Anatomy and etiology of long thoracic nerve compression. The long thoracic nerve is an exclusively motor nerve that originates from the ventral branches of the C5, C6, and C7 spinal nerves. It passes along with other components of the brachial plexus under the clavicle, then goes down the anterolateral wall chest to the serratus anterior. This big 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 with trauma or with severe physical activity, involving the shoulder girdle in movement. Neuropathy of the long thoracic nerve may be due to idiopathic plexopathy of the brachial plexus.
Clinical picture of the long thoracic nerve mononeuropathies of the long thoracic nerve include pain and weakness in the shoulder joint. Patients have difficulty abducting the arm or lifting it above the head. In the position of the patient with arms extended forward and emphasis on the wall, the phenomenon of "pterygoid scapula" is manifested. The shoulder blade rises above the chest because the weakened serratus muscle cannot hold it.
Diagnosis of the long thoracic nerve set on the basis of the aforementioned clinical signs and the detection on EMG of fibrillation potentials affecting only the serratus anterior muscle. It is technically difficult to determine the long thoracic nerve conduction velocity (PNV), other nerves have normal PNV.
Suprascapular nerve. Compression of the suprascapular nerve.
Anatomy and etiology of suprascapular nerve compression. The suprascapular nerve is a purely motor nerve that originates from the superior bundle of the brachial plexus and passes through the suprascapular notch along the superior edge of the scapula to the supraspinatus and abdominal muscles. The suprascapular nerve is most commonly damaged in injuries associated with excessive anterior flexion at the shoulder joint.
He may be involved in pathological process with idiopathic plexopathy of the brachial plexus.
Clinical picture is pain in the back shoulder joint and weakness of the supraspinatus and infraspinatus muscles. The supraspinatus provides abduction of the arm, while the infraspinatus is responsible for outward rotation of the arm.
Diagnosis set on the basis of anamnesis, clinic, physical data and EDI. Conventional NSNS examinations are normal, but examinations of motor NSNS with recordings from the supraspinatus muscle may reveal a decrease in amplitude or a prolongation of the latency compared to the healthy side.
Posterior scapular nerve
Anatomy and etiology of posterior scapular nerve compression. The posterior scapular nerve (PLN) is a purely motor nerve that originates from the superior bundle of the brachial plexus and passes through the scalene medius to the rhomboid and levator scapula muscles. The defeat of the LN is relatively rare.
Clinical picture of compression of the posterior scapular nerve includes pain in the scapular region and weakness of the rhomboid and levator scapula muscles.
Diagnosis of posterior scapular nerve compression set on the basis of clinical signs and EMG data, revealing fibrillation potentials related to the muscles innervated by the MN. There are no satisfactory methods for estimating WNV for HNV.
Dorsal nerve of the scapula - n. dorsalis scapulae (C5) descends along the medial edge of the scapula together with 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 vascular bundle a.vv. etn. suprascapularis. The bundle 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 that covers it. This nerve innervates m. supraspinatus, m. infraspinatus and 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 axillary 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 is a. thoracica lateralis.
Subscapular nerve
Subscapular nerve - n. subscapularis (С5-С8) passes along the lateral and inferior 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 region of its surgical neck. It gives branches to the shoulder joint, to the muscles m. deltoideus and m. teres minor. In addition, in the posterior region 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.
Passing from the neck to the upper limb, the brachial plexus enters the axilla, in 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 armpit corresponding to trigonum pectoralis, the bundles are separated from each other, and here one can distinguish fasciculus lateralis et medialis, as well as fasciculus posterior. When moving to the third floor of the armpit - 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 for the formation of n. medianus, as well as n. musculocutaneus.
The second leg n comes out of the medial bundle. medianus, n. ulnaris, n. cutaneus brachii and antebrachii medialis.
Back beam - 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 bundle). The nerve lies in front of a. axillaris, then lies in sulcus bicipitalis medialis, where it passes next to a. brachialis. In the upper third of the furrow, it lies laterally from 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 flexors of the fingers along the midline in the sulcus medianus and enters the palm under the retinaculum flexorum, where it can be mistaken for a tendon. On the forearm, the nerve gives branches to all the muscles of the forearm, except m. flexor carpi ulnaris. In addition, n. medianus in the upper third of the forearm gives 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 enters the palm, gives off a superficial cutaneous branch, which innervates a small area of the thenar skin and the palm. On the palm n. medianus innervates the skin of 3.5 fingers, starting from the thumb and ending with the medial surface of the ring finger, as well as thenar muscles, except for m. adductor policis longus and deep head of t. flexor policis brevis, as well as the first and second worm-like muscles (Fig. 11).
Musculocutaneous nerve
Musculocutaneous nerve - n. musculocutaneus (C5-C7). In the upper part of the shoulder, the nerve perforates 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 cubital fossa, becomes the cutaneous nerve - n. cutaneus antebrachii lateralis, which innervates the skin of the radial side of the forearm and thenar skin from the back (Fig. 8).
Ulnar nerve
Ulnar nerve - n. ulnaris (С7-С8, YOU). Passes along the medial surface of the shoulder and on the border of the middle and lower third of the shoulder pierces the medial intermuscular septum together with a. et v. collateralis ulnaris superior (Fig. 9), enters the posterior shoulder bed, goes down, around the medial epicondyle of the shoulder and lies in the sulcus cubitalis posterior (Fig. 12). Here it is covered only by the skin, subcutaneous fatty tissue and its own fascia. On the forearm, the nerve passes into the sulcus ulnaris and lies in the neurovascular bundle a., vv., n. ulnaris (Fig. 10).
The first branches n. ulnaris appear on the forearm - these are rami articulares to the elbow joint. Further there are branches to m. flexor carpi ulnaris and adjacent part m. flexor digitorum profundus.
