Radial artery, veins and superficial branch of the radial nerve. Anatomy of the radial nerve and treatment of lesions Topographic anatomy of the radial nerve on the forearm

The radial nerve is formed from the posterior bundle of the brachial plexus and is a derivative of the ventral branches of the CV - CVIII spinal nerves. The nerve descends along the posterior wall of the axilla, located behind the axillary artery and located sequentially on the belly of the subscapularis muscle and on the tendons latissimus muscle back and teres major muscle. Having reached the brachiomuscular angle between the inner part of the shoulder and the lower edge of the posterior wall of the axilla, the radial nerve is adjacent to a dense connective tissue band formed by the connection of the lower edge of the latissimus dorsi muscle and the posterior tendon of the long head of the triceps brachii muscle. Here is the site of possible, especially external, compression of the radial nerve. The nerve then lies directly on the humerus in the groove of the radial nerve, otherwise called the spiral groove. This groove is limited by the places of attachment to the bone of the external and internal heads of the triceps brachii muscle. This forms the radial nerve canal, also called the spiral, brachioradial or brachiomuscular canal. In it, the nerve describes a spiral around the humerus, passing from the inside and back in the anteriolateral direction. The spiral canal is the second site of potential compression of the radial nerve. From it on the shoulder branches go to the triceps brachii muscle and the olecranon muscle. These muscles extend the upper limb at the elbow joint.

A test to determine their strength: the examinee is asked to straighten a limb that is previously slightly bent at the elbow joint; the examiner resists this movement and palpates the contracted muscle.

The radial nerve at the level of the outer edge of the shoulder at the border of the middle and lower thirds of the shoulder changes the direction of its course, turns in front, pierces the external intermuscular septum, passing into the anterior compartment of the shoulder. Here the nerve is especially vulnerable to compression. Below, the nerve passes through the initial part of the brachioradialis muscle: it also innervates the long extensor carpi radialis and descends between it and the brachialis muscle.

The brachioradialis muscle (innervated by the CV - CVII segment) flexes the upper limb at the elbow joint and pronates the forearm from a supinated position to a midline position.

A test to determine its strength: the subject is asked to bend the limb at the elbow joint and at the same time pronate the forearm from the supination position to the middle position between supination and pronation; the examiner resists this movement and palpates the contracted muscle.

The long extensor carpi radialis (innervated by the CV - CVII segment) extends and abducts the hand.

Test to determine muscle strength: they ask you to straighten and abduct the hand; the examiner resists this movement and palpates the contracted muscle. Having passed brachialis muscle, the radial nerve crosses the capsule elbow joint and approaches the instep support. In the ulnar region, at the level of the lateral epicondyle of the shoulder or a few centimeters above or below it, the main trunk of the radial nerve is divided into superficial and deep branches. The superficial branch goes from the subbrachioradialis muscle to the forearm. In its upper third, the nerve is located outward from the radial artery and above the styloid process of the radius passes through the gap between the bone and the tendon of the brachioradialis muscle to the dorsal surface of the lower end of the forearm. Here this branch divides into five dorsal digital nerves (nn. Digitales dorsales). The latter branch in the radial half of the dorsal surface of the hand from the nail phalanx of the first, middle phalanx of the second and radial half of the third fingers.

The deep branch of the radial nerve enters the gap between the superficial and deep bundles of the supinator and is directed to the dorsum of the forearm. The dense fibrous upper edge of the superficial fascicle of the arch support is called the arcade of Froese. Under the arcade of Froese is also the site of the most likely occurrence of radial nerve tunnel syndrome. Passing through the supinator canal, this nerve is adjacent to the neck and body radius and then exits onto the dorsum of the forearm, under the short and long superficial extensors of the hand and fingers. Before exiting the dorsum of the forearm, this branch of the radial nerve supplies the following muscles.

The extensor carpi radialis brevis (innervated by the CV-CVII segment) is involved in wrist extension.
The supinator (innervated by the CV-CVIII segment) rotates and supinates the forearm.

A test to determine the strength of this muscle: the subject is asked to supinate the limb extended at the elbow joint from a pronated position; the examiner resists this movement.

On the dorsum of the forearm, the deep branch of the radial nerve innervates the following muscles.

The extensor digitorum (innervated by the CV-CVIII segment) extends the main phalanges of the II-V fingers and at the same time the hand.

A test to determine its strength: the subject is asked to straighten the main phalanges of the II - V fingers, when the middle and nail ones are bent; the examiner resists this movement.

The extensor carpi ulnaris (innervated by segment CVI - CVIII) extends and adducts the wrist.

A test to determine its strength: the subject is asked to straighten and adduct the hand; the examiner resists this movement and palpates the contracted muscle. The continuation of the deep branch of the radial nerve is the dorsal interosseous nerve of the forearm. It passes between the extensors of the thumb to the wrist joint and sends branches to the following muscles.

The abductor pollicis longus muscle (innervated by segment CVI - CVIII) abducts the first finger.

A test to determine its strength: the subject is asked to abduct and slightly straighten the finger; the examiner resists this movement.

The extensor pollicis brevis (innervated by segment CVI-CVIII) extends the main phalanx of the first finger and abducts it.

Test to determine its strength: the subject is asked to straighten the main phalanx of the first finger; the examiner resists this movement and palpates the tense tendon of the muscle.

The extensor pollicis longus (innervated by segment CVII-C VIII) extends the nail phalanx of the first finger.

Test to determine its strength: the examinee is asked to straighten the nail phalanx of the first finger; the examiner resists this movement and palpates the tense tendon of the muscle.

The extensor index finger (innervated by the CVII-CVIII segment) straightens the index finger.

Test to determine its strength: the subject is asked to straighten the second finger; the examiner resists this movement.

The extensor of the little finger (innervated by the CVI - CVII segment) extends the fifth finger.

Test to determine its strength: the subject is asked to straighten the fifth finger; the examiner resists this movement.

The posterior interosseous nerve of the forearm also gives off thin sensory branches to the interosseous septum, periosteum of the radius and ulna, back surface carpal and carpometacarpal joints.

The radial nerve is predominantly motor and supplies mainly the muscles that extend the forearm, hand, and fingers.

To determine the level of damage to the radial nerve, you should know where and how the motor and sensory branches arise from it. The posterior cutaneous nerve of the shoulder branches into the region of the axillary exit. It supplies the dorsum of the shoulder almost to the olecranon. The posterior cutaneous nerve of the forearm is separated from the main trunk of the nerve at the brachioaxillary angle or in the spiral canal. Regardless of the location of the branch, this branch always passes through the spiral canal, innervating the skin of the posterior surface of the forearm. The branches to the three heads of the triceps brachii muscle arise in the area of the axillary fossa, the brachioaxillary angle and the spiral canal. The branches to the brachioradialis muscle usually arise below the spiral canal and above the lateral epicondyle of the shoulder. The branches to the extensor carpi radialis longus usually arise from the main trunk of the nerve, although below the branches to the previous muscle, but above the supinator. The branches to the extensor carpi radialis brevis may arise from the radial nerve, its superficial or deep branches, but also usually above the entrance to the supinator canal. Nerves to the supinator can branch above or at the level of this muscle. In any case, at least part of them passes through the arch support channel.

