The bone between the hip and the knee is the femur. It is the longest and strongest bone in the body. The femur articulates proximally with the acetabulum and distally with the tibia and patella. The knee joint is formed by articulations of the femur, tibia, and patella. The knee joint enables flexion, extension, and minimal rotation of the femur and tibia. Also, it plays an important role in supporting the weight of the body during static positions and dynamic movement during gait.
Actions of the Knee Complex
The articulations between the femur, tibia, and patella form the knee joint and enable the following actions (Figure 36-1A):
- Flexion. Movement in the sagittal plane, decreasing the knee joint angle.
- Extension. Movement in the sagittal plane, increasing the knee joint angle.
- Medial rotation. Movement toward the midline in the transverse or axial plane.
- Lateral rotation. Movement away from the midline in the transverse or axial plane.
A. Actions of the knee joint. B. Compartments of the thigh. C. Muscles of the anterior compartment of the thigh.
The muscles of the thigh are divided by their fascial compartments (anterior, medial, and posterior) and may cross the hip or knee joint (Figure 36-1B). Identifying which joints the muscles cross and the side on which they cross can provide useful insight into the actions of these muscles (Table 36-1).
Table 36-1. Muscles of the Thigh |Favorite Table|Download (.pdf)
Table 36-1. Muscles of the Thigh
Anterior compartment of the thigh
T12–L1 vertebral bodies and discs
Lumbar spine flexion, posterior pelvic tilt
Anterior rami (L1)
T12–L5 transverse processes, vertebral bodies and discs
Lesser trochanter of femur
Flexes and externally rotates thigh at hip joint; flexes trunk (psoas major)
Anterior rami (L1–L3)
Femoral n. (L2, L3)
Anterior superior iliac spine
Inferomedial to tibial tuberosity (pes anserinus)
Flexes thigh at hip joint and flexes leg at knee joint
Femoral n. (L2, L3)
Anterior inferior iliac spine
Flexes thigh at hip joint and extends leg at knee joint
Femoral n. (L2–L4)
Lateral part of intertrochanteric line, margin of greater trochanter, lateral margin of gluteal tuberosity, lateral lip of linea aspera
Quadriceps femoris tendon
Extends leg at knee joint
Medial part of intertrochanteric line, pectineal line, medial lip of linea aspera, medial supracondylar ridge
Femur: upper two-thirds of anterior and lateral surfaces
Medial compartment of the thigh
Oblique line extending from base of lesser trochanter to linea aspera on posterior surface of proximal femur