At the level of the wrist joint, branches depart to the skin of the hypothenar. Here, the nerve gives off skin branches to the back of the hand, where it innervates the skin of the V, VI and ulnar half of the III 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 surface branch gives 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 subtendonous space of the hand, accompanying the deep palmar arterial arch. There it gives branches to all muscles of the little finger (hypothenar), all 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 emerges from the posterior bundle in the armpit, 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 out, pierces the lateral intermuscular septum from back to front and exits in the cubital fossa between m. brachioradialis and m. brachialis (Fig. 10).
On the shoulder, the nerve gives: material from the site
- Muscular branches for m. triceps brachii and m. anconeus. From branch r. anconeus leaves a small branch to the lateral epicondyle of the shoulder 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 back 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. Innervates the skin of the posterior surface of the forearm.
- Muscular branches to m. brachioradialis and m. extensor carpi radialis longus.
In the region of the cubital fossa in the sulcus cubitalis lateralis anterior, the radial nerve divides into superficial and deep branches.
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The upper limb is innervated from C5-C8 roots with small additions of Th1 and C4. These roots form three bundles: lateral, posterior and medial. They go together in the 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, thoracic nerves, dorsal scapular nerve, suprascapular nerve, thoracic nerve, subclavian nerve, and subscapular nerve.Muscular branches supply the scalenus muscles and the longus colli muscle of the neck.
Subclavian nerve (C5, C6), a very delicate nerve, innervates the subclavian muscle.
Long thoracic nerve (C5-C7) Supplies a front gear muscle. Failure of the function is detected in the position (installation) of the scapula, when its medial edge lags behind the chest. In this case, one speaks of "pterygoid blades".
Thoracic nerves (C5-Th1) Supply pectoralis major and minor muscles.
Dorsal nerve of the scapula (C5) innervates both rhomboid muscles and partly the muscle that lifts the scapula. This muscle also has branches from the cervical plexus. A movement disorder is detected by checking the action of the muscle.
Suprascapular nerve (C4-C6).
It supplies the supraspinatus, cavitary, and partially teres minor muscles. Isolated damage is very rare. Because of this, the resultant force in case of violation of movements decreases slightly. The supraspinatus muscle abducts the arm and supports the abduction of the deltoid muscle as a fixation muscle. The abdominal and small round muscles are involved in external rotation.
Supplies the latissimus dorsi and teres major muscles. It is best to determine their slight weakness in the position of the patient lying on his stomach. He simultaneously raises both arms in internal rotation and resists the backs of his shoulders.
Supplies a subscapularis muscle and a big round muscle. They show their weakness clinically only in internal rotation.
Subclavian part of the brachial plexus
Forms a knot 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 muscle of the shoulder, the coracoid shoulder muscle and shoulder muscle. Failure of the function of the brachialis and biceps brachii muscles is usually easy to identify.
Damage to the coracobrachial muscle, which is involved in adduction (adduction) and flexion in the shoulder joint, is difficult to fix. The nerve, after it has transmitted the motor branch, runs as the lateral cutaneous nerve of the forearm in the region of the forearm and supplies its radial region.
Axillary nerve (C5, C6) short and strong, supplies two motor muscles, namely the deltoid muscle and the small round muscle. It is necessary to be able to determine mainly the failure of the deltoid muscle, while the failure of the small round muscle does not play a big role.
Its sensitive branch is considered as the lateral cutaneous nerve. It innervates the lateral (lateral) 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 ulnar flexor of the wrist and the ulnar part of the deep flexor of the fingers, in the future, all the tenar muscles, with the exception of the adductor thumb muscle, and the internal, deep horizontal head flexor thumb short. It also innervates the first worm-like muscles.
So, the median nerve innervates the following muscles: pronator round, radial flexor of the wrist, long palmar muscle, superficial flexor of the fingers, deep flexor of the fingers (lateral head), long flexor thumb, pronator quadratus, abductor pollicis brevis, opposing thumb, flexor pollicis brevis (superficial head), and finally 1st and 2nd worm-like muscles.
Violation of movements in case of damage to the median nerve occurs necessarily, a number of other movements will depend on the radial and ulnar nerves innervating the balancing muscles. Functional failure at first glance seems to be less significant based on the extensive area of innervation of these nerves.
Table 1.7. Median nerve (innervation of roots C6
The entire median nerve can be examined in clinical examination. Based on the signs and symptoms, a decision is made about his condition.
1. Position of the hand: thanks to the intact long extensor and adductor (adductor muscle), it is possible to approach the 1st finger to the rest of the fingers. In this case, they say about the "monkey's paw".
2. Test of isolated flexion of the terminal phalanx of the index finger: the middle link is fixed in extension. With violations of the median nerve, flexion of the terminal phalanx is impossible due to paralysis of the deep flexor of the fingers.
3. Test of the 1st finger: the fingers of the hands move one to the other, that is, the 1st finger to the rest. On the side of the paresis, there is no movement of the 1st finger.
4. Circular test: the tip of the 1st finger moves along the bodies of the metacarpal (metacarpal) bones. On the side of the lesion, movement is not possible in full (up to the 5th metacarpal), but only for the first half, if the adductor thumb 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 squeezes the hands into a fist. On the side of the violation, it is impossible to bend the first three fingers, they remain unbent.
6. Opposition and abduction of the 1st finger are impossible.
7. Sign of the bottle: when grasping the bottle on the weaker side of the paresis, slight pressure is exerted on it. A skin fold forms between the 1st and forefinger due to weak abduction and opposition of the 1st finger, i.e. the bottle is not held tightly.
8. Cam test: on the side of paralysis, the patient cannot clench his 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 impossible for the round pronator, in addition, to perform pronation (inward rotation).
Sensitivity: in the thenar area and the flexor surface of the 1st finger, in the middle part of the palm, in the 2nd, 3rd and partially 4th fingers and, finally, on the dorsal side of the distal phalanges of the 2nd and 3rd fingers. In general, not a very extensive zone of sensitivity. Significant and frequent autonomic disturbances and causalgia are observed.
