TODD "reversion OF TYPE." 35P 



^Reversion of Tyfe" in the Digastric Muscle of the Hu- 

 man Being. 

 By Charles A. Todd, M.D. 



No. 1. 



HUMAN LOWER JAW, UNDER SURFACE. 



1. Anterior bellies, muse, digastricus. 2. Posterior bellies, muse, digastriciis. 

 3. Abnormal arrang^ement of fibres of the anterior bellies. 



While engaged, several years back, in dissecting the head of 

 a boy aged about seven years, I found a condition of one of the 

 large muscles attached to the lower jaw that I had never before 

 observed, nor could I find any reference to such a condition in 

 any works on human anatomy within my reach. The anomaly 

 was this : The very important depressor muscle of the lower 

 jaw, the digastricus on the right side, divided its anterior belly 

 into two portions, one part being attached to the jaw as usual, 

 the other passing across the median line to join its fellow upon 

 the left. In the diagram, it will be observed that a bundle ot 

 these errant fibres make an arch with the left anterior belly,, 

 while the rest pass onwards in the same general direction with 