Let us consider the levels of damage to the radial nerve. At the level of the brachioaxillary angle, the radial nerve and the branches that arise from it in the axillary fossa to the triceps brachii muscle can be pressed against the dense tendons of the latissimus dorsi and major muscles. pectoral muscle in the tendon corner of the axillary exit area. This angle is limited by the tendons of these two muscles and the long head of the triceps brachii muscle. Here, external compression of the nerve can occur, for example, due to improper use of a crutch - the so-called “crutch” paralysis. The nerve may also be compressed by the back of a chair for office workers or by the edge of an operating table over which the shoulder hangs during surgery. Compression of this nerve implanted under the skin is known chest driver heart rate. Internal compression of the nerve at this level occurs with fractures of the upper third of the shoulder. Symptoms of damage to the radial nerve at this level are distinguished primarily by the presence of hypoesthesia on the posterior surface of the shoulder, to a lesser extent by weakness of forearm extension, as well as the absence or decrease in the reflex from the triceps brachii muscle. When pulled upper limbs forward to the horizontal line, a “dangling or falling hand” is revealed - a consequence of paresis of extension of the hand in the wrist joint and the II - V fingers in the metacarpophalangeal joints.

In addition, there is weakness in extension and abduction of the first finger. Supination of the extended upper limb also fails, whereas with preliminary flexion at the elbow joint, supination is possible due to the biceps muscle. Elbow flexion and pronation of the upper limb is impossible due to paralysis of the brachioradialis muscle. Muscle wasting of the dorsal surface of the shoulder and forearm may be detected. The hypoesthesia zone includes, in addition to the posterior surface of the shoulder and forearm, the outer half of the dorsum of the hand and the first finger, as well as the main phalanges of the second and radial half of the third finger. Compression of the radial nerve in the spiral canal usually results from a fracture of the humerus in the middle third. Nerve compression may occur soon after a fracture due to tissue swelling and increased pressure in the canal. Later, the nerve suffers when it is compressed by scar tissue or callus. With spiral canal syndrome, there is no hypoesthesia in the shoulder. As a rule, it does not suffer and triceps shoulder, since the branch to it is located more superficially - between the lateral and medial heads of this muscle - and is not directly adjacent to the bone. In this tunnel, the radial nerve is displaced along the long axis of the humerus during contraction of the triceps muscle. The callus formed after a shoulder fracture can prevent such movements of the nerve during muscle contraction and thereby contribute to its friction and compression. This explains the occurrence of pain and paresthesia on the dorsal surface of the upper limb during extension in the elbow joint against the action of a resistance force for 1 minute with incomplete post-traumatic damage to the radial nerve. Painful sensations can also be caused by finger compression for 1 minute or by tapping the nerve at the level of compression. Otherwise, symptoms similar to those noted with damage to the radial nerve in the region of the brachioaxillary angle are revealed.

At the level of the external intermuscular septum of the shoulder, the nerve is relatively fixed. This is the site of the most common and simplest compression lesion of the radial nerve. It is easily pressed against the outer edge of the radius during deep sleep on a hard surface (gloss, bench), especially if the head presses against the shoulder. Due to fatigue, and more often in a state of alcoholic intoxication, a person does not wake up in time, and the function of the radial nerve is turned off (“sleepy” paralysis, “garden bench paralysis”). With “sleep paralysis” there is always motor loss, but there is never weakness of the triceps brachii muscle, i.e. paresis of forearm extension and decreased reflex from the triceps brachii muscle. Some patients may experience loss of not only motor functions, but also sensory ones, but the zone of hypoesthesia does not extend to the back surface of the shoulder.

In the lower third of the shoulder above the lateral epicondyle, the radial nerve is covered by the brachioradialis muscle. Here the nerve can also be compressed when the lower third of the humerus is fractured or when the head of the radius is displaced.

Symptoms of damage to the radial nerve in the supracondylar region may be similar to sleep paralysis. However, in the nervous case there is no isolated loss of motor functions without sensory ones. The mechanisms of occurrence of these types of compression neuropathies are also different. The level of nerve compression approximately coincides with the location of the shoulder injury. Determining the upper level of provoking painful sensations on the dorsum of the forearm and hand during tapping and digital compression along the projection of the nerve also helps in differential diagnosis.

In some cases, it is possible to determine compression of the radial nerve by the fibrous arch of the lateral head of m. triceps. The clinical picture corresponds to the above. Pain and numbness on the back of the hand in the area supplying the radial nerve may periodically intensify with intense manual work, while running long distances, with sharp flexion of the upper limbs at the elbow joint. This causes compression of the nerve between the humerus and the triceps muscle. It is recommended that such patients pay attention to the angle of flexion in the elbow joint when running and stop manual labor.

A fairly common cause of lesions of the deep branch of the radial nerve in the area of the elbow joint and upper forearm is compression by a lipoma or fibroma. They can usually be palpated. Removal of the tumor usually leads to recovery.

Among other causes of damage to the branches of the radial nerve, mention should be made of bursitis and synovitis of the elbow joint, especially in patients with rheumatoid polyarthritis, a fracture of the proximal head of the radius, traumatic vascular aneurysm, and professional overexertion with repeated rotational movements of the forearm (conducting, etc.). Most often, the nerve is affected in the canal of the supinator fascia. Less commonly, this happens at the level of the elbow joint (from the place where the radial nerve passes between the brachialis and brachioradialis muscles to the head of the radius and long flexor radialis wrist), which is referred to as radial tunnel syndrome. The cause of compression-ischemic damage to the nerve may be the fibrous band in front of the head of the radius, the dense tendon edges of the short extensor carpi radialis or the arcade of Froese.

Supinator syndrome develops when the posterior interosseous nerve is damaged in the area of the arcade of Froese. It is characterized by night pain in the outer parts of the elbow area, on the back of the forearm and, often, on the back of the wrist and hand. Daytime pain usually occurs during manual work. Rotational movements of the forearm (supination and pronation) especially contribute to the appearance of pain. Patients often note weakness in the hand that appears during work. This may be accompanied by poor coordination of hand and finger movements. Local tenderness is detected upon palpation at a point located 4 - 5 cm below the external epicondyle of the shoulder in the groove radial to the long extensor carpi radialis.

Tests are used that cause or increase pain in the hand, for example, a supination test: both palms of the subject are tightly fixed on the table, the forearm is bent at an angle of 45 ° and placed in the position of maximum supination; the examiner tries to move the forearm to a pronated position. This test is performed for 1 minute; it is considered positive if pain appears on the extensor side of the forearm during this period.

Middle finger extension test: pain in the hand can be caused by prolonged (up to 1 min) extension of the third finger with resistance to extension.

There is weakness in supination of the forearm, extension of the main phalanges of the fingers, and sometimes there is no extension in the metacarpophalangeal joints. Paresis of abduction of the first finger is also detected, but extension of the terminal phalanx of this finger is preserved. When the functions of the short extensor and abductor pollicis longus muscles are lost, radial abduction of the hand in the plane of the palm becomes impossible. With an extended wrist, deviation of the hand to the radial side is observed due to loss of function of the extensor carpi ulnaris, while the long and short extensor carpi radialis are intact.

The posterior interosseous nerve may be compressed at the level of the middle or lower part of the instep support by dense connective tissue. Unlike the “classical” supinator syndrome caused by compression of the nerve in the area of the arcade of Froese, in the latter case the symptom of digital compression is positive at the level of the lower edge of the muscle rather than the upper one. In addition, paresis of finger extension with “lower supinator syndrome” is not combined with weakness of forearm supination.