Table 1.8. Ulnar nerve (innervation of roots C5-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 the first branch in the forearm, the main branching occurs only in the palm. Sensitive cutaneous branches supply the dorsal region and the palmar side of the ulnar edge of the hand, the 5th finger and the ulnar half of the 4th finger. Inconstantly 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 short flexor of the thumb, the muscle that abducts the thumb, and the 1st and 2nd worm-like muscles.
And so it innervates the following muscles: in the forearm, the ulnar flexor of the wrist and the internal (medial) head of the deep flexor of the fingers, in the hand, the adductor thumb muscle, the interosseous muscles (palmar and dorsal), the 3rd and 4th worm-like muscles, from the short flexor of the thumb, the inner, deep horizontal head, further the short palmar muscle, the muscle that removes the little finger, the muscle that opposes the little finger and the short flexor of the little finger.
A number of clinical symptoms during the test of disorders of the ulnar nerve, thanks to which a conclusion can be drawn.
1. Position of the hand: the 1st finger is bent at the interphalangeal joint, the 4th and 5th fingers are extended at the metacarpophalangeal joints, and bent at the other joints. The 2nd and 3rd fingers are less involved due to the well-preserved 2nd and 3rd lumbrical muscles. The little finger is fixed with struts due to the predominance of the activity of the extensor muscle of the fingers. In this case, they talk about the claw-like position of the fingers.
2. Study of isolated adduction (adduction) and abduction (abduction) of the little finger. On the interested 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 compressed with the 1st and forefinger and tries to stretch it in different sides. On the side of the lesion, flexion in the distal phalanges of the fingers is impossible, so the paper will only be clamped in the healthy hand.
4. Drawing a circle: when testing isolated flexion, the main joints will maintain extension of the 2nd and 3rd fingers, and the 4th and 5th fingers will be bent (paralysis of the 3rd and 4th lumbrical muscles)
5. When examining the mobility of the middle finger: on the side of the lesion, a lateral tilt of the middle finger is impossible.
Sensitivity is manifested in the ulnar half of the back of the hand, also in the hypotener, in the little finger and the ulnar side of the 4th finger.
Radial nerve (C5-C6).
It gives two sensory branches in the shoulder: the posterior cutaneous nerve of the shoulder and further distally the posterior cutaneous nerve of the forearm. After branching, the motor branch goes to the skin of the rear of the hand.
The radial nerve thus supplies the skin of the hand with sensory branches in a large area, namely the posterior cutaneous nerve of the arm, the dorsal region of the shoulder, the posterior cutaneous nerve of the forearm, the dorsal region of the forearm. Two branches of nerves supply the radial half of the rear of the hand.
Table 1.9. Radial nerve (innervation of roots C5-C8). Branch height for individual muscles
It supplies the entire motor musculature of the dorsal side of the shoulder and the dorsal and radial sides of the forearm. This triceps shoulder, ulnar muscle, brachioradialis muscle, long and short radial extensor wrist, arch support, extensor of the fingers, extensor of the little finger, extensor carpi ulnaris, long muscle that abducts the thumb, long and short extensors of the thumb, extensor of the index finger.
Symptoms of damage to the radial nerve.
1. The position of the hand: the forearm is pronated, bent at the wrist joint and the proximal joints of the fingers, the 1st finger is lowered down. In clinical observation, they talk about a fallen hand.
2. Finger fold test: The patient is unable to fold the extended fingers because the hand is in palmar flexion.
3. Extensor test: extension of the arm and major finger joints is not possible. When tested, the fingers come to extension only in the interphalangeal joints due to the worm-like muscles.
4. In case of damage above the center of the shoulder (humerus), the brachioradialis muscle is also involved, flexion and supination suffer, in addition, the triceps muscle of the shoulder and the ulna muscle, extension at the elbow is impaired.
Sensitivity is broken from the place of damage.
Medial cutaneous nerve of the forearm is a long, thin nerve. From it, the skin of the palmar and ulnar areas of the forearm is supplied with sensitive branches.
Medial cutaneous nerve of the shoulder- thin nerve, 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 foramens, 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 that make it up Fig. 8.3. Shoulder plexus. I - primary upper beam; II - primary middle beam; III - primary lower beam; P - secondary posterior bundle; L - secondary outer beam; M - secondary internal beam; 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. 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 branches 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 zone 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 that 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. From it begin the axillary and radial nerves. 2. The lateral bundle is made up of the joined anterior branches of the upper and partially middle trunks (C5 C6I, C7). From this bundle originate the musculocutaneous nerve and part (external pedicle - C7) of the median nerve. 3. The medial bundle is a continuation of the anterior branch of the lower primary bundle; from it the ulnar nerve, the cutaneous medial nerves of the shoulder and forearm, as well as part of the median nerve (internal pedicle - C8) are formed, which connects to the external pedicle (in front of the axillary artery), together they form a single trunk of the median nerve. Nerves formed in the brachial plexus belong to the nerves of the neck, shoulder girdle and arm. Nerves of the neck. The innervation of the neck involves short muscle branches (rr. musculares), innervating the deep muscles: intertransverse muscles (mm. intertrasversarif); the long muscle of the neck (m. longus colli), tilting the head to its side, and with the contraction of both muscles, tilting it forward; anterior, middle and posterior scalene muscles (mm. scaleni anterior, medius, posterior), which, with a fixed chest, tilt to their side cervical region spine, and with bilateral contraction, tilt it forward; if the neck is fixed, then the scalene muscles, contracting, raise the 1st and 2nd ribs. Nerves shoulder girdle . The nerves of the shoulder girdle originate 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 (t. subclavius), which, when contracted, shifts the clavicle down and medially. 2. The anterior pectoral nerves (pp. thoracales anteriores, C5-Th1) innervate the pectoralis major and minor muscles (mm. pectorales major et minor). The contraction of the first of them causes the adduction and rotation of the shoulder inward, the contraction of the second - the displacement of the scapula forward and downward. 3. The suprascapular nerve (p. suprascapular, C5-C6) innervates the supraspinatus and infraspinatus muscles (t. supraspinatus et t. infraspinatus); the first contributes to the abduction of the shoulder, the second rotates it outward. Sensitive branches of this nerve innervate the shoulder joint. 