BRACHIAL PLEXUS

From Big Medical Encyclopedia

BRACHIAL PLEXUS [plexus brachialis (PNA, JNA, BNA)] — the neuroplex formed by front branches four lower cervical and the I chest spinal nerves. Sometimes of page the thin branch from the IV cervical and the II chest nerves joins P.

Anatomy

the page is located P. in a lower part of lateral area of a neck and in an axillary cavity (axillary area, T.). Total length it apprx. 15 — 20 cm. Nerves of a texture innervate muscles, skin, joints and other formations of an upper extremity and nek-ry muscles of a neck. Front branches of the spinal nerves forming P. of page after escaping of intervertebral foramens are located in interladder space (a crack between front and average scalenes), and front branches of the V—VII cervical nerves go vertically down, a branch of the VIII cervical nerve — in the horizontal direction, a front branch of the I chest nerve — vertically up. Connecting among themselves, they form three nervous trunks in a big supraclavicular pole: upper (truncus sup.), formed by front branches of the V—VI cervical nerves; average (truncus med.), being continuation of a front branch of the VII cervical nerve; lower (truncus inf.), formed by branches of the VIII cervical and the I chest nerves. Upper and average trunks lie above a subclavial artery, lower — behind it. These trunks form a supraclavicular part of a texture (pars supraclavicularis) from which short nerves, the innervating muscles of a belt of an upper extremity, except for a trapezoid muscle (m. trapezius), nek-ry muscles of a neck and a shoulder joint form. Trunks of a texture, in turn, are divided into front and back divisions (divisiones anteriores et posteriores), to-rye, having passed under a clavicle in an axillary cavity, form a subclavial part of a texture (pars infraclavicu-laris), and back divisions of all three trunks create a back bunch (fasc. posterior), front divisions of upper and average trunks — a medial bunch (fasc. medialis), front division of the lower trunk proceeds in a lateral bunch (fasc. lateralis). These bunches surround an axillary artery from three parties: from lateral — a lateral bunch, with medial — a medial bunch, behind — a back bunch.

Depart from a supraclavicular part of a texture: dorsal nerve of a shovel, long chest, nadlopatochny, subclavial, infrascapular, axillary, medial and lateral chest nerves. 1. The dorsal nerve of a shovel (n. dorsalis scapulae) is formed of an upper trunk, contains Cv fibers, is located along medial edge of a shovel, innervates big and small rhomboid muscles (mm. rhomboideus major et minor) and the muscle raising a shovel (m. levator scapulae). 2. The long chest nerve (n. thoracicus longus) is formed of upper and average trunks, contains Cv nerve fibrils — CVII, goes on the surface of a front gear muscle (m. serratus anterior) and innervates it. 3. The Nadlopatochny nerve (n. suprascapularis) is formed of an upper trunk, contains Cv fibers — CVI, goes on the dorsal surface of a shovel where innervates over - and under-ostnuyu muscles (mm. supraspinatus et infraspinatus). 4. The subclavial nerve (n. subclavius) is formed of an upper trunk, contains Cv fibers, innervates the muscle (m. subclavius) of the same name. 5. Medial and lateral chest nerves [nn. pectorales medialis et lateralis (subclavial part of a brachial plexus, T.)] form from all three trunks, contain Cv fibers — CVIII and Thj, several thin branches go on a front surface of a breast where innervate big and small pectoral muscles (mm. pectorales major et minor). 6. Infrascapular nerve [n. subscapularis (subclavial part of a brachial plexus, T.)] it is formed of all three trunks, contains Cv fibers — CVIII, two-three branches goes down on a front surface of the muscle (m. subscapularis) of the same name, innervating her and big round muscle (t. teres major). The branch of this nerve going along lateral edge of a shovel is called a grudospinny nerve (n. thoracodorsalis) and innervates the broadest muscle of a back (t. latissimus dorsi). 7. Axillary, or axillary, nerve [n. axillaris (subclavial part of a brachial plexus, T.)] forms from upper and average trunks, contains CV—CVII fibers. Through a quadrilateral opening (foramen quadrilaterum) passes to a back surface of a shoulder where innervates a deltoid muscle (m. deltoideus), a small round muscle (. teres minor) and a shoulder joint, and its skin branch (n. cutaneus brachii lateralis) innervates skin of deltoid area and adjacent sites of a posterolateral surface of a shoulder.

Fig. 1. Diagrammatic representation of a subclavial part of a brachial plexus: 1 — an axillary artery, 2 — an axillary vein, 3 — a brachial plexus, 4 — chest nerves, 5 — an axillary nerve, 6 — an infrascapular nerve, 7 — a long chest nerve, 8 — grudospinny a nerve, 9 — a medial cutaneous nerve of a shoulder, 10 — a beam nerve, 11 — an elbow nerve, 12 — a medial cutaneous nerve of a forearm, 13 — a median nerve, 14 — a musculocutaneous nerve.

