fibers innervate m. cremaster And tunica dartos, sensitive – the skin of the front and inner thighs in the upper third. When the nerve is damaged, the cremasteric reflex decreases or disappears and sensitivity disorders occur (most often pain in the groin area) in the corresponding area.

Femoral nerve (n. femoralis) is formed from the anterior branches of the L 1 -L 4 spinal nerves. Innervates the iliopsoas muscle (flexes the thigh at the hip joint and the spine in the lumbar region), the quadriceps femoris muscle (flexes the thigh and lower leg, turns the bent lower leg inward). Sensitive fibers innervate the skin of the lower two-thirds of the anterior surface of the thigh and the anterior inner surface of the leg. It is affected by injuries, spontaneous hematomas along its course, inguinal lymphadenitis, appendicular abscess, etc.

Rice. 27. Lumbosacral plexus:

A – lumbar plexus: 1 – iliohypogastric nerve; 2 – ilioinguinal nerve; 3 – genitofemoral nerve; 4 – lateral cutaneous nerve of the thigh; 5 – obturator nerve; 6 – femoral nerve.

B– sacral plexus: 7 – superior gluteal nerve; 8 – inferior gluteal nerve; 9 – sciatic nerve; 10 – common peroneal nerve; 11 – tibial nerve; 12 – posterior cutaneous nerve of the thigh; 13 – pudendal nerve ( n. pudendum); 14 – coccygeal nerve ( n. coccygeus)

When the nerve below the inguinal ligament is damaged, pain first occurs in the groin area, radiating to the lower back and thigh; Extension of the lower leg is impossible, atrophy of the quadriceps femoris muscle is noticeable, the knee reflex is lost, sensitivity on the anterior inner surface of the lower leg is impaired. If the nerve above the inguinal ligament is damaged, sensitivity disorders on the anterior surface of the thigh, impaired flexion of the hip (bringing it to the stomach) and lifting of the body in supine position; gait is difficult (the leg is excessively extended in knee joint) and especially climbing stairs. When the nerve is irritated, Wassermann's symptom appears: with the patient lying on his stomach, raising a straight leg or bending the knee joint causes pain in the groin area or along the front surface of the thigh.

Obturator nerve (n. obturatorius) is formed from the anterior branches of the L 4 -L 5 spinal nerves and is located behind or inside the psoas major muscle. Motor fibers innervate the hip adductor muscles. Sensory fibers innervate the lower half of the inner thigh. Nerve damage is possible at the beginning of its discharge (with a retroperitoneal hematoma).

If the nerve is damaged, it is difficult to adduct the leg, it is impossible to put one leg on the other, and in addition, there are sensory disturbances in the corresponding area.

Lateral cutaneous nerve of the thigh (n. cutaneus femoris lateralis) is formed from fibers of the roots L 2 -L 3 and innervates the skin of the outer surface of the thigh. When a nerve is damaged, sensitivity disorders occur in the innervation zone; when irritated, paresthesia and numbness occur in the same area of ​​the skin (Bernhardt-Roth disease, or meralgia paresthetica).

Sacral plexus (plexus sacralis) (Fig. 27, B). Formed from the anterior branches of the L 4 -S 3 roots, located on the anterior surface of the sacrum and piriformis muscle. The nerves emanating from it exit through the greater sciatic foramen. The sacral plexus connects to the lumbar plexus through the anterior branch of the S 1 spinal nerve. Damage to the sacral plexus or its constituent roots causes loss of function of the nerves emerging from it.

Superior gluteal nerve (n. gluteus superior) is formed from fibers of L 4, L 5 and S 1 roots. Innervates the gluteus minimus and medius muscles and the tensor muscle fascia lata hips that abduct the thigh outward. If this nerve is damaged, hip abduction is difficult; Bilateral lesions are characterized by a “duck” gait.

Inferior gluteal nerve (n. gluteus inferior) is formed from fibers of L 5, S 1, S 2 roots and innervates the large gluteal muscle and joint capsule hip joint. When the nerve is damaged, extension (abduction backwards) of the hip and straightening of the torso when standing in a bent forward position are impaired.

Posterior cutaneous nerve of the thigh (n. cutaneus femoris posterior) is formed from the anterior branches of the S 1 -S 2 roots and innervates the skin lower sections buttocks, scrotum (labia majora), perineum and back of the thigh to the popliteal fossa.

Sciatic nerve (n. ischiadicus) is a direct continuation of the anterior branches of the L 4 -S 3 spinal nerves. At the level of the thigh, the nerve gives off branches to the biceps femoris, semimembranosus and semitendinosus muscles, which flex the lower leg and rotate it outward or inward. In the upper part of the popliteal fossa, the sciatic nerve is divided into the tibial and common peroneal nerves, although the subepineural separation of both portions of the nerve usually occurs in the pelvic cavity.

When the sciatic nerve is damaged above the gluteal fold, there is an inability to flex the leg, as well as loss of function of the peroneal and tibial nerves (palsy of the foot and fingers, loss of the Achilles reflex and anesthesia of the entire leg and foot). In addition, damage to the sciatic nerves is often accompanied by severe pain. When the nerve is irritated, Lasegue's symptom is characteristic: pain along the sciatic nerve when raising the leg straightened at the knee joint in a supine position. When the sciatic nerve is affected below the gluteal fold, as a rule, predominantly the peroneal or tibial nerve is affected.

Common peroneal nerve (n. peroneus communis) is formed from L 4 -S 2 spinal nerves. Its main branches are the superficial peroneal ( n. peroneus superficialis) and deep peroneal nerve ( n. peroneus profundus). Muscular branches of the superficial peroneal nerve innervate the long and short peroneal muscles, raising the outer edge of the foot, as a result of which the foot pronates and abducts, and the cutaneous branches innervate the dorsum of the foot and the lateral region of the leg. When the nerve is damaged, abduction and elevation of the outer edge of the foot are disrupted, and sensitivity in the corresponding area is disrupted.

The muscular branches of the deep peroneal nerve innervate the anterior tibialis muscle, long and short extensor toes, which straighten, adduct and supinate the foot, straighten the proximal phalanges of the toes; cutaneous branches - a wedge-shaped area of ​​​​the skin of the dorsum of the foot between the first and second toes. Damage to the nerve leads to impaired dorsiflexion of the toes, atrophy of the anterior group of leg muscles, and sensitivity disorder in the corresponding area. Signs of damage to the common peroneal nerve are foot drop (“horse foot”), inability to extend the foot, “cock” gait (steppage) (Fig. 28), inability to stand and walk on heels, sensitivity disorder on the dorsum of the foot and in the lateral region of the lower leg.

Tibial nerve (n. tibialis) is formed from L 4 -S 3 spinal nerves. The muscle branches innervate the triceps surae muscle (flexes the foot), tibialis posterior muscle (flexes the foot, rotates it outward and adducts), flexor toes (flexes the foot and its toes). Sensitive branches innervate the posterior region of the leg, the sole and plantar surface of the fingers with access to the rear of the distal phalanges and the lateral edge of the foot.

When the tibial nerve is damaged, the foot takes on a specific appearance: a protruding heel, a deepened arch and a claw-like position of the toes ( pes calcaneus); inability to plantar flex the foot and its toes, walk and stand on the toes. Sensitivity in the posterior region of the leg, sole, and toes decreases, and vegetative-trophic disorders and causalgia often occur.