4. The subscapular nerves (pp. subscapulars, C5-C7) innervate the subscapularis muscle (t. subscapularis), which rotates the shoulder inward, and the large round muscle (t. teres major), which rotates the shoulder inward (pronation), abducts it back and leads to the torso. 5. The 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 hand above the horizontal level. The defeat of the posterior nerves of the chest leads to asymmetry of the shoulder blades. When moving in the shoulder joint, the winged shape of the scapula on the side of the lesion is characteristic. 6. The thoracic nerve (p. thoracodorsal, C7-C8) innervates the latissimus dorsi muscle (t. latissimus dorsi), 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 hand are formed from the secondary bundles of the brachial plexus. The axillary and radial nerves are formed from the posterior longitudinal bundle, the musculocutaneous nerve and the external pedicle of the median nerve are formed from the external secondary bundle; 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, abducts the shoulder to a horizontal level and pulls it back or forward, as well as a small round 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 (p. 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). With damage to the axillary nerve, the arm hangs like a whip, the removal of the shoulder to the side forward or backward is impossible. 2. Radial nerve (n. radialis, C7 partly C6, C8, Th1) - mixed; but mainly motor, it innervates mainly the extensor muscles of the forearm - the triceps muscle of the shoulder (t. triceps brachii) and the ulnar muscle (t. apponens), the extensors of the hand and fingers - the long and short radial extensors of the wrist (mm. extensor carpi radialis longus et brevis) and the extensor of the fingers (t. extensor digitorum), the arch support of the forearm (t. supinator), the brachioradialis muscle (t. brachioradialis), which takes part in flexion and pronation of the forearm, as well as the muscles that cover the thumb of the hand ( tt. abductor pollicis longus et brevis), short and long extensors of the thumb (tt. 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 back of the shoulder; the lower lateral cutaneous nerve of the shoulder (n. cutaneus brachii lateralis inferior), which innervates 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) , involved in the innervation of the back surface of the hand, as well as the back surface of 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 - 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. Hanging brush with damage to the radial nerve. Rice. 8.7. The test of dilution of the palms and fingers in case of damage to the right radial nerve. On the side of the lesion, bent fingers “glide” along the palm of a healthy hand. characteristic feature damage to the radial nerve is a hanging brush, located in the position of pronation (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 an extended forearm, are impossible; the carporadial periosteal reflex is reduced or not elicited. In the case of a high lesion of the radial nerve, the extension of the forearm is also impaired due to paralysis of the triceps muscle of the shoulder, while the tendon reflex from the triceps muscle of the shoulder is not caused. If you attach your palms to each other, and then try to spread them, then on the side of the lesion of the radial nerve, the fingers do not straighten, sliding along the palmar surface of a 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. Especially often damage to the radial nerve occurs with fractures of the shoulder. Often, infections or intoxications, including chronic alcohol intoxication, are also the cause of damage to the radial nerve. 3. Musculocutaneous nerve (n. musculocutaneus, C5-C6) - mixed; motor fibers innervate the biceps muscle of the shoulder (t. biceps brachii), which flexes the arm at the elbow joint and supinates the bent forearm, as well as the shoulder muscle (t. brachialis) y involved in flexion of the forearm, and the coracobrachial muscle (t. coracobrachial ^ ^ contributing 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 to the elevation of the thumb.When the musculocutaneous nerve is affected, the flexion of the forearm is disturbed. This comes to light especially clearly with the supinated forearm, since flexion of the pronated forearm is possible due to the brachioradialis innervated by the radial nerve (i.e. brachioradialis).Prolapse of the tendon reflex from the biceps of the shoulder, raising the shoulder anteriorly is also characteristic.Sensitivity disorder can be detected on the outside forearm (Fig. 8.4) 4. Median nerve (p. medianus) - mixed; is formed from a part of the fibers of the medial and lateral bundle of the brachial plexus. At shoulder level, the median nerve does not give branches. The muscular branches (rami musculares) extending from it to the forearm and hand innervate the round pronator (i.e. pronator teres), penetrating the forearm and contributing to its flexion. radial flexor wrist (t. flexor carpi radialis), along with flexion of the wrist, diverts the hand to the radial side and participates in flexion of the forearm. The long palmar muscle (t. palmaris longus) stretches the palmar aponeurosis and is involved in flexion of the hand and forearm. The superficial flexor of the fingers (t. digitorum superficialis) flexes the middle phalanges of the II-V fingers, participates in the flexion of the hand. In the upper third of the forearm, the palmar branch of the median nerve (ramus palmaris n. mediant) departs from the median nerve. It passes in front of the interosseous septum between the long flexor of the thumb and the deep flexor of the fingers and innervates the long flexor of the thumb (i.e. flexor pollicis longus), which flexes the nail phalanx of the thumb; part of the deep flexor of the fingers (t. flexor digitorum profundus), which flexes the nail and middle phalanges of the II-III fingers and the hand; square pronator (t. pronator quadratus), penetrating the forearm and hand. At the level of the wrist, the median nerve divides into 3 common palmar digital nerves (pp. digitaks palmares communes) and their own palmar digital nerves (pp. digitaks palmares proprii) extending from them. They innervate the short muscle that abducts the thumb (t. abductor pollicis brevis), the muscle that opposes the thumb of the hand (t. opponens policis), the short flexor of the thumb (t. flexor pollicis brevis) and I-11 vermiform 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, II, III fingers and the radial side of the IV finger, as well as the back 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 elevation of the thumb atrophy over time. The thumb in such cases is in the same plane with the rest. As a result, the palm acquires a typical form for lesions of the median nerve, known as the “monkey hand” (Fig. 8.8a). If the median nerve is affected at the level of the shoulder, there is a disorder of all functions, depending on its condition. To identify impaired functions of the median nerve, the following tests can be carried out: a) when trying to clench the hand into a fist, I, II, and partly III fingers remain extended (Fig. 8.86); if the palm is pressed against the table, then the scratching movement with the nail of the index finger fails; c) to hold a strip of paper between the thumb and forefinger due to the impossibility of bending 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 vegetative fibers, when it is damaged, trophic disorders are usually pronounced and more often than when any other nerve is damaged, causalgia develops, manifesting itself in the form of sharp, burning, diffuse pain. Rice. 8.8. Damage to the median nerve. a - "monkey brush"; b - when squeezing the hand into a fist, fingers I and II do not bend. 5. Ulnar nerve (n. ulnaris, C8-Th1) - mixed; it begins in the axilla 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 depart from the ulnar nerve to the following muscles: the ulnar flexor of the hand (i.e., flexor carpi ulnaris), the flexor and adductor hand; the medial part of the deep flexor of the fingers (t. 