The ankle joint is a complex structure that plays a central role in movement, enabling walking, running, and maintaining balance. Many people are curious about the specific names of the bones and structures that form this intricate joint, particularly the bony prominences that are easily felt. This article clarifies the precise anatomical name for the inner ankle.
Identifying the Medial Malleolus
The prominent bony knob on the inner side of your ankle is called the medial malleolus (malleolus medialis). This structure is part of the tibia, the larger of the two lower leg bones (shin bone). The medial malleolus extends downward from the lower end of the tibia, forming a visible projection. It is easily palpable.
The medial malleolus articulates with the talus, a foot bone between the shin and heel bones, contributing to ankle joint formation. Its surface is smooth where it meets the talus and rough where ligaments and tendons attach. The anterior border of the medial malleolus is continuous with the tibial shaft, while the posterior border features a groove that accommodates tendons such as the tibialis posterior and flexor digitorum longus.
Role in Ankle Stability
The medial malleolus plays an important role in ankle joint stability. It forms part of the bony mortise, a socket-like structure that cradles the talus, allowing for hinge-like movements (plantarflexion and dorsiflexion). The integrity of this bony structure helps maintain proper ankle alignment.
This bony projection serves as an attachment point for the strong deltoid ligament (medial collateral ligament). The deltoid ligament is a triangular band that connects the medial malleolus to several bones in the foot, including the talus, calcaneus (heel bone), and navicular bone. This ligament complex stabilizes the ankle joint and helps prevent excessive outward turning of the foot (eversion).
Common Conditions Affecting the Inner Ankle
Various conditions can affect the medial malleolus and surrounding structures. One condition is a medial malleolus fracture, a break in the bone. These fractures often involve the articular surface of the ankle joint and can occur as isolated injuries or in conjunction with other ankle injuries, such as those to the outer ankle.
Another common issue is a deltoid ligament sprain, involving stretching or tearing of the strong ligaments attached to the medial malleolus. These sprains result from the foot turning excessively outward (eversion injury) or direct trauma. Symptoms include pain, swelling, and tenderness on the inner side of the ankle, sometimes accompanied by bruising and difficulty bearing weight. While less common than outer ankle sprains, deltoid ligament injuries can lead to instability if not properly addressed.
Posterior tibial tendon dysfunction (PTTD) affects a major tendon running behind the medial malleolus. This tendon helps support the arch of the foot and plays a role in walking. When the posterior tibial tendon becomes inflamed, overstretched, or tears, it can lead to pain along the inner ankle, swelling, and a gradual flattening of the foot’s arch. If left untreated, PTTD can progress, causing increased pain and potentially leading to significant foot deformity and arthritis.