Rice. 28."Cock" gait (steppage) with damage to the peroneal nerve

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The brachial plexus (plexus brachialis) is formed by the anterior branches of the four lower cervical spinal nerves (C V -C VIII), which are also joined by a small portion of the anterior branch of the fourth cervical spinal nerve and most of the first thoracic nerve. The connection of the branches leads to the formation of three primary trunks of the brachial plexus - upper, middle and lower (truncus superior, medius et inferior; color Fig. 1). The redistribution of nerve fibers belonging to different segments of the spinal cord (from C IV - Th I) causes the division of the primary trunks into anterior and posterior trunks of the second order. When they merge, new forms of structural association of nerve fibers arise - bundles of the brachial plexus or secondary trunks.

The brachial plexus is located in the spatium interscalenum between the anterior and middle scalene muscles (m. scalenus anterior et medius) together with the subclavian artery. This part of it is called supraclavicular (pars supraclavicular, color. Fig. 2). From here, the second-order nerve trunks are directed laterally and downward into the axillary region, forming the infraclavicular part of the brachial plexus (pars infraclavicularis).

At the very beginning of the formation of the brachial plexus, muscle branches extend from it to the scalene muscles (mm. scaleni) and to the long muscle of the neck (m. longus colli). Here, between the deep muscles of the neck, an accessory root begins from the anterior branch of the fifth cervical spinal nerve phrenic nerve. Above and below the collarbone, nerves emerge from the brachial plexus to provide movement to the shoulder girdle and shoulder.

The dorsal nerve of the scapula (n. dorsalis scapulae) comes from C V. Innervates the rhomboid muscles (mm. rhomboidei) and the levator scapulae muscle (m. levator scapulae).

The suprascapular nerve (n. suprascapular) comes from C V -C VI. Runs along the front edge trapezius muscle(m. trapezius) to the supraspinatus and then infraspinatus fossa. Innervates the supraspinatus and infraspinatus muscles (mm. supra-et infraspinatus) and the capsule of the shoulder joint. The long thoracic nerve (n. thoracicus longus) comes from C V - C VII. Penetrates under the pectoralis minor muscle medially from the axillary cavity. Innervates the serratus anterior muscle (m. serratus anterior). The subclavian nerve (n. subclavius) comes from C V. The branch of insignificant thickness follows to the subclavian muscle (m. subclavius) and innervates it. The medial and lateral thoracic nerves originate from C V -Th I. They supply the pectoralis major and minor muscles with nerve fibers (mm. pectorales major et minor). The subscapular nerve (n. subscapularis) comes from C V -CVII. Innervates the muscle of the same name and the teres major muscle (m. teres major). The thoracodorsal nerve (n. thoracodorsalis) comes from C VII -C VIII. It is inserted into the broad dorsi muscle (m. latissimus dorsi) and innervates it.

Three bundles of the infraclavicular part of the brachial plexus - medial, lateral and posterior (fasciculus medialis, lateralis et posterior) - are divided into nerves of the upper limb, differing in considerable length. The ulnar nerve, the medial cutaneous nerve of the shoulder (n. cutaneus brachii medialis), the medial cutaneous nerve of the forearm (n. cutaneus antebrachii medialis) and the medial root of the median nerve begin from the medial bundle in the axillary cavity. From the lateral fascicle arise the lateral root of the median nerve and the musculocutaneous nerve. The posterior bundle gives rise to the axillary and radial nerves (tsvetn. Fig. 3).

The ulnar nerve (n. ulnaris) is genetically related to the spinal cord segments from C VII to Th I. Located closer to the medial surface of the shoulder and forearm. Approaching the hand, it gives off skin branches to its palmar and dorsal surfaces. It ends with superficial and deep branches that innervate all the muscles of the hand, with the exception of the abductor and opponens pollicis (m. adductor et opponens pollicis) and the superficial head of the short flexor pollicis (m. flexor pollicis brevis). In the forearm, this nerve innervates flexor ulnaris hands (m. flexor carpi ulnaris) and part of the deep flexor of the digitorum (m. flexor digitorum profundus).

The median nerve (n. medianus) comes from C V -Th I. On the shoulder it goes along with the brachial artery and crosses the ulnar fossa in the middle. On the forearm it innervates the anterior group of muscles, except for the muscles innervated by the ulnar nerve, and passes to the hand under the transverse ligament. Innervates the muscles of the hand, to which the ulnar nerve does not reach, as well as the skin of the palm.

The musculocutaneous nerve (n. musculocutaneus) comes from C V -C VIII, innervates the anterior group of muscles of the shoulder and ends as a cutaneous nerve of the lateral surface of the forearm (n. cutaneus antebrachii lateralis).

The radial nerve (n. radialis) comes from C V -C VIII. Along the brachiomuscular canal it reaches the elbow, where it divides into deep and superficial branches. Innervates m. triceps brachii and posterior group muscles of the forearm, as well as the skin of the dorsum of the shoulder, forearm and part of the hand.

The axillary nerve (n. axillaris) comes from C V -C VII. Its short and thick trunk goes through the quadrilateral foramen to the neck of the humerus, where it is divided into branches to the deltoid and teres minor muscles (m. deltoideus et teres minor) and to the lateral surface of the skin of the shoulder (color. Fig. 4).

The brachial plexus includes (through the gray connecting branches from the stellate and two upper thoracic sympathetic nodes) autonomic conductors, spreading along with somatic motor and sensory fibers along all branches of the brachial plexus.

Pathology of the brachial plexus - see Neuralgia, Neuritis, Plexitis.

Rice. 1. Nerves of the brachial plexus: 1 - fasc. lat. plexus brachialis; 2 - fasc. post, plexus brachialis; 3 - fasc med. plexus brachialis; 4 - n. radialis; 5 - n. medianus; 6 - n. cutaneus brachii med.; 7 - n. ulnaris; 8 - n. cutaneus antebrachii med.; 9 - r. superficialis n. ulnaris; 10 - r. profundus n. ulnaris; 11 - nn. digitales palmares proprii; 12 - nn. digitales dorsales; 13 - nn. digitales palmares communes; 14 - n. cutaneus antebrachii lat. 15 - 1. superficialis n. radialis; 16 -I. profundus n. radialis; 17 - n. cutaneus brachii lat.; 18 - a. axillaris 19 - n. musculocutaneus; 20 - nn. supraclaviculares.

Rice. 2 . Supraclavicular brachial plexus: 1 - n. phrenicus; 2-m. anterior n. thoracici I; 3 - n. thoracicus longus; 4 - n. thoracodorsalis; 5-n. intercostobrachialis 5 - n. medianus; 7 - n. cutaneus antebrachii med.; 8 - n. radialis; 9 - n. ulnaris; 10 -a. axillaris; 11-a. muscu locutaneus; 12 - n. suprascapularis; 13 - nn. supraclaviculares; 14 - plexus cervicalis.

Rice. 3 . Scheme of the structure of the brachial plexus: 1 - n. culaneus brachii med.; 2 - n. cutaneus antebrachii medialis; 3 - n. ulnaris; 4 - n. radialis; 5 - n. medianus; 6 - n. axillaris; 7 - n. musculocutaneus; 8 - fasciculus lat.; 9 - n. suprascapularis; 10 - fasciculus post.; 11 - n. thoracicus longus; 12 - fasciculus med.

