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

ankle The ankle, or 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 joi ...

. Each leg is supported by two bones, the

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

on the inner side (medial) of the leg and the

fibula The fibula or calf bone is a leg bone on the lateral side of the tibia, to which it is connected above and below. It is the smaller of the two bones and, in proportion to its length, the most slender of all the long bones. Its upper extremity i ...

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". (It is cognate with '' mallet''.)

Medial malleolus

The medial malleolus is found at the foot end of the

. The medial surface of the

lower extremity of tibia The tibia (; ), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outside of the tibia); it connects ...

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 se ...

, 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 Concave or concavity may refer to: Science and technology * Concave lens * Concave mirror Mathematics * Concave function, the negative of a convex function * Concave polygon, a polygon which is not convex * Concave set * The concavity of a ...

, 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 Also known as the Malleolar groove. There are two malleolar sulci, medial and lateral. The medial malleolar sulcus is the posto-inferior groove just lateral to the medial malleolus on the distal part of the tibia. It is where the tendons of th ...

, directed obliquely downward and medially, and occasionally double; this sulcus lodges the tendons of the Tibialis posterior and

Flexor digitorum longus The flexor digitorum longus muscle is situated on the tibial side of the leg. At its origin it is thin and pointed, but it gradually increases in size as it descends. It serves to flex the second, third, fourth, and fifth toes. Structure The fl ...

. * 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 *

Posterior tibial artery The posterior tibial artery of the lower limb is an artery that carries blood to the posterior compartment of the leg and plantar surface of the foot. It branches from the popliteal artery via the tibial-fibular trunk. Structure The poster ...

* Posterior tibial vein *

Tibial nerve The tibial nerve is a branch of the sciatic nerve. The tibial nerve passes through the popliteal fossa to pass below the arch of soleus. Structure Popliteal fossa The tibial nerve is the larger terminal branch of the sciatic nerve with root val ...

* Flexor hallucis longus

Lateral malleolus

The lateral malleolus is found at the foot end of the

, 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 anterior talofibular ligament is a ligament in the ankle. It passes from the anterior margin of the fibular malleolus, anteriorly and laterally, to the talus bone, in front of its lateral articular facet. It is one of the lateral ligaments o ...

. * The ''posterior border'' is broad and presents the shallow

, 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 of the

that involves the

lateral malleolus A malleolus is the bony prominence on each side of the human ankle. Each leg is supported by two bones, the tibia on the inner side (medial) of the leg and the fibula on the outer side (lateral) of the leg. The medial malleolus is the promine ...

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 fracture of the

that involves the

, the medial malleolus, and the distal posterior aspect of the

, which can be termed the

posterior malleolus The tibia (; ), 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 outside of the tibia); i ...

. 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