The superficial branches of the radial nerve at the level of the lower forearm and wrist may be compressed by a tight watch strap or handcuffs (“prisoner's palsy”). However, the most common cause of nerve damage is injury to the wrist and lower third of the forearm.

Compression of the superficial branch of the radial nerve during a fracture of the lower end of the radius is known as “Thurner syndrome,” and damage to the branches of the radial nerve in the area of the anatomical snuffbox is called radial carpal tunnel syndrome. Compression of this branch is a common complication of de Quervain's disease (ligamentitis of the first canal of the dorsal carpal ligament). Pass through this channel extensor brevis and long abductor muscle of the first finger.

When the superficial branch of the radial nerve is affected, patients often experience numbness on the back of the hand and fingers; Sometimes there is a burning pain on the back of the first finger. The pain may spread to the forearm and even the shoulder. In the literature, this syndrome is called Wartenberg paresthetic neuralgia. Sensitive loss is often limited to the hypoesthesia path on the inner back side of the first finger. Often, hypoesthesia can extend beyond the first finger to the proximal phalanges of the second finger and even to the rear of the main and middle phalanges of the third and fourth fingers.

Sometimes the superficial branch of the radial nerve thickens at the wrist. Finger compression of such a “pseudoneuroma” causes pain. The tapping symptom is also positive when tapping along the radial nerve at the level of the anatomical snuffbox or the styloid process of the radius.

The differential diagnosis of radial nerve damage is carried out with spinal root syndrome CVII, in which, in addition to weakness of extension of the forearm and hand, paresis of shoulder adduction and flexion of the hand is detected. If motor loss is absent, the location of pain should be taken into account. When the CVII root is damaged, pain is felt not only on the hand, but also on the dorsum of the forearm, which is not typical for damage to the radial nerve. In addition, radicular pain is provoked by head movements, sneezing, and coughing.

Thoracic outlet level syndromes are characterized by the occurrence or intensification of painful sensations in the arm when turning the head to the healthy side, as well as when performing some other specific tests. At the same time, the pulse in the radial artery may decrease. It should also be taken into account that if at the level of the thoracic outlet the part of the brachial plexus corresponding to the CVII root is compressed, then a picture similar to the lesion of this root described above will arise.

Electroneuromyography helps determine the level of damage to the radial nerve. You can limit yourself to research using needle electrodes of the triceps brachii, brachioradialis, extensor digitorum and extensor index finger muscles. With supinator syndrome, the first two muscles will be preserved, and in the last two, during their complete voluntary relaxation, spontaneous (denervation) activity may be detected in the form of fibrillation potentials and positive sharp waves, and also with maximum voluntary muscle tension - the absence or decrease of potentials motor units. When the radial nerve on the shoulder is irritated, the amplitude of the muscle action potential from the extensor of the index finger is significantly lower than when the nerve is electrically stimulated below the supinator channel on the forearm. Establishing the level of damage to the radial nerve can also be helped by studying latent periods - the time of conduction of a nerve impulse and the speed of propagation of excitation along the nerve. To determine the speed of propagation of excitation along the motor fibers of the tympanic nerve, electrical stimulation is carried out in various points. The highest level of irritation is the Botkin-Erb point, located a few centimeters above the collarbone in the posterior triangle of the neck, between the posterior edge of the sternocleidomastoid muscle and the collarbone. Below, the radial nerve is irritated at the point of exit from the axillary fossa in the groove between the coracobrachialis muscle and the posterior edge of the triceps brachii muscle, in the spiral groove at the level of the middle of the shoulder, and also at the border between the lower and middle third of the shoulder, where the nerve passes through the intermuscular septum, even more distally - 5 - 6 cm above the external epicondyle of the shoulder, at the level of the elbow (humeroradial) joint, on the back of the forearm 8 - 10 cm above the wrist or 8 cm above the styloid process of the radius. Recording electrodes (usually concentric needles) are inserted into the site of maximum response to stimulation of the nerve of the triceps muscle - the shoulder, brachialis, brachioradialis, extensor digitorum, extensor index finger, extensor pollicis longus, abductor longus or extensor pollicis brevis. Despite some differences in the points of nerve stimulation and the places where the muscle response is recorded, normally similar values of the speed of excitation propagation along the nerve are obtained. Its lower limit for the neck-armpit area is 66.5 m/s. On a long section from the supraclavicular Botkin-Erb point to the lower third of the shoulder average speed sometimes 68-76 m/s. In the area “axillary fossa - 6 cm above the external epicondyle of the shoulder” the speed of propagation of excitation is on average 69 m/s, and in the area “6 cm above the external epicondyle of the shoulder - the forearm is 8 cm above the styloid process of the radius” - 62 m/s at abduction of muscle potential from the extensor of the index finger. From this it can be seen that the speed of excitation propagation along the motor fibers of the radial nerve in the shoulder is approximately 10% higher than in the forearm. The average values on the forearm are 58.4 m/s (fluctuations are from 45.4 to 82.5 m/s). Since lesions of the radial nerve are usually unilateral, taking into account individual differences in the speed of propagation of excitation along the nerve, it is recommended to compare the indicators on the diseased and healthy sides. By examining the speed and time of conduction of the nerve impulse from the neck to the various muscles innervated by the radial first, it is possible to differentiate the pathology of the plexus and different levels of nerve damage. Lesions of the deep and superficial branches of the radial nerve are easily distinguished. In the first case, only pain occurs in the upper limb and motor loss can be detected, but superficial sensitivity is not impaired.

In the second case, not only pain is felt, but also paresthesia, there is no motor loss, but superficial sensitivity is impaired.

Compression of the superficial branch in the ulnar region should be differentiated from its involvement at the level of the wrist or lower third of the forearm. The area of pain and sensitive loss may be the same. However, the voluntary forced extension test of the wrist will be positive if the superficial branch is compressed only at the proximal level as it passes through the extensor carpi radialis brevis. Tests with tapping or digital compression along the projection of the superficial branch should also be carried out. The upper level, at which these effects cause paresthesia on the back of the hand and fingers, is the likely site of compression of this branch. Finally, the level of nerve damage can be determined by injecting 2 - 5 ml of a 1% solution of novocaine or 25 mg of hydrocortisone into this place, which leads to a temporary cessation of pain and/or paresthesia. If the nerve block is performed below the point of compression, the intensity of the pain will not change. Naturally, pain can be temporarily relieved by blocking the nerve not only at the level of compression, but also above it. To distinguish between distal and proximal lesions of the superficial branch, 5 ml of a 1% novocaine solution is first injected at the border of the middle and lower third of the forearm at its outer edge. If the block is effective, this indicates a lower level of neuropathy. If there is no effect, a repeated block is performed, but in the area of the elbow joint, which relieves pain and indicates the upper level of damage to the superficial branch of the radial nerve.

