250 



PHYSIOLOGY AND HEALTH. 



the chest and give room for the lungs ; and, finally, at the 

 FIG. XXXVI. neck it is erect. Notwithstanding these 



Spine, or Back-bone, curves, the top of the spine, the resting- 

 place of the head, is vertically over the 

 sacrum, on which the last bone of the 

 spine rests. This arrangement of the 

 bones of the spine gives this column 

 great strength and flexibility. 



599. The pelvis forms the base of the 

 trunk, (Fig. XXXII, rf.) It is composed of 

 three bones the two hip bones and the 

 sacrum, which is apparently a continua- 

 tion of the spine. These bones are spread 

 out to form a sort of basin, on which the 

 abdomen rests. The spine stands on the 

 sacrum, and the thigh bones are attached 

 to the hip bones. 



a, Resting-place of the head. 

 a, b, Seven cervical vertebrae. 

 c, d, Twelve dorsal vertebrae. 

 if e, f, Five lumbar vertebras. 



ff> <7 <7 Spinous processes. 

 h, h, Intervertebral cartilages. 

 t, Sacrum, a part of the pelvis. 



CHAPTER III. 



Upper Extremity. Arm. Wrist. Hand. Lower Extremity. 

 Leg. Foot. Arch of the Foot. Shape of the Foot. Natural. 

 Deformed. 



600. THE upper extremity includes the collar-bone or 

 clavicle, the shoulder-blade, upper arm, fore-arm, wrist, hand, 



