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VII. On a Group of Varieties of the Muscles of the Human NecJc , Shoulder , and Chest , 
with their transitional Forms and Homologies in the Mammalia. By John Wood, 
F.R.C.S . , Examiner in Anatomy at the University of London; Professor of Surgery 
in King's College, London , and Surgeon to King's College Hospital. Communicated 
by Dr. Shardey, Sec. R.S. 
Received June 17, — Read June 17, 1869. 
In the 1 Proceedings of the Royal Society,’ between the years 1864 and 1868 inclusive, 
were published five series of observations upon variations in Human Myology, made 
in the Anatomical Rooms of King’s College, London. These observations extended 
over 202 dissected subjects; they were restricted chiefly to the muscles of the head 
and neck and those acting upon the extremities, and did not include the numerous 
irregularities wdiich are usually found in those of the back. 
From the extensive range of the subject, and the importance of ascertaining as far as 
possible the statistical frequency of the abnormal forms, there was little opportunity 
afforded of giving due prominence to many of the specimens which were entitled to spe- 
cial distinction, either from their first appearance in the records of anatomical science, 
or from their homological importance as transitional forms, or as representatives of 
muscles hitherto found only in certain classes of animals. 
Many others had, indeed, been recorded by the older or more modern writers under 
various names, as irregularities of the muscle with which they were connected or con- 
tiguous. A great number of these, I believe, were mere varieties of the same transi- 
tional specimens, and were placed in this series for the first time in their proper relation 
and true homological significance to each other. 
After some years of practical observation and bibliographical research, I have brought 
together some of the more interesting groups of these muscular varieties in illustration 
of the working of the law of variation in modifying muscular formations in the human 
subject ; producing, in some instances, muscles which appear at first to be remarkably 
aberrant from the ordinary human construction, and identical in some with those which 
have usually been considered as peculiarly animal formations. 
From this point of view one of the most interesting groups of muscles is that of the 
muscles which connect the neck and shoulder. From the variability of the bones of the 
shoulder-girdle and the dissimilar habits and requirements of the different classes of ani- 
mals, it is not surprising to meet with a perplexing variety in the different portions of their 
muscular apparatus ; but it is striking to find that a great tendency to the same kind 
of variability is to be found in the shoulder of Man, in which it exists to an extent which 
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