This is a large, thick, strong bone, extending obliquely downward and forward from the hip-joint above to the stifle-joint below. The shaft presents a number of roughened places for the attachment of muscles. For the same purpose there are also several bony prominences and ridges, notably the trochanter minor externas on the upper third of the outer surface, the trochanter minor internus near the upper third of the inner surface.

The superior extremity is formed by the head, a rounded projection which fits into the acetabulum or cup in the innominate bone to form the hip-joint, and on the outer side of this a considerable eminence (trochanter major) for the attachment of some of the large muscles of the croup. Behind and below the trochanter major a somewhat deep cavity exists, called the trochanteric fossa, into which some smaller muscles are inserted.

The lower extremity presents four large prominences - two behind, the condyles, which are separated by a deep notch (inter-condyloid fossa), and two in front, the trochlea, with which the patella articulates. Above the outer condyle behind is a deep depression termed the supra-condyloid fossa.

Fig. 308. - Os Femoris (Anterior Aspect).

1 Head. 2 Internal Trochanter. 3 4 Tuberosities for Ligamentous Insertion. 5 Internal and External Trochlea. 6 Trochanter Minor Externus. 7 Great Trochanter.