Symptoms of involvement of the ulnar nerve and its branches

The ulnar nerve (n. Ulnaris). The ulnar nerve is formed from the fibers of CVIII-T: spinal nerves, which pass supraclavicularly in the composition of the primary lower trunk of the brachial plexus and subclavicularly - in the secondary medial bundle. Less often the ulnar nerve additionally includes fibers from the CVII rootlet.

The nerve is located first to the inside of the axillary and upper part of the brachial artery. Then, at the level of the middle third of the shoulder, the ulnar nerve departs from the brachial artery. Below the middle of the shoulder, the nerve passes through the opening through the opening in the medial intermuscular septum of the shoulder and, being meshed by it and the medial head of the triceps brachii muscle, moves downward, reaching a gap between the medial epicondyle of the shoulder and the ulnar process of the ulna. The section of the fascia, thrown between these two formations, is called the supracondylar ligament, and in the lower bone-fibrous canal - by the supracondylar-elbow trench. The thickness and consistency of the fascia site in this place range from a thin and cobweblike to a dense and similar bundle of formation. In this tunnel, the nerve is usually attached to the periosteum of the medial epigastrium in the furrow of the ulnar nerve and is accompanied by a recurrent ulnar artery. Here is the upper level of possible compression of the nerve in the ulnar region. Continuation of the supracondylar-elbow groove is the slit of the elbow flexor of the wrist. It exists at the level of the upper attachment point of this muscle. This second probable place of compression of the ulnar nerve is called a cubital tunnel. The walls of this channel are bounded from the outside by the ulnar process and the elbow joint, from the inside - by the medial nadmishelk and the ulnar collateral ligament, partially adjacent to the inner lip of the humerus block. The roof of the cubital canal is formed by a fascial ribbon that extends from the ulnar process to the inner epicondyle, covering the ulnar and humeral bundles of the elbow flexor of the wrist and the space between them. This fibrous ribbon, which has the shape of a triangle, is called the aponeurosis of the elbow flexor of the wrist, and its particularly thickened proximal base is an arcuate ligament. The ulnar nerve emerges from the cubital canal and is further located on the forearm between the ulnar flexor of the wrist and the deep flexor of the fingers. From the forearm to the hand, the nerve passes through the fibro-fibrous canal of Guyon. Its length is 1-1.5 cm. This is the third tunnel, in which the ulnar nerve can be squeezed. The roof and the bottom of the Guyon canal are connective tissue formations. The upper one is called the rear carpal ligament, which is a continuation of the superficial fascia of the forearm. This ligament is supported by the tendon fibers of the elbow flexor of the wrist and the short palmar muscle. The bottom of the Huyon channel is formed predominantly by the extension of the flexor flexor retainer, which covers the carpal tunnel in its radial part. In the distal part of the Guyon canal, its bottom includes, in addition to the flexor retainer, also pea-hook-shaped and a pea-papular ligament.

The next level of possible compression of the deep branch of the ulnar nerve is a short tunnel through which this branch and the ulnar artery pass from the Guyon canal into the deep space of the palm. This tunnel is called pea-hook-like. The roof of the entrance to this channel is formed by a connective tissue, arranged between the pea-bones and the hook of the hook-shaped bone. This dense convex tendon arc is the site of the beginning of the muscle - the short flexor of the little finger. The bottom of the entrance to the tunnel is a pea-crocheted ligament. Passing between these two formations, the ulnar nerve then turns outward around the hook of the hook-shaped bone and passes under the beginning of the short flexor of the little finger and the muscle opposing the little finger. On the ridge of a pea-hook-shaped canal and distal to it from the deep branch, the fibers go to all their own muscles of the hand, supplied with the ulnar nerve, except for the muscle that removes the little finger. The branch to it usually departs from the common trunk of the ulnar nerve.

In the upper third of the forearm from the ulnar nerve branches branch to the next muscles.

The ulnar flexor of the hand (innervated by segment CIII-TX) bends and brings the brush.

A test to determine its strength: the subject is offered to bend and bring the brush; The examiner is resisting this movement and palpating the contracted muscle.

Deep flexor of fingers; its ulnar part (innervated by segment VIII - TI) bends the nail phalanx of IV - V fingers.

Tests to determine the action of the elbow portion of this muscle:

• the hand of the subject is laid down with the palm of his hand and pressed firmly against a hard surface (table, book), after which he is suggested to do a scratching motion with his fingernail;
• The subject is asked to fold his fingers into a fist; with the paralysis of this muscle, the folding of the fingers into a fist occurs without the participation of IV and V fingers.

