The neck is flattened from before backward, contracted in the middle, and broader laterally than medially. The vertical diameter of the lateral half is increased by the obliquity of the lower edge, which slopes downward to join the body at the level of the
lesser trochanter, so that it measures one-third more than the antero-posterior diameter. The medial half is smaller and of a more circular shape. The anterior surface of the neck is perforated by numerous vascular
foramina. Along the upper part of the line of junction of the anterior surface with the head is a shallow groove, best marked in
elderly subjects; this groove lodges the orbicular fibers of the capsule of the
hip joint. The posterior surface is smooth, and is broader and more concave than the anterior: the posterior part of the
capsule of the hip-joint is attached to it about 1 cm above the
intertrochanteric crest. The superior border is short and thick, and ends laterally at the
greater trochanter; its surface is perforated by large foramina. The inferior border, long and narrow, curves a little backward, to end at the lesser trochanter.
Angle of inclination The angle is widest in infancy, and becomes lessened during growth, so that at
puberty it forms a gentle curve from the axis of the body of the bone. In the adult, the neck forms an angle of about 125° with the body, but this varies in inverse proportion to the development of the
pelvis and the stature. The angle decreases during the period of growth, but after full growth has been attained it does not usually undergo any change, even in old age; it varies considerably in different persons of the same age.
Coxa vara is a
deformity of the
hip, whereby the angle between the head and the shaft of the
femur is reduced to less than 120 degrees. Its opposite is
coxa valga. In the
female, in consequence of the increased width of the pelvis, the neck of the femur forms more nearly a right angle with the body than it does in the
male. It is smaller in short than in long bones, and when the pelvis is wide. In addition to projecting upward and medialward from the body of the femur, the neck also projects somewhat forward; the amount of this forward projection is extremely variable, but on an average is from 12° to 14°. ==Fracture==