MUSCLES OF THE AODY. 121 



border is attached by strong fascia to the border of the clavo- 

 trapezius (Fig. 68, d}. The outer surface is in relation with 

 the longissimus capitis (Fig. 73, g), clavotrapezius (Fig. 

 68, d}, cleidomastoid (Fig. 73, d), platysma, and the skin. 

 The inner surface is in relation caudad with the supraspinatus 

 and with a mass of fat and a lymphatic gland which occupy the 

 hollow of the shoulder. Craniad it is in relation with the 

 cleidomastoid (Fig. 73, */), the scalenus (Fig. 73, /"), the 

 longus capitis (Fig. 73, e), and the obliquus superior (Fig. 



7L ') 



Action. Pulls the scapula craniad. 



M. latissimus dorsi (Fig. 68, m\ Fig. 65, q\ Fig. 77, e). 

 A large triangular sheet covering rather more than the dorso- 

 cranial half of the abdomen and thorax. It arises from the 

 middorsal line, from the pelvis to the fifth thoracic spine, and 

 is inserted into the humerus. 



Origin from the tips of the neural spines of the vertebrae 

 from the fourth or fifth thoracic to about the sixth lumbar. 

 As far as the tenth or eleventh thoracic vertebra the origin is 

 directly by muscle-fibres. Caudad of this is a broad triangular 

 tendon which may be so closely united to the tendons of the 

 underlying muscles that it cannot be separated. The muscle 

 passes cranioventrad, the fibres converging to the axilla. In 

 the axilla a part of the cutaneus maximus and the epitrochle- 

 aris (Fig. 65, r] take origin from the outer surface. 



Insertion. The muscle then ends in a flat tendon, to the 

 cranial surface of which the fibres of the teres major (Fig. 

 77, c] are attached. Five to ten millimeters from the humerus 

 the muscle-fibres of the teres give place to the tendon-fibres, 

 and the conjoined tendon of the teres and latissimus which is 

 thus formed (Fig. 79, d'} is inserted into a rough elongated 

 area (Fig. 82, /) which lies parallel with the pectoral ridge on 

 the medial surface of the shaft of the humerus (Fig. 48, g). 

 The teres tendon forms the proximal part of the conjoined 

 tendon. A part of the tendon of the latissimus may join the 

 pectoralis minor at its distal or caudal border (Fig. 65), and 

 thus it may contribute to the formation of both pillars of the 

 bicipital arch (Fig. 65, /'). 



