40 ANATOMY AND PHYSIOLOGY. 



are two prominences which serve as levers for the attachment of 

 strong muscles. The lower ends of the thigh-bones are large, and 

 rest on the heads of the tibia and fibula shin-bones. Their lower 

 ends are much nearer one another than their upper ends, thus 

 bringing the points of support underneath the weight of the body. 

 The bones of the leg are two. The tibia, or shin, is the inner and 

 the larger, placed perpendicularly under the body ; it has a broad 

 end above to articulate with the thigh-bone, and a smaller one 

 below to unite with the foot in the ankle-joint. One of its ridges 

 is felt under the skin the whole way down, and is the part usually 

 known as the shin. The outer bone, called the fibula, passes from 

 the upper end of the shin-bone to the lower ; it is connected with 

 the ankle-joint, but forms no part of the knee-joint ; it has no con- 

 nexion with the thigh-bone, and therefore supports no part of the 

 weight of the body. It serves to increase the breadth of the 

 leg, without adding much to the weight, and is connected in 

 its whole length to the shin-bone by a strong membrane or inter- 

 osseous ligament, which serves to give attachment to muscles as 

 well as if it had been bone, with the advantage of being much 

 lighter. The lower ends of these two bones make the projections 

 which are called the inner and outer ankles, or malleolus. 



Intermediate to the thigh and leg is the kneepan, patella, a 

 bone which corresponds to the elbow in the upper extremity. It 

 glides on the smooth anterior part of the thigh-bone, is attached to 

 the shin-bone by a strong ligament, and has the powerful extensor 

 muscles of the leg inserted in it. It increases the power of these 

 muscles, by throwing their attachment forward, and therefore further 

 from the centre of motion of the leg, thus conferring on them the 

 advantage of a lever power. 



The foot consists of twenty-six bones. Seven of these form the 

 tarsus, or solid part of the foot, to which no English word corres- 

 ponds ; five compose the instep, or metatarsus, and the remaining 

 fourteen are the joints of the toes. One of the bones of the tarsus 

 is shaped above like a pulley, and is received between the projec- 

 tions of the two bones of the leg forming the two ankles, so that 

 by its motion the foot is bent up at right angles to the leg, or 

 pointed with the toes downward. The bone of the heel projects 

 nearly an inch and a half backwards, giving a strong lever for the 

 insertion of the powerful muscles which form the calf of the leg. 

 The next bone is in front of the pulley-like bone, and in some 

 persons is very movable, admitting of much lateral motion across 



