Leg bones and the joints of the lower limb

The lower limb bears the weight of the body. Hence the bones of lower limbs are bigger and stronger than their counterparts in upper limbs. The thigh has one bone called femur.

Femur forms the hip joint with the hip bone. You can feel the hip bone on either side if you run your hands down the waist.

Still below you can feel a part of the femur which is called greater trochanter. In contrast to the shallow cavity of the scapula, the socket for head of femur (acetatubulum) in the hip bone is much deeper.

The head of femur is much bigger than that of humerus. This joint is very stable at the cost of mobility as we do not need wide range of movements at the hip.

The stability of hip joint is further enhanced by a ligament between the head of femur and the margin of the socket in the hip bone. The cavity of the socket is further deepened by a circular cartilage attached to the rim of the acetabulum. This cartilage is called labrum.

Dislocation of hip joint is rare as opposed to shoulder joint. However congenital hip dislocation is occasionally seen.

The knee joint is also a weight bearing joint and its structure is different from that of elbow joint. There are two bones in the leg-tibia and fibula. Tibia is situated medially and articulates with lower end of femur. The articular surfaces of femur and tibia are larger than those of bones forming elbow joint.

As the knee joint is subjected to more wear and tear the articular surfaces are protected by special cartilages called menisci (singular=meniscus). There are two of them-medial and lateral. They act as shock absorbers.

To enhance stability there are ligaments inside the joint. They are called cruciate ligaments. There are two in a joint called anterior and posterior. They are attached to upper end of tibia and the lower end of femur. The ligaments cross each other and resemble the letter X. They are very strong and help in keeping the bones is place.

Another unique feature of the knee joint is the presence of an extra bone called patella which is situated in front forming the knee cap. This bone is within the tendon of the quadriceps muscle the contraction of which results in extension of knee joint (straightening). The patella protects the front of knee joint and increases the strength of the quadriceps muscle.

The lower ends of tibia and fibula produce the bony protuberances of the ankle. They are called medial malleolus and lateral malleolus (plural=malleoli).

The leg bones articulate with the ankle bones. There are seven bones in the ankle as opposed to eight in the wrist. They are called tarsal bones. Two of the tarsal bones are quite big as they have to directly bear the weight of the body. They are calcaneus and talus.

The calcaneus is situated in the back of the foot under the heel area. The talus is situated above the calcaneus and articulates with the tibia above. On the sides it articulates with the malleoli. In front of calcaneus is another bone called cuboid which is situated on the lateral side of the foot. This bone articulates with the fourth and fifth metatarsal bones in front.

In front of talus is a bone called navicular bone which articulates with three bones in front of it. The latter are called cuneiform bones. The cuneiform bones articulate with the first three metatarsal bones.

There are five bones in each foot. They are called metatarsal bones. They are arranged is such a way that they form a bony arch along with the tarsal bones which gives the characteristic shape to the feet. The bony arches enhance beauty.

Like the fingers all the toes except the big toe have three bones called phalanges. They are shorter compared to phalanges of the fingers. The big toe is on the same plane as the other toes as the feet do not perform any skilled work.

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