DISSECTION OF THE ANTERIOR LIMB. 11 



dissector proceeds to examine the structures over the inner surface of 

 the scapula and humerus. 



INNER ASPECT OP THE SHOULDER AND ARM. 



Directions. — The dissector should now identify the terminal portions 

 of the muscles already dissected, and cut them off within an inch or 

 two of their insertion, except in the case of the latissimus dorsi, which 

 is to be left at its present length until its nerve and artery have been 

 followed. The posterior superficial pectoral should be cut away on a 

 level with the olecranon, but care is to be taken not to disturb the 

 vessels and nerves which it covers. The aponeurosis which the panni- 

 culus sends within the shoulder will now be observed, and, at its upper 

 border, a small glistening band passing to be inserted into the internal 

 tuberosity of the humerus. 



The next step is to dissect out the axillary and brachial vessels, and 

 the remaining branches of the brachial plexus ; and this is an operation 

 demanding time and care. While an assistant holds the nerves on the 

 stretch, the fat and areolar connective-tissue which surround them and 

 the vessels are to be cleaned away piecemeal, always proceeding fi'om 

 the main trunks to the branches. In doing this the dissector will meet 

 two groups of lymphatic glands. 



Brachial Lymphatic Glands. The upper group consists of a cluster 

 placed behind the brachial vessels, on a level with the middle of the 

 humerus. The lower group consists of one or two glands in relation to 

 the vessels, just above the elbow-joint. 



The Axillary Artery (Plates 5 and 6). This vessel has already 

 been seen passing in a curved direction from the anterior border of the 

 1st rib, across the inner aspect of the shoulder-joint, where it rests 

 above the terminal insertion of the posterior deep pectoral, and on the 

 tendon of the subscapularis. It passes on to the teres major, and is 

 continued as the brachial artery. In this course it gives off four 

 vessels, viz., the inferior cervical, external thoracic, suprascapular, and 

 subscapular. The first two have already been dissected in the axilla. 



The Suprascapular Artery (Plate 5) is a small, tortuous vessel 

 springing from the upper surface of the axillary artery about the middle 

 of its extra- thoracic course. It passes upwards for a short distance, and 

 then divides into branches, the longest of which passes over the sub- 

 scapularis to reach the anterior deep pectoral. A branch passes in 

 between the subscapularis and the supraspinatus, while smaller branches 

 are expended in the tendons about the shoulder. 



The Subscapular Artery (Plates 5 and 6) is a comparatively large 

 vessel, and beyond its origin the parent trunk is much reduced in 

 calibre. It arises at the interstice between the subscapularis and teres 



