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Show 870.] MYOLOGY OF CHAMAELEON PARSONII. 871 The flexor profundus digitorum (figs. 10, 14, 15, 16, & 28, F. D) takes origin by only two heads. The first of these arises from the internal condyle in union with the similarly arising head of the flexor longus poliicis, and similarly embraced by the tendons of origin of the flexor carpi radialis. The second head springs from the radial side of the olecranon, and from the radial aspect of the ulna for about its upper three-fourths, its summit being contiguous (fig. 16) to the ulnar side of the insertion of the brachialis an.tl^us- The two parts of the muscle having united about the middle of the forearm, it extends distad, and ends in a strong tendon which passes in a deep groove at the distal end of the ulna, and side by side with the tendon of the flexor longus poliicis. The tendon then bifurcates. The radial bifurcation very soon receives a short slip from the ulnar bifurcation, then a long slip from the flexor longus poliicis (its fourth and most ulnad tendon), and finally a long and very delicate slip, one more from the ulnar bifurcation. It then goes to the fourth digit. The ulnar bifurcation gives first a very short, and then a long and very delicate slip to the radial bifurcation, and then goes to the fifth digit. Deepest flexor surface of right forearm. B. Biceps. F. D. Flexor profundus digitorum. P. A. Pronator accessorius. P. Q. Pronator quadratus. P. T. Pronator teres. 8. L. Supinator longus. Lumbricales (fig. 23). There are three lumbrical muscles in the hand. The first of these arises from the ulnar side of the long flexor tendon of the fourth digit, and goes to the same side of the same digit. The second arises from the radial side of the long flexor of the fourth digit, and goes to the same side of the same (fourth) digit. The third arises from the ulnar side of the long flexor tendon of the third digit, and goes to the same (ulnar) side of the same (third) digit. Flexor brevis digitorum. This muscle is confined entirely to the hand. It springs from the annular ligament which passes from the first to the fifth metacarpal, and is inserted into the digits, the long flexor tendons passing between its fibres. Flexor brevis poliicis (fig. 8, B. P). A thick, short muscle which may perhaps be thus named arises from the palmar ossicle and annular ligament, and is inserted into the radial margin of the P R O C . Z O O L . S o c - 1 8 7 0 , No. LVIII. |