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 elevation of the little finger (hypotenar). On the border between the middle and lower thirds 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 (n. digitales dorsales), which terminate in the skin of the back 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 palmar muscle, which pulls the skin to the palmar aponeurosis, then it is divided into common and proper palmar digital nerves (n. 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 final phalanges, as well as the back side of the nail phalanx of the fifth finger. The deep branch penetrates deep into the palm of the hand, goes to the radial side of the hand and innervates the following muscles: the muscle that leads to the greater palea (t. adductor policis), the adductor V finger (t. abductor digiti minim f), which flexes the main phalanx of the V finger, the muscle , which opposes the V finger (i.e. opponens digiti minimi) - she brings the little finger to the midline of the brush and opposes it; deep head of the short flexor of the thumb (ie flexor pollicis brevis); worm-like muscles (tt. lumbricales), muscles that flex the main and extensor the middle and nail phalanges of the II and IV fingers; palmar and dorsal interosseous muscles (mm. interossei palmales et dorsales), which flex the main phalanges and simultaneously extend the other phalanges of the II-V fingers, as well as the fingers abducting the II and IV from the middle (III) finger and adducting the 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 back surface of the V and partly the IV fingers and the palmar surface of the V, IV and partly III fingers (Fig. 8.4, 8.5). In cases of damage to the ulnar nerve due to developing atrophy interosseous muscles , as well as overextension of the main and flexion of the remaining phalanges of the fingers, a claw-like brush is formed, resembling a bird's paw (Fig. 8.9a). To identify signs of damage to the ulnar nerve, the following tests can be carried out: a) when trying to clench the hand into a fist, V, IV, and partly III, the fingers bend insufficiently (Fig. 8.96); b) scratching movements with the nail of the little finger do not work out with the palm tightly pressed to the table; c) if the palm rests on the table, then spreading and bringing the fingers together are not successful; d) the patient cannot hold a strip of paper between the index and straightened thumbs. 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, departs from the medial bundle of the brachial plexus, at the level of the axillary fossa has connections with the external skin branches (rr. cutani laterales) II and III of the thoracic nerves ( pp. thoracales) and innervates the skin of the medial surface of the shoulder to the elbow joint (Fig. 8.4). Fig. 8.9. Signs of damage to the ulnar nerve: claw-like brush (a), when the hand is compressed into a fist V and IV, the fingers do not bend (b) Fig. 8.10 Thumb test In the right hand, pressing a strip of paper is possible only with a straightened thumb due to its adductor muscle innervated by the ulnar nerve (a sign of damage to the median nerve). thumb (a sign of damage to the ulnar nerve). in the medial groove of his biceps muscle, innervates the skin of the inner surface of the forearm (Fig. 8.4). Syndromes of lesions of the brachial plexus. Along with an isolated lesion of 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 supraclavicular and subclavian regions, fracture of the clavicle, 1st rib, periostitis of the 1st rib, dislocation of the humerus. Sometimes the plexus is affected due to its overstretching, with a quick and strong abduction of the arm back. Damage to the plexus is also possible in a position where the head is turned in the opposite direction, and the hand is 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 weights on the shoulders, 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 supraclavicular and subclavian region. Total brachial plexopathy leads to flaccid paralysis of all muscles of the shoulder girdle and arm, while only the ability to “lift the shoulder girdle” can 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 anatomical structure of the brachial plexus, the syndromes of damage to its trunks (primary bundles) and bundles (secondary bundles) are different. Syndromes of damage to the trunks (primary bundles) of the brachial plexus occur when the supraclavicular part of it is damaged, while syndromes of damage to the upper, middle and lower trunks can be distinguished. I. Syndrome of lesions of 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 foramens, 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 that make it up Fig. 8.3. Shoulder plexus. I - primary upper beam; II - primary middle beam; III - primary lower beam; P - secondary posterior bundle; L - secondary outer beam; M - secondary internal beam; 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. 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 branches 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 zone 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 that 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. From it begin the axillary and radial nerves. 2. The lateral bundle is made up of the joined anterior branches of the upper and partially middle trunks (C5 C6I, C7). From this bundle originate the musculocutaneous nerve and part (external pedicle - C7) of the median nerve. 3. The medial bundle is a continuation of the anterior branch of the lower primary bundle; from it the ulnar nerve, the cutaneous medial nerves of the shoulder and forearm, as well as part of the median nerve (internal pedicle - C8) are formed, which connects to the external pedicle (in front of the axillary artery), together they form a single trunk of the median nerve. Nerves formed in the brachial plexus belong to the nerves of the neck, shoulder girdle and arm. Nerves of the neck. The innervation of the neck involves short muscle branches (rr. musculares), innervating the deep muscles: intertransverse muscles (mm. intertrasversarif); the long muscle of the neck (m. longus colli), tilting the head to its side, and with the contraction of both muscles, tilting it forward; anterior, middle and posterior scalene muscles (mm. 