Anatomy and features of the fibular
The long, slender fibula runs parallel to the lateral aspect of the tibia and is an important structure of the lower limb. The fibula head is a distinct anatomical landmark that can be easily palpated just to the right of the tibiofibular ridge and serves as an attachment point for several ligaments and muscles.
The slender bony shaft of the calf bone has unique biomechanical properties, creating an efficient load distribution system that transmits only about 10 per cent of body weight through the calf, with the majority of the weight transferred through the stronger, thicker shin bone.
The bony body of the calf bone forms a characteristic sharp shape that continues distally, and this structure provides an ideal shape for muscle attachments and ligamentous connections.
This sharp shape continues distally into the lateral malleolus (from the Latin malleus, meaning hammer), which is an important anatomical landmark and functional structure that can be easily palpated in the ankle region.
The malleus performs an important biomechanical function as a sophisticated pulley structure that allows the tendons of the long and short calf muscles [fibularis (peroneus) longus and brevis] in particular to move smoothly, which is key to ankle stability and mobility. The medial surface of the sesamoid contains a specialised articular facet for the talus, which is an integral component of the talocrural joint in the ankle and plays a crucial role in maintaining normal motion and stability of the ankle.
Structural characteristics of the distal tibia
The distal end of the tibia has a progressively widening anatomical structure that allows it to adapt to different loads and stresses transmitted through the ankle joint, effectively distributing the pressure generated during weight bearing.
On the medial surface of the distal shin bone is the medial malleolus, a distinctive protrusion that plays an important role in the stability of the ankle. On the medial aspect of the medial malleolus, there are specialised articular surfaces for the delicate articulation with the navicular bone, allowing for smooth joint movement.
In the anatomy of the ankle, these articular surfaces form an important but relatively small part of the tarsometatarsal joint and contribute to overall ankle stability. On the lateral surface of the distal calf bone is the fibular notch, a triangular-shaped concavity specifically designed to stably accommodate the distal end of the calf bone at the distal tibiofibular joint, which is essential for maintaining the structural integrity of the ankle joint.
As a unique anatomical feature in adults, the distal end of the shin bone has a specialised structure that twists laterally along its long axis at an angle of approximately 20-30 degrees to the body end, which provides optimal foot positioning during gait. This natural torsion can be clearly seen in the slightly supinated foot position observed, particularly in the standing position, which is essential for normal gait patterns.
This characteristic torsion of the calf is referred to by the technical term lateral tibial torsion, based on the relative orientation of the distal end of the shin bone to the proximal end, and is important for normal biomechanical function of the lower limb.