Warren Harmon Lewis 165 



muscles join it. The portion of tlie supraspinatus on the anterior one- 

 fourth of the median surface of the scapula is distinct, but after it 

 passes the acromion it is inseparably' connected with the infraspinatus 

 and deltoid and pectoral muscles. These muscles shade off into the 

 23roximal end of the humerus. The main portion of each of these 

 muscles contains muscle fibers. The suprascapular nerve supplies the 

 supra- and infraspinatus muscles. 



The subscapularis muscle arises from the posterior one-half of the 

 median surface of the scapula and passes beneath the coracoid process 

 to the humerus. The circumflex nerve separates a portion of it from 

 the teres major muscle, but the scapular portions of the two are closely 

 imited, as is also the long head of the triceps. A branch from the 

 circumflex and another from the posterior cord of the brachial plexus 

 supply the subscapularis. 



The teres major and latissimus dorsi muscles are closely associated at 

 "their humeral end. The latissimus dorsi' lies in the lateral thoracic 

 region, extending posteriorly as far as the fourth rib. It has no attach- 

 ments to the ribs or vertebral column. The two muscles are inserted 

 together into the proximal portion of the humerus. The teres major 

 arises from the axillary border of the scapula near its posterior angle. 

 The common portion of the latissimus and teres passes close to the 

 posterior cord of the brachial plexus, from which a large branch is given 

 off that runs into the latissimus and has a brush-like ending near the 

 posterior limit of the muscle. A smaller branch of the posterior cord 

 is given off to the teres major. 



The triceps muscle extends along the posterior and lateral surfaces of 

 the humerus, extending from the scapula to the ulna. Indications of 

 the three heads are present. The portion of the muscle lying near the 

 insertion of the latissimus dorsi and the infraspinatus muscles is not 

 sharply defined from them. The musculo-spiral nerve passes through 

 the muscle and gives branches to it. 



The biceps and coracohracJnaUs muscles lie along the median side of 

 the humerus, extending from the coracoid process to the radius. The 

 two heads of the biceps are quite closely united nearly to their origins, 

 Avhich are but a short distance apart. The portion of the coracoid 

 process from which the long head arises must ultimately become a por- 

 tion of the head of scapula. The attachment of the coracobrachialis to 

 the humerus is by condensed tissue, as is the distal end of the biceps to 

 the radius. The distal end of the biceps blends with the brachialis and 

 the flexor mass. The musculo-cutaneous pierces this group and gives 

 off branches to it. 



