The bones of the lower limb are a versatile group. They range from the irregularly-shaped hip bone, the long bones of the thigh and calf regions to the small bones of the foot. Together, this diverse group is well adapted for weight bearing in the erect posture and movements like walking and running.
Learn the names of these bones and their structure and functions.
The Hip Bone
This bone forms the skeleton in the region of the hips and buttocks. It is an irregular bone made up of three parts:
- Ilium – This is the upper part of the hip bone. It is spread out and shaped like a fan.
- Ischium – This is the thick and strong part of the hip bone in the region of the buttocks. In fact, the ischial tuberosity, a thickened part of this bone, is the part we sit on.
- Pubis – This part of the hip bone forms the front of the pelvic region. A part of it can be felt just below the abdomen.
All three parts of the hip bone meet at the acetabulum, a cup-shaped depression into which the head of the thigh bone fits neatly to form the hip joint. The right and left hip bones connect with the sacrum and coccyx in the lower part of the vertebral column to complete the skeleton of the pelvis.
Femur – The Thigh Bone
The femur is the strongest of the long bones in the body and is the only bone in the thigh region. Its uppermost part is shaped like a well-rounded head that sits in the acetabulum of the hip bone to form the hip joint. A thin neck connects the head with the shaft of the bone and is often the site of fracture in the elderly.
The lower part of the femur is slightly flattened and spread out and forms part of the knee joint. The thick shaft of the femur lies at the core of the thigh, completely surrounded by strong muscles like the quadriceps and hamstrings.
Patella – The Knee Cap
The knee cap, the prominent part of the front of the knee, is actually formed by a separate bone called the patella. This is a sesamoid bone as it lies within the tendon of the muscle quadriceps femoris, a powerful muscle in the front of the thigh.
When the lower limb is straightened out, the patella can be felt and even grasped with fingers and moved from side to side.
Tibia and Fibula – Bones of the Leg
Anatomically speaking, the term ‘leg’ only corresponds to the region of the lower limb between the knee and ankle joints. The tibia and fibula are the two long bones in the leg. Of these, the tibia is longer and stouter.
The upper end of the tibia is part of the knee joint. Much of the tibia is quite superficial and forms the shin where it can be easily felt. The fibula is a slender bone that lies just beside the tibia. It does not reach all the way up to the knee joint above, but its lower end, along with the lower end of the tibia, forms part of the ankle joint. The lower ends of both bones can be felt as prominent parts called malleoli on either side of the ankle joint.
Bones of the Foot
The skeleton of the foot is formed by several small bones – the tarsal bones, metatarsal bones and phalanges. The tarsal bones are located in the region of the ankle and heel, arranged in two rows. In the first row are two bones, the talus and the calcaneus. The talus, situated above the calcaneus, connects with lower parts of the tibia and fibula in the ankle joint. The heel is formed by the calcaneus.
The next row lies in front of the first and consists of one cuboid and three cuneiform bones, arranged side by side. These bones connect with the five metatarsal bones which lie in front of them. The metatarsals in turn, connect with the phalanges, the bones that lie in the toes. While the great toe has two phalanges, all the other toes have three each.
The bones of the lower limb – the hip bone, femur, tibia, fibula and bones of the foot – are adapted for weight bearing in the erect posture in human beings.
Sources
Romanes, G.J., Cunningham’s Manual of Practical Anatomy. (Oxord University Press; 15th Edition, 2003)
Lakshmi Ananth - Lakshmi Ananth is a practising ENT, head and neck surgeon and has faculty position at a medical college. She is specially interested in ...
Join the Conversation