A smooth prominence on a bone where it forms a joint with another bone.
The femur or thigh bone is found in the
upper leg and is the longest bone in the body. The femur articulates proximally
with the acetabulum of the pelvis to form the hip joint, and distally with the
tibia and patella to form the knee joint.
Proximally, the femur exhibits four key
regions. The femoral head projects medially and superiorly and articulates with
the acetabulum of the pelvis to form the hip joint. Immediately lateral to the
head is the neck that connects the head with the shaft. It is narrower than the
head to permit a greater range of movement at the hip joint.
Located superiorly on the main shaft,
lateral to the joining of the neck, the greater trochanter is a projection to
which the abductor and lateral rotator muscles of the leg attach.
on the main shaft, but inferiorly to the neck joint, is the lesser trochanter. A
much smaller projection than the greater trochanter, the psoas major and iliacus
muscles attach here.
The shaft descends in a slightly medial
direction that is designed to bring the knees closer to the body’s center of
gravity, increasing stability. Due to the widening of the female pelvis this
angle is greater in women and can lead to increased knee instability.
features of the shaft are the proximal gluteal tuberosity to which the gluteus
maximus attaches, and the distal adductor tubercle to which the adductor magnus
Distally, the femur exhibits five key
regions. Two rounded regions, termed the medial and lateral condyles, articulate
with the tibia at the most anterior projection of the patella.
Between the two
condyles lies the intercondylar fossa, a depression in which key knee ligaments
attach; this significantly strengthens the knee joint and protects it against
Finally, the two epicondyles, the medial and lateral, lie immediately
proximal to the condyles; they are also regions where key internal knee ligaments