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 the 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.
Diagnosis of the long thoracic nerve 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 plexopathy of the brachial plexus.
Clinical picture consists of pain in the back 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 a 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.
Dorsal nerve of the scapula - n. dorsalis scapulae (C5) descends along the medial edge of the scapula along with the ramus descendens art. transversae coli. Provides innervation m. rhomboideus and m. levator scapulae.
Suprascapular nerve
Suprascapular nerve - n. suprascapularis (from C5 and C6) on the neck is part of the neurovascular bundle a.vv. etn. suprascapularis. The bun crosses the neck in an oblique direction, from front to back and reaches the incisura scapulae. Here the artery and veins pass into the fossa supraspinata through the notch, and the nerve passes over the ligament covering it. This nerve innervates m. supraspinatus, m. infraspinatus and the capsule of the shoulder joint.
Long thoracic nerve
Long thoracic nerve - n. thoracicus longus (from C5-C7) - the nerve passes from the neck to the subarchial fossa, then to the limb and immediately lies along the lateral edge of the chest wall, along the anterior edge of m. serratus anterior superior and gives it innervation. Usually in the upper part of the anterior chest wall next to it there is a. thoracica lateralis.
Subscapular nerve
Subscapular nerve - n. subscapularis (C5-C8) runs along the lateral and lower edge of the scapula and gives off branches to m. subscapularis, m. teres major and m. latissimus dorsi.
Axillary nerve
Axillary nerve - n. axillaris (C5-C6) is the largest nerve of all the short branches of the supraclavicular part of the brachial plexus. The axillary nerve goes to the foramen quadrilaterum and enters the posterior surface of the humerus in the area of its surgical neck. It gives branches to the shoulder joint, to the muscles m. deltoideus and m. teres minor. In addition, in the area of the rear edge deltoid muscle the axillary nerve gives off the cutaneous branch n. cutaneus brachii lateralis superior to the skin deltoid region and posterolateral region of the shoulder.
Moving from the neck to the upper limb, the brachial plexus enters the axillary cavity, its first floor, corresponding to the trigonum claviopectoralis. It enters here in the form of three bundles, covered with a single fascial capsule. In the second floor of the axilla, corresponding to the trigonum pectoralis, the bundles are separated from each other, and here the fasciculus lateralis et medialis, as well as the fasciculus posterior, can be distinguished. When moving to the third floor of the axillary cavity - trigonum subpectoralis - the bundles are divided into separate nerves, which are long branches of the brachial plexus, with the exception of n. axillaris.
Lateral bundle - gives one leg to form n. medianus, as well as n. musculocutaneus.
The second leg n emerges from the medial bundle. medianus, n. ulnaris, n. cutaneus brachii and antebrachii medialis.
Posterior bundle - gives n. radialis and n. axillaris (Fig. 8).
Median nerve
Median nerve - n. medianus (C5 - C8+ Th1) is formed by the fusion of two legs (one from the medial bundle, the second from the lateral). The nerve lies in front of a. axillaris, then lies in the sulcus bicipitalis medialis, where it passes next to a. brachialis. In the upper third of the groove it lies lateral to the artery, in the middle third in front of a. brachialis and in the lower third medially from it (Fig. 9). The nerve does not give branches on the shoulder. In the cubital fossa, the nerve passes medially from the artery under m. pronator teres, and then lies between the superficial and deep flexor digitorum in the midline in the sulcus medianus and exits onto the palm under the retinaculum flexorum, where it can be mistaken for a tendon. On the forearm, the nerve gives branches to all muscles of the forearm, except m. flexor carpi ulnaris. In addition, n. medianus in the upper third of the forearm gives off to n. interosseus anterior, which lies on the interosseous membrane along with a. et vv. interossea anterior and innervates m. flexor digitorum profundus, m. flexor policis longus and m. pronator quadratus, as well as the wrist joint (Fig. 10).
Through the canalis carpalis, the nerve penetrates the palm and gives off a superficial cutaneous branch, which innervates a small area of thenar skin and palm. On the palm n. medianus innervates the skin of 3.5 fingers, starting with the thumb and ending with the medial surface ring finger, as well as thenar muscles, except m. adductor policis longus and the deep head of the t. flexor policis brevis, as well as the first and second lumbrical muscles (Fig. 11).
