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Show 1903.] THE MUSCLES OF THE UNGULATA. 275 that of the sartorius, while from its lower margin it gives off an expansion to the inner side of the tendo Achillis which blends with similar expansions of the biceps and semitendinosus to form the sheath for that tendon. This sheath has already been discussed under the head of the semitendinosus. The muscle seems so constant in the various families that it is needless to repeat each individual record, especially as there are thirty-four of them fairly evenly distributed over the order; it will be sufficient to point oat that according to Murie (XXXII.) the muscle is absent in the Giraffe, while Chauveau (II.) says that in the Camel its origin is bifid, the anterior branch being the smaller. Meckel (VII.), on the other hand, says that there are four heads to the gracilis in the Camel, so that it is clear that further knowledge is needed on this point. The nerve-supply in every animal we dissected was the obturator. Muscles of the Anterior Femoral Region. Sartorius {Ilio-tibialis).-The origin of this muscle is usually not so high as the anterior superior spine of the ilium, more often it comes from the iliac fascia covering the insertion of the psoas parvus as well as from Poupart's ligament close by. In the Ox (35, 36, 37), Sheep (41, 42, 46, 48), and Goat (50) it has another origin from the pubis just internal to the femoral vessels, but the two origins soon join so that the vessels pierce the conjoined origin. The insertion is into the upper part of the tibia by means of the fascia of the thigh; sometimes the fleshy fibres reach as far as, or even beyond, the knee, but more often they are lost in the fascia lata or join the tendon of the gracilis before the knee is reached. In the Perissodactyla the sartorius seems rather better developed than in the rest of the Ungulata, at all events it remains fleshy below the knee in the Horse (63), Tapir (58, 59, 60, 61), and Rhinoceros (71). Sometimes the muscle is absent, this was the case in Hyrax (74, 75); and we have no doubt that what Meckel describes in this animal (78) as sartorius is really tensor fasciae femoris. It was also absent in Anderson's Elephant (79), and Cuvier and Laurillard (84) do not figure it, though it is definitely described by Miall and Greenwood (81) as well as by Paterson and D u n (85). On comparing this muscle in the Ungulata with its condition in other orders, it will be seen that it is better developed than in many of them, and may cover in the femoral vessels, making a definite Hunter's canal. Its nerve-supply in the Pig, Sheep, Duiker-bok, Harnessed Antelope, and Elephant is the anterior crural, the special branch to it passing over (superficial to) the femoral vessels a little below Poupart's ligament. The Quadriceps extensor cruris has only a few points of special interest so far as our observations go. The rectus, as is usual in mammals, always has a reflected head, and often a straight head too, though the two may be continuous and so only one is described. W e have so far not met with a single ungulate in 18* |
