CHAPTER XIII. 

 THE LOWER EXTREMITIES. 



The lower extremities resemble the upper very closely 

 in the arrangement of the bones, muscles, arteries, and 

 nerves, though modifications occur, due to the difference 

 in function of the lower limbs. There is one long bone 

 in the upper part or thigh, the femur, and two in the 

 lower part or leg, the tibia and fibula, while over the 

 knee-joint is the patella or knee cap. The ankle has 

 seven bones and the foot nineteen like the hand. 



The Femur. The femur is the longest bone in the 

 body, being about one-fourth the height of the person. 

 It inclines toward its fellow at the knee in order to 

 bring the knee-joints near the center of gravity in walk- 

 ing, the amount of inclination varying with the width 

 of the hips and the height of the person. On account 

 of the greater width of hip the tendency to knock- 

 knee is greater in women than in men. 



The shaft of the femur is enlarged at the extremities 

 and is slightly curved forward, the concavity being 

 strengthened at the back by a longitudinal ridge, the 

 linea aspera, along part of which the gluteus maximus 

 muscle is attached. The head, which is covered with 

 cartilage, except for an oval depression for the attach- 

 ment of the ligamentum teres, one of the ligaments of 

 the hip joint, and which articulates with the hollow of 

 the acetabulum in the os innominatum, projects consid- 

 erably upward, inward, and forward from the shaft, 

 the neck varying much in length and angle. It is gen- 

 erally more horizontal in women than in men and in 

 rickets the great weight on the softened bone tends to 

 press the head down, causing the deformity known as 



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