Proceedings of the scientific meetings of the Zoological Society of London, 1889

Page 44

16 MESSRS. F. E. BEDDARD AND F. TREVES ON THE [Jan. 15, radius, and, becoming tendinous above the wrist, is inserted into the proximal end of the radial metacarpal bone. Flexor sublimis (perforatus).-Arises, in common with the flexor profundus, from the flexor condyle. Passes down as a large fleshy muscle; becomes tendinous at wrist, under annular ligament, and there divides into three small tendons, expanding into sheath at bases of phalanges, from inner side of which sheath expansions go forward to be inserted into the base of the second phalanx. _ Flexor profundus (perforans).-This has a similar origin to last described muscle (flexor sublimis). Becomes a very big tendon, and dividing over the metacarpus lower than the above, passes through a thick sheath to the base of the last phalanx. Palmaris longus.-This is a muscle which is apparently not described in the Horse, arising by a short thick fleshy belly from the olecranon ; the fleshy part of the muscle is short and is succeeded by a wide and thin tendon which passes into flexor profundus at the wrist. Interossei.-There are four interossei muscles. The presence of a palmaris longus, if we are right in thus identifying the muscle described above under that name, is interesting for the reason that it does not occur in the Horse, but does in the Tapir. The following table shows the resemblances and differences between the Rhinoceros, Horse, and Tapir in the extensor and flexor muscles of the arm :- Ext. comm. digit.. Ext. lat. digit. Ext. obi. met. Flexor ext. met. Rhinoceros. Origin:-(1) Extensor con­dyle ; (2) upper part of ulna and radius ; (3) from ulnar border of radius to halfway down that bone. Insertion upon all 3 digits. .. Origin:-(1) Extensor con­dyle ; (2) shaft of ulna. Ins. 1st phalanx of ulnar digit and (by a slight ten­don) to middle digit. .. Origin by one head from exterior condyle and shaft of radius; by 2nd head from radius. Ins., radial metacarpal. .. Origin from extensor con­dyle and olecranon. Ins. into pisiform. Horse. Origin:-(1) Extensor con­dyle; (2) humerus below extensor condyle; (3) the anterior border of external ligament of articulation of elbow; (4) superior and external tuberosity of radius; (5) external bor­der of radius. Origin. From external tube­rosity of radius and from shaft of radius and ulna, not from humerus. Origin. Only one head from external side of radius. Insertion by 2 tendons: (1) on to pisiform; (2) outer metacarpal.