Musculocutaneous nerve
Musculocutaneous nerve - n. musculocutaneus (C5-C7). In the upper part of the shoulder, the nerve pierces m. coracobrachialis and innervates m. coracobrachialis, t. biceps brachii and t. brachialis. On the shoulder, the nerve lies laterally between m. biceps and m. brachialis, and then, passing to the ulnar fossa, becomes the cutaneous nerve - n. cutaneus antebrachii lateralis, which innervates the skin of the radial side of the forearm and the skin of the thenar on the back side (Fig. 8).
Ulnar nerve
Ulnar nerve - n. ulnaris (C7-C8, YOU). It passes along the medial surface of the shoulder and, at the border of the middle and lower third of the shoulder, pierces the medial intermuscular septum along with a. et v. collateralis ulnaris superior (Fig. 9), enters the posterior bed of the shoulder, goes down, bending around the medial epicondyle of the shoulder and lies in the sulcus cubitalis posterior (Fig. 12). Here it is covered only by skin, subcutaneous fatty tissue and its own fascia. On the forearm, the nerve passes into the sulcus ulnaris and lies as part of the neurovascular bundle a., vv., n. ulnaris (Fig. 10).
The first branches of n. ulnaris appear on the forearm - this is rami articulares to the elbow joint. Next come the branches to m. flexor carpi ulnaris and the adjacent part of m. flexor digitorum profundus.
At the level of the wrist joint, branches extend to the hypothenar skin. Here the nerve gives off cutaneous branches to the back of the hand, where it innervates the skin of the V, VI and ulnar half of the third finger r. dorsalis n. ulnaris (Fig. 10).
Another branch of ramus palmaris n. ulnaris at the level of the pisiform bone is divided into superficial and deep branches. The superficial branch gives off a branch to m. palmaris brevis, to the skin of the ulnar side of the palm and nn. digitales palmares proprii to both sides of the little finger and the ulnar side of the fourth finger.
Deep branch n. ulnaris passes into the subtendinous space of the hand, accompanying the deep palmar arterial arch. There it gives branches to all the muscles of the little finger (hypothenar), all the interosseous muscles m.m. interossei, the third and fourth worm-shaped muscles (m.m. lumbricales), as well as m. adductor policis, etc. flexor policis brevis (deep head). In addition, the final part of the deep branch n. ulnaris is an anastomosis with n. medianus (Fig. 11).
Radial nerve
Radial nerve - n. radialis (C5-C8, Th1). The nerve leaves the posterior bundle in the armpit area and passes behind a. axillaris and in the upper part of the shoulder area lies between the muscles, enters the canalis nervi radialis, accompanied by a. profunda brachii (Fig. 12), bends around the humerus in a spiral direction from the inside to the outside, pierces the lateral intermuscular septum from back to front and exits in the ulnar fossa between m. brachioradialis and m. brachialis (Fig. 10).
On the shoulder the nerve gives off: Material from the site
- Muscular branches for m. triceps brachii and m. anconeus. From branch r. anconeus gives off a small branch to the lateral epicondyle of the humerus and capsule elbow joint.
- Posterior and lateral, inferior cutaneous branches of the shoulder, n.n. cutan ei brachii posterior et lateralis inferior - for the skin of the posterior and lower part of the lateral surface of the shoulder.
- Posterior cutaneous nerve of the forearm n. cutaneus anterbrachii posterior - lateral posterior terminal nerve of the forearm. Inners the skin of the posterior surface of the forearm.
- Muscular branches to m. brachioradialis and m. extensor carpi radialis longus.
In the area of the ulnar fossa in the sulcus cubitalis lateralis anterior, the radial nerve is divided into superficial and deep branches.
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The upper limb has innervation from the roots C5-C8 with minor additions Th1 and C4. These roots form three bundles: lateral, posterior and medial. They go together in a plexus to the shoulder joint and are divided into two main trunks - the supraclavicular and subclavian parts.
Supraclavicular part of the brachial plexus
The supraclavicular part of the brachial plexus contains the following nerve branches: muscular branches, long thoracic nerve, pectoral nerves, dorsal scapular nerve, suprascapular nerve, thoracodorsal nerve, subclavian nerve and subscapular nerve.Muscular branches supply the scalene muscles and the longus colli muscle.
