| OCR Text |
Show 1903.] THE MUSCLES OF THE UNGULATA. 281 instance, with the exception of Hyrax, we have met with in the whole order of any trace of a fleshy flexor brevis digitorum. Slips are given off which act as flexores perforati to all four digits. In the Suidae (4, 7, 11, 12, 13, 14) the fleshy belly in the calf is also fairly large and is wrapped up in the outer head of the gastrocnemius; passing round the tuber calcis its tendon gains the sole and usually divides into three slips for the index, medius, and annularis digits, though occasionally (12) it goes to all four digits. In the rest of the Artiodactyla its fleshy belly is much smaller, and its tendon, after passing round the pulleylike surface on the back of the tuberosity of the calcaneum, enters the sole and gives off a loop from its deep surface which surrounds the flexores tibialis et fibularis, then the tendon divides for the medius and annularis digits, and each slip acts as a flexor per-foratus before being inserted into the middle phalanx. In the Ox especially the perforation of the tendon takes up a good deal of its length, and a section through the perforans and perforatus tendons shows the former enclosed by a complete ring of the latter. In Borcatherium (23) Chatin describes tendons to all four digits. In the Perissodactyla the muscle rises from the supracondylar fossa and passes to the middle phalanges of all the toes, i. e. one in the Horse and three in the Rhinoceros and Tapir. In the Subungulata, Hyrax (74, 75) has a fleshy flexor brevis developed in the sole. The nerve-supply is always the internal popliteal. Popliteus.-There is but little of special interest about this muscle in the Ungulata; it rises as usual from the outer surface of the external condyle and is inserted into the upper quarter or third of the posterior surface of the tibia. As a rule no sesamoid is developed in its tendon, though we found one in our Tapir. The anterior tibial artery apparently always passes in front of the muscle. With regard to the nerve-supply the Duiker-bok (54) and Harnessed Antelope (55) have a branch from the internal popliteal entering the muscle at its lower border but not curving round that border as in Man, in addition there are two or three smaller branches entering the posterior surface. Flexor fibularis {Flexor longus hallucis of human anatomy).- This, except in the Camel and Elephant, is much larger than the flexor tibialis, and rises from the posterior surface of the tibia a little lower than the latter; it winds round the internal malleolus and is soon afterwards joined by the flexor tibialis ; it then divides into a variable number of tendons which pierce those of the flexor brevis digitorum or continuation of the plantaris, and are inserted into the terminal phalanges. In the Hippopotamidae, Suidae, and Borcatherium there are four tendons, in the other Artiodactyla only two; in the Rhinoceros, Tapir, and Hyrax three, in the Horse one; and in the Elephant the combined flexores tibialis et fibularis give tendons to all five digits, though the chief contribution is from the tibialis. It is always supplied by the posterior tibial nerve. |
