A malleolus is the bony prominence on each side of the human

ankle The ankle, the talocrural region or the jumping bone (informal) is the area where the foot and the leg meet. The ankle includes three joints: the ankle joint proper or talocrural joint, the subtalar joint, and the inferior tibiofibular joint. The ...

. Each leg is supported by two bones, the

tibia The tibia (; : tibiae or tibias), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two Leg bones, bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outsi ...

on the inner side (medial) of the leg and the fibula on the outer side (lateral) of the leg. The medial malleolus is the prominence on the inner side of the ankle, formed by the lower end of the tibia. The lateral malleolus is the prominence on the outer side of the ankle, formed by the lower end of the fibula. The word ''malleolus'' (), plural ''malleoli'' (), comes from Latin and means "small

hammer A hammer is a tool, most often a hand tool, consisting of a weighted "head" fixed to a long handle that is swung to deliver an impact to a small area of an object. This can be, for example, to drive nail (fastener), nails into wood, to sh ...

". (It is

cognate In historical linguistics, cognates or lexical cognates are sets of words that have been inherited in direct descent from an etymological ancestor in a common parent language. Because language change can have radical effects on both the s ...

with '' mallet''.)

Medial malleolus

The medial malleolus is found at the foot end of the

. The medial surface of the lower extremity of tibia is prolonged downward to form a strong pyramidal

process A process is a series or set of activities that interact to produce a result; it may occur once-only or be recurrent or periodic. Things called a process include: Business and management * Business process, activities that produce a specific s ...

, flattened from without inward - the medial malleolus. * The ''medial surface'' of this process is convex and subcutaneous. * The ''lateral'' or ''articular surface'' is smooth and slightly concave, and articulates with the talus. * The ''anterior border'' is rough, for the attachment of the anterior fibers of the deltoid ligament of the ankle-joint. * The ''posterior border'' presents a broad groove, the malleolar sulcus, directed obliquely downward and medially, and occasionally double; this sulcus lodges the tendons of the tibialis posterior and flexor digitorum longus. * The ''summit'' of the medial malleolus is marked by a rough depression behind, for the attachment of the deltoid ligament. The major structure that passes anterior to the medial malleolus is the saphenous vein. Structures that pass behind medial malleolus deep to the flexor retinaculum: * Tibialis posterior tendon * Flexor digitorum longus * Posterior tibial artery * Posterior tibial vein * Tibial nerve * Flexor hallucis longus

Lateral malleolus

The lateral malleolus is found at the foot end of the fibula, of a pyramidal form, and somewhat flattened from side to side; it descends to a lower level than the medial malleolus. * The ''medial surface'' presents in front a smooth triangular surface, convex from above downward, which articulates with a corresponding surface on the lateral side of the talus. Behind and beneath the articular surface is a rough depression, which gives attachment to the posterior talofibular ligament. * The ''lateral surface'' is convex, subcutaneous, and continuous with the triangular, subcutaneous surface on the lateral side of the body. * The ''anterior border'' is thick and rough and marked below by a depression for the attachment of the anterior talofibular ligament. * The ''posterior border'' is broad and presents the shallow malleolar sulcus, for the passage of the tendons of the peronæi longus and brevis. * The ''summit'' is rounded and gives attachment to the calcaneofibular ligament. A major structure that is located between the lateral malleolus and the Achilles tendon is the sural nerve.

Clinical significance

Fracture

A bimalleolar fracture is a

fracture Fracture is the appearance of a crack or complete separation of an object or material into two or more pieces under the action of stress (mechanics), stress. The fracture of a solid usually occurs due to the development of certain displacemen ...

of the

that involves the lateral malleolus and the medial malleolus. Studies have shown that bimalleolar fractures are more common in women, people over 60 years of age, and patients with existing comorbidities. A trimalleolar fracture is a

of the

that involves the lateral malleolus, the medial malleolus, and the distal posterior aspect of the

, which can be termed the posterior malleolus. The trauma is sometimes accompanied by ligament damage and dislocation.

Additional images

File:Slide2WIKI.JPG, Ankle joint. Deep dissection. Lateral view. File:Slide4CEC3.JPG, Ankle joint. Deep dissection. File:Slide5CEC4.JPG, Ankle joint. Deep dissection. File:3D Medical Animation Fibula Structure.jpg, Image showing the lateral malleolus as part of the fibula. File:Left lateral malleolus avulsion fracture.jpg, X-ray avulsion fracture of the summit of the left lateral malleolus.

References

{{Authority control Bones of the lower limb Tibia Fibula