Rice. 4. Projections of innervation segments onto the skin of the upper limb.

The brachial plexus (plexus brachialis) is formed from the anterior branches of the C5 Th1 spinal nerves (Fig. 8.3). The spinal nerves, from which the brachial plexus is formed, leave the spinal canal through the corresponding intervertebral foramina, passing between the anterior and posterior intertransverse muscles. The anterior branches of the spinal nerves, connecting with each other, first form 3 trunks (primary bundles) of the brachial plexus, which make up it Fig. 8.3. Brachial plexus. I - primary superior bundle; II - primary middle bundle; III - primary lower bundle; P - secondary posterior bundle; L—secondary outer bundle; M - secondary internal bundle; 1 - musculocutaneous nerve; 2 - axillary nerve; 3 - radial nerve; 4 - median nerve; 5 - ulnar nerve; 6 - internal cutaneous nerve; 7 - internal cutaneous nerve of the forearm. the supraclavicular part, each of which is connected by means of white connecting branches to the middle or lower cervical vegetative nodes. 1. The superior trunk arises from the connection of the anterior rami of the C5 and C6 spinal nerves. 2. The middle trunk is a continuation of the anterior branch of the C7 spinal nerve. 3. The lower trunk consists of the anterior branches of the C8, Th1 and Th2 spinal nerves. The trunks of the brachial plexus descend between the anterior and middle scalene muscles above and behind the subclavian artery and pass into the subclavian part of the brachial plexus, located in the area of ​​the subclavian and axillary fossae. At the subclavian level, each of the trunks (primary bundles) of the brachial plexus is divided into anterior and posterior branches, from which 3 bundles (secondary bundles) are formed, which make up the infraclavicular part of the brachial plexus and are named depending on their location relative to the axillary artery (a. axillaris), which they surround. 1. The posterior bundle is formed by the fusion of all three posterior branches of the trunks of the supraclavicular part of the plexus. The axillary and radial nerves begin from it. 2. The lateral bundle consists of the connected anterior branches of the upper and partially middle trunks (C5 C6I, C7). From this bundle originate the musculocutaneous nerve and part (external peduncle - C7) of the median nerve. 3. The medial bundle is a continuation of the anterior branch of the lower primary bundle; from it are formed the ulnar nerve, the cutaneous medial nerves of the shoulder and forearm, as well as part of the median nerve (internal leg - C8), which connects to the external leg (in front of the axillary artery), together they form a single trunk of the median nerve. The nerves formed in the brachial plexus belong to the nerves of the neck, shoulder girdle and arm. Nerves of the neck. The innervation of the neck involves short muscle branches (rr. musculares), innervating deep muscles: intertransverse muscles (t. intertrasversarif); the long neck muscle (longus colli), which tilts the head in its direction, and when both muscles contract, tilts it forward; anterior, middle and posterior scalene muscles (scaleni anterior, medius, posterior), which, with a fixed chest, tilt to their side cervical region the spine, and with bilateral contraction, tilt it forward; if the neck is fixed, then the scalene muscles, contracting, raise the 1st and 2nd ribs. Nerves of the shoulder girdle. The nerves of the brachial girdle begin from the supraclavicular part of the brachial plexus and are primarily motor in function. 1. The subclavian nerve (n. subclavius, C5-C6) innervates the subclavian muscle (m. subclavius), which, when contracted, moves the clavicle down and medially. 2. The anterior thoracic nerves (thoracales anteriores, C5-Th1) innervate the pectoralis major and minor muscles (pectorales major et minor). Contraction of the first of them causes adduction and internal rotation of the shoulder, contraction of the second causes the scapula to shift forward and downward. 3. The suprascapular nerve (n. suprascapular, C5-C6) innervates the supraspinatus and infraspinatus muscles (t. supraspinatus et t. infraspinatus); the first promotes abduction of the shoulder, the second rotates it outward. The sensory branches of this nerve innervate the shoulder joint. 4. The subscapular nerves (subscapulars, C5-C7) innervate the subscapularis muscle, which rotates the shoulder inward, and the teres major muscle, which rotates the shoulder inward (pronation), abducts it back and leads to the body. 5. Posterior nerves of the chest (nn, toracaies posteriores): the dorsal nerve of the scapula (n. dorsalis scapulae) and the long nerve of the chest (n. thoracalis longus, C5-C7) innervate the muscles, the contraction of which ensures the mobility of the scapula (i.e. levator scapulae, t. rhomboideus, m. serratus anterior). The last of them helps to raise the arm above the horizontal level. Damage to the posterior nerves of the chest leads to asymmetry of the shoulder blades. When moving the shoulder joint, winging of the scapula on the affected side is characteristic. 6. The thoracodorsal nerve (n. thoracodorsal, C7-C8) innervates the latissimus dorsi muscle, which brings the shoulder to the body, pulls it back to the midline and rotates it inward. Nerves of the hand. The nerves of the arm are formed from secondary bundles of the brachial plexus. The axillary and radial nerves are formed from the posterior longitudinal fascicle, and the musculocutaneous nerve and the external pedicle of the median nerve are formed from the external secondary fascicle; from the secondary internal bundle - the ulnar nerve, the internal leg of the median nerve and the medial cutaneous nerves of the shoulder and forearm. 1. Axillary nerve (n. axillaris, C5-C7) - mixed; innervates the deltoid muscle (i.e. deltoideus), which, when contracted, abducts the shoulder to a horizontal level and pulls it back or forward, as well as the teres minor muscle (i.e. teres minor), rotating the shoulder outward. The sensitive branch of the axillary nerve - the superior external cutaneous nerve of the shoulder (n. cutaneus brachii lateralis superior) - innervates the skin above the deltoid muscle, as well as the skin of the outer and partly posterior surface of the upper part of the shoulder (Fig. 8.4). When the axillary nerve is damaged, the arm hangs like a whip, and moving the shoulder forward or backward is impossible. 