Subclavian nerve (C5, C6), a very delicate nerve, innervates the subclavian muscle.
Long thoracic nerve (C5-C7) supplies the serratus anterior muscle. Failure of function is detected in the position (installation) of the scapula, when its medial edge lags behind the chest. In this case they speak of “wing-shaped blades”.
Thoracic nerves (C5-Th1) supply the pectoralis major and minor muscles.
Dorsal scapular nerve (C5) innervates both rhomboid muscles and partly the levator scapulae muscle. This muscle also has branches from the cervical plexus. The movement disorder is detected by testing the action of the muscle.
Suprascapular nerve (C4-C6).
It supplies the supraspinatus, abdominal muscles and partly the teres minor muscle. Isolated damage is very rare. Because of this, the resultant force during movement disturbances decreases slightly. The supraspinatus abducts the arm and supports deltoid abduction as a tether muscle. The cavitary and teres minor muscles are involved in external rotation.
Supplies the latissimus dorsi and teres major muscles. It is best to determine their mild weakness with the patient lying on his stomach. He simultaneously lifts both arms in internal rotation and applies resistance to the back of the shoulders.
supplies the subscapularis and teres major muscles. They show their weakness clinically only in internal rotation.
Infraclavicular part of the brachial plexus
Forms a node from which the nerves of the arm and hand emerge. These are the musculocutaneous nerve, axillary nerve, median nerve, ulnar nerve, radial nerve and sensory medial cutaneous nerve of the forearm and medial cutaneous nerve of the shoulder.Musculocutaneous nerve (C4-C6) innervates, together with the motor bundle, the biceps brachii muscle, the coraco- brachialis muscle and brachialis muscle. Failure of the brachialis and biceps brachii muscles is usually easy to identify.
Damage to the coracobrachialis muscle, which is involved in adduction and flexion of the shoulder joint, is difficult to fix. The nerve, after transmitting the motor branch, runs as the lateral cutaneous nerve of the forearm in the forearm region and supplies its radial region.
Axillary nerve (C5, C6) short and strong, supplies two motor muscles, namely the deltoid muscle and the teres minor muscle. You need to be able to determine mainly the failure of the deltoid muscle, while the failure of the teres minor muscle does not play a big role.
Its sensitive branch is considered the lateral cutaneous nerve. It innervates the lateral (side) side of the shoulder girdle and arm.
Median nerve (C6-Th1, sometimes also C5) is a very long nerve, its branch goes to the forearm and to the hand.
As a result (see Table 1.7), the median nerve innervates all the muscles of the inner surface of the forearm, with the exception of the flexor carpi ulnaris and the ulnar part of the deep flexor digitorum, subsequently all the thenar muscles, with the exception of the adductor pollicis muscle and the internal, deep horizontal head flexor brevis thumb brushes It also innervates the first lumbrical muscles.
So, the median nerve innervates the following muscles: pronator teres, flexor carpi radialis, longus palmaris muscle, flexor digitorum superficialis, flexor digitorum profundus ( lateral head), flexor longus pollicis, pronator quadratus, abductor pollicis brevis, oppons pollicis, flexor pollicis brevis (superficial head) and finally the 1st and 2nd lumbricals.
Movement impairment when the median nerve is damaged necessarily occurs; a number of other movements will depend on the radial and ulnar nerves innervating the balancing muscles. Functional failure appears at first glance to be less significant based on the large area of innervation of these nerves.
Table 1.7. Median nerve (innervation of C6 roots
The entire median nerve can be examined clinically. Based on the signs and symptoms, a decision is made about his condition.
1. Hand position: thanks to the intact extensor longus and adductor (adductor muscle), it is possible to bring the 1st finger closer to the other fingers. In this case they talk about the “monkey's paw”.
2. Isolated flexion test of the terminal phalanx of the index finger: the middle link is fixed in extension. With disorders of the median nerve, flexion of the terminal phalanx is impossible due to paralysis of the deep flexor digitorum.
3. Test of the 1st finger: the fingers of the hands move one towards the other, that is, the 1st finger towards the rest. There is no movement of the 1st finger on the paresis side.
4. Circular test: the tip of the 1st finger moves along the bodies of the metacarpal (metacarpal) bones. On the affected side, movement is not possible in full (up to the fifth metacarpal), but only for the first half, if the adductor pollicis muscle is preserved, movement is possible. The second part of the movement (opposition) is impossible to perform with the 1st finger.
