88 THE SUPERIOR EXTREMITY 



bursa. Inflate the bursa with a blowpipe, and notice that, as air 

 is blown in, the capsule of the shoulder- joint is distended. If 

 the wall of the bursa has been injured in the course of previous 

 dissections, open it with the scalpel and examine the interior 

 with a blunt probe. Note its extent and its continuity with the 

 interior of the shoulder- joint through a large aperture in the 

 anterior part of the articular capsule. 



Bursa Subscapularis. The subscapular bursa is formed 

 by the prolongation of the synovial stratum of the capsule of 

 the shoulder- joint through an aperture in the upper and 

 anterior part of the fibrous stratum. It extends laterally 

 between the subscapularis and the medial part of the articular 

 capsule, medially between the subscapularis and the anterior 

 surface of the neck of the scapula and the root of the coracoid 

 process, and it facilitates the movement of the subscapularis 

 on the front of the head and neck of the scapula. 



Dissection. Cut through the subscapularis vertically below 

 the coracoid process, and detach from its deep surface the bursa, 

 which lies between it and the scapula and the capsule of the 

 shoulder. Turn the medial part of the muscle towards the 

 vertebral border of the scapula, and as you detach it from the 

 bone note the tendinous intersections by which it is connected 

 with the ridges on the costal surface of the scapula. Note also 

 the anastomosis between branches of the subscapular and trans- 

 verse scapular arteries which ramify on its deep surface. Turn 

 the lateral portion towards the humerus, detaching it from the 

 lateral part of the front of the capsule of the shoulder to which 

 it is adherent, and verify its attachment to the lesser tubercle of 

 the humerus and to the bone immediately distal to the tubercle. 

 Do not fail to notice that, as it crosses the shoulder- joint to its 

 insertion, it lies behind the coraco-brachialis and the short head 

 of the biceps. 



Divide the supraspinatus medial to the coracoid process. 

 Turn the medial part towards the vertebral border of the scapula 

 and verify its attachment to the spine and to the dorsal surface 

 of the scapula, and dissect out the branches of the transverse 

 scapular artery and the suprascapular nerve which pass to its 

 deep surface. Turn the lateral part towards the humerus, 

 forcing it beneath the coraco-acromial arch, and as you do that 

 avoid injury to the transverse scapular vessels and the supra- 

 scapular nerve which lie beneath it. Note that as the tendon 

 of the muscle crosses the top of the shoulder- joint it is firmly 

 attached to the capsule before it reaches its insertion into the 

 superior facet on the greater tubercle of the humerus. Divide 

 the infraspinatus medial to the lateral border of the spine of 

 the scapula. Verify the attachment of the medial part to the 

 inferior surface of the spine and the dorsal surface of the body 

 of the scapula, dissecting out the vessels and nerves from its 

 deep surface. Follow the lateral part to its insertion into the 

 middle facet on the greater tubercle of the humerus. and, as the 

 muscle is displaced, take care not to injure the transverse scapular 



