root or primary

Lesion СVI of a root or primary average fascicle of a plexus causes appreciable abaissement of functions of a radial nerve (remains m. brachioradialis and т. supinator) and partial - median (fibers of order ultram its top leg, in particular, for m. flexor carpi radialis, m. pronator teres, etc.).
Primary fascicles of a plexus share further on forward and back branches. From forward branches of the top and average fascicles (CV, CVI; СVII) the secondary external fascicle (fasciculus lateralis) is made. The secondary internal fascicle is made Of forward branches of the bottom fascicle (CVIII-DII) (fasciculus medialis). At last, from all back branches of primary fascicles (CV, CVI, СVII, СVIII, DI, DII) the secondary back fascicle (fasciculus posterior) is formed. Names of secondary fascicles are caused by their locating rather a. axillaris round which they are located.
Secondary fascicles of a plexus are in a subclavial fossa; further they form nervous trunks of the top extremity: an external fascicle, - n. musculo-cutaneus and the top leg n. mediani; a back fascicle. - n. axillaris and n. radialis, and an internal fascicle. - n. ulnaris, the bottom leg n. mediani and пn. cutanei brachii and antibrachii mediales (fig. 83 see).
The lesion of an external fascicle of a plexus causes full disturbance of function n. musculo-cutanei, partial - n. mediani (fibers of its top leg, in particular m. pronator teres) and limited - n. radialis (mm. brachio-radialis, supinator).
Thus, similarity of a clinical picture of a lesion of the top primary fascicle and a lesion of the secondary external consists in abaissement both in that and in other case of function of a musculocutaneous nerve and the limited abaissement of function radial (for the account mm. brachio-radialis and supinator). The difference consists that at a lesion of a primary top fascicle this combination includes still function abaissement n. axillaris, which at. A lesion of an external secondary fascicle does not suffer; but in the latter case there is a partial lesion n. mediani.
The lesion of an internal fascicle of a plexus and lesion of the bottom primary fascicle give a similar clinical picture, i.e. A lesion combination n. ulnaris, nn. cutanei brachii et antibrachii mediales and a partial lesion n. mediani, its bottom leg. Symptom Горнера in this case as at more distal lesion, it is not observed (see above).
The lesion of a back fascicle is characterised by a lesion combination n. axillaris and n. radialis (except for kept mm. vpxl brachio-radialis and supinator). Similarity to a clinical picture of a lesion of an average primary fascicle consists in identical abaissement of function n. radialis; a difference that at a lesion of a primary average fascicle function n. axillaris remains, but function n instead is partially broken. mediani, its top leg.
Thus, fibers of the bottom primary fascicle pass in structure of a secondary internal fascicle of a plexus that causes similarity of a clinical picture at their lesion. N. radialis in the basic function suffers and at a lesion primary average and secondary back fascicles, but in the first case - in a combination with a partial lesion n. mediani, an in the second (a back fascicle) - with a lesion n. axillaris.
Function n. axillaris drops out as at a lesion primary top, and a secondary back fascicle because of corresponding transition of its fibers.
At last, n. musculo-cutaneus suffers equally and at a lesion primary top and secondary external fascicles, but century the first case - in a combination with n. axillaris, and in the second - with a partial lesion n. mediani.
At lesion CV - CVI roots or a primary top fascicle of a plexus (in a supraclavicular fossa) as it is observed at paralysis Эрба, the nerve suffers in a combination with n. musculo-cutaneus.
At a lesion of a secondary back fascicle (in a subclavial fossa) function n. axillaris it is broken together with n. radialis.
Impellent fibers of a nerve иннервируют m. deltoideus (and m. teres minor), sensitive - a skin of an external surface of a shoulder (n. cutaneus brachii lateralis).
At a lesion n. axillaris the atrophy of a deltoid muscle, impossibility of a raising of a shoulder in a face-to-face plane to a horizontal line and sensitivity disturbance in a skin of external area of a shoulder (fig. 84 and 85) is observed.