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 shoulder girdle originate 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 (t. subclavius), which, when contracted, shifts the clavicle down and medially. 2. The anterior pectoral nerves (pp. thoracales anteriores, C5-Th1) innervate the pectoralis major and minor muscles (mm. pectorales major et minor). The contraction of the first of them causes the adduction and rotation of the shoulder inward, the contraction of the second - the displacement of the scapula forward and downward. 3. The suprascapular nerve (p. suprascapular, C5-C6) innervates the supraspinatus and infraspinatus muscles (t. supraspinatus et t. infraspinatus); the first contributes to the abduction of the shoulder, the second rotates it outward. Sensitive branches of this nerve innervate the shoulder joint. 4. The subscapular nerves (pp. subscapulars, C5-C7) innervate the subscapularis muscle (t. subscapularis), which rotates the shoulder inward, and the large round muscle (t. teres major), which rotates the shoulder inward (pronation), abducts it back and leads to the torso. 5. The 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 hand above the horizontal level. The defeat of the posterior nerves of the chest leads to asymmetry of the shoulder blades. When moving in the shoulder joint, the winged shape of the scapula on the side of the lesion is characteristic. 6. The thoracic nerve (p. thoracodorsal, C7-C8) innervates the latissimus dorsi muscle (t. latissimus dorsi), 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 hand are formed from the secondary bundles of the brachial plexus. The axillary and radial nerves are formed from the posterior longitudinal bundle, the musculocutaneous nerve and the external pedicle of the median nerve are formed from the external secondary bundle; 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, abducts the shoulder to a horizontal level and pulls it back or forward, as well as a small round muscle (t. teres minor), which rotates the shoulder outward. The sensitive branch of the axillary nerve - the upper 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). With damage to the axillary nerve, the arm hangs like a whip, the removal of the shoulder to the side forward or backward is impossible. 2. Radial nerve (n. radialis, C7 partly C6, C8, Th1) - mixed; but mainly motor, it innervates mainly the extensor muscles of the forearm - the triceps muscle of the shoulder (t. triceps brachii) and the ulnar muscle (t. apponens), the extensors of the hand and fingers - the long and short radial extensors of the wrist (mm. extensor carpi radialis longus et brevis) and the extensor of the fingers (t. extensor digitorum), the arch support of the forearm (t. supinator), the brachioradialis muscle (t. brachioradialis), which takes part in flexion and pronation of the forearm, as well as the muscles that cover the thumb of the hand ( t. abductor pollicis longus et brevis), short and long extensors 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 back of the shoulder; the lower lateral cutaneous nerve of the shoulder (n. cutaneus brachii lateralis inferior), which innervates 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) , involved in the innervation of the back surface of the hand, as well as the back surface of 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 - 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. Hanging brush with damage to the radial nerve. Rice. 8.7. The test of dilution of the palms and fingers in case of damage to the right radial nerve. On the side of the lesion, bent fingers “glide” along the palm of a healthy hand. A characteristic sign of a lesion of the radial nerve is a hanging brush, located in the position of pronation (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 an extended forearm, are impossible; the carporadial periosteal reflex is reduced or not elicited. In the case of a high lesion of the radial nerve, the extension of the forearm is also impaired due to paralysis of the triceps muscle of the shoulder, while the tendon reflex from the triceps muscle of the shoulder is not caused. If you attach your palms to each other, and then try to spread them, then on the side of the lesion of the radial nerve, the fingers do not straighten, sliding along the palmar surface of a 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. Especially often damage to the radial nerve occurs with fractures of the shoulder. Often, infections or intoxications, including chronic alcohol intoxication, are also the cause of damage to the radial nerve. 3. Musculocutaneous nerve (n. musculocutaneus, C5-C6) - mixed; motor fibers innervate the biceps muscle of the shoulder (t. biceps brachii), which flexes the arm at the elbow joint and supinates the bent forearm, as well as the shoulder muscle (t. brachialis) y involved in flexion of the forearm, and the coracobrachial muscle (t. coracobrachial ^ ^ contributing 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 to the elevation of the thumb.When the musculocutaneous nerve is affected, the flexion of the forearm is disturbed. This comes to light especially clearly with the supinated forearm, since flexion of the pronated forearm is possible due to the brachioradialis innervated by the radial nerve (i.e. brachioradialis).Prolapse of the tendon reflex from the biceps of the shoulder, raising the shoulder anteriorly is also characteristic.Sensitivity disorder can be detected on the outside forearms (Fig. 8.4). 4. Median nerve (p. medianus) - mixed; is formed from a part of the fibers of the medial and lateral bundle of the brachial plexus. At shoulder level, the median nerve does not give branches. The muscular branches (rami musculares) extending from it to the forearm and hand innervate the round pronator (i.e. pronator teres), penetrating the forearm and contributing to its flexion. The radial flexor of the wrist (i.e. flexor carpi radialis), along with flexion of the wrist, diverts the hand to the radial side and participates in flexion of the forearm. The long palmar muscle (t. palmaris longus) stretches the palmar aponeurosis and is involved in flexion of the hand and forearm. The superficial flexor of the fingers (t. digitorum superficialis) flexes the middle phalanges of the II-V fingers, participates in the flexion of the hand. In the upper third of the forearm, the palmar branch of the median nerve (ramus palmaris n. mediant) departs from the median nerve. It passes in front of the interosseous septum between the long flexor of the thumb and the deep flexor of the fingers and innervates the long flexor of the thumb (i.e. flexor pollicis longus), which flexes the nail phalanx of the thumb; part of the deep flexor of the fingers (t. flexor digitorum profundus), which flexes the nail and middle phalanges of the II-III fingers and the hand; square pronator (t. pronator quadratus), penetrating the forearm and hand. At the level of the wrist, the median nerve divides into 3 common palmar digital nerves (pp. digitaks palmares communes) and their own palmar digital nerves (pp. digitaks palmares proprii) extending from them. They innervate the short muscle that abducts the thumb (t. abductor pollicis brevis), the muscle that opposes the thumb of the hand (t. opponens policis), the short flexor of the thumb (t. flexor pollicis