Diagnosis of the location of compression of the superficial branch can also be helped by studying the spread of excitation along the sensory fibers of the radial nerve. The conduction of a nerve impulse through them is completely or partially blocked at the level of compression of the superficial branch. With a partial blockade, the time and speed of propagation of excitation along the sensory nerve fibers slow down. Various research methods are used. With the orthodromic technique, excitation along the sensory fibers spreads towards the conduction of the sensitive impulse. To do this, the stimulating electrodes are placed more distally on the limb than the abducent electrodes. With the antidromic technique, the spread of excitation along the fibers in the opposite direction is recorded - from the center to the periphery. In this case, the proximal electrodes located on the limb are used as stimulating ones, and the distal electrodes are used as discharge electrodes. The disadvantage of the orthodromic technique, compared to the antidromic one, is that with the former, lower potentials are recorded (up to 3 - 5 μV), which may be within the noise limits of the electromyograph. Therefore, the antidromic technique is considered more preferable.

It is better to place the most distal electrode (stimulating in the orthodromic technique and abducting in the antidromic technique) not on the dorsum of the first finger. and in the area of the anatomical snuffbox, approximately 3 cm below the styloid process, where a branch of the superficial branch of the radial nerve passes over the tendon of the extensor pollicis longus. In this case, the amplitude of the response is not only higher, but also subject to less individual fluctuations. The same advantages are applied to the distal electrode not on the first finger, but on the space between the first and second metatarsal bones. The average speed of excitation propagation along the sensory fibers of the radial nerve in the area from the leaf electrodes to the lower parts of the forearm in the orthodromic and antidromic directions is 55-66 m/s. Despite individual fluctuations, the speed of excitation propagation along the symmetrical sections of the nerves of the limbs in individuals on both sides is approximately the same. Therefore, it is not difficult to detect a slowdown in the speed of propagation of excitation along the fibers of the superficial branch of the radial nerve when it is unilaterally damaged. The speed of excitation propagation along the sensory fibers of the radial nerve is somewhat different in individual areas: from the spiral groove to the ulnar region - 77 m/s, from the ulnar region to the middle of the forearm - 61.5 m/s, from the middle of the forearm to the wrist - 65 m/s , from the spiral groove to the middle of the forearm - 65.7 m/s, from the elbow to the wrist - 62.1 m/s, from the spiral groove to the wrist - 65.9 m/s. A significant slowdown in the rate of propagation of excitation along the sensory fibers of the radial nerve on its two upper segments will indicate a proximal level of neuropathy. Similarly, the distal level of damage to the superficial branch can be detected.

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RADIAL NERVE [nervus radialis(PNA, JNA, BNA)] is a long nerve of the brachial plexus, innervating the dorsal muscles of the upper limb, the skin of the posterolateral surface of the lower half of the shoulder, forearm and hand.

Anatomy

RADIAL NERVE (color fig. 1-3) starts from the posterior bundle of the brachial plexus (fasc. post, plexus brachialis). Contains nerve fibers most often from segments C5-8, less often from C5-Th1 or C5-7, which are sent to the L. n. as part of all three trunks of the brachial plexus (trunci plexus brachialis), mainly as part of the upper trunk, to a lesser extent - the middle and lower. From the posterior fascicle of the brachial plexus of the L. n. usually departs within the axillary cavity (cavum axillare) at the level of the pectoralis minor muscle behind the axillary artery. In the axillary cavity L. n. is the thickest nerve of the brachial plexus (see). However, after the departure of the muscle branches already at the level of the middle of the shoulder, it becomes thinner and includes fibers mainly only for the forearm and hand. At the level of the upper third of the shoulder, the diameter of the left n. is 3.4-4.6 mm. The largest number of bundles (up to 52, on average 24-28 bundles) is contained in the nerve in the axillary cavity, the smallest (minimum 2, on average 8 bundles) is at the level of the middle of the shoulder. The initial part of the nerve contains up to 22 thousand pulpy nerve fibers and 6-8 thousand non-pulpate ones, in the middle third of the shoulder - 12-15 thousand and 2.5-5 thousand, respectively. Among the pulpy fibers, the diameter is 1 - 3 microns (small) make up 3-11%, 3.1-5 microns (medium) -8-12%, 5.1 - 10 microns (large) - 70-86%, St. 10 microns (very large) - up to 14%. On the shoulder of L. n. located next to the deep artery of the shoulder in the posterior osteofascial space in the brachiomuscular canal (canalis humeromuscularis). Then, perforating the lateral intermuscular septum, it passes into the lateral anterior ulnar groove, where it is located between the brachioradialis muscle - laterally and the brachialis - medially. In the upper part of the named groove in front of the head of the radius, L. n. is divided into two terminal branches: superficial and deep.

L.n. gives off the following branches: 1) articular branch (g. articularis) - to the capsule shoulder joint; 2) posterior cutaneous nerve of the shoulder (n. cutaneus brachii post.) - to the skin of the back of the shoulder; this branch usually originates in the axillary cavity, passes over the long head of the triceps brachii muscle, penetrating the brachial fascia below the insertion of the deltoid muscle, and branches in the skin of the lateral posterior surface of the lower half of the shoulder; 3) lower lateral, cutaneous nerve of the shoulder (n. cutaneus brachii lat. inf.), formed below the previous one, running next to it and branching in the skin of the lateral surface of the lower third of the shoulder; 4) muscular branches (rr. musculares), among which the proximal ones are distinguished, separating from the L. ii. in the axillary cavity to the long, lateral and medial heads of the triceps muscle, to the olecranon muscle, and distal, extending from the L. n. in the depth of the groove between the brachioradialis and brachialis muscles to the lateral part of the brachialis muscle, to the brachioradialis muscle (this branch sends a thin branch to the capsule of the elbow joint), to the long and short extensor radialis of the hand; 5) posterior cutaneous nerve of the forearm (n. cutaneus antebrachii post.), formed within the brachiomuscular canal, piercing the brachial fascia in the interval between the lateral and medial heads of the triceps muscle, emerging, accompanied by the radial collateral artery, dorsally from the lateral epicondyle of the humerus to the dorsal surface of the forearm , giving off multiple branches to the skin; 6) superficial branch (g. superficialis), which arises as a terminal branch on the flexor surface of the brachioradialis joint and spreads in the radial groove of the forearm under the brachioradialis muscle. In the lower third of the forearm it passes under the tendon of the brachioradialis muscle to the back of the hand, where it is divided into the dorsal digital nerves (nn. digitales dorsales) for the skin of the back of the hand, fingers I and II, the radial side of the third finger (proximal phalanges); 7) a deep branch (r. profundus), passing through the instep, surrounding the neck of the radius, emerging on the back of the forearm, where it is divided into numerous muscle branches (rr. musculares) to the extensor muscles. The continuation of the deep branch is the posterior interosseous nerve (n. interosseus post.), innervating the long muscle, abductor pollicis, short and extensor longus thumb, extensor of the index finger; it gives off a branch to the capsule of the wrist joint.

L.n. forms connections with neighboring nerves. Among them, the most important are between the branches of the radial and axillary nerves, between the superficial branch of the L. n. and the lateral cutaneous nerve of the forearm, as well as the dorsal branch of the ulnar nerve (see). There are differences in the length of the zone of innervation of the cutaneous branches of the L. n. So, for example, on the back of the hand, in some cases the dorsal digital nerves innervate the skin of only the 1st and 2nd fingers, and in others - the 1st, 2nd, 3rd, 4th and radial surfaces of the 5th finger.

