EXPLANATION OF PLATE III. 



Fig. 1. The HUMAN SKELETON divided into three principal parts ; the Head 

 (1,) the Trunk (2,) and the extremities (3 and 4.) Physiologists enu- 

 merate as many as 260 bones ; but some of these bones, which are 

 separated in early life, are afterwards united, so as to admit of the fol- 

 lowing enumeration : Cranium, 8 ; Face, 14 ; Internal ears, 8 ; Verte- 

 bral column, 24 ; Chest,-26; Pelvis, 11; Upper extremities, 68; Lower 

 extremities, 64 ; in the whole, 223. 



1. The bones of the Skull, divided into two sets, viz., those of the Cranium, 



or case for the brain, and those of the Face. 



2. The Trunk, composed of the Spine, or Vertebral column, extending from 



a to dj the Chest, including the Ribs, and Sternum or Breast-bone, (e;) 

 the Pelvis ; the circle of bones on which the Spine rests. 



The Spine, extending from a to c?, in the erect man, supports the head upon 

 its summit, (a,) while its base rests upon the sacrum (d.) It consists 

 of 24 bones, called Vertebrae, (Lat. verto, to turn,) because the trunk 

 is turned by their motion upon each other. It is the center about 

 which the limbs move, and the chief support of the skeleton. 



The Cervical vertebrae, (the 7 bones of the neck,) extend from a to 6; the 

 middle, dorsal or back vertebrae, from b to c, and the 5 lowest or lum- 

 bar vertebrae, from c to d. 



3. and 4. Are the last main divisions, consisting of the upper and lower 



extremities. 



3. The upper extremities (the arms) consist of the scapula, A, or shoulder- 



blade, the Clavicle or collar-bone, B, the Humerus, or bone of the upper 

 arm, (c,) the Ulna, (D,) situated on the inner side, and the Radius, (E,) 

 on the outer side of the fore-arm, the Carpus, (Car;) the 8 small bones 

 of the wrist, the 5 bones of the metacarpus between the wrist, and the 

 bones of the fingers, (Met.,) and the bones of the fingers, called Pha- 

 langes, (Pha ,) of which the thumb has two, and the fingers three each. 



4. The lower extremities, or legs, consist of the Femur or thigh bone, (F,) 



which is the largest bone of the body, the Tibia or shin-bone, (G,) on 

 the front and inner part, and the Fibula, (H,) at the outer part of the 

 leg, the Patella or knee-pan, (i,) the Tarsus, the 7 bones forming the 

 heel and instep, (Tar.,) the metatarsus (Met.,) between the instep and the 

 toes, and Phalanges of the toes similar in number and arrangement to 

 those of the fingers. 



Fig. 2. SKELETON OF A CHIMPANZEE. The ape that comes nearest to man. 

 3 and 4 show how the extremities terminating with long fingers, and a 

 small feeble thumb set far back, adapt it for climbing rather than walk- 

 ing, thus differing from those organs in man. 



1. The Cranium, showing none of the fine sweep of the forehead seen in 



man, and indicating a small cerebral development as compared with 

 him. 



2. The Vertebral column, without the pyramidal form seen in man, and not 



adapted to an erect posture. 



Pelvis, narrow as compared with that of man. (See description in the 

 text.) 



