1864.] Mr. J. Wood on some Varieties in Human Myology. 299 



III. On some Varieties in Human Myology.'^ By John Wood, 

 F.R.C.S.; Demonstrator of Anatomy in King^s College, London. 

 Communicated by Professor Huxley, F.R.S. Received May 6, 

 1864 



(Abstract.) 



The paper gives the results of the author's observations on human muscular 

 variations observed during the last fifteen years, and extending over upwards 

 of six hundred subjects. Many of the more striking varieties were drawn 

 by the author from the subject, and form a series of thirty-seven illus- 

 trations accompanying the paper. Some of them he has not found placed 

 on record by any authority he has consulted. The author classifies these 

 muscular variations as follows, viz. : — 



Variations with redundancy. 



1st. Those which have an origin in a development totally independent 

 of any other muscles or tendons. 



2nd. Those which consist of extensions or offsets from normal muscles 

 or tendons, and of muscular fibres replacing tendons, and tendinous fibres 

 intersecting muscles. 



3rd. Those which are formed by simple areolar separation or segrega- 

 tion of muscles. 



These are given in the order of their rarity, and of their comparative 

 value in reference to the muscular anatomy of the lower animals. 



Variations with deficiency. 



1st. Those produced by total suppression of the germs of muscles. 



2nd. Those resulting from amalgamation with neighbouring muscles, 



3rd. Those from atrophy or degeneration subsequent to their formation. 



All the illustrations belong to the former class, which supply the most 

 fitting subjects for them. 



The frequency of varieties of all kinds in the human subject is very great. 

 Few subjects are to be found entirely free from them. Muscular variations 

 are rather more common in the male sex. In them, also, variations with 

 redundancy calculated to increase muscular power, such as are classed in 

 the 2nd division of that section, are more common, but may be also associ- 

 ated in the same individual with anomalies from defect or diminution. The 

 same individual is frequently found subject to more than one irregularity, 

 a muscular irregularity of a marked kind being generally associated with 

 several others. Probably the source is hereditary, as is undoubtedly the 

 case with those which result in deformity. Muscular variations are more 

 common in the arm, back, leg, and head, and least common, as a rule, in 

 the abdomen, the groin excepted. They are generally more or less sym- 

 metrical, though often much more evident on one side than the other. 

 Distinct developments are usually found on both sides. Variations by 