Pathology

L.n. is most often affected by wounds and fractures of the shoulder, less often the forearm, with intoxication (lead, alcohol), with compression of the nerve during sleep, especially during intoxication (sleep paralysis, drunken paralysis), when walking on crutches (crutch paralysis), with prolonged fixation hands to the operating table during anesthesia, as well as during prolonged compression with hooks during surgery. Pathology L. n. may also be caused by a tumor emanating from the surrounding tissues and compressing the nerve, or a neuroma (schwannoma, neurofibroma). Malignant tumors of L. n. are rarely observed. When L. is affected. in the shoulder area, the function of the extensors of the shoulder, forearm and hand is lost; the forearm is bent in relation to the shoulder, the hand droops, and the fingers are in a semi-bent state (Fig. 1). Sensitivity disorders with lesions of L. n. (Fig. 2) are noted on the dorsum of the shoulder, forearm, on the dorsum of the radial half of the hand, on the proximal and middle phalanges of the first, second and partially third fingers. Due to connections with other nerves, these disorders have a much smaller area of cutaneous innervation.

When L. is affected. in the middle and lower third of the shoulder and upper third of the forearm, the function of the triceps muscle is preserved, paralysis of the extensor digitorum of only the proximal phalanges is noted, and the extension of the middle and distal phalanges is partially preserved due to the function of the interosseous muscles. Depending on the location of the injury, the reflex from the triceps muscle may fall out. When the nerve in the area of the wrist joint is damaged, its terminal branch, which contains many autonomic fibers, is affected, resulting in swelling, coldness and blue discoloration of the dorsum of the hand; pain is extremely rare.

With paralysis of the wrist extensors, the function of the flexors may also suffer, which often leads to incorrect diagnosis of simultaneous damage to the median and ulnar nerve, so the use of tests that help clarify the diagnosis is very important.

The main tests used to diagnose L. n. lesions: 1) both hands approach each other with their palms so that all fingers of the same name come into contact; when the fingers of the healthy hand move away from the fingers of the patient, palmar flexion of the fingers is noted on the side of the affected nerve; 2) when asked to shake the doctor’s hand or form a fist, the flexion position of the drooping hand increases.

Lesions of L. n. can be primary (as a result of injury, tumor) and secondary (when the nerve is involved in scars, compressed by tumors, a plaster cast due to swelling of soft tissues). There are isolated and combined injuries (together with blood vessels and bone).

The symptoms of the lesion are determined by the nature and level of the pathol, the process, depending on which motor and sensory disorders manifest themselves to a greater or lesser extent.

The order of sequential restoration of muscle function during L. n. regeneration. next: wrist extensors, general finger extensors, longus muscle, abductor thumb and arch support.

Treatment of lesions of L. n. determined by the nature of the patol, the impact (trauma, intoxication, ischemia, allergy). Conservative treatment is aimed at stimulating nerve regeneration and eliminating pain. Dehydrating, desensitizing agents, vitamins, calcium preparations, ATP, lidase, nicotinic acid, complamin, nikoshpan, analgesics (analgin, butadione, reopirin, brufen, etc.), and in some cases acupuncture are used. Physiotherapy (thermal procedures, novocaine electrophoresis, UV erythema therapy), exercise therapy, and massage are prescribed.

Operations are indicated for wedge, nerve rupture, tumors, nerve compression, pain syndrome. For wounds, there are primary (together with surgical treatment of the wound), delayed (in the first weeks) and late (3 months after the wound) operations. In case of combined damage to the nerve and bone, one-stage and two-stage operations are performed. The latter are indicated in cases of impossibility of qualified restoration of the anatomical integrity of the nerve during the first operation, in the presence of an infected bone fracture. The phasing of interventions for combined injuries consists of preparing the nerve for plastic surgery and osteosynthesis, followed by neurorrhaphy (see Nerve suture). Access to the nerve during operations is shown in Figure 3.

The operation is effective with early, atraumatic, radical intervention. They perform neurolysis (see), tumor removal, nerve neuroma, neurorrhaphy, nerve autoplasty. Nerve grafting with preserved nerves is ineffective. The condition for successful neurorrhaphy is that the intervention is atraumatic, the fibers of the central and peripheral ends of the nerve are accurately compared without tension, and individual bundles are sutured using micro-neurosurgical techniques. Benign tumors of L. n. (neurinoma-schwannoma, neurofibroma) are subject to removal in case of pain and increasing symptoms of loss of nerve function. In case of malignancy of the tumor, the operation is aimed at its removal with resection of the nerve and extended excision of surrounding tissue to prevent metastasis. Subsequent radiation and chemotherapy complete the treatment. Sometimes radiation treatment is given before surgery.

Bibliography: Atlas of the peripheral nervous and venous systems, ed. V. N. Shevku-nenko, p. 47, L., 1949; Blinov B.V., Bystritsky M.I. and P about p about in I.F. Rehabilitation of patients with fractures of the diaphysis of the humerus and damage to the radial nerve, Vestn, hir., t. 115, No. 8, p. 96, 1975; Internal structure peripheral nerves, ed. A. N. Maksimenkova, L., 1963, bibliogr.; Voiculescu V. and Popescu F. Progressive non-traumatic palsy of the deep branch of the radial nerve, Romanian, med. review, no. 4, p. 55, 1969; Grigorovich K. A. Nerve surgery, L., 1969, bibliogr.; Kalnberz V.K., Lishnevsky S.M. and Filippova R.P. Muscle plasticity in radial nerve palsy, Proceedings of Rizhsk. scientific research, Institute of Traumatology, and Ortho., vol. 10, p. 189, 1971, bibliogr.; Karchi-k I N S.I. Traumatic lesions of peripheral nerves, L., 1962, bibliogr.; Kovanov V.V. and Travin A.A. Surgical anatomy of the upper extremities, M., 1965; Experience of Soviet medicine in the Great Patriotic War, 1941 - 1945, vol. 20, p. 68, M., 1952; O s i n a M. I. Errors and complications in the treatment of injuries of the radial nerve combined with a fracture of the shoulder, in the book: Relevant. Issues, trauma, and orthotics, ed. M. V. Volkova, V. 3, p. 27, M., 1971; Khoroshko V.N. Injuries of peripheral limbs and their physiotherapy, M., 1946; C 1 a g a M. Das Nervensys-tem des Menschen, Lpz., 1959.

D. G. Schaefer; S. S. Mikhailov (an.), V. S. Mikhailovsky (neurosurgeon).

Features of surgical anatomy of the radial nerve

at shoulder level

Yu.A. Zolotova

The details of radial nerve anatomy at the level of humerus

Regional clinical center for specialized types of medical care (maternity and childhood), Vladivostok

In a study of 20 anatomical objects, the location of the radial nerve in relation to the middle of the posterior surface of the humerus, the acromial process of the scapula, and the olecranon was determined. The point of intersection of the radial nerve with the axis of the humerus was located 1.5 ± 0.5 cm (from 0.5 cm to 2 cm) proximal to the middle of the shoulder, dividing the distance “acromion - olecranon” into 2 segments, constituting 45.6% and 54.4% of the conditional length of the shoulder, respectively. The data obtained can be used to identify the radial nerve during surgical interventions and various manipulations on the shoulder. Key words: shoulder, radial nerve, topography.

