DISSECTION OF THE BACK 57 



they approach the lower part of the scapula. The highest 

 fibres pass almost horizontally towards that point ; the lowest 

 fibres ascend almost vertically ; whilst the intermediate 

 fibres show varying degrees of obliquity. As a result of the 

 convergence of fibres, the muscle is greatly reduced in width ; 

 and it sweeps over the inferior angle of the scapula in the 

 form of a thick, fleshy band, which winds round the lower 

 margin of the teres major muscle and terminates in a 

 narrow, flat tendon, which is inserted into the floor of the 

 intertubercular sulcus of the humerus (Fig. 45, p. 107). The 

 insertion cannot be studied at present, but will be seen later. 

 With the teres major muscle, the latissimus dorsi forms the 

 posterior fold of the axilla. At first it is placed on the dorsal 

 aspect of the teres major, then it is folded round its lower 

 border, and finally it is inserted in front of it. To the 

 peculiar relationship of the two muscles is due the full, 

 rounded appearance of the posterior axillary fold. 



The latissimus dorsi is supplied by the thoraco-dorsal nerve. 

 It is an adductor, retractor, and medial rotator of the upper 

 extremity. 



Two Inter-muscular Spaces. (i) A triangular space 

 mapped out by the inferior border of the trapezius, the superior 

 border of the latissimus dorsi, and the base of the scapula, 

 should now be noticed (Fig. 26, p. 52). Within the limits of 

 that triangle a small portion of the rhomboideus major can be 

 seen, and also a varying amount of the wall of the thorax a 

 part of the sixth intercostal space and the borders of the ribs 

 which bound it above and below. It is well to note that 

 this is the only part of the thoracic wall on the posterior 

 aspect of the trunk which is not covered by muscles. (2) 

 Between the last rib and the crest of the ilium the anterior 

 border of the latissimus dorsi generally overlaps the 

 posterior border of the external oblique muscle of the 

 abdominal wall. Sometimes, however, a narrow triangular 

 interval exists between the two muscles, in which is seen a 

 small part of the internal oblique muscle. That space is 

 termed the trigonum lumbale (Petiti] (Fig. 26, p. 52). It is a 

 weak part of the wall of the abdomen, and occasionally some 

 of the contents of the abdomen are protruded through it, 

 forming a lumbar hernia. 



Dissection. Reflection of the Trapezius. On the second day 

 the dissector must begin by reflecting the trapezius, working, it 