2. Radial nerve (n. radialis, C7 partly C6, C8, Th1) - mixed; but predominantly motor, innervates mainly the extensor muscles of the forearm - the triceps brachii muscle (triceps brachii) and the elbow muscle (apponens), extensors of the hand and fingers - long and short radial extensor carpi (t. extensor carpi radialis longus et brevis) and extensor digitorum (i.e. extensor digitorum), supinator of the forearm (t. supinator), brachioradialis muscle (t. brachioradialis), which takes part in flexion and pronation of the forearm, as well as muscles that abduct the thumb (t. abductor pollicis longus et brevis), short and long extensors thumb (t. extensor pollicis brevis et longus), extensor of the index finger (t. extensor indicis). Sensitive fibers of the radial nerve make up the posterior cutaneous branch of the shoulder (p. cutaneus brachii posteriores), which provides sensitivity to the posterior surface of the shoulder; the lower lateral cutaneous nerve of the shoulder (n. cutaneus brachii lateralis inferior), innervating the skin of the lower outer part of the shoulder, and the posterior cutaneous nerve of the forearm (n. cutaneus antebrachii posterior), which determines the sensitivity of the posterior surface of the forearm, as well as superficial branch(ramus superficialis), involved in the innervation of the dorsum of the hand, as well as the posterior surface of the I, II and half of the III fingers (Fig. 8.4, Fig. 8.5). Rice. 8.4. Innervation of the skin of the surface of the hand (a - dorsal, b - ventral). I - axillary nerve (its branch is the external cutaneous nerve of the shoulder); 2 - radial nerve (posterior cutaneous nerve of the shoulder and posterior cutaneous nerve of the forearm); 3 - musculocutaneous nerve (external cutaneous nerve of the forearm); 4 - internal cutaneous nerve of the forearm; 5 - internal cutaneous nerve of the shoulder; 6 - supraclavicular nerves. Rice. 8.5. Innervation of the skin of the hand. 1 - radial nerve, 2 - median nerve; 3 - ulnar nerve; 4 - external nerve of the forearm (branch of the musculocutaneous nerve); 5 - internal cutaneous nerve of the forearm. Rice. 8.6. Drooping hand due to damage to the radial nerve. Rice. 8.7. Palm and finger spread test for lesions of the right radial nerve. On the affected side, the bent fingers “slide” along the palm of the healthy hand. A characteristic sign of damage to the radial nerve is a drooping hand in a pronated position (Fig. 8.6). Due to paresis or paralysis of the corresponding muscles, extension of the hand, fingers and thumb, as well as supination of the hand with the extended forearm are impossible; the carporadial periosteal reflex is reduced or not evoked. In the case of high damage to the radial nerve, the extension of the forearm is also impaired due to paralysis of the triceps brachii muscle, while the tendon reflex from the triceps brachii muscle is not evoked. If you put your palms next to each other and then try to separate them, then on the side of the radial nerve lesion the fingers do not straighten, sliding along the palmar surface of the healthy hand (Fig. 8.7). The radial nerve is very vulnerable; in terms of the frequency of traumatic lesions, it ranks first among all peripheral nerves. Damage to the radial nerve occurs especially often with fractures of the shoulder. Often the cause of damage to the radial nerve is also infection or intoxication, including chronic alcohol intoxication. 3. Musculocutaneous nerve (n. musculocutaneus, C5-C6) - mixed; motor fibers innervate the biceps brachii muscle, which flexes the arm at the elbow joint and supinates the bent forearm, as well as brachialis muscle(t. brachialis)y involved in flexion of the forearm, and the coracobrachial muscle (t. coracobrachial^^ promoting the elevation of the shoulder anteriorly. Sensitive fibers of the musculocutaneous nerve form its branch - the external cutaneous nerve of the forearm (n. cutaneus antebrachii lateralis), providing sensitivity of the skin of the radial side of the forearm up to the eminence of the thumb. When the musculocutaneous nerve is damaged, the flexion of the forearm is impaired. This is especially evident with a supinated forearm, since flexion of the pronated forearm is possible due to the brachioradialis muscle innervated by the radial nerve. also loss of the tendon reflex from the biceps brachii muscle, raising the shoulder anteriorly. Sensitivity disorder can be detected on the outer side of the forearm (Fig. 8.4. Median nerve (p. medianus) - mixed; formed from part of the fibers of the medial and lateral bundle). brachial plexus. At the level of the shoulder, the median nerve does not give branches. The muscular branches (rami musculares) extending from it to the forearm and hand innervate the pronator teres (i.e. pronator teres), pronating the forearm and promoting its flexion. Flexor radialis wrist (i.e. flexor carpi radialis), along with flexion of the wrist, retracts the hand to the radial side and participates in flexion of the forearm. The palmaris longus muscle stretches the palmar aponeurosis and is involved in flexion of the hand and forearm. The superficial flexor of the fingers (t. digitorum superficialis) bends the middle phalanges of the II-V fingers and participates in flexion of the hand. In the upper third of the forearm, the palmar branch of the median nerve (ramus palmaris n. mediant) departs from the median nerve. It passes in front of the interosseous septum between the flexor pollicis longus and the flexor digitorum profundus and innervates flexor longus thumb (i.e. flexor pollicis longus), flexing the nail phalanx of the thumb; part of the deep flexor of the fingers (i.e. flexor digitorum profundus), which flexes the nail and middle phalanges of the II-III fingers and the hand; square pronator (pronator quadratus), pronating the forearm and hand. At the level of the wrist, the median nerve is divided into 3 common palmar digital nerves (digitaks palmares communes) and the own palmar digital nerves extending from them (digitaks palmares proprii). They innervate the abductor pollicis brevis muscle, the opponens policis muscle, the flexor pollicis brevis muscle and the I-11 lumbrical muscles. (mm. lumbricales). Sensitive fibers of the median nerve innervate the skin in the area of ​​the wrist joint (its anterior surface), the eminence of the thumb (thenar), I, I, III fingers and the radial side of the IV finger, as well as the dorsal surface of the middle and distal phalanges of the II and III fingers ( Fig. 8.5). Damage to the median nerve is characterized by a violation of the ability to oppose the thumb to the rest, while the muscles of the eminence of the thumb atrophy over time. The thumb in such cases ends up in the same plane as the rest. As a result, the palm takes on the typical shape of the median nerve lesion, known as the “monkey hand” (Fig. 8.8a). If the median nerve is affected at the level of the shoulder, a disorder occurs in all functions depending on its condition. To identify impaired functions of the median nerve, the following tests can be performed: a) when trying to clench the hand into a fist, fingers I, II and partly III remain straightened (Fig. 8.86); if the palm is pressed to the table, then the scratching movement with the nail of the index finger is not possible; c) to hold a strip of paper between the thumb and index finger due to the inability to bend the thumb, the patient brings the straightened thumb to the index finger - thumb test. Due to the fact that the median nerve contains a large number of autonomic fibers, when it is damaged, trophic disorders are usually pronounced and more often than when any other nerve is damaged, causalgia develops, manifested in the form of a sharp, burning, diffuse pain. Rice. 8.8. Damage to the median nerve. a - “monkey hand”; b - when the hand is clenched into a fist, fingers I and II do not bend. 