202 
Proceedings of the Royal Society of Edinburgh. [Sess. 
VIII. — The Short Muscles of the Hand of the Agile Gibbon 
(Hylobates agilis), with Comments on the Morphological 
Position and Function of the Short Muscles of the Hand 
of Man.* By Duncan C. L. Fitzwilliams, M.D., Ch.M., F.R.C.S., 
Surgeon-in-Charge of Out-Patients, St Mary’s Hospital, London. 
Communicated by Sir Wm. Turner. (With Two Plates.) 
(MS. received November 22, 1909. Read December 6, 1909.) 
The kindness of Professor Cunningham has enabled me to carry out the 
dissection of a gibbon in his possession. The dissection was performed in 
1905, in the Anatomical Department of the University of Edinburgh. The 
following paper is a description of the short muscles of the hand of the 
animal, to which is added a consideration of the primitive position and 
function of the short muscles of the human hand. 
In dealing with the nerve supply of the various muscles, it is necessary 
to explain that the median nerve, high up in the forearm, gave off a strong 
branch of communication to the ulnar nerve. The fibres thus supplied to 
the ulnar were traced down to the muscles in which they ended. This 
explains the phrase constantly met with in which the nerve supply is 
described as coming from the median by way of the deep division of the 
ulnar nerve. In this animal the nerves freely communicated with one 
another in the forearm. The median, even, gave off a large branch which 
passed backwards with the posterior interosseous artery, joined the 
posterior interosseous nerve, and ended in the pronator quadratus. This is 
one of the very few reported instances in which the anterior and posterior 
divisions of the nerves forming the brachial plexus have been found to 
communicate with one another. Hepburn f noted that the pronator 
quadratus muscle was supplied by the posterior interosseous nerve in 
a gibbon, but did not state the true origin of the fibres. 
Short Muscles of the Thumb. 
Abductor Pollicis. 
Origin . — From the sesamoid bone (prepollex) and the ligaments which 
bind that bone to the scaphoid and trapezium, from the outer side of the 
* This paper is an abstract of part of my thesis entitled “ An Essay on the Anatomy of 
the Gibbon {Hylobates Agilis ), with Notes on Comparative Anatomy,” presented for the 
degree of M.D. in the University of Edinburgh, 1905. 
t Jo-urn. Anat. and Physiol ., 1893. 
