SCAPULAR REGION. '137 



DISSECTION VI. 



SCAPULAR REGION. 



The subject should be restored to its position with the face upper- 

 most. All the muscles which attach the upper extremity to the thorax 

 have, with a single exception, been examined, and if they have been 

 divided it will be held only by the clavicle and serratus magnus 

 muscle. The clavicle should be divided in the middle; the bundle 

 of nerves and the artery cut through opposite the second rib, and tied 

 in a bunch to the fragment of clavicle remaining. This exposes the 

 serratus rnaguus muscle. 



The SERRATUS MAGNUS MUSCLE covers a large portion of 

 the thoracic parietes, and forms the inner wall of the axilla ; 

 it arises by nine muscular slips, arranged in a curved line, 

 th4 convexity of which looks forward, from the anterior 

 surface of eight upper ribs, two slips being attached to the 

 second rib, and the lower of its slips indigitating with the 

 external oblique muscle of the abdomen ; it is inserted into 

 the whole length of the posterior border of the scapula. 

 The inferior thoracic and subscapular arteries ramify on 

 the surface of this muscle, and the long thoracic nerve (p. 

 103) passes dow/i from behind the axillary plexus, to be dis- 

 tributed to it. 



The division of this muscle will complete the separation of the 

 upper extremity from the thorax. In accomplishing this, it must be 

 remembered that some important branches of the subclavian artery 

 are distributed to the dorsum of the scapula, and these should be so 

 divided as not to interfere with their further examination. 



The SUBSCAPULARIS MUSCLE lies upon the inner surface 

 of the scapula, covered in by a fibrous lamina which is but 

 slightly adherent to it; this being removed, it will be found 

 to arise from the inner surface of that bone, except at its 

 inferior and superior angles ; it is inserted by a broad flat 

 tendon, which forms a part of the capsular ligament of the 

 shoulder-joint, into the lesser tuberosity of the humerus. A 

 band of fibres, two or three inches in length, is sometimes 

 found extending from the scapula to the neck of the hu- 

 merus, just below this muscle. The belly of this muscle is 

 intersected longitudinally by aponeurotic lamina?, attached 

 to the ridges of the scapula. The subscapular nerve, arising 

 from the posterior part of the brachial plexus, will be seen 

 entering this muscle immediately after its origin, penetrating 



12* 



