2.3.4 Pulley-like structures around the ankle joint
We’ll see more of the bones and ligaments of the foot in the next section. For now, we’ve seen enough to understand how the joints of the ankle region move. Before we go on to look at the muscles that produce those movements, we need to take a look at some important pulley-like structures that are attached to the bones of the ankle region. These are called retinacula, the singular of which is retinaculum. Each retinaculum guides and keeps in place a set of tendons that pass from the leg to the foot. There’s a retinaculum on the front of the ankle, and one on each side of the ankle, behind and below each malleolus.
Here on the front are the upper part and the lower part of the extensor retinaculum. These aren’t isolated structures, they’re localized thickenings of this layer of investing deep fascia, which we’ll meet later. Four tendons, a nerve and an artery pass under the extensor retinaculum.
On the lateral aspect, behind the malleolus, here’s the peroneal retinaculum. It accommodates the tendons of two peroneal muscles as they pass around the lateral malleolus.
On the medial side the flexor retinaculum fans out from the back of the medial malleolus. The space beneath the flexor retinaculum is divided into four separate tunnels. Three tendons, and the posterior tibial vessels and nerve, pass through these tunnels as they pass around the ankle and into the foot.