The Tibia and Fibula are the two bones in the leg. The more massive tibia lies medial to the slender fibula. Only the tibia articulates with the femur at the knee. Both bones participate in the ankle joint and articulate with the talus. .
The tibia and the fibula articulate also with each other proximally and distally at the tibiofibular joints. They are also connected throughout their entire lenght by an interosseous membrane (a tough, flexible fibrous membrane).
The tibia is the shin bone.
It may be palpated throughout its length on the front of the leg
from the knee to the medial side of the ankle.
It transmits the weight of the body to the foot.
Examine its proximal end, and note two nearly separate, shallow,
smooth depressions (= medial and lateral condyles) which articulate with the femur.
Just distal to these on the anterior surface is a low vertical ridge (= tibial tuberosity)
to which the strong ligament of the patella attaches.
Note also the inferior projection, the medial malleolus
that forms the inner bulge of the ankle and articulates with the talus.
The fibula does not reach the femur but articulates with the tibia at both its proximal and distal ends. Movement between these bones is limited. Compare with the upper limb. Its lower end is the distal malleolus that forms the big lateral ankle bulge.
Examine the ankle joint.
The distal ends of the tibia and fibula together form a flat
topped arch which encloses the talus (one of the tarsal bones)
so as to permit free movement in one plane (dorsiflexion and plantar flexion),
but limited movement from side to side (inversion and eversion).
Distal projections on the medial side of the tibia and the lateral
side of the fibula help to stabilize the joint and form the
prominent projections palpable on either side of the ankle
(medial and lateral malleoli).