26 INTRODUCTION. 



The skull, globe-like, rests poised, or nearly so, on the summit of 

 the vertebral column ; its facial portion being so placed as to give the 

 greatest advantage to the organs of the senses seated in it, connected 

 with the exercise of their respective offices. But this anterior direc- 

 tion of the visage, in the natural erect attitude, decidedly militates against 

 a quadrupedal posture ; for, from the situation of the condyles of the 

 skull, independently of the structure of the cervical portion of the column, 

 and of the arrangement of its muscles, the head could not be raised, 

 so as to admit of a free range to the organs of vision, were such a posture 

 assumed. The vertebral column, which sustains the head, ribs, thoracic 

 viscera, and upper limbs, regularly and considerably enlarges, as it de- 

 scends, in proportion to the gradual increment of the superincumbent 

 pressure ; while, in order to allow a favourable distribution of the impended 

 weight, it forms a series of gentle curves, alternating in opposite direc- 

 tions ; the curve of the cervical region being convex anteriorly, that of 

 the dorsal region concave, and that of the lumbar region, again, convex. 

 The solidified termination of the spinal column is denominated the sacrum ; 

 it makes an obtuse angle with the spine, and forms the posterior wall 

 of the pelvis, to which latter the whole weight of the trunk is trans- 

 mitted ; and on which, also, immediately rests the main portion of the 

 abdominal viscera ; so that the entire pressure of the upper parts is here 

 concentrated. The pelvis constitutes the basis of the trunk; and its 

 strength, form, relative position, and wide expanse enable it efficiently to 

 support the superstructure ; the iliac regions are widely expanded, while the 

 sacrum curves forward ; the whole forming a basin-like cavity, the walls 

 of which not only enclose certain viscera, and support those of the 

 abdomen, but, as before stated, constitute also the broad basis of the 

 entire trunk : the lower limbs now receive the burden, and are 

 sufficient for its easy maintenance. The femur is most powerfully 

 articulated with the pelvis, by means of a round head, deeply lodged 

 in a socket, or acetabulum, and adequately secured by ligaments : 

 it is the strongest and largest of all the long bones in the human 

 frame. Owing to the length of its neck (cervix femoris), which con- 

 nects the head of the bone with the shaft, and forms an angle with the 

 latter, the femur is thrown laterally out from the pelvis, so as to 

 give room for the voluminous muscles of the thigh, and, by the disen- 

 gagement of the shaft from the hip-joint, to admit an increased extent of 

 rotation also. Thus, the transverse dimensions of the base of the trunk 

 are enlarged greater firmness in standing being the result, without 

 impediment to progression. The shaft of the femur is not perpendicu- 

 lar, but inclines inward, so that the knees approach each other, and are 

 brought perpendicularly under the pelvis, the weight of the body bearing 

 obliquely upon them ; this oblique direction of the femur necessitates 



