OCR Text |
Show 872 MR ST. GEORGE MIVART ON THE [Dec. 6, pollex distad and radiad of the insertion of the extensor ossis metacarpi poliicis. Flexor brevis minimi digiti. Another small muscle arises from tbe ulnar side of the palmar ossicle, and is inserted into the ulnar side of the fifth digit. Adductor digiti tertii (fig. 9, A3). This springs from the ligament connecting tbe third and forth metacarpals, and is inserted into the ulnar side of the third digit. Adductor digiti quarti (fig. 9, A4). Another small muscle arises from the same ligament, connecting the third and fourth metacarpals, and is inserted into the radial side of the fourth digit. The extensores metacarporum are very numerous, but are all short muscles, except tbe one which goes to the pollex. Extensores I. and II. or extensor ossis metacarpi poliicis* (figs. 8, 9, 10, 11 & 12, M. P). This is a very large and even a double muscle, like the homotypal muscle of the pes. The longer part arises (in intimate connexion with the deeper part of the supinator longus) from the lower end of the humerus, close to its articulation with the radius. Passing downward, it joins the shorter part a little above the wrist. This shorter part springs from the radiad aspect of the ulna for its whole length. Passing downward and radiad, it unites with the longer part, and the united muscle is inserted into the radial aspect of the dorsum of the distal end of the first metacarpal bone. Part of deepest flexor surface of right forearm. B. Biceps. B. A. Brachialis anticus. F. D. Flexor profundus digitorum. P. A. Pronator accessorius. P. Q. Pronator quadratus. Extensor m. III. (fig. 9, E3). This little muscle arises from the extensor aspect of the styloid process of the radius, and is inserted into the distal part of the dorsum of the first metacarpal. Extensor m. IV. (figs. 9 & 11, E4). This takes origin just beneath and beside the last-described muscle, and is similarly inserted into the second metacarpal. The extensor m. V. (figs. 9 & 11, Eb) arises just beneath and beside the last described, and is similarly inserted into the third metacarpal. A few of its fibres take origin from the ulnar carpal ossicle. The extensor m. VI. (figs. 9 & 11, E6) springs from the central carpal ossicle, and from the dorsum of the first three metacarpals. * Meckel, I. c. p. 382. |