THE BONES OF THE LOWER EXTREMITY 97 



ligaments are present, as in life, the real boundaries of 

 the outlet are the subpubic ligament and the rami of 

 the os pubis and ischium in front, the great sacro- 

 sciatic ligaments and the tip of the coccyx behind, 

 and the tuberosities of the ischia on each side. 



The Femur. The femur (thigh bone) is the largest, 

 longest, and strongest bone of the skeleton. It is convex 

 in front and concave behind, and when the body is 

 erect the femur is inclined inward and slightly back- 

 ward. It is divisible into an upper and lower extremity 

 and a shaft. 



The Upper Extremity. This presents a head, a neck, 

 and a great and small trochanter. The head is joined to 

 the shaft by the neck, it is round and forms more than 

 a half sphere. It articulates with the acetabulum of 

 the innominate bone. Just below and behind the centre 

 of the head is a depression for the interarticular or 

 round ligament of the hip- joint, which is attached 

 by its upper end to the centre of the acetabulum. 

 The neck is narrow just at the junction of the head, 

 constricted in the centre, and widens as the base is 

 approached; is flattened slightly anteriorly and poste- 

 riorly, concave above and below. The direction of 

 the neck is slightly upward, forward, and inward, 

 being set upon the shaft at an angle of 125 degrees. 

 The junction of the neck with the shaft shows in front 

 and behind a slight elevation or roughened surface of 

 bone called the anterior and posterior intertrochan- 

 teric lines, and they afford attachment to the capsular 

 ligament and ligament of Bigelow. The posterior 

 intertrochanteric line in the middle receives the 

 quadratus femoris. The small trochanter is a small 

 projection of the bone seen at the inferior aspect of 

 the base of the neck when it unites with the shaft. 

 The great trochanter is a projection of bone extending 

 upward beyond the neck. It can be felt under the skin. 

 It is quadrilateral in shape, with its base attached to 

 the shaft of the femur. 



