The =femur= or thigh bone (Os femoris) is the largest and most massive
of the long bones. It extends obliquely downward and forward,
articulating with the acetabulum above and the tibia and patella below.
It presents for examination a shaft and two extremities.
The =shaft= or =body= (Corpus femoris) is in general cylindrical, but
flattened behind, and larger above than below. The =anterior= and
=lateral surfaces= are continuous and strongly convex from side to side;
there is often a central vertical rough line on the proximal part, but
otherwise these surfaces are smooth. They are covered by the quadriceps
femoris muscle. The =posterior surface= is wide, flat, and smooth in its
proximal fourth. Below this part there is a rough elevation externally
for the attachment of the femoral tendon of the biceps femoris, and a
rough line internally to which the quadratus femoris is attached. The
middle third is narrower, and is rough for the attachment of the
adductor muscle. Just below this area an oblique groove crosses the
surface, indicating the position of the femoral vessels. The =internal
border= bears on its proximal part the =internal trochanter= or
=trochanter minor=, a thick rough ridge, to which the ilio-psoas muscle
is attached. From this a rough line curves up to the front of the neck
and indicates the limit of the attachment of the vastus internus muscle.
A narrow rough area about the middle gives attachment to the pectineus
muscle, and the =nutrient foramen= is usually found just in front of
this mark. The =supracondyloid crest= is situated below the groove for
the femoral vessels, and gives origin to the inner head of the
gastrocnemius. The =external border= is prominent in its upper part, and
bears at the junction of its proximal and middle thirds the =external=
or =third trochanter= (Trochanter tertius); this process is curved
forward, and furnishes insertion to the tendon of the superficial
gluteus muscle. At the lower part is found the =supracondyloid= or
=plantar fossa= (Fossa plantaris), in which the superficial flexor
arises; it is bounded externally by a thick rough margin, to which the
outer head of the gastrocnemius muscle is attached.
[Illustration:
FIG. 63.—RIGHT FEMUR OF HORSE, EXTERNAL VIEW.
]
[Illustration:
FIG. 64.—RIGHT FEMUR OF HORSE, POSTERIOR VIEW.
]
[Illustration: