THE BONES. 47 



Radius. Situated in the external side of the fore-arm, towards 

 the thumb. 



Carpus or Wrist. Composed of eight bones, which lie close to 

 each other in a double row. Situated between the fore-arm and 

 metacarpus. Divided into two rows, superior and inferior. In the 

 superior row are (from the thumb to the little finger) os scaphoides, 

 or naviculare ; os lunare ; os cuneiforme ; and os orbiculare, or 

 sub-rotundum. In the lower, os trapezium ; os trapezoides ; os 

 magnum, and os unciforme. 



Metacarpus. Situated between the carpus and fingers. Com- 

 posed of five longitudinal bones ; one of the thumb, and four 

 metacarpal bones of the fingers. Use To form the middle part of 

 the hand. 



Fingers. Situated at the inferior extremity of the metacarpus. 

 Composed of a thumb and four fingers. The thumb has two bones, 

 and each finger three, which are called phalanges. Use To form 

 the fingers, which are the instruments of touch, defence, and labor. 



BONES OF THE INFERIOR EXTREMITIES. 



The bones of the inferior extremity are, the femur, patella, tibia, 

 fibula, the bones of the tarsus, metatarsus, and toes. 



Femur. Situated between the pelvis and tibia. 



Tibia. Situated in the inside of the leg, between the femur and 

 tarsus. 



Fibula. Situated in the outer part of the leg, by the side of the 

 tibia. 



Patella, or Knee-pan. Situated in the sinus between the con- 

 diles of the femur, and above the tibia. 



Tarsus. Situated between the leg and metatarsus. Composed 

 of seven bones, placed in a double row. 



Metatarsus. Situated between the tarsus and toes. Composed 

 of five longitudinal bones. 



Toes. The great toe is composed of two small bones ; each of 

 the other toes, of three small bones, called phalanges. 



PERIOSTEUM. 



Definition. A membrane which invests the external and internal 

 surface of all the bones except the crowns of the teeth. Names. 

 Pericranium on the cranium ; periorbita on the orbits ; perichon- 

 drium, when it covers cartilages ; and peridesmium, when it covers 

 ligaments. Substance fibrous, furnished with arteries^ veins, nerves, 

 and absorbent vessels. Use To distribute the vessels on the exte** 

 nal and internal surface of bones. 