5. Ulnar nerve (n. ulnaris, C8-Th1) - mixed; it begins in the axillary fossa from the medial fascicle of the brachial plexus, descends parallel to the axillary, and then brachial artery and goes to the internal condyle of the humerus and at the level of the distal part of the shoulder passes along the groove of the ulnar nerve (sulcus nervi ulnaris). In the upper third of the forearm, branches extend from the ulnar nerve to the following muscles: flexor carpi ulnaris, flexor carpi ulnaris, flexor and adductor muscles; the medial part of the deep flexor of the fingers (i.e. flexor digitorum profundus), which flexes the nail phalanx of the IV and V fingers. In the middle third of the forearm, the cutaneous palmar branch (ramus cutaneus palmaris) departs from the ulnar nerve, innervating the skin of the medial side of the palm in the area of ​​the eminence of the little finger (hypothenar). At the border between the middle and lower third of the forearm, the dorsal branch of the hand (ramus dorsalis manus) and the palmar branch of the hand (ramus volaris manus) are separated from the ulnar nerve. The first of these branches is sensitive, it goes to the back of the hand, where it branches into the dorsal nerves of the fingers (digitales dorsales), which end in the skin of the dorsal surface of the V and IV fingers and the ulnar side of the III finger, while the nerve of the V finger reaches its nail phalanx , and the rest reach only the middle phalanges. The second branch is mixed; its motor part is directed to the palmar surface of the hand and at the level of the pisiform bone is divided into superficial and deep branches. The superficial branch innervates the short palmaris muscle, which pulls the skin to the palmar aponeurosis; it is later divided into common and proper palmar digital nerves (digitales pa/mares communis et proprii). The common digital nerve innervates the palmar surface of the fourth finger and the medial side of its middle and terminal phalanges, as well as the dorsum of the nail phalanx of the fifth finger. The deep branch penetrates deep into the palm, goes to the radial side of the hand and innervates the following muscles: the adductor policis muscle, the adductor digiti minim f, the flexor phalanx of the fifth finger, the muscle , opposing the V finger (i.e. opponens digiti minimi) - it brings the little finger to the midline of the hand and opposes it; deep head of the short flexor pollicis brevis (flexor pollicis brevis); vermiform muscles (tm. lumbricales), muscles that flex the main and extend the middle and nail phalanges of the II and IV fingers; palmar and dorsal interosseous muscles (t. interossei palmales et dorsales), flexing the main phalanges and simultaneously extending the other phalanges of the II-V fingers, as well as abductor II and IV fingers from the middle (III) finger and adductor II, IV and V fingers to the average. Sensitive fibers of the ulnar nerve innervate the skin of the ulnar edge of the hand, the dorsum of the fifth and partly fourth fingers, and the palmar surface of the fifth, fourth and partly third fingers (Fig. 8.4, 8.5). In cases of damage to the ulnar nerve, due to developing atrophy of the interosseous muscles, as well as hyperextension of the main and flexion of the remaining phalanges of the fingers, a claw-shaped hand is formed, reminiscent of a bird's paw (Fig. 8.9a). To identify signs of damage to the ulnar nerve, the following tests can be performed: a) when trying to clench the hand into a fist, fingers V, IV and partly III are not bent enough (Fig. 8.96); b) scratching movements with the nail of the little finger with the palm pressed tightly to the table are not successful; c) if the palm lies on the table, then spreading and bringing the fingers together fails; d) the patient cannot hold a strip of paper between the index finger and straightened thumb. To hold it, the patient needs to sharply bend the terminal phalanx of the thumb (Fig. 8.10). 6. Cutaneous internal nerve of the shoulder (n. cutaneus brachii medialis, C8-Th1 - sensitive, originates from the medial fascicle of the brachial plexus, at the level of the axillary fossa has connections with the external cutaneous branches (rr. cutani laterales) of the II and III thoracic nerves ( pp. thoracales) and innervates the skin of the medial surface of the shoulder to the elbow joint (Fig. 8.4. Signs of damage to the ulnar nerve: claw-shaped hand (a), when the hand is clenched into a fist, the fifth and fourth fingers do not bend (b) 8.10. Thumb test: In the right hand, pressing a strip of paper is possible only with a straightened one. thumb due to its adductor muscle, innervated by the ulnar nerve (a sign of damage to the median nerve). On the left, pressing a strip of paper is carried out due to the innervation of the median nerve longus muscle flexing the thumb (a sign of damage to the ulnar nerve). 7. Cutaneous internal nerve of the forearm (n. cutaneus antebrachii medialis, C8-7h2) - sensitive, arises from the medial bundle of the brachial plexus, is located in the axillary fossa next to the ulnar nerve, descends along the shoulder in the medial groove of its biceps muscle, innervates the skin of the internal the lower surface of the forearm (Fig. 8.4). Brachial plexus lesion syndromes. Along with isolated damage to individual nerves emerging from the brachial plexus, damage to the plexus itself is possible. Damage to the plexus is called plexopathy. The etiological factors of damage to the brachial plexus are gunshot wounds of the supra- and subclavian areas, fracture of the clavicle, first rib, periostitis of the first rib, dislocation of the humerus. Sometimes the plexus is affected due to its overstretching, when the arm is quickly and strongly pulled back. Damage to the plexus is also possible in a position where the head is turned in the opposite direction and the hand is placed behind the head. Brachial plexopathy can be observed in newborns due to traumatic injury during complicated childbirth. Damage to the brachial plexus can also be caused by carrying heavy weights on the shoulders or on the back, especially with general intoxication with alcohol, lead, etc. Compression of the plexus can be caused by an aneurysm of the subclavian artery, additional cervical ribs, hematomas, abscesses and tumors of the supra- and subclavian region. Total brachial plexopathy leads to flaccid paralysis of all muscles of the shoulder girdle and arm, while only the ability to “raise the shoulder girdle” may be preserved due to the preserved function of the trapezius muscle, innervated by the accessory cranial nerve and the posterior branches of the cervical and thoracic nerves. In accordance with the anatomical structure of the brachial plexus, there are different syndromes of damage to its trunks (primary bundles) and bundles (secondary bundles). Syndromes of damage to the trunks (primary bundles) of the brachial plexus occur when the supraclavicular part is damaged, and syndromes of damage to the upper, middle and lower trunks can be distinguished. I. Syndrome of damage to the upper trunk of the brachial plexus (the so-called upper brachial plexopathy of Erb-Duchenne>