The long nerves going on an upper extremity are formed of a subclavial part of a texture (fig. 1). Musculocutaneous, median, elbow, beam nerves, a medial cutaneous nerve of a shoulder and a medial cutaneous nerve of a forearm concern to them. 1. The musculocutaneous nerve (n. musculocutaneus) is formed of a lateral bunch, contains fibers of front branches of the V—VII cervical nerves, probodat a coronoid and humeral muscle (m. coracobrachialis) and branches in front group of muscles of a shoulder; innervates coronoid and humeral, a biceps of a shoulder (m. biceps brachii) and a humeral muscle (. brachialis). It passes into a lateral cutaneous nerve of a forearm (n. cutaneus antebrachii lateralis) which goes down on lateral edge of a forearm, innervates skin of this area and area of an eminence of a thumb (thenar) on a brush. 2. The median nerve (n. medianus) forms from two roots coming from medial and lateral bunches contains fibers of front branches the V—VIII cervical and the I chest nerves (see. Median nerve ). 3. The elbow nerve (n. ulnaris) is formed of a medial bunch, contains CVn fibers — CVIII, ThT (see. Elbow nerve ). 4. The beam nerve (n. radialis) is formed of a back bunch, contains Cv fibers — CVIII, Th1 (see. Beam nerve ). 5. The medial cutaneous nerve of a shoulder (n. cutaneus brachii medialis) is formed of a medial bunch, contains fibers from C8 and Th1, innervates skin of an anteromedial surface of a shoulder. 6. The medial cutaneous nerve of a forearm (n. cutaneus antebrachii medialis) is formed of a medial bunch, contains fibers CVIII and Thr, innervates skin of a medial surface of a forearm.

Pathology

injuries (wounds of a neck, a prelum splinters of a bone are the Most frequent reason of defeat of P. of page at fractures of a clavicle or a head of a humeral bone at dislocation of a shoulder, a birth trauma of a texture, etc.). P.'s pathology of page can be caused by a prelum it in axillary area crutches, falling arm-distance, a strong zaprokidyvaniye of hands for the head during sleep. Tumors of a backbone, a top of a lung, an aneurysm of subclavial or axillary arteries, cervical edges can be the cause of defeat of P. of page. Sometimes P. of page is surprised at infectious diseases (flu, quinsy, a brucellosis, tuberculosis, syphilis, etc.), intoxications (carbon monoxide, lead, arsenic, alcohol, etc.).

Defeat of separate trunks or P.'s bunches of page is more often observed, is much more rare — all texture, at the same time a wedge, the picture is defined by hl. obr. level of damage of P. of page. So, at damage of all texture there comes the sluggish flaccid paralysis or paresis of muscles of an upper extremity with absence or decrease in sensitivity, tendon and periosteal jerks, with vegetative and trophic rassaroystvo of the same extremity and is frequent with painful points in over - and subclavial poles (a point of Erba).

Fig. 2. The child with right-hand paralysis Dyushenna — Erba: atrophy of muscles of a belt of an upper extremity and shoulder; the right hand is not raised and not taken aside.

Damage of an upper trunk of P. of page leads to so-called upper paralysis of Dyushenn — Erba of whom droop of a hand and its turn inside are characteristic, impossibility to lift and take away a shoulder (fig. 2), to bend a hand in an elbow joint, difficulty of supination, decrease in sensitivity on the lateral surface of a shoulder and forearm, morbidity in a point of Erba over a clavicle, lack of a reflex from a biceps and decrease in a karporadialny reflex (see. Dyushenna — Erba paralysis ).

Disturbance of functions of the muscles innervated by a beam nerve (function of a humeroradial muscle and an instep support remains), and functions of a beam sgibatel of a wrist and the round pronator innervated by a median nerve can cause damage to an average trunk of P. of page.

At defeat of the lower trunk of P. of page there is so-called lower paralysis Dezherin-Klyumpka (see. Dezherin-Klyumpka paralysis ), which is characterized by a flaccid paralysis of muscles of a sgibately brush and fingers, loss of sensitivity on an inner surface of a shoulder, forearm and brush and Bernard's symptom complex — Horner (narrowing of a pupil and palpebral fissure, an enophthalmos) on the party of paralysis (see. Bernard — Horner a syndrome ).

Defeat of a lateral bunch of P. of page on a wedge, a picture is similar to defeat of an upper trunk of a texture and is shown by dysfunction of a musculocutaneous nerve, partial disturbance of functions of beam and median nerves. Paralysis of a biceps of a shoulder, humeroradial muscle, the round pronator, a long palmar muscle and paresis of sgibatel of fingers and a brush is noted.

Full dysfunction of an elbow nerve, medial cutaneous nerves of a shoulder and forearm, and also partial dysfunction of a median nerve is characteristic of defeat of a medial bunch of P. of page that on a wedge, a picture is similar to defeat of the lower trunk of a texture; there is no Bernard's syndrome — Horner, as well as at more distal defeat of P. of page. At damage "a back bunch of P. of page dysfunction of beam and axillary nerves is noted. Damage of an axillary nerve is shown by paralysis and an atrophy of a deltoid muscle (the patient cannot raise a hand up) and disturbance of sensitivity of skin of deltoid area.

Diagnosis the wedge, a picture with disorders of the movements, reflexes, sensitivity and vegetative and trophic disturbances is based on characteristic.

Treatment

Treatment of defeats of P. of page is directed first of all to elimination of the reason which caused damage, and also recovery of the damaged nerve fibrils of a texture, improvement of their conductivity on the prevention of contractures and elimination of vegetative and trophic frustration; at the same time drug treatment, a fiziobalneoterapiya, LFK, massage is widely carried out. In the presence of indications operational treatment is applied. The important part in recovery of the broken functions P. of page is assigned to sanatorium treatment.

See also Plexitis .



Bibliography: Grigorovich K. A. Surgical treatment of injury of nerves, D., 1981; Kaptelin A. F. and L and with-with to and I am JI. A. Labor therapy in traumatology and orthopedics, M., 1979; Lurye A. S. Surgery of a brachial plexus, M., 1968; A. V Triumphs. Topical diagnosis of diseases of a nervous system, page 84, L., 1974; Physical factors in complex treatment and prevention of internal and nervous diseases, under the editorship of A. N. Obrosov, page 364, M., 1971. See also bibliogr, to St. Plexitis .

N. I. Strelkova; F. V. Sudzilovsky (An.).

Яндекс.Метрика