100 



INTRODUCTION. 



extremity, terminating a short neck, rising obliquely upward, from two 

 large projections at its base : the larger and higher of these is known 

 by the name of the trochanter major ; the smaller and lower by that of 

 trochanter minor : they serve for the attachment of the rotatory muscles 

 of the thigh. 



The inferior extremity of the thigh bone enlarges into a pulley-like arti- 

 culating surface, which enters into the construction of the knee. The head 

 of the thigh-bone (fig. 104) is firmly braced down, in the 

 cup-like cavity of the pelvis, by various ligaments ; and, 

 in particular, by one, a, the ligamentum teres, which arises 

 from the top of the head itself, and is affixed to the bottom 

 of the cavity ; so that when the hip-joint is dislocated, this 

 ligament must necessarily be ruptured : in some few Mam- 

 malia it is wanting. It is not possessed by the Orang 

 Outan (though it is found in the Chimpanzee and Gibbons), nor by 

 the Elephant, the Sloth, the Seal, the Enhydra, the Walrus, or the 

 Ornithorhy nchus .* 



In most Mammalia the thigh-bone is much shorter than in the human 

 subject, and is so concealed as not to be perceptible in the limb as it 

 appears in the living animal ; whence has arisen the erroneous practice oi 



calling that part the thigh, which really cor- 

 responds to the leg. 



The knee-joint (fig. 105), that is, the arti- 

 culation of the tibia, or large bone of the leg, 

 with the extremity of the os femoris is firmly 

 knit and well secured by ligaments, being also 

 protected, in front, by a bone called the patella, 

 or knee-cap. This bone may be regarded as a 

 moveable olecranon, enveloped by the tendon 



Lateral and anterior view of the knL- of the powerful CXtCnSOr mUSCleS of the leg, 



o, femur; i, pateiia; c , tibia; <*, Simla, which tendon is inserted into the exterior part 

 of the top of the tibia. It is not found in the Bats ; nor does it occur in the 

 Kangaroo, and several other marsupial animals ; at least, in these ani- 

 mals, it exists but in a state of cartilage. The tibia, so named from its 

 resemblance to an ancient flute, and which forms the principal bone of 

 the leg, is assisted by a slender bone, termed the fibula (or perone), which 

 runs along it somewhat laterally, and forms the outer point of the ankle ; 

 the inner portion being formed by the tibia. At its two ends the fibula 

 is enlarged and compressed, the upper end being united to the tibia, the 

 lower having an attachment to the base of the foot (fig. 106). 



In ruminants, and the solid-hoofed Mammalia, the fibula is at its mini- 



* It is said to be wanting in the Tucutuco (Ctenomys Braziliensis), a small rodent animal. See 

 Zool. Voyage, Beagle, Mamm. p. 80 ; but of this there is some doubt. 