While 20 anatomical objects were studied, the location of radial nerve was determined with respect to the middle of humeral back surface, clavicular acromial process, olecranon. The point of radial nerve intersection with humeral axis was 1.5±0.5 cm (0.5-2 cm) proximal with respect to the middle of humerus, thereby dividing “acromion - olecranon” distance into 2 parts, amounting to 45 .6% and 54.4% of conventional humeral length, respectively. The data obtained can be used for radial nerve identification during surgical interventions and different manipulations in the humerus. Keywords: humerus, radial nerve, topography.

Damage to the radial nerve at the level of the shoulder is a disabling injury, as it is accompanied by almost complete loss of function of the upper limb. Paralysis of the extensors of the hand and fingers makes it difficult to perform various grips and extension of the hand, and sharply reduces grip strength. Both rough work and subtle manipulations, such as writing or knitting, become difficult to perform. Unfortunately, quite often injuries of the radial nerve are iatrogenic in nature and, if the patient goes to court, then this complication becomes not only a clinical problem, but also a medical one.

MATERIAL AND ME

Anatomical studies were carried out on 20 corpses of male (18) and female (2) people who died between the ages of 36 and 62 years. The most commonly used posterior approach by surgeons was simulated, Henry (Fig. 1). The incision was made along the line connecting the acromion process of the scapula and the olecranon process. At the level of the V-shaped gap, the long and lateral heads of the triceps brachii muscle were bluntly and sharply pulled apart, and then the fibers of the medial head were bluntly pulled apart.

wildly legal. In order to prevent iatrogenic damage to the radial nerve, when performing therapeutic manipulations and operations at the shoulder level, it is recommended to avoid contact with the nerve, and if this is not possible, then the nerve should be identified during surgical access, mobilized and carefully protected. In this regard, the study of the surgical anatomy of the radial nerve is of practical importance.

Purpose of the study: to identify the topography features of the radial nerve in relation to the posterior surface of the humerus.

triceps ki. The radial nerve was identified and prepared along the posterior surface of the shoulder. The detected nerve was taken onto a rubber holder. Using a metal ruler, we determined the length of the shoulder (the distance from the acromial process of the scapula to the olecranon), the location of the radial nerve in relation to the middle of the posterior surface of the humerus, the acromial process of the scapula, and the olecranon.

RESULTS

The length of the arm of the anatomical objects (the distance from the acromion process of the scapula to the olecranon process) averaged 35.3 ± 1.7 cm (from 32 cm to 37.5 cm). The radial nerve crossed the middle of the posterior surface of the diaphysis of the shoulder at an acute angle from the inside out and from top to bottom at a distance of 16.1 ± 0.7 cm (from 14.8 cm to 16.9 cm) from the acromion and at a distance of 19.2 ± 1.2 cm (from 17.2 cm

up to 20.6 cm) from the olecranon process. The point of intersection of the radial nerve with the axis of the humerus was located 1.5 ± 0.5 cm (from 0.5 cm to 2 cm) proximal to the middle of the shoulder (half the distance from the acromial process of the scapula to the olecranon). Thus, the radial nerve divided the conditional length of the shoulder into two unequal segments: upper - 45.6%, lower - 54.4% (Fig. 2).

Rice. 2. Diagram of the projection of the radial nerve along the posterior surface of the shoulder. Conditional length of the shoulder (acromion-olecranon distance) - 100%; the distance from the olecranon to the intersection of the radial nerve with the posterior surface of the humerus - 54.4%; distance from the acromion to the intersection of the radial nerve with the posterior surface of the humerus - 45.6%

DISCUSSION

To determine safe zones and projection anatomy of the radial nerve on the shoulder, a number of surgeons have proposed various anatomical landmarks and diagrams. However, many of them use “inconvenient” anthropometric points that are difficult to determine. In addition, the use of schemes using the absolute value in relation to one anthropometric point is often ineffective, since the length of the upper arm varies from patient to patient.

According to V.V. Kovanova, A.A. Travina, the radial nerve crosses the middle of the posterior surface of the humerus at a distance of 9-10 cm downward from the acromial process of the scapula. It is at this level that one should look for it. However, the distance expressed in centimeters from a single anatomical landmark cannot be universal due to the significant variability of the shoulder length between patients.

M. Gervin et al. during the study of 10 anatomical objects, it was established that the radiation

the nerve in relation to the posterior surface of the shoulder is located 20.7 ± 1.2 cm (74% of the entire length of the shoulder) proximal to the internal epicondyle of the shoulder and 14.2 ± 0.6 cm (51% of the entire length of the shoulder) proximal to the external epicondyle. The authors considered the length of the shoulder to be the distance from the internal epicondyle of the shoulder to the medial aspect of the anatomical neck, which averaged 28.0 ± 1.9 cm. At first glance, this scheme seems more practical, but it is difficult to accurately determine the “medial aspect” of the anatomical neck of the humerus in the clinic by inspection or palpation is unrealistic.

The significant variability in the length of the shoulder among different individuals also explains, apparently, the contradictory recommendations for searching for the radial nerve in relation to the lateral epicondyle of the shoulder and the outer surface of the shoulder. According to V.V. Kovanova and A.A. Travina, the radial nerve is located 8 cm above the external epicondyle. According to G. Bodner et al. , the radial nerve should be looked for 10 cm above the lateral epicondyle of the shoulder.

In the anatomical study, we chose the acromion and olecranon as anthropometric points, which are convenient to use in the clinic, since they are easily determined even in conditions of severe swelling or deformity of the limb. The distance from the acromion process of the scapula to the intersection of the radial nerve with the middle of the posterior surface of the shoulder in our study was 16.1 ± 0.7 cm (from 14.8 cm to 16.9 cm). This value differs significantly from 9-10 cm described by V.V. Kova-

new, A.A. Travin, apparently also due to the significant variation in arm length. Linking the projection of the radial nerve to the conventional length of the shoulder (the distance from the acromion to the olecranon), in our opinion, significantly eliminates individual differences in the size of the shoulder and makes the process of searching for the radial nerve more universal and predictable.

The findings are similar to the results of a previously conducted clinical study in which the position of the radial nerve in relation to the middle of the posterior surface of the humerus was analyzed during shoulder surgery in 21 patients. In the mentioned study, the radial nerve also crossed the humerus slightly above (0.5-3 cm) the midpoint of the acromion-olecranon distance.

Thus, an anatomical study showed that the radial nerve is projected onto the middle of the posterior surface of the humerus proximal to the middle of the conventional length of the shoulder by 0.5-2 cm, dividing the distance “acromion - olecranon” into 2 segments, constituting 45.6% and 54 .4% of the conventional arm length, respectively. The discovered feature of the projection of the radial nerve can be taken into account when performing surgical interventions and various manipulations on the shoulder.

LITERATURE

1. Grishin, I. G. Tendon-muscular transposition in the treatment of consequences of injuries of the median, ulnar and radial nerves / I. G. Grishin // Vestn. traumatology and orthopedics named after. N. N. Priorova. - 1998. - No. 4. - P. 23-26.

2. Devyatova, M.V. Exercise therapy for spinal osteochondrosis and diseases of the peripheral nervous system / M.V. Devyatova. - M.: Medicine, 1983. - 160 p.

3. Zolotov, A. S. Visualization of the radial nerve during surgical access to the humerus / A. S. Zolotov, Yu. A. Zolotova // Vestn. traumatology and orthopedics named after. N. N. Priorova. - 2008. - N° 2. - P. 69-72.

