ON TWO CASES OF MUSCULAR ABNORMALITY 



IN THE CAT. 1 



RAYMOND PEARL. 



The muscular anomalies here described were found by the 

 writer in specimens of the domestic cat used for dissection in 

 class work in the University of Michigan. As both of the cases 

 presented certain interesting features it seemed advisable to pub- 

 lish an account of them at this time. 



I. A CASE OF ABNORMAL INSERTION OF THE M. 

 LATISSIMUS DORSI. 



In the cat the tendon of insertion of the M. latissimus dorsi 

 normally is in two parts. One of these parts- is joined by the 

 muscle and tendon fibers of the M. teres major, and the conjoined 

 tendon of these two muscles is inserted on the medial side of the 

 shaft of the humerus. The other portion of the latissimus ten- 

 don, which may not be always present according to Reighard and 

 Jennings, 2 joins with the pectoralis minor, reaching the bone 

 along the line of insertion of the pectoralis minor. This line is 

 along almost exactly the middle of the ventral face of the hum- 

 erus. As a consequence of the existence of their different lines 

 of insertion the two portions of the latissimus tendon form an 

 arch, which makes up a part of the bicipital arch. 



In a well-formed, adult male cat dissected by the writer the 

 very peculiar arrangement at the insertion end of the M. latissimus 

 dorsi shown in Fig. I was found on both sides of the body. 

 From the cranial border of the latissimus a slip (Fig. I, .r), about 

 4 cms. long and 6 mm. wide passed craniad above that portion 

 of the latissimus which joins the pectoralis minor (Fig. I, y). 

 This slip was inserted by fleshy fibers on the surface of the M. 

 pectoantibrachialis on the medial surface of the leg, just beneath 



1 Contributions from the Zoological Laboratory of the University of Michigan, 

 No. 65. 



2 Reighard, L, and H. S. Jennings, "Anatomy of the Cat." New York, 1901 

 p. 121. 



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