44 HUMAN PHYSIOLOGY. 



in form. The lumbar portion, in the Chimpanzee and Orang, is not of the same 

 proportional strength; and contains but four vertebrae, instead of five. The 

 processes for the attachment of the dorso-spinal muscles to this part, are pecu- 

 liarly large and strong in Man; and this arrangement is obviously adapted to 

 overcome the tendency, which the weight of the viscera in front of the column 

 would have, to draw it forwards and downwards. On the other hand, the 

 spinous processes of the cervical and dorsal vertebrae, which are in other Mam- 

 malia large and strong, for the attachment of the ligaments and muscles that 

 support the head, have comparatively little prominence in Man, his head being 

 nearly balanced on the top of the column. The base of the human vertebral 

 column is placed on a sacrum of greater proportional breadth, than that of any 

 other animal; this sacrum is fixed between two widely-expanded ilia; and the 

 whole pelvis is thus peculiarly broad. In this manner, the femoral articulations 

 are thrown very far apart, so as to give a wide basis of support ; and by the 

 oblique direction of the pelvis, the weight of the body is transmitted almost 

 vertically from the top of the sacrum to the upper part of the thigh-bones. 

 The pelvis of the anthropoid Apes is very differently constructed; as will be seen 

 in the adjoining cut (Fig. 2), in which the skeleton of the Orang is placed in 

 proximity with that of Man. It is much larger and narrower; its alas extend 

 upwards rather than outwards, so that the space between the lowest ribs and 

 the crest of the iliac bones is much less than in Man; their surfaces are nearly 

 parallel to that of the sacrum, which is itself longer and narrower ; and the 

 axis of the pelvis is nearly parallel with that of the vertebral column. The 

 position of the human femur, in which its head is most securely retained in its 

 deep aeetabulum, is that which it has, when supporting the body in the erect 

 attitude; in the Chimpanzee and Orang, its analogous position is an obliquo 

 angle to the long axis of the pelvis, so that the body leans forwards in front of 

 it; in many Mammalia, as in the Elephant, it forms nearly a right angle with 

 the vertebral column; and in several others, as the Horse, Ox, &c. ; the angle 

 which it makes with the axis of the pelvis and vertebral column is acute. In 

 this respect, then, the skeleton of Man presents an adaptation to the erect pos- 

 ture, which is exhibited by that of no other Mammal. 



5. The lower extremities of Man are remarkable for their length ; which is 

 proportionably greater than that which we find in any other Mammalia, except 

 the Kangaroo tribe. The chief difference in their proportional length, between 

 Man and the semi-erect Apes, is seen in the thigh ; and . it is from the relative 

 length of this part in him, as well as from the comparative shortness of his an- 

 terior extremities, that his hands only reach the middle of his thighs, whilst in 

 the Chimpanzee they hang on a level with the knees, and in the Orang they 

 descend to the ankles. The Human femur is distinguished by its form and 

 position, as well as by its length. The obliquity and length of its neck still 

 further increase the breadth of the hips ; whilst they cause the lower extremities 

 of the femora to be somewhat obliquely directed towards each other, so that the 

 knees are brought more into the line of the axis of the body. This arrangement 

 is obviously of great use in facilitating the purely biped progression of Man, in 

 which the entire weight of the body has to be alternately supported on each 

 limb ; for if the knees had been kept further apart, the whole body must have 

 been swung from side to side at each step, so as to bring the centre of gravity 

 over the top of each tibia ; as is seen, to a certain extent, in the female sex, 

 whose walk, owing to the greater breadth of the pelvis and the separation be- 

 tween the knees, is less steady than that of the male. There is a very marked 

 contrast between the knee-joint of Man, and that even of the highest Apes. In 

 the former, the opposed extremities of the femur and the tibia are expanded, so 

 as to present a very broad articulating surface ; and the internal condyle of the 

 femur being the longer of the two, they are in the same horizontal plane in the 