4. Kovanov, V.V. Surgical anatomy of the upper extremities / V.V. Kononov, A.A. Travin. - M.: Medicine, 1965. - 600 p.

5. Müller, M. E. Guide to internal osteosynthesis: a technique recommended by the AO group (Switzerland) / M. E. Müller [et al.]. - M.: AdMarginem, 1996. - P. 427-452.

6. Avoiding complications in the treatment of humeral fractures / J. O. Anglen // J. Bone Joint Surg. - 2008. - Vol. 90-A, No. 7. - P. 1580-1589.

7. Radial nerve palsy associated with humeral shaft fracture: evaluation with US - Initial experience / G. Bodner // Radiology. -2001. - Vol. 219. - P. 811-816.

8. Freeland, A. E. The humerus / A. E. Freeland, J. L. Hughes // Atlas of orthopedic surgical approaches / ed. by S. L. ^lton, A. J. Hall. - Butterworth Heinemann Ltd, 1993. - P. 147-156.

9. Gervin, M. Alternative operative exposure of the posterior aspect of the humeral diaphysis / M. Gervin, R. N. Hotchkiss, A. J. Weiland // J. Bone Joint Surg. - 1996. - Vol. 78-A, No. 11. - P. 1690-1695.

10. Examination of postoperative peripheral nerve lesions with high-resolution sonography / S. Peer // Am. J. Roentgen. - 2001. -Vol. 177. - P. 415-419.

The manuscript was received on March 14, 2009.

Zolotova Yulia Aleksandrovna - traumatologist-orthopedist Regional Clinical Center for Specialized Types of Medical Care (maternity and childhood), Vladivostok; tel. 8-4232-31-05-63, E-mail: [email protected].

Table of contents of the topic “Brachial plexus, plexus brachialis”:

Radial nerve, n. radialis. Medial cutaneous nerve of the forearm, n. cutaneus antebrachii medialis.

Medial cutaneous nerve of the forearm, n. cutaneus antebrachii medialis also from the medial bundle of the plexus (from C8, Th1), in the axillary fossa lies next to n. ulnaris; in the upper part of the shoulder is located medial from brachial artery next to v. basilica, together with which it pierces the fascia and becomes subcutaneous.
This nerve innervates the skin on the ulnar (medial) side of the forearm to the wrist joint.

N. radialis, radial nerve(C5-C8, Th1), forms a continuation of the posterior bundle of the brachial plexus. It passes behind the brachial artery along with a. profunda brachii on the back side of the shoulder, spirals around the humerus, located in the canalis humeromuscularis, and then, piercing the lateral intermuscular septum from back to front, exits into the space between m. brachioradialis and m. brachialis. Here the nerve divides into superficial ( ramus superficialis) and deep ( ramus profundus) branches.
Before that n. radialis gives the following branches:

Rami musculares on the shoulder for extensors - m. triceps and m. anconeus. The last branch also supplies the capsule of the elbow joint and the lateral epicondyle of the shoulder, so when the latter becomes inflamed (epicondylitis), pain occurs along the entire radial nerve.

Nn. cutanei brachii posterior et lateralis inferior branch in the skin of the back and lower section posterolateral surfaces of the shoulder.

N. cutaneus anterbrachii posterior originates from the radial nerve in the canalis humeromuscularis, exits under the skin above the beginning of m. brachioradialis and extends to the dorsum of the forearm.

Rami musculares go to m. brachioradialis, etc. extensor carpi radialis longus.

Ramus superficialis goes to the forearm in the sulcus radialis lateral to a. radialis, and then in the lower third of the forearm through the gap between the radius and tendon m. brachioradialis moves to the back of the hand and supplies five dorsal branches, nn. digitales dorsales, on the sides of fingers I and II, as well as the radial side of III.

These branches usually end at the level of the last interphalangeal joints. Thus, each finger is supplied by two dorsal and two palmar nerves running on both sides. Dorsal nerves originate from n. radialis And n. ulnaris, innervating each 2 1/2 fingers, and the palmar ones - from n. medianus And n. ulnaris, with the first supplying 3 1/2 fingers (starting with the thumb), and the second supplying the remaining 1 1/2 fingers.

Ramus profundus passes through m. supinator and, having supplied the latter with a branch, goes to the dorsal side of the forearm, innervating m. extensor carpi radialis brevis and all posterior muscles of the forearm. Continuation deep branch, n. interosseus (antebrachii) posterior, descends between the extensors of the thumb to the wrist joint, which innervates.

Out of progress n. radialis it is clear that it innervates all extensors on both the shoulder and forearm, and on the latter also the radial muscle group. Accordingly, the skin on the extensor side of the shoulder and forearm is also innervated by it. The radial nerve - a continuation of the posterior bundle - is, as it were, posterior nerve hands.

In the neurology of “mononeuropathies,” one of the main problems is the problem of determining the “level of nerve damage,” since an adequate clinical expert assessment of the severity of the disease and its prognosis, as well as the adequate development of treatment and preventive measures, depends on the “adequacy of its solution.” Let us consider the basic principles of “level” diagnosis of neuropathy using the example of the radial nerve (n. radialis). It should first be noted that a “level” diagnosis of neuropathy is advisable only in the absence of clear indications of the level of influence of the exogenous provoking factor (for example, a fracture of the “ray in a typical place” or a fracture of the humerus at the level of its c/3), which requires identification level of nerve pathology according to the basic principles of topical diagnosis in neurology (in particular, according to the “level principle”), as well as in the differential diagnosis of causes limiting one or another action in a limb - pathology of the musculoskeletal system or a “purely neurogenic” cause (for example, the pathology of the superficial branch of the radial nerve in a fracture of the radius in the lower part, i.e. in a fracture of the radius in a “typical place” will never cause limitations in the extension of the hand and fingers, but will only cause pathological deficit or irritative phenomena). Before moving on to the level diagnosis (and its principles) of the pathology of the radial nerve, it is necessary, firstly, to consider the course of the radial nerve and its main (“ramal”) dichotomies, secondly, to consider the muscles and areas of the skin that innervate the radial nerve, and thirdly, correlate the first with the second, then decide at what level which muscles and areas of the skin innervate the radial nerve (its branches).