The brachial plexus (plexus brachialis) is formed from the anterior branches of the C5 Th1 spinal nerves (Fig. 8.3). The spinal nerves, from which the brachial plexus is formed, leave the spinal canal through the corresponding intervertebral foramina, passing between the anterior and posterior intertransverse muscles. The anterior branches of the spinal nerves, connecting with each other, first form 3 trunks (primary bundles) of the brachial plexus, which make up it Fig. 8.3. Brachial plexus. I - primary superior bundle; II - primary middle bundle; III - primary lower bundle; P - secondary posterior bundle; L—secondary outer bundle; M - secondary internal bundle; 1 - musculocutaneous nerve; 2 - axillary nerve; 3 - radial nerve; 4 - median nerve; 5 - ulnar nerve; 6 - internal cutaneous nerve; 7 - internal cutaneous nerve of the forearm. the supraclavicular part, each of which is connected by means of white connecting branches to the middle or lower cervical vegetative nodes. 1. The superior trunk arises from the connection of the anterior rami of the C5 and C6 spinal nerves. 2. The middle trunk is a continuation of the anterior branch of the C7 spinal nerve. 3. The lower trunk consists of the anterior branches of the C8, Th1 and Th2 spinal nerves. The trunks of the brachial plexus descend between the anterior and middle scalene muscles above and behind the subclavian artery and pass into the subclavian part of the brachial plexus, located in the area of ​​the subclavian and axillary fossae. At the subclavian level, each of the trunks (primary bundles) of the brachial plexus is divided into anterior and posterior branches, from which 3 bundles (secondary bundles) are formed, which make up the infraclavicular part of the brachial plexus and are named depending on their location relative to the axillary artery (a. axillaris), which they surround. 1. The posterior bundle is formed by the fusion of all three posterior branches of the trunks of the supraclavicular part of the plexus. The axillary and radial nerves begin from it. 2. The lateral bundle consists of the connected anterior branches of the upper and partially middle trunks (C5 C6I, C7). From this bundle originate the musculocutaneous nerve and part (external peduncle - C7) of the median nerve. 3. The medial bundle is a continuation of the anterior branch of the lower primary bundle; from it are formed the ulnar nerve, the cutaneous medial nerves of the shoulder and forearm, as well as part of the median nerve (internal leg - C8), which connects to the external leg (in front of the axillary artery), together they form a single trunk of the median nerve. The nerves formed in the brachial plexus belong to the nerves of the neck, shoulder girdle and arm. Nerves of the neck. Short muscle branches (rr. musculares) that innervate deep muscles participate in the innervation of the neck: intertransverse muscles (t. intertrasversarif); the long neck muscle (longus colli), which tilts the head in its direction, and when both muscles contract, tilts it forward; anterior, middle and posterior scalene muscles (t. scaleni anterior, medius, posterior), which, with a fixed chest, tilt the cervical spine to their side, and with bilateral contraction, tilt it forward; if the neck is fixed, then the scalene muscles, contracting, raise the 1st and 2nd ribs. Nerves of the shoulder girdle. The nerves of the brachial girdle begin from the supraclavicular part of the brachial plexus and are primarily motor in function. 1. The subclavian nerve (n. subclavius, C5-C6) innervates the subclavian muscle (m. subclavius), which, when contracted, moves the clavicle down and medially. 2. The anterior thoracic nerves (thoracales anteriores, C5-Th1) innervate the pectoralis major and minor muscles (pectorales major et minor). Contraction of the first of them causes adduction and internal rotation of the shoulder, contraction of the second causes the scapula to shift forward and downward. 3. The suprascapular nerve (n. suprascapular, C5-C6) innervates the supraspinatus and infraspinatus muscles (t. supraspinatus et t. infraspinatus); the first promotes abduction of the shoulder, the second rotates it outward. The sensory branches of this nerve innervate the shoulder joint. 4. The subscapular nerves (subscapulars, C5-C7) innervate the subscapularis muscle, which rotates the shoulder inward, and the teres major muscle, which rotates the shoulder inward (pronation), abducts it back and leads to the body. 5. Posterior nerves of the chest (nn, toracaies posteriores): the dorsal nerve of the scapula (n. dorsalis scapulae) and the long nerve of the chest (n. thoracalis longus, C5-C7) innervate the muscles, the contraction of which ensures the mobility of the scapula (i.e. levator scapulae, t. rhomboideus, m. serratus anterior). The last of them helps to raise the arm above the horizontal level. Damage to the posterior nerves of the chest leads to asymmetry of the shoulder blades. When moving the shoulder joint, winging of the scapula on the affected side is characteristic. 6. The thoracodorsal nerve (n. thoracodorsal, C7-C8) innervates the latissimus dorsi muscle, which brings the shoulder to the body, pulls it back to the midline and rotates it inward. Nerves of the hand. The nerves of the arm are formed from secondary bundles of the brachial plexus. The axillary and radial nerves are formed from the posterior longitudinal fascicle, and the musculocutaneous nerve and the external pedicle of the median nerve are formed from the external secondary fascicle; from the secondary internal bundle - the ulnar nerve, the internal leg of the median nerve and the medial cutaneous nerves of the shoulder and forearm. 1. Axillary nerve (n. axillaris, C5-C7) - mixed; innervates the deltoid muscle (t. deltoideus), which, when contracted, retracts the shoulder to a horizontal level and pulls it back or forward, as well as the teres minor muscle (t. teres minor), which rotates the shoulder outward. The sensitive branch of the axillary nerve - the superior external cutaneous nerve of the shoulder (n. cutaneus brachii lateralis superior) - innervates the skin above the deltoid muscle, as well as the skin of the outer and partly posterior surface of the upper part of the shoulder (Fig. 8.4). When the axillary nerve is damaged, the arm hangs like a whip, and moving the shoulder forward or backward is impossible. 2. Radial nerve (n. radialis, C7 partly C6, C8, Th1) - mixed; but predominantly motor, innervates mainly the extensor muscles of the forearm - the triceps brachii muscle (triceps brachii) and the elbow muscle (apponens), extensors of the hand and fingers - long and short radial extensor carpi (t. extensor carpi radialis longus et brevis) and the extensor digitorum (extensor digitorum), the supinator of the forearm (supinator), the brachioradialis muscle (brachioradialis), which is involved in flexion and pronation of the forearm, as well as the muscles that encircle the thumb ( tt. abductor pollicis longus et brevis), short and long extensor of the thumb (t. extensor pollicis brevis et longus), extensor of the index finger (t. extensor indicis). Sensitive fibers of the radial nerve make up the posterior cutaneous branch of the shoulder (p. cutaneus brachii posteriores), which provides sensitivity to the posterior surface of the shoulder; the lower lateral cutaneous nerve of the shoulder (n. cutaneus brachii lateralis inferior), innervating the skin of the lower outer part of the shoulder, and the posterior cutaneous nerve of the forearm (n. cutaneus antebrachii posterior), which determines the sensitivity of the posterior surface of the forearm, as well as the superficial branch (ramus superficialis) , participating in the innervation of the dorsum of the hand, as well as the posterior surface of the I, II and half of the III fingers (Fig. 8.4, Fig. 8.5). Rice. 8.4. Innervation of the skin of the surface of the hand (a - dorsal, b - ventral). I - axillary nerve (its branch is the external cutaneous nerve of the shoulder); 2 - radial nerve (posterior cutaneous nerve of the shoulder and posterior cutaneous nerve of the forearm); 3 - musculocutaneous nerve (external cutaneous nerve of the forearm); 4 - internal cutaneous nerve of the forearm; 5 - internal cutaneous nerve of the shoulder; 6 - supraclavicular nerves. Rice. 8.5. Innervation of the skin of the hand. 1 - radial nerve, 2 - median nerve; 3 - ulnar nerve; 4 - external nerve of the forearm (branch of the musculocutaneous nerve); 5 - internal cutaneous nerve of the forearm. Rice. 8.6. Drooping hand due to damage to the radial nerve. Rice. 8.7. Palm and finger spread test for lesions of the right radial nerve. On the affected side, the bent fingers “slide” along the palm of the healthy hand. A characteristic sign of damage to the radial nerve is a drooping hand in a pronated position (Fig. 8.6). Due to paresis or paralysis of the corresponding muscles, extension of the hand, fingers and thumb, as well as supination of the hand with the extended forearm are impossible; the carporadial periosteal reflex is reduced or not evoked. In the case of high damage to the radial nerve, the extension of the forearm is also impaired due to paralysis of the triceps brachii muscle, while the tendon reflex from the triceps brachii muscle is not evoked. If you put your palms next to each other and then try to separate them, then on the side of the radial nerve lesion the fingers do not straighten, sliding along the palmar surface of the healthy hand (Fig. 8.7). The radial nerve is very vulnerable; in terms of the frequency of traumatic lesions, it ranks first among all peripheral nerves. Damage to the radial nerve occurs especially often with fractures of the shoulder. Often the cause of damage to the radial nerve is also infection or intoxication, including chronic alcohol intoxication. 