Human Physiology. 165 



skull is removed, and the dura mater, or tough membrane, raised 

 to show the hemispheres and convolutions of the cerebrum. 

 The brain fills the head to a line passing around it across the 

 eyes and the opening of the ears. The face, it will be observed, 

 occupies only an angle of 

 the profile, and is made up 

 of the nose, cheekbones, 

 and upper and lower jaws. 

 Joined to twelve of the 

 vertebrae, or spinal bones, 

 are the ribs which, with the 

 breast-bone, form the chest 

 or thorax, which contains j 

 the heart and lungs, and 

 which should expand and 

 contract freely at every 

 breath. At the lower end 

 of the spine it forms, with 

 two large, strong, thin Fig IS ._THE BRAIN EXPOSED. 

 bones, the basin or pelvis, 



which contains the viscera of the lower abdomen. This 

 is considerably larger in the female than in the male, which 

 gives her greater breadth at the hips, a form very necessary to 

 the processes of maternity. Shoulder blades are loosely attached 

 to the upper ribs, which are braced by collar bones, joined to 

 the breast-bone. The large bone of the arm is united by a 

 shallow ball-and-socket joint to the shoulder blade, the two 

 bones of the fore-arm join this, in a compound joint, at the 

 elbow; eight small bones form a flexible wrist, and then come 

 the nineteen bones of the hand, thumb, and fingers. Similarly, 

 the thigh-bones are united by deep ball-and-socket joints to the 

 pelvis; the leg-bones on each side by a hinge-joint to the thigh, 

 and a more flexible one to the foot, which is an arch of bones, 

 cartilages, tendons, admirably perfect in contrivance and mech- 