Course of the radial nerve : the radial nerve is formed from the [secondary] posterior brachial plexus and is a derivative of the ventral branches of the CV - CVIII spinal nerves; along the posterior axillary cavity, the nerve descends down, located in the axillary artery and located sequentially on the belly of the subscapularis muscle, on the tendons of the latissimus dorsi muscle and the teres major muscle; Having reached the brachioaxillary angle between the inner part of the shoulder and the lower edge of the posterior wall of the axillary cavity, the radial nerve is adjacent to a dense connective tissue band formed by the connection of the lower edge of the latissimus dorsi muscle and the posterior tendon part of the long head of the triceps brachii muscle (in the area where the radial nerve exits the axillary fossa from its the main trunk gives off the posterior cutaneous nerve of the shoulder); further, the nerve lies directly on the humerus and the groove of the radial nerve, otherwise called “[gutter]”, in this canal the nerve describes a spiral around the humerus, passing from the inside and back in the anteroposterior direction; then the nerve at the level of the outer edge of the shoulder at the border of the middle and lower third of the shoulder changes the direction of its course, turns forward and pierces the external intermuscular septum, passing into the anterior compartment of the shoulder; below, the nerve passes through the initial part of the brachioradialis muscle and descends between it and the brachialis muscle; after passing the brachialis muscle, the radial nerve crosses the capsule of the elbow joint and passes to the supinator; in the ulnar region at the level of the external epicondyle of the shoulder or a few centimeters above or below it, the main trunk of the radial nerve into superficial and deep branches; the superficial branch goes under the brachioradialis muscle on the forearm; in its upper third, the nerve is located outward from the radial artery, passes through the gap between the bone and the tendon of the brachioradialis muscle to the dorsal lower end of the forearm; here this branch is divided into five dorsal digital nerves (nn. digitales dorsales); the latter branch in the radial half of the dorsal surface of the hand from the nail phalanx of the first, middle phalanx of the second and radial half of the third fingers; the branch of the radial nerve enters the gap between the superficial and deep fascicles of the supinator and is directed to the dorsum of the forearm (the dense fibrous upper edge of the superficial fascicle of the supinator is called the arcade of Froese); penetrating through the supinator canal, the deep branch of the radial nerve is adjacent to the neck and body of the radius and then exits onto the dorsum of the forearm, under the short and long superficial extensors of the hand and fingers. The continuation of the deep branch of the radial nerve is the dorsal (posterior) interosseous nerve of the forearm - it passes between the extensors of the thumb to the wrist joint. Thus, we can distinguish four most important (from a clinical point of view) parts of the radial nerve: 1. main trunk (motor and sensory function) - at the level of the humerus, 2. superficial branch (sensory function), 3. internal branch (motor function ) and its continuation – 4. posterior (dorsal) interosseous nerve (motor and sensory function).

Muscles innervated by the radial nerve: 1. triceps brachii, ulnar muscle (their innervation is during the passage of the radial nerve in the axillary fossa, at the level of the brachioaxillary angle and in the spiral canal); 2. brachioradialis muscle, long extensor carpi radialis (their innervation is at the level of the lower third of the humerus, after the nerve passes through the external intermuscular septum); 3. short extensor carpi radialis, supinator (their innervation is at the level of the upper part of the upper third of the forearm); 4. extensor digitorum [main phalanges], extensor ulnaris (their innervation is at the level of the lower part of the upper third of the forearm); 5. further innervation of the muscles is carried out by the dorsal (posterior) interosseous nerve: abductor pollicis longus, extensor pollicis brevis, extensor pollicis longus, extensor of the index finger, extensor of the little finger (their innervation is at the level of the middle third of the humerus, after the passage of the nerve through the external intermuscular septum).

Sensory innervation: the posterior cutaneous nerve branches in the area of the axillary exit (supplies the dorsum of the shoulder almost to the olecranon); the posterior cutaneous nerve of the forearm is separated from the main trunk of the nerve at the brachioaxillary angle or in the spiral canal (regardless of the location of the branch, this branch always passes through the spiral canal, innervating the posterior surface of the forearm); at the level of the lower part of the dorsum of the forearm, the superficial branch is divided into five dorsal digital nerves (nn. digitales dorsales), which innervate the skin of the radial half of the dorsal surface of the hand from the nail phalanx of the first, middle phalanx of the second and radial half of the third fingers; The posterior (dorsal) interosseous nerve of the forearm gives off thin sensory branches to the interosseous septum, the periosteum of the radius and ulna, and the posterior surface of the wrist and carpometacarpal joints.

Thus, the radial nerve innervates: the muscles of the posterolateral part of the shoulder, forearm and hand (which extend the shoulder, forearm, hand, fingers [main phalanges], supinate the forearm and hand, abduct the hand to the radial and ulnar sides, etc.), the skin of the back of the shoulder , forearms and hands (see diagram), etc.

Depending on the level (height) of the lesion in the syndrome of complete lesion of the radial nerve, 8 clinically significant levels of compression can be distinguished:

1. at the level of the upper third of the shoulder (humeral-axillary angle)	1. the presence of hypoesthesia on the posterior surface of the shoulder, forearm, the radial half of the dorsal surface of the hand from the nail phalanx of the first finger, the middle phalanx of the second and the radial half of the third finger; 2. weakness of forearm extension; 3. absence (decreased) reflex from the triceps brachii muscle; 4. when stretching the arms forward to a horizontal line, a “dangling” or “falling” hand is revealed (paresis of the extensors of the hand and extensors of the II - V fingers in the metacarpophalangeal joints); 5. weakness of extension and abduction of the first finger; 6. lack of supination of the arm extended at the elbow joint; 7. inability to flex the elbow of the pronated arm (paralysis of the brachioradialis muscle); 8. wasting of the muscles of the dorsal surface of the shoulder and forearm (in case of long-term damage);
2. at the level of the middle third of the shoulder (in a spiral channel)	The clinical picture corresponds to radial nerve syndrome at the level of the brachioaxillary angle with the exception of: 1. there is no hypoesthesia on the shoulder; 2. the triceps muscle does not suffer; 3. pain and paresthesia appear on the dorsum of the arm when extending the elbow joint against resistance for 1 minute or when tapping the nerve at the level of compression;
3. at the level of the external intermuscular septum of the shoulder (most common place of compression):	see paragraph 2
4. at the level of the lower third of the shoulder (above the external epicondyle):	see paragraph 2
5. at the level of the elbow joint and the upper part of the forearm (most often in the feces of the supinator fascia, in the area of the arcade of Froese):	1. the presence of night pain in the outer parts of the elbow area, on the back of the forearm, and sometimes on the back of the wrist and hand; 2. the appearance of daytime pain during manual work (especially rotational movements of the forearm - supination and pronation); 3. the presence of weakness in the hand that appears during manual work; 4. local pain on palpation at a point 4–5 cm below the external epicondyle of the shoulder; 5. positive data from the “supination test” (if pain appears on the extensor side of the forearm within 1 minute); 6. positive test of extension of the middle finger (the appearance of pain in the hand during prolonged – up to 1 min – extension of the third finger with resistance to its extension); 7. weakness of supination of the forearm; 8. weakness or lack of extension of the main phalanges of the fingers; 9. weakness of abduction of the first finger (while maintaining extension of the terminal phalanx of this finger); 10. impossibility of radial abduction of the hand in the plane of the palm; 11. deviation of the hand to the radial side with the wrist extended;
6. at the level of the middle or lower part of the instep support:	1. (unlike point 5) finger compression syndrome is detected at the level of the lower edge of the instep support (and not the upper); 2. paresis of the finger extensors is not combined with weakness of the forearm supinator;
7. at the level of the lower part of the forearm and at the level of the wrist:	1. numbness on the back of the hand and fingers I – III; 2. sometimes burning pain on the back of the fingers; 3. positive “tapping symptom” when tapping along the radial nerve at the level of the styloid process of the radius; 4. sometimes the presence of thickening of the superficial branch of the radial nerve in the wrist area - the appearance of a “pseudoneuroma”, digital compression of which causes pain;
8. at the level of the anatomical snuffbox (for example, with de Quervain’s disease):	1. disturbance of sensitivity in the autonomous zone of the anatomical snuffbox; 2. violation of abduction of the first finger; 3. weakness of extension of the first finger; 4. positive “tapping symptom” along the branches of the radial nerve at the level of the anatomical snuffbox.