40 PROCEEDINGS OF THE ACADEMY OF [1889. 



turning inwards to pass over the inner border of the rectus ; others 

 passed directly downward, while still others turned outwards and 

 downwards over the external oblique. There were no fibres con- 

 tinuous with those of the abdominal muscles, and none inserted into 

 the ribs or sternum. This arrangement of the muscle seems to be 

 the normal one ; though, in the majority of cases either origin or 

 insertion, or both, may be materially different. The chief arterial 

 supply was derived from a branch, of considerable size, from the 

 internal mammary artery, which perforated the third intercostal 

 space. I regret my inability to trace the nerve supply. Shepherd 

 found the nerve almost constantly lying between the upper and 

 lower divisions of the pectoral. 



On the right side, the muscle was quite the same in origin and 

 insertion, and of similar size, except for the additional portion that 

 will now be described. The subclavian muscle of the left side was 

 larger, and more fleshy than the normal one of the right side, and 

 none of its fibres were inserted into the costal cartilage, the upper 

 ones uniting with the manubrium, but the larger number passing 

 downward and inwards, through a space left in the origin of the 

 pectoral from the sternum, and, forming a slender, round tendon 

 which passed obliquely to the right side of the sternum to be inserted, 

 partly into the side of the sternum and upper border of the costal 

 cartilage of the fourth rib, but chiefly to blend with the sternalis. 

 As though to correct the oblique action that it otherwise would have 

 had, there was an additional sternalis on the right side, arising from 

 the middle fibres of the sterno-mastoid tendon to blend partly with 

 the muscular fibres of the subclavius tendon, but also terminating 

 in a long tendon of its own that had an insertion into the costal 

 cartilage of the fifth rib. This accessory sternalis, in its widest part, 

 was a half inch in width. Some fibres of the pectoralis also sent a 

 small tendon to join that of the subclavius. 



The thorax was unusually long and cylindrical, and contracted 

 below the cartilage of the fifth rib, as though constricted by a 

 bandage. Traction in the freshly dissected parts produced but little 

 effect upon the sterno-mastoid, notwithstanding the fact that the 

 sternal portion was distinct from the clavicular portion for an un- 

 usually long distance. Traction upward, however, produced a very 

 distinct tightening of the abdominal sheath and constriction of the 

 lower part of the thorax. The muscle here certainly was a " Span- 