5. Symptom of folded hands: the patient clenches his hands into a fist. On the side of the disorder, bending of the first three fingers is impossible; they remain straightened.
6. Opposition and abduction of the 1st finger is impossible.
7. Bottle sign: When grasping the bottle on the weaker side of the paresis, slight pressure is applied to it. A skin fold is formed between the 1st and index fingers due to weak abduction and opposition of the 1st finger, i.e. the bottle is not held tightly.
8. Fist test: on the side of paralysis, the patient cannot clench a fist, since the flexion of the first three fingers is defective.
9. If the median nerve is damaged above the branching of a certain branch, it is also impossible for the pronator teres to perform pronation (inward rotation).
Sensitivity: in the area of the thenar and flexor surface of the 1st finger, in the middle part of the palm, in the 2nd, 3rd and part of the 4th fingers and, finally, on the dorsal side of the distal phalanges of the 2nd and 3rd fingers. In general, not a very wide sensitivity zone. Significant and frequent autonomic disorders and causalgia are observed.
Table 1.8. Ulnar nerve (innervation of C5 roots-Th1). Branch height for individual muscles
The ulnar nerve is a long and powerful nerve that receives fibers from the C5-Th1 roots. It gives off its first branch in the forearm, the main branching occurs only in the palm. Sensitive cutaneous branches supply the dorsal region and palmar side of the ulnar edge of the hand, the 5th finger and the ulnar half of the 4th finger. Inconsistently the entire 4th and ulnar side of the 3rd finger.
The ulnar nerve supplies motor fibers mainly to the small muscles of the hand, with the exception of the opposing muscles, the flexor pollicis brevis, the abductor pollicis muscle, as well as the 1st and 2nd lumbrical muscles.
And so it innervates the following muscles: in the forearm flexor ulnaris the wrists and the internal (medial) head of the deep flexor digitorum, in the hand the adductor pollicis muscle, interosseous muscles (palmar and dorsal), the 3rd and 4th lumbrical muscles, from the short flexor pollicis the internal, deep horizontal head, then the short palmaris, abductor digiti minimi, opponens minimi and flexor digiti brevis.
A number of clinical symptoms when testing for ulnar nerve disorders, through which a conclusion can be made.
1. Hand position: the 1st finger is bent at the interphalangeal joint, the 4th and 5th fingers are extended at the metacarpophalangeal joints, and the other joints are bent. The 2nd and 3rd digits are less involved due to the well-preserved 2nd and 3rd lumbrical muscles. The little finger is secured with spacers due to the predominant activity of the extensor digitorum muscle. In this case, they talk about the claw-shaped position of the fingers.
2. Study of isolated adduction (adduction) and abduction (abduction) of the little finger. On the affected side, the patient cannot make these movements with the little finger.
3. Paper test (for the adductor of the 1st finger): the patient holds a sheet of paper between the 1st and index fingers and tries to stretch it in different sides. On the affected side, flexion in the distal phalanges of the fingers is impossible, so the paper will be grasped only in the healthy hand.
4. Drawing a Circle: When tested in isolated flexion, the major joints will maintain extension of the 2nd and 3rd fingers, while the 4th and 5th fingers will be flexed (3rd and 4th lumbricals paralysis)
5. When examining the mobility of the middle finger: on the affected side, lateral tilt of the middle finger is impossible.
Sensitivity manifests itself in the ulnar half of the dorsum of the hand, also in the hypotenera, in the little finger and the ulnar side of the 4th finger.
Radial nerve (C5-C6).
It gives off two sensory branches in the shoulder: the posterior cutaneous nerve of the shoulder and then distally the posterior cutaneous nerve of the forearm. After branching, the motor branch goes into the skin of the dorsum of the hand.
The radial nerve thus supplies the skin of the arm with sensory branches in a large area, namely the posterior cutaneous nerve of the shoulder, the dorsal region of the shoulder, the posterior cutaneous nerve of the forearm, and the dorsal region of the forearm. Two branches of nerves supply the radial half of the dorsum of the hand.