3. Musculocutaneous nerve (n. musculocutaneus, C5-C6) - mixed; motor fibers innervate the biceps brachii muscle, which flexes the arm at the elbow joint and supinates the bent forearm, as well as the brachialis muscle, which is involved in flexing the forearm, and the coracobrachial muscle, which promotes raising the shoulder anteriorly. Sensitive fibers of the musculocutaneous nerve form its branch - the external cutaneous nerve of the forearm (n. cutaneus antebrachii lateralis), which provides sensitivity to the skin of the radial side of the forearm up to the elevation of the thumb. When the musculocutaneous nerve is damaged, flexion of the forearm is impaired. is detected especially clearly with a supinated forearm, since flexion of the pronated forearm is possible due to the brachioradialis muscle innervated by the radial nerve (the so-called brachioradialis). Loss of the tendon reflex from the biceps brachii muscle is also characteristic, raising the shoulder anteriorly. Sensitivity disorder can be detected on the outer side. forearms (Fig. 8.4). 4. Median nerve (p. medianus) - mixed; formed from part of the fibers of the medial and lateral bundle of the brachial plexus. At the level of the shoulder, the median nerve does not give branches. The muscular branches (rami musculares) extending from it to the forearm and hand innervate the pronator teres (pronator teres), which pronates the forearm and promotes its flexion. The radial flexor carpi radialis (flexor carpi radialis), along with flexion of the wrist, retracts the hand to the radial side and participates in flexion of the forearm. The palmaris longus muscle stretches the palmar aponeurosis and is involved in flexion of the hand and forearm. The superficial flexor of the fingers (t. digitorum superficialis) bends the middle phalanges of the II-V fingers and participates in flexion of the hand. In the upper third of the forearm, the palmar branch of the median nerve (ramus palmaris n. mediant) departs from the median nerve. It passes in front of the interosseous septum between the long flexor pollicis and the deep flexor of the fingers and innervates the long flexor pollicis longus, which flexes the nail phalanx of the thumb; part of the deep flexor of the fingers (i.e. flexor digitorum profundus), which flexes the nail and middle phalanges of the II-III fingers and the hand; square pronator (pronator quadratus), pronating the forearm and hand. At the level of the wrist, the median nerve is divided into 3 common palmar digital nerves (digitaks palmares communes) and the own palmar digital nerves extending from them (digitaks palmares proprii). They innervate the abductor pollicis brevis muscle, the opponens policis muscle, the flexor pollicis brevis muscle and the I-11 lumbrical muscles. (mm. lumbricales). Sensitive fibers of the median nerve innervate the skin in the area of ​​the wrist joint (its anterior surface), the eminence of the thumb (thenar), I, I, III fingers and the radial side of the IV finger, as well as the dorsal surface of the middle and distal phalanges of the II and III fingers ( Fig. 8.5). Damage to the median nerve is characterized by a violation of the ability to oppose the thumb to the rest, while the muscles of the eminence of the thumb atrophy over time. The thumb in such cases ends up in the same plane as the rest. As a result, the palm takes on the typical shape of the median nerve lesion, known as the “monkey hand” (Fig. 8.8a). If the median nerve is affected at the level of the shoulder, a disorder occurs in all functions depending on its condition. To identify impaired functions of the median nerve, the following tests can be performed: a) when trying to clench the hand into a fist, fingers I, II and partly III remain straightened (Fig. 8.86); if the palm is pressed to the table, then the scratching movement with the nail of the index finger is not possible; c) to hold a strip of paper between the thumb and index finger due to the inability to bend the thumb, the patient brings the straightened thumb to the index finger - thumb test. Due to the fact that the median nerve contains a large number of autonomic fibers, when it is damaged, trophic disorders are usually pronounced and more often than when any other nerve is damaged, causalgia develops, manifested in the form of a sharp, burning, diffuse pain. Rice. 8.8. Damage to the median nerve. a - “monkey hand”; b - when the hand is clenched into a fist, fingers I and II do not bend. 5. Ulnar nerve (n. ulnaris, C8-Th1) - mixed; it begins in the axillary fossa from the medial bundle of the brachial plexus, descends parallel to the axillary and then the brachial artery and goes to the internal condyle of the humerus and at the level of the distal part of the shoulder passes along the groove of the ulnar nerve (sulcus nervi ulnaris). In the upper third of the forearm, branches extend from the ulnar nerve to the following muscles: flexor carpi ulnaris, flexor carpi ulnaris, flexor and adductor muscles; the medial part of the deep flexor of the fingers (i.e. flexor digitorum profundus), which flexes the nail phalanx of the IV and V fingers. In the middle third of the forearm, the cutaneous palmar branch (ramus cutaneus palmaris) departs from the ulnar nerve, innervating the skin of the medial side of the palm in the area of ​​the eminence of the little finger (hypothenar). At the border between the middle and lower third of the forearm, the dorsal branch of the hand (ramus dorsalis manus) and the palmar branch of the hand (ramus volaris manus) are separated from the ulnar nerve. The first of these branches is sensitive, it goes to the back of the hand, where it branches into the dorsal nerves of the fingers (digitales dorsales), which end in the skin of the dorsal surface of the V and IV fingers and the ulnar side of the III finger, while the nerve of the V finger reaches its nail phalanx , and the rest reach only the middle phalanges. The second branch is mixed; its motor part is directed to the palmar surface of the hand and at the level of the pisiform bone is divided into superficial and deep branches. The superficial branch innervates the short palmaris muscle, which pulls the skin to the palmar aponeurosis; it is later divided into common and proper palmar digital nerves (pp. digitales pa/mares communis et proprii). The common digital nerve innervates the palmar surface of the fourth finger and the medial side of its middle and terminal phalanges, as well as the dorsum of the nail phalanx of the fifth finger. The deep branch penetrates deep into the palm, goes to the radial side of the hand and innervates the following muscles: the adductor policis muscle, the adductor digiti minim f, the flexor phalanx of the fifth finger, the muscle , opposing the V finger (i.e. opponens digiti minimi) - it brings the little finger to the midline of the hand and opposes it; deep head of the short flexor pollicis brevis (flexor pollicis brevis); vermiform muscles (tm. lumbricales), muscles that flex the main and extend the middle and nail phalanges of the II and IV fingers; palmar and dorsal interosseous muscles (t. interossei palmales et dorsales), flexing the main phalanges and simultaneously extending the other phalanges of the II-V fingers, as well as abductor II and IV fingers from the middle (III) finger and adductor II, IV and V fingers to the average. Sensitive fibers of the ulnar nerve innervate the skin of the ulnar edge of the hand, the dorsum of the fifth and partly fourth fingers, and the palmar surface of the fifth, fourth and partly third fingers (Fig. 8.4, 8.5). In cases of damage to the ulnar nerve, due to developing atrophy of the interosseous muscles, as well as hyperextension of the main and flexion of the remaining phalanges of the fingers, a claw-shaped hand is formed, reminiscent of a bird's paw (Fig. 8.9a). To identify signs of damage to the ulnar nerve, the following tests can be performed: a) when trying to clench the hand into a fist, fingers V, IV and partly III are not bent enough (Fig. 8.96); b) scratching movements with the nail of the little finger with the palm pressed tightly to the table are not successful; c) if the palm lies on the table, then spreading and bringing the fingers together fails; d) the patient cannot hold a strip of paper between the index finger and straightened thumb. To hold it, the patient needs to sharply bend the terminal phalanx of the thumb (Fig. 8.10). 