M76: Enthesopathies of lower limb, excluding foot

M76.7: Peroneal tendinitis

The fibularis muscles are located on the outside of your lower leg. You use your fibularis muscles to tip your foot to one side, for example. This involves pointing the inside of the foot downwards and the sole of your foot away from your other foot.

An inflammation in the fibularis muscles can affect tendons, tendon sheaths, bursas or joint capsules. Tendons are made up of very firm connective tissue. Tendons attach muscles to bones. A tendon sheath is a covering for the tendon. It cushions the tendon and contains a small amount of fluid. This reduces friction between the tendon and its surroundings. A bursa is a cushion of connective tissue filled with fluid. For example, there is a bursa beneath tendons or between bones and skin. The bursa prevents the tissue from