Most muscles in the medial compartment are innervated mainly by the obturator nerve (except the pectineus, which is innervated by the femoral nerve, and part of the adductor magnus, which is innervated by the tibial division of the sciatic nerve).
Most muscles in the posterior compartment of the thigh and the leg and in the sole of the foot are innervated by the tibial part of the sciatic nerve (except the short head of the biceps femoris in the posterior thigh, which is innervated by the common fibular division of the sciatic nerve).
The anterior and lateral compartments of the leg and muscles associated with the dorsal surface of the foot are innervated by the common fibular part of the sciatic nerve.
In addition to innervating major muscle groups, each of the major peripheral nerves originating from the lumbar and sacral plexuses carries general sensory information from patches of skin (Fig. 6.19). Sensation from these areas can be used to test for peripheral nerve lesions:
The femoral nerve innervates skin on the anterior thigh, medial side of the leg, and medial side of the ankle.
The obturator nerve innervates the medial side of the thigh.
The tibial part of the sciatic nerve innervates the lateral side of the ankle and foot.
The common fibular nerve innervates the lateral side of the leg and the dorsum of the foot.
Nerves related to bone
The common fibular branch of the sciatic nerve curves laterally around the neck of the fibula when passing from the popliteal fossa into the leg (Fig. 6.20). The nerve can be rolled against bone just distal to the attachment of biceps femoris to the head of the fibula. In this location, the nerve can be damaged by impact injuries, fractures to the bone, or leg casts that are placed too high.
Large veins embedded in the subcutaneous (superficial) fascia of the lower limb (Fig. 6.21) often become distended (varicose). These vessels can also be used for vascular transplantation.
The most important superficial veins are the great and small saphenous veins, which originate from the medial and lateral sides, respectively, of a dorsal venous arch in the foot.
The great saphenous vein passes up the medial side of the leg, knee, and thigh to pass through an opening in deep fascia covering the femoral triangle and join with the femoral vein.
The small saphenous vein passes behind the distal end of the fibula (lateral malleolus) and up the back of the leg to penetrate deep fascia and join the popliteal vein posterior to the knee.
The external surfaces of the pelvic bones, sacrum, and coccyx are predominantly the regions of the pelvis associated with the lower limb, although some muscles do originate from the deep or internal surfaces of these bones and from the deep surfaces of the lumbar vertebrae, above (Fig. 6.22).
Each pelvic bone is formed by three bones (ilium, ischium, and pubis), which fuse during childhood. The ilium is superior and the pubis and ischium are anteroinferior and posteroinferior, respectively.
The ilium articulates with the sacrum. The pelvic bone is further anchored to the end of the vertebral column (sacrum and coccyx) by the sacrotuberous and sacrospinous ligaments, which attach to a tuberosity and spine on the ischium.
The outer surface of the ilium, and the adjacent surfaces of the sacrum, coccyx, and sacrotuberous ligament are associated with the gluteal region of the lower limb and provide extensive muscle attachment. The ischial tuberosity provides attachment for many of the muscles in the posterior compartment of the thigh, and the ischiopubic ramus and body of the pubis are associated mainly with muscles in the medial compartment of the thigh. The head of the femur articulates with the acetabulum on the lateral surface of the pelvic bone.