brevis) and I-11 vermiform 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, II, III fingers and the radial side of the IV finger, as well as the back 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 elevation of the thumb atrophy over time. The thumb in such cases is in the same plane with the rest. As a result, the palm acquires a typical form for lesions of the median nerve, known as the “monkey hand” (Fig. 8.8a). If the median nerve is affected at the level of the shoulder, there is a disorder of all functions, depending on its condition. To identify impaired functions of the median nerve, the following tests can be carried out: a) when trying to clench the hand into a fist, I, II, and partly III fingers remain extended (Fig. 8.86); if the palm is pressed against the table, then the scratching movement with the nail of the index finger fails; c) to hold a strip of paper between the thumb and forefinger due to the impossibility of bending 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 vegetative fibers, when it is damaged, trophic disorders are usually pronounced and more often than when any other nerve is damaged, causalgia develops, manifesting itself in the form of sharp, burning, diffuse pain. Rice. 8.8. Damage to the median nerve. a - "monkey brush"; b - when squeezing the hand into a fist, fingers I and II do not bend. 5. Ulnar nerve (n. ulnaris, C8-Th1) - mixed; it begins in the axilla 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 depart from the ulnar nerve to the following muscles: the ulnar flexor of the hand (i.e., flexor carpi ulnaris), the flexor and adductor hand; the medial part of the deep flexor of the fingers (t. 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 elevation of the little finger (hypotenar). On the border between the middle and lower thirds 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 (n. digitales dorsales), which terminate in the skin of the back 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 palmar muscle, which pulls the skin to the palmar aponeurosis, further it is 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 final phalanges, as well as the back side of the nail phalanx of the fifth finger. The deep branch penetrates deep into the palm of the hand, goes to the radial side of the hand and innervates the following muscles: the muscle that leads to the greater palea (t. adductor policis), the adductor V finger (t. abductor digiti minim f), which flexes the main phalanx of the V finger, the muscle , opposing the V finger (t. opponens digiti minimi) - it brings the little finger to the midline of the brush and opposes it; deep head of the short flexor of the thumb (ie flexor pollicis brevis); worm-like muscles (tt. lumbricales), muscles that flex the main and extensor the middle and nail phalanges of the II and IV fingers; palmar and dorsal interosseous muscles (mm. interossei palmales et dorsales), which flex the main phalanges and simultaneously extend the other phalanges of the II-V fingers, as well as the fingers abducting the II and IV from the middle (III) finger and adducting the 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 back surface of the V and partly the IV fingers and the palmar surface of the V, IV and partly III 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-like brush is formed, resembling a bird's paw (Fig. 8.9a). To identify signs of damage to the ulnar nerve, the following tests can be carried out: a) when trying to clench the hand into a fist, V, IV, and partly III, the fingers bend insufficiently (Fig. 8.96); b) scratching movements with the nail of the little finger do not work out with the palm tightly pressed to the table; c) if the palm rests on the table, then spreading and bringing the fingers together are not successful; d) the patient cannot hold a strip of paper between the index and straightened thumbs. 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, departs from the medial bundle of the brachial plexus, at the level of the axillary fossa has connections with the external skin branches (rr. cutani laterales) II and III of the thoracic nerves ( pp. thoracales) and innervates the skin of the medial surface of the shoulder to the elbow joint (Fig. 8.4). Fig. 8.9. Signs of damage to the ulnar nerve: claw-like brush (a), when the hand is compressed into a fist V and IV, the fingers do not bend (b) . Rns. 8.10. Thumb test. In the right hand, pressing a strip of paper is possible only 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, the paper strip is pressed by the long muscle innervated by the median nerve, which flexes the thumb (a sign of damage to the ulnar nerve). 7. Cutaneous internal nerve of the forearm (n. cutaneus antebrachii medialis, C8-7h2) - sensitive, departs 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 internal early surface of the forearm (Fig. 8.4). Syndromes of lesions of the brachial plexus. Along with an isolated lesion of 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 supraclavicular and subclavian regions, fracture of the clavicle, 1st rib, periostitis of the 1st rib, dislocation of the humerus. Sometimes the plexus is affected due to its overstretching, with a quick and strong abduction of the arm back. Damage to the plexus is also possible in a position where the head is turned in the opposite direction, and the hand is 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 weights on the shoulders, 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 supraclavicular and subclavian region. Total brachial plexopathy leads to flaccid paralysis of all muscles of the shoulder girdle and arm, while only the ability to “lift the shoulder girdle” can 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, the syndromes of damage to its trunks (primary bundles) and bundles (secondary bundles) differ. Syndromes of damage to the trunks (primary bundles) of the brachial plexus occur when the supraclavicular part of it is damaged, while 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> occurs when the anterior branches of the V and VI cervical spinal nerves are damaged (traumatic) or the part of the plexus in which these nerves are connected, 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. Upper brachial Erb-Duchenne plexopathy is characterized by a combination of signs of damage to the axillary nerve, long thoracic nerve, anterior thoracic nerves, subscapular nerve, dorsal nerve of the scapula, 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, brachial, brachioradial muscles and arch support), impaired shoulder abduction, flexion and supination of the forearm. As a result, the hand hangs down like a whip, is adducted and pronated, the patient cannot raise his hand, bring his hand to his mouth. If the hand is passively supinated, it will immediately turn inward again. The reflex from the biceps muscle and the radiocarpal (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 supraclavicular Erb point. A few weeks after the defeat of the plexus, an increasing hypotrophy of the paralyzed muscles appears. Erb-Duchenne brachial plexopathy often occurs with injuries, it is possible, in particular, when falling on an outstretched arm, it may be a consequence of plexus compression during a long stay with the arms wound under the head. Sometimes it appears in newborns with pathological childbirth. 