A test to determine the strength of this muscle: suggest bending the distal phalanx of IV-V fingers; the examiner fixes the proximal and middle phalanges in the unfolded state and exerts resistance to the bending of the distal phalanges.

At the level of the middle third of the forearm from the ulnar nerve is a sensitive palmar branch that innervates the skin of the area of the pinky's elevation and somewhat higher. Below (along the border with the lower third forearm, 3 to 10 cm above the wrist), one more sensitive back branch of the hand departs. This branch does not suffer from pathology in the canal of Guyon. It passes between the tendon of the elbow flexor of the hand and the ulna on the back of the hand and divides into five back nerves of fingers that terminate in the skin of the back surface of V, IV and the ulnar side of the third finger. In this case, the nerve of the fifth finger is the longest and reaches the nail phalanx, the rest reach only the middle phalanges.

The continuation of the main trunk of the ulnar nerve is called its palmar branch. It enters the Guyon canal and is divided 4 to 20 mm below the styloid process of the radius bone into two branches: superficial (predominantly sensitive) and deep (predominantly motor).

The superficial branch passes under the transverse wrist ligament and innervates the short palmar muscle. This muscle tightens the skin to the palmar aponeurosis (innervated by segment CIII-TI).

Below the ramus superficialis is divided into two branches: the actual finger palmar nerve (which supplies the palm surface of the elbow side of the V finger) and the common digital palmar nerve. The latter goes in the direction of the IV interdigital space and is divided into two of its own digital nerves, which continue along the palmar surface of the radial and ulnar sides of the fourth finger. In addition, these finger nerves send branches to the back of the nail phalanx V and the ulnar half of the middle and nail phalanx of the fourth finger.

The deep branch penetrates into the palm of the palm through the gap between the flexor V of the finger and the muscle that removes the little finger. This branch is directed in an arc-like manner to the radial side of the hand and supplies the following muscles.

The muscle that leads the thumb (innervated by the segment of CVIII).

Tests to determine its strength:

• the subject is offered to lead I finger; the examiner is resisting this movement;
• the subject is offered to press the object (strip of heavy paper, tape) with the main phalanx of the first finger to the metacarpal bone of the index; The examiner draws this item.

When this muscle is paralyzed, the patient reflexively presses the object with the nail phalanx of the first finger, i.e., uses a long flexor of the 1st finger innervated by the median nerve.

Muscle, subtending the little finger (innervated by the segment of the CIII-TI).

A test to determine its strength: the subject is offered to withdraw V finger; the examiner is resisting this movement.

A short flexor flexor (innervated by segment CIII) flexes the phalanx of the fifth finger.

The test to determine its strength: the subject is offered to bend the proximal phalanx V of the finger, and the other fingers to unbend; the examiner is resisting this movement.

The muscle, opposing the little finger (innervated by the segment CVII - СVIII), pulls the V finger to the middle line of the hand and contrasts it.

The test for determining the action of this muscle: suggest to bring the unbent V finger to the 1st finger. When the muscle is paresis, there is no movement of the fifth metacarpal bone.

Short flexor of the thumb; its deep head (innervated by segment CVII-TI) is supplied together with the median nerve.

The vermiform muscles (innervated by segment CIII-TI) flex the main and extend the middle and nail phalanges of the II-V fingers (I and II mm., Lumbricales are supplied with the median nerve).

The interosseous muscles (back and palmar) flex the main phalanges and simultaneously unbend the middle nail phalanges of the II-V fingers. In addition, the rear interosseous muscles divert the II and IV fingers from III; palmar - lead II, IV and V fingers to the third finger.

Test for the determination of the action of vermiform and interosseous muscles: they suggest flexing the main phalanx of II-V fingers and simultaneously unbend the middle and nail.

With the paralysis of these muscles, the clawlike position of the fingers arises.

Tests to determine the strength of these mice:

• the subject is offered to bend the main phalanx of the II - III fingers when the middle and the nail are unbent; the examiner is resisting this movement;
• the same is suggested for IV-V fingers;
• then they propose to unravel the middle phalanx of the II-III fingers when the main phalanx is bent; the examiner is resisting this movement; d) the same examiner does for IV - V fingers.

The test for determining the action of the dorsal interosseous muscles: the subject is suggested to spread his fingers with the horizontal position of the hand.

Tests to determine their strength: suggest withdrawing the II finger from III; the examiner is resisting this movement and palpating the contracted muscle; The same is done for the fourth finger.

The test for determining the action of palmar interosseous muscles: the subject is offered to bring his fingers in the horizontal position of the hand.

