PELVIC LIMBS. 79 
defi¢iency to the bottom of the cup. The deficiency, incisura 
acetabuli, or acetabular notch (a’), is closed naturally by a 
ligament, and the groove gives origin to the ligament (liga- 
mentum teres) which attaches the head of the femur. 
Femur (Fig. 56).—The femur is the 
proximal bone of the posterior extremity. 
It consists of enlarged proximal and 
distal ends connected by a nearly cylin- 
drical shaft. The proximal end presents 
on its medial side a hemispherical head 
(2) which fits into the acetabulum. It is 
supported by a neck (4) which is con- 
tracted near the head and expanded dorso- 
ventrally where it joins the remainder of 
the bone. The medial surface of the head 
presents near its ventral border a depres- 
sion (¢) for the insertion of the round liga- 
ment of the femur. Ventrad the articular 
surface of the head extends as an acute 
projection onto the shaft, so that the whole 
articular surface appears somewhat pear- 
shaped. On the lateral side of the proxi- 
mal end opposite the head is a projecting 
mass, the great trochanter (@), forming 
the end of the shaft. On the medial side 
of the great trochanter at its junction with 
the neck is a deep fossa, the trochanteric 
fossa or digital fossa (e) for the insertion 
of muscles. From the ventral surface of P!% so TEFL Femur, 
the great trochanter a ridge, the inmter-  u, head; 4, neck; ¢, de- 
trochanteric line (7), is continued distad, oe ee 
ending in a pyramidal projection, the 4 trochanteric fossa; /, 
lesser trochanter (g), which serves for jcrrochanteric Tine; gs 
lesser trochanter; 4, linea 
the insertion of muscles. A second ridge aspera; 7, medial condyle; 
: : J, lateral condyle; 4, inter- 
is continued to the lesser trochanter from ‘ondyloid fossa; 'Z, lateral 
the neck. A slight but well-marked ¢Picondyle. 
ridge, the spiral ridge or line, runs round two sides of the 
neck parallel to the second ridge. 
