The bones of the lower limb correspond to a designated region of the lower limb. There is a hip region with two hip bones - right and left, each composed of an ilium, ischium, and pubis. Moving distally, we have a thigh with the femur. Though we think of the leg from the hip down, the anatomical term "leg" actually refers to the portion of the lower limb from the knee to ankle, consisting of the tibia and fibula. Continuing towards the ground, we find the ankle with the tarsals, and finally, we reach the foot, composed of metatarsals and phalanges.

Figure 13-1
Anterior view of the right pelvic bone and sacrum.

Figure 13-2
Right lateral view of the pelvis.

Figure 13-3
Right femur, anterior view (left); posterior view (right).

Figure 13-4
Right tibia and fibula, anterior aspect (left) and posterior aspect (right).

Figure 13-5
Bones of the right foot, dorsal aspect.

The hip bones, or pelvic bones, join the upper body, to the lower propulsive units - the lower limbs. This massive bony ring houses the pelvic viscera, articulates with the vertebral column at the sacroiliac joint, transfers weight from upper body to lower body, and articulates with the lower limbs at the hip joints.

The pelvic bone or hip bone is really two sets of three bones each. Both the right and left side are identical and composed of an ilium, an ischium and a pubic bone. These three bones all converge at the deep hip joint socket, the acetabulum. (Figure 13-1)

The ilium is the most prominent and superior bone of the three. It forms the top part of acetabulum triad and has two large "wings," forming the crests of the ilia. These are really the hip bones that we can feel at or near our waist.

The ischium forms the posterior and inferior part of the acetabulum, and is the posterior inferior part of the hip bone. We sit on the large ischial tuberosities. (Figure 13-2)

The pubic bone forms the anterior portion of the acetabulum, and the anterior and medial part of the hip bone, and joins its partner from the opposite side at the pubic symphysis.

The pelvic girdle is composed of the right and left hip bones joined anteriorly at the pubic symphysis and posteriorly at the two sacroiliac joints. Some anatomists include the sacrum in the pelvic girdle. Without it the two ilia would not be joined and a complete girdle could not be formed.

The femur is the longest bone in the human body and the only bone found in the thigh. It has a very stable deep bony articulation with the hip bone, but a rather weak, unstable articulation distally with the leg bone or tibia at the knee. (Figure 13-3)

The tibia (shin) supports the entire body weight, and gives rise to many important powerful muscles attaching to the ankle or foot. This bone helps with balance and locomotion. The distal end of the tibia, the medial malleolus forms the medial bony portion of the leg's part of the ankle joint. (Figure 13-4)

The smaller, non-weight bearing bone found in the leg is the fibula. The fibula serves as the attachment site for ankle and foot muscles. Its distal end forms the lateral malleolus, the bony portion of the leg's part of the ankle joint.

The tarsal bones of the ankle are arranged in a classic arch - arches support weight better than straight structural lines. The tarsal bones support the body and provide attachment sites for muscles that maintain bipedal posture and mobility. (Figure 13-5)

Large metatarsals tolerate the tremendous weight loads resulting from standing erect .

The phalanges of the foot are short. Unlike the fingers, toes are not very mobile or dexterous and therefore haven't the need for long phalanges.