Tests to determine the strength of palmar interosseous muscles:

• the subject is offered to clamp a flat object (tape, paper) between the second and third fingers; the examiner tries to pull it out;
• offer to lead II finger to III; The examiner is resisting this movement and palpating the contracted muscle.

Symptoms of defeat of the ulnar nerve consists of motor, sensory, vasomotor and trophic disorders. Due to the paresis of m. Flexoris carpi ulnaris and the predominance of the action of the muscles-antagonists the brush deviates to the ray side. Because of the mm cutter. Adductoris pollicis and antagonistic action m. Abductoris pollicis longus et brevis I finger outward; The retention of objects between the I and II fingers is difficult. Also a few are allocated from the IV finger of the V finger. The predominance of the extensor function leads to a hyperextension of the basic and bent position of the nail phalanges of the fingers - a "claw-shaped brush" typical of the ulnar nerve is developed. Clawedness is more pronounced in the IV and V fingers. Violation of the reduction and dilution of the fingers, the patient can not grasp and hold the objects between the fingers. Develops atrophy of the muscles of the first back spacing, hypotenar and interosseous muscles.

Sensitive disorders extend to the ulnar part of the hand from the palmar side, region V and the ulnar side of the IV fingers, from the rear side - to the area of V, IV and half of the third finger. Deep sensitivity is impaired in the joints of the V finger.

Often observed cyanosis, coldness of the inner edge of the hand and especially the little finger, thinning and dry skin.

When the ulnar nerve is affected at different levels, the following syndromes occur.

Cubital ulnar nerve syndrome develops with rheumatoid arthritis, with osteophytes of the distal end of the humerus, fractures of the epicondyle of the humerus and bones forming the elbow joint. This increases the angle of movement of the ulnar nerve and lengthens its path on the shoulder and forearm, which is noticeable when flexing the forearm. There is microtraumatization of the ulnar nerve, and it is affected by the compression-ischemic mechanism (tunnel syndrome).

Occasionally, a habitual displacement of the ulnar nerve (dislocation) occurs, facilitated by innate factors (the posterior position of the medial epicondyle, the narrow and shallow epicondyle-elbow groove, the weakness of the deep fascia and ligamentous formations above this gutter) and acquired (weakness after injury). When the forearm is bent, the ulnar nerve is displaced to the anterior surface of the inner epicondyle and returns back to the posterior surface of the epicondyle when it extends. External compression of the nerve happens in people who are long in one position (at a desk, desk).

Subjective, sensitive symptoms usually appear earlier than motor symptoms. Paresthesias and numbness are localized in the zone of supply of the ulnar nerve. A few months or years, the weakness and hypotrophy of the corresponding muscles of the hand are added. With an acute cubital syndrome caused by compression of the nerve during surgery, sensations of numbness appear immediately after exiting anesthesia. The paresis of long muscles (for example, the elbow wrist flexor) is detected less often than the paresis of the muscles of the wrist. Hypesesia is localized on the palmar and dorsal surfaces of the hand, the V finger and the ulnar side of the IV finger.

The defeat of the ulnar nerve on the hand occurs in the form of the following options:

1. with sensitive fallouts and weakness of the muscles of the hand;
2. without sensory deposition, but with the paresis of all the muscles of the hand, supplied with the ulnar nerve;
3. without loss of sensitivity, but with weakness of the muscles innervated by the ulnar muscle, excluding the muscles of the hypotenar;
4. only with sensitive fallouts, in the absence of motor.

There are three types of syndromes, combining isolated lesions of the deep motor branch into one group. The first type of syndrome includes the paresis of all the ulnar muscles of the wrist, as well as the loss of sensitivity along the palmar surface of the hypotenar, IV and V fingers. These symptoms can be caused by compression of the nerve slightly above the Huyong canal or in the canal itself. In the second type of syndrome, weakness of the muscles innervated by the deep branch of the ulnar nerve appears. Surface sensitivity in the brush is not disturbed. The nerve can be squeezed in the region of the hook of the hook-bone between the place of the adherent muscle and the flexor flexor when passing the ulnar nerve through the little finger that opposes the muscle and, less often, when the nerve crosses the palm of the back of the tendons of the finger flexors and in front of the metacarpal bones. The number of affected muscles depends on the site of compression along the course of the deep branch of the ulnar nerve. With fractures of the forearm bones, tunnel syndromes can occur simultaneously, compression of the median and ulnar nerve in the wrist area - the third type of syndrome.

[1], [2], [3], [4], [5]