1412 



CLINICAL AND TOPOGRAPHICAL ANATOMY 



the vessels and nerves in relation to them, must be remembered. The chief vessels 

 are the axillary on the lateral wall, brought into prominence when the arm is 

 abducted, as in removal of the mamma, and the subscapular on the posterior wall. 

 The apex is felt, when the finger is pushed upward in an operation here, to be 

 bounded by the clavicle in front, the first rib behind, and the coracoid some- 

 what laterally. The base is concave, omng to the coraco-clavicular (costo- 

 coracoid) membrane as it descends to blend with the sheath of the pectoralis 

 minor, giving also a process to the axillary fascia which unites the anterior 

 and posterior boundaries. This process also sends septa to the skin. 



An axillary abscess, always to be opened early to avoid subsequent interference with the 

 movements of the shoulder, is reached by an incision on the medial wall, midway between the an- 

 terior and posterior boundaries, so as to avoid the long thoracic and subscapular vessels, respec- 

 tively, the back of the knife being directed toward the lateral wall. The only vessel on this wall 

 is the superior thoracic, which lies high up. Additional safety is given by the use of Hilton's 

 method. For exploration of the axilla the best incision is an angular one, the two limbs being 

 placed in a line with the anterior margin of the great pectoral, and in the line of the axillary 

 vessels. This runs from a point on the centre of the clavicle (the limb being at a right angle 

 to the trunk) to the medial margin of the coraco-brachialis. If this be obliterated by swelling, 

 the above line should be prolonged to the middle of the bend of the elbow, which will give the 

 guide to the brachial also. Collateral circulation. If the first part of the artery be tied, the 

 channels are the same as in ligature of the third part of the subclavian (q.v.). In ligature 

 of the third part of the axUlary, if the ligature be above the circumflex arteries, the chief vessels 

 concerned are the transverse scapular (suprascapular) and thoraco-acromial above and the 



Fig. 1130. — Diagrammatic Section of Shoulder through the Intertubercular 

 (Bicipital) Groove. (Anderson.) 



Deltoid 

 Subacromial bursa 



Capsule of shoulder-joint 

 Long tendon of biceps 



Synovial membrane lining cap- 

 sule and biceps tendon 



Extra-articular portion of biceps 

 tendon 



Acromion 



Glenoid lip (ligament) 



Glenoid cavity 



Glenoid lip (ligament) 



Inner fold of capsule and 

 synovial membrane 



Humerus 



posterior circumflex below. If the ligature be below the circumflex, the anastomoses will be 

 those concerned in ligature of the brachial above the profunda (p. 1414). The lymphatic 

 nodes in the axilla have been mentioned at p. 719, (fig. 5G6). 



The depression of the axillary fossa is best marked when the arm is raised from the side 

 to an angle of about 45°, and when the nmsclcs bounding it in front and behind are contracted. 

 In proportion as the arm is rai.sed, the hollow becomes less, the head of the humerus now pro- 

 jecting into it. When the folds are relaxed by bringing the arm to the side, the fingers can be 

 pushed into the space so as to examine it. 



The a.xiihiry (circumflex) nerve and posterior circumflex vessels wind around the humerus 

 under the deltoid; a line drawn at a right angle to the humerus and a little above the centre 

 ■of this muscle marks their position on the surface. 



To trace the synovial membrane of the shoulder-joint is a comparatively 

 simple matter (fig. 1130). Covering l)oth aspects of the free edge of the glenoid 

 ligament, it lines the inner aspect of the capsule, whereby it reaches the articular 

 margin of the head of the humerus; there is a distinct reflection, below, from the 

 capsule on to the humeral neck before the rim of the cartilage is reached. 



An cxtcn.sive protrusion of synovial membrane takes place in the form of a synovial bursa, 

 at the medial and anterior part of the capsule, near tlie root of the coracoid process imder the 

 tendon of the sub.soHi)ulariH. Another protrusion takes place between the two tuberosities 

 along the intertubercular groove, as low as the insertion of the pectoralis major. A third 

 Hynovial protru.sion may be seen, but not frequently, at the lateral or posterior aspect, in the 

 form of a bursa, under the iiifra-spiriatus tciidon. Thus the continuity of the capsule is inter- 

 rupted by two and sometimes three synovial protrusions. 