2. Syndrome of damage to 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 three-headed muscle of the shoulder, the extensor of the thumb and the long abductor of the thumb are not completely affected, since along with the fibers of the VII cervical spinal nerve, fibers that have come to 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 tendon of the triceps muscle and the wrist (carpo-radial) reflex are not called. Sensitive disturbances are limited to a narrow band of hypalgesia on the dorsal surface of the forearm and the radial part of the dorsal surface of the hand. 3. The syndrome of lesions of the lower trunk of the brachial plexus (lower brachial plexopathy Dejerine-Klumpke) occurs when the 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 inner pedicle). In this regard, with Dejerine-Klumke paralysis, paralysis or paresis of the muscles, mainly of the distal part of the arm, occurs. It suffers mainly from the ulnar part of the forearm and hand, where sensory disturbances and vasomotor disorders are detected. It is impossible or difficult to extend and abduct the thumb due to paresis of the short extensor of the thumb and the muscle that abducts the thumb, innervated by the radial nerve, since the impulses going to these muscles pass through the fibers that are part of the VIII cervical and I thoracic spinal cords. cerebral nerves and the lower trunk of the brachial plexus. Sensitivity on the arm is impaired on the medial side of the shoulder, forearm and hand. If, simultaneously with the defeat of the brachial plexus, the white connecting branches leading to the stellate node (ganglion stellatum) also suffer, then manifestations of Horner's syndrome are possible (narrowing of the pupil, palpebral fissure and mild enophthalmos. In contrast to the combined paralysis of the median and ulnar non- ditches, the function of the muscles innervated by the external leg of the median nerve, with the syndrome of the lower trunk of the brachial plexus, is preserved.Dejerine-Klumke palsy often occurs due to a traumatic lesion of the brachial plexus, but may also be the result of compression of it by the cervical rib or Pancoast's tumor.Syndromes of lesions of the bundles (secondary bundles) of the brachial plexus arise in pathological processes and injuries in the subclavian region and, in turn, are divided into lateral, medial and posterior fascicular syndromes.These syndromes practically correspond to the clinic of the combined lesion of the peripheral nerves formed from the corresponding bundles of the brachial plexus. bundle is manifested by a violation of the functions of the musculocutaneous nerve and the upper pedicle of the median nerve, the syndrome of the posterior bundle is characterized by a violation of the functions of the axillary and radial nerve, and the syndrome of the medial bundle is expressed by a violation of the functions of the ulnar nerve, the medial pedicle of the median nerve, medial cutaneous nerves shoulders and forearms. With the defeat of two or three (all) bundles of the brachial plexus, there is a corresponding summation of clinical signs characteristic of syndromes in which its 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. 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) along with the subclavian artery. This part of it is called supraclavicular (pars supraclavicular, tsvetn. fig. 2). From here, the nerve trunks of the second order are directed laterally and down to the axillary region, forming the subclavian part of the brachial plexus (pars infraclavicularis).
At the very beginning of the formation of the brachial plexus, muscle branches depart 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 from the anterior branch of the fifth cervical spinal nerve, an additional root of the phrenic nerve begins. Above and below the clavicle, nerves exit from the brachial plexus, providing movement of the shoulder girdle and shoulder.
The dorsal nerve of the scapula (n. dorsalis scapulae) comes from C V. It innervates the rhomboid muscles (mm. rhomboidei) and the muscle that lifts the scapula (m. levator scapulae).
The suprascapular nerve (n. suprascapular) comes from C V -C VI. Passes along the anterior edge of the trapezius muscle (m. trapezius) to the supraspinatus, and then the infraspinatus fossae. It innervates the supraspinatus and infraspinatus muscles (mm. supra-et infraspinatus) and the capsule of the shoulder joint. The long nerve of the chest (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. A branch of slight thickness follows the subclavian muscle (m. subclavius) and innervates it. The medial and lateral nerves of the chest are derived from C V -Th I. They supply nerve fibers to the pectoralis major and minor muscles (mm. pectorales major et minor). The subscapular nerve (n. subscapularis) comes from C V -CVII. Innervates the muscle of the same name and the large round muscle (m. teres major). The thoracic-spinal nerve (n. thoracodorsalis) comes from C VII -C VIII. Implemented in broad muscle back (m. latissimus dorsi) and innervates it.
Three bundles of the subclavian part of the brachial plexus - medial, lateral and posterior (fasciculus medialis, lateralis et posterior) - are divided into nerves of the upper limb, which are of considerable length. From the medial bundle in the axillary cavity, 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 lateral bundle arise the lateral root of the median nerve and the musculocutaneous nerve. The posterior bundle gives 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. It is located closer to the medial surface of the shoulder and forearm. Approaching the brush, gives skin branches to its palmar and dorsal surfaces. It ends with superficial and deep branches that innervate all the muscles of the hand, with the exception of the abductor and opposing muscles of the thumb (m. adductor et opponens pollicis) and the superficial head of the short flexor of the thumb (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 goes along with brachial artery, in the middle crosses the cubital fossa. On the forearm, it innervates the anterior muscle group, in addition to the muscles that the ulnar nerve innervates, 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 muscle group of the shoulder and ends as the cutaneous nerve of the lateral surface of the forearm (n. cutaneus antebrachii lateralis).
The radial nerve (n. radialis) comes from C V -C VIII. Through the brachio-muscular canal it reaches the elbow bend, where it is divided into deep and superficial branch. Innervates m. triceps brachii and the posterior muscle group 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 a four-sided opening to the neck of the humerus, where it is divided into branches to the deltoid and small round muscles (m. deltoideus et teres minor) and to the lateral surface of the skin of the shoulder (printing. Fig. 4).
The composition of the brachial plexus includes (through gray connecting branches from the stellate and two upper thoracic sympathetic nodes) autonomic conductors that spread 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. muscle 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 on the skin of the upper limb.
