THE SHOULDER-GIRDLE. 251 



superior border. The omohyoid muscle, if the shoulder is drawn outward and the 

 head turned to the opposite side, is drawn upward above the clavicle. 



Behind the upper portion of the clavicle is the suprascapular artery and above 

 it runs the transverse cervical artery, a branch of the thyroid axis. Both these 

 vessels cross over the scalenus anterior muscle on which, toward its inner edge, is 

 lying the phrenic nerve. In front of the scalenus anterior runs the subclavian vein 

 and behind it is the subclavian artery with the cords of the brachial plexus above 

 and to its outer side. Below and in front are attached the pectoralis major and 

 deltoid muscles; the space between them forms the subclavicular triangle and occu- 

 pies the outer half of the middle third of the bone. The cephalic vein pierces the 

 costocoracoid membrane at this point to enter the subclavian vein. 



On the under surface of the bone is the subclavius muscle, covered with a 

 strong membrane. To the inner side of this muscle is the costoclavicular ligament. 

 Beneath the clavicle, about its middle, passes the subclavian artery, separated from 

 the vein in front by the scalenus anterior muscle. Below and beneath the subclavian 

 artery, which rests directly on it, is the pleura. The internal mammary artery passes 

 behind the inner extremity of the clavicle opposite the cartilage of the first rib. 



The clavicle is the first bone in the body to ossify, and it has one epiphysis at 

 its sternal end which appears about the seventeenth year and joins the shaft from 

 the twentieth to the twenty-fifth year. In removing the bone it is first loosened at 

 its outer extremity by dividing the acromioclavicular and coracoclavicular (conoid 

 and trapezoid) ligaments. 



Excision of the Scapula. The removal of the scapula necessitates the 

 division of a large number of muscles, for which see pages 226 and 227. The sub- 

 scapular artery at the anterior border, about 2. 5 cm. (i in. ) below the head or glenoid 

 process, and the suprascapular at the suprascapular notch, are to be ligated before 

 removing the bone. Skirting the posterior edge is the posterior scapular, the 

 continuation of the transverse cervical artery; it is to be avoided when detaching 

 the muscles. The acromial branches of the acromial thoracic artery ramify over the 

 acromion process; they are not so large as those already mentioned. 



Mr. Jacobson suggests that if safety permits one should allow the acromion 

 process to remain, as it preserves the point of the shoulder and to some extent, the 

 functions of the trapezius muscle. 



Excision of the Head of the Humerus. The incision for the removal 

 of the head of the humerus should be commenced just outside of the coracoid 

 process and be carried 10 cm. (4 in. ) downward in a direction toward the middle 

 of the humerus, where the deltoid inserts. This incision may be made while the arm 

 is somewhat abducted but it does not go in the groove between the deltoid and 

 pectoralis major muscles. This groove contains the cephalic vein and the humeral 

 branch of the acromial thoracic artery, and hence is to the inner side of the coracoid 

 process and as the incision is to the outer side, it passes through the deltoid near 

 its anterior edge (Fig. 265). 



The incision goes through the muscle and exposes the capsule of the joint. The 

 sides of the wound are to be retracted and, if the long head of the biceps muscle is 

 not recognized by sight, the finger is inserted and the arm rotated. The bicipital 

 groove can be felt and the tendon identified. 



The capsule is to be incised along the outer edge of the long tendon of the 

 biceps and as the arm is rotated inward the supraspinatus, infraspinatus, and teres 

 minor muscles are to be detached from the greater (posterior) tuberosity. The 

 biceps tendon is again brought into view by rotating the arm outward and its sheath 

 (transverse ligament) slit up and the tendon luxated inward. 



The attachment of the capsule and subscapularis muscle to the lesser (anterior) 

 tuberosity is then divided while the arm is rotated outward. The biceps tendon lies 

 in the bicipital groove between the two tuberosities. When the arm is lying with the 

 palm upward, in a supine position, the bicipital groove looks directly anteriorly in a 

 longitudinal line passing midway between the two condyles of the lower end. The 

 position of the head and groove can be told by observing the position of the condyles. 

 The head is directly above the internal condyle and the groove is on the anterior sur- 

 face above a point midway between the condyles. After the capsule has been opened 



