Page 204 - Clinical Anatomy

ECA3 7/18/06 6:45 PM Page 189

The brachial plexus 189

Note.◊There is a rich anastomosis of arteries around all major joints. Apart
from remembering this fact, the clinical student need not commit to
memory the numerous named branches involved.

The brachial plexus

The brachial plexus is of great practical importance to the surgeon.
It may be damaged in open, closed or obstetrical injuries, be pressed upon
by a cervical rib or be involved in tumour. It is encountered, and hence put
in danger, in operations upon the root of the neck.
The plexus is formed as follows (Fig. 138):
1◊◊five roots derived from the anterior primary rami of C5, 6, 7, 8 and T1;
link up into:
2◊◊three trunks formed by the union of
•◊◊C5 and 6 (upper);
•◊◊C7 alone (middle);
•◊◊C8 and T1 (lower)
which split into:
3◊◊six divisions formed by each trunk dividing into an anterior and poste-
rior division; which link up again into:
4◊◊three cords
•◊◊a lateral, from the fused anterior divisions of the upper and middle
trunks;

Fig. 138◊Scheme of the
brachial plexus.