6. Cutaneous internal nerve of the shoulder (n. cutaneus brachii medialis, C8-Th1 - sensitive, originates from the medial fascicle of the brachial plexus, at the level of the axillary fossa has connections with the external cutaneous branches (rr. cutani laterales) of the II and III thoracic nerves ( pp. thoracales) and innervates the skin of the medial surface of the shoulder to the elbow joint (Fig. 8.4. Signs of damage to the ulnar nerve: claw-shaped hand (a), when the hand is clenched into a fist, the fifth and fourth fingers do not bend (b) . Rns. 8.10. Thumb test. In the right hand, pressing a strip of paper is only possible with a straightened thumb due to its adductor muscle, innervated by the ulnar nerve (a sign of damage to the median nerve). On the left, pressing the strip of paper is carried out due to the long muscle flexor of the thumb innervated by the median nerve (a sign of damage to the ulnar nerve). 7. Cutaneous internal nerve of the forearm (n. cutaneus antebrachii medialis, C8-7h2) - sensitive, arises from the medial bundle of the brachial plexus, is located in the axillary fossa next to the ulnar nerve, descends along the shoulder in the medial groove of its biceps muscle, innervates the skin of the internal the lower surface of the forearm (Fig. 8.4). Brachial plexus lesion syndromes. Along with isolated damage to individual nerves emerging from the brachial plexus, damage to the plexus itself is possible. Damage to the plexus is called plexopathy. The etiological factors of damage to the brachial plexus are gunshot wounds of the supra- and subclavian areas, fracture of the clavicle, first rib, periostitis of the first rib, dislocation of the humerus. Sometimes the plexus is affected due to its overstretching, when the arm is quickly and strongly pulled back. Damage to the plexus is also possible in a position where the head is turned in the opposite direction and the hand is placed behind the head. Brachial plexopathy can be observed in newborns due to traumatic injury during complicated childbirth. Damage to the brachial plexus can also be caused by carrying heavy weights on the shoulders or on the back, especially with general intoxication with alcohol, lead, etc. Compression of the plexus can be caused by an aneurysm of the subclavian artery, additional cervical ribs, hematomas, abscesses and tumors of the supra- and subclavian region. Total brachial plexopathy leads to flaccid paralysis of all muscles of the shoulder girdle and arm, while only the ability to “raise the shoulder girdle” may be preserved due to the preserved function of the trapezius muscle, innervated by the accessory cranial nerve and the posterior branches of the cervical and thoracic nerves. In accordance with the anatomical structure of the brachial plexus, there are different syndromes of damage to its trunks (primary bundles) and bundles (secondary bundles). Syndromes of damage to the trunks (primary bundles) of the brachial plexus occur when the supraclavicular part is damaged, and syndromes of damage to the upper, middle and lower trunks can be distinguished. I. Syndrome of damage to the upper trunk of the brachial plexus (the so-called upper brachial plexopathy Erb-Duchenne> occurs when there is damage (usually traumatic) to the anterior branches of the V and VI cervical spinal nerves or the part of the plexus in which these nerves connect, forming after passing between the scalene muscles of the upper trunk. This place is located 2-4 cm above the collarbone, approximately a finger's width behind the sternocleidomastoid muscle and is called Erb's supraclavicular point. Erb-Duchenne superior brachial plexopathy is characterized by a combination of signs of damage to the axillary nerve, long thoracic nerve, anterior thoracic nerves, subscapular nerve, dorsal scapular nerve, musculocutaneous and part of the radial nerve. Characterized by paralysis of the muscles of the shoulder girdle and proximal parts of the arm (deltoid, biceps, brachialis, brachioradialis and supinator muscles), shoulder abduction, flexion and supination of the forearm are impaired. As a result, the arm hangs like a whip, is adducted and pronated, the patient cannot raise his arm or bring his hand to his mouth. If you passively supinate your arm, it will immediately turn inward again. The reflex from the biceps muscle and the wrist (carporadial) reflex are not evoked, and radicular type hypalgesia usually occurs on the outer side of the shoulder and forearm in the Cv-CVI dermatome zone. Palpation reveals pain in the area of ​​Erb's supraclavicular point. A few weeks after the plexus is damaged, increasing wasting of the paralyzed muscles appears. Erb-Duchenne brachial plexopathy most often occurs due to injuries, it is possible, in particular, when falling on an outstretched arm, it may be a consequence of compression of the plexus during a long stay with the arms placed under the head. Sometimes it appears in newborns during pathological births. 2. Syndrome of lesion of the middle trunk of the brachial plexus occurs when the anterior branch of the VII cervical spinal nerve is damaged. In this case, violations of the extension of the shoulder, hand and fingers are characteristic. However, the triceps brachii muscle, the extensor pollicis muscle and the abductor pollicis longus muscle are not completely affected, since, along with the fibers of the VII cervical spinal nerve, fibers that enter the plexus along the anterior branches of V and VI also participate in their innervation cervical spinal nerves. This circumstance is an important sign in the differential diagnosis of the syndrome of damage to the middle trunk of the brachial plexus and selective damage to the radial nerve. The reflex from the triceps tendon and the radiocarpal (carpo-radial) reflex are not evoked. Sensory disturbances are limited to a narrow strip of hypalgesia on the dorsum of the forearm and the radial part of the dorsum of the hand. 3. Syndrome of damage to the lower trunk of the brachial plexus (inferior brachial plexopathy Dejerine-Klumpke) occurs when nerve fibers entering the plexus along the VIII cervical and I thoracic spinal nerves are damaged, with signs of damage to the ulnar nerve and cutaneous internal nerves of the shoulder and forearm, and also parts of the median nerve (its internal peduncle). In this regard, with Dejerine-Klyumke paralysis, paralysis or paresis of the muscles occurs, mainly in the distal part of the arm. It affects mainly the ulnar part of the forearm and hand, where sensory disturbances and vasomotor disorders are detected. Extension and abduction of the thumb are impossible or difficult due to paresis of the short extensor pollicis and the abductor pollicis muscle, innervated by the radial nerve, since the impulses going to these muscles pass through the fibers that make up the VIII cervical and I thoracic spinal cord. cerebral nerves and the lower trunk of the brachial plexus. Sensation in the arm is impaired on the medial side of the shoulder, forearm and hand. If, simultaneously with damage to the brachial plexus, the white connecting branches leading to the stellate ganglion (ganglion stellatum) also suffer, then manifestations of Horner’s syndrome are possible (narrowing of the pupil, palpebral fissure and mild enophthalmos. In contrast to the combined paralysis of the median and ulnar nerves, The function of the muscles innervated by the external leg of the median nerve is preserved in the syndrome of the lower trunk of the brachial plexus. Dejerine-Klumke palsy most often occurs due to traumatic damage to the brachial plexus, but it can also be a consequence of compression by the cervical rib or Pancoast tumor. Syndromes of lesions of the bundles (secondary bundles). brachial plexus occur during pathological processes and injuries in the subclavian region and, in turn, are divided into lateral, medial and posterior bundle syndromes. These syndromes practically correspond to the clinical picture of combined lesions of peripheral nerves formed from the corresponding bundles of the brachial plexus. bundle is manifested by dysfunction of the musculocutaneous nerve and the upper leg of the median nerve, posterior bundle syndrome is characterized by dysfunction of the axillary and radial nerve, and medial bundle syndrome is expressed by dysfunction of the ulnar nerve, medial leg of the median nerve, medial cutaneous nerves shoulder and forearm. When two or three (all) bundles of the brachial plexus are affected, a corresponding summation of clinical signs occurs, characteristic of syndromes in which individual bundles are affected.