Table 1.9. Radial nerve (innervation of C5 roots-C8). Branch height for individual muscles
It supplies all the motor muscles of the dorsal side of the shoulder and the dorsal and radial side of the forearm. This triceps shoulder, olecranon, brachioradialis, extensor carpi radialis longus and brevis, supinator, extensor digitorum, extensor of the little finger, extensor carpi ulnaris, abductor pollicis longus, extensor pollicis longus and brevis, extensor of the index finger.
Symptoms of radial nerve damage.
1. Hand position: forearm pronated, bent at the wrist joint and proximal joints of the fingers, 1st finger down. When clinically observed, they speak of a fallen arm.
2. Finger folding test: the patient cannot fold the extended fingers because the hand is in palmar flexion.
3. Extensor Test: Extension of the arm and major finger joints is impossible. During testing, the fingers come to extension only at the interphalangeal joints due to the lumbrical muscles.
4. With injuries above the center of the shoulder (humerus), the brachioradialis muscle is also involved, flexion and supination are affected, in addition, the triceps brachii and olecranon muscles are affected, extension at the elbow is impaired.
Sensitivity is impaired from the site of injury.
Medial cutaneous nerve of the forearm is a long, thin nerve. It supplies the skin of the palmar and ulnar areas of the forearm with sensitive branches.
Medial cutaneous nerve of the shoulder- a thin nerve that innervates the skin of the ulnar side of the shoulder.
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 subclavian 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. This is where the axillary and radial nerves. 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 (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. Nerve 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 sensory branch of the axillary nerve is 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 shoulder (Fig. 8.4). When the axillary nerve is damaged, the arm hangs like a whip, and moving the shoulder to the side 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 ulnar muscle (apponens), the extensors of the hand and fingers - the long and short radial extensors of the wrist (t. extensor carpi radialis longus et brevis) and extensor digitorum (extensor digitorum), supinator of the forearm (supinator), brachioradialis muscle (brachioradialis), which is involved in flexion and pronation of the forearm, as well as 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 (n. 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 feature lesion of 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 innervated radial nerve brachioradialis muscle (t. brachioradialis). Also characteristic is loss of the tendon reflex from the biceps brachii muscle, raising the shoulder anteriorly. Sensory disturbances can be detected on the outer side of the forearm (Fig. 8.4). 4. Median nerve (p. medianus) - mixed; is 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, abducts 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 the 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 large number autonomic fibers, when it is damaged, trophic disturbances 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 (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 (t. 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 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 possible only with the 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 flexor muscle innervated by the median nerve. thumb (a sign of damage to the ulnar nerve). 7. Cutaneous internal nerve of the forearm (n. cutaneus antebrachii medialis, C8-7h2) - sensitive, originates from the medial bundle of the brachial plexus, in the axillary fossa is located next to the ulnar nerve, descends along the shoulder. in the medial groove of its biceps muscle, innervates the skin of the inner 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. The cause of compression of the plexus can be 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 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. According to anatomical structure The brachial plexus has 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 subclavian 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 to the side 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 ulnar muscle (apponens), the extensors of the hand and fingers - the long and short radial extensors of the wrist (t. extensor carpi radialis longus et brevis) and extensor digitorum (extensor digitorum), supinator of the forearm (supinator), brachioradialis muscle (brachioradialis), which is involved in flexion and pronation of the forearm, as well as 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 (n. 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; is 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, abducts 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 the 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 (t. 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. The cause of compression of the plexus can be 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 superior brachial plexopathy of 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 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 as a result of 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.
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 scalene muscles(mm. scaleni) and to the long muscle of the neck (m. longus colli). Here, between the deep muscles of the neck, the accessory root of the phrenic nerve begins from the anterior branch of the fifth cervical spinal nerve. Above and below the collarbone, nerves emerge from the brachial plexus to provide movement of 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. It passes along the anterior edge of the trapezius muscle (m. trapezius) to the supraspinatus and then the 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. Implemented in broad muscle back (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, which differ 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 segments of the spinal cord 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. Ends with superficial and deep branches, innervating all the muscles of the hand, with the exception of the abductor and opposition muscles of the thumb (m. adductor et opponens pollicis) and the superficial head of the short flexor pollicis (m. flexor pollicis brevis). On the forearm, this nerve innervates the ulnar flexor of the hand (m. flexor carpi ulnaris) and part of the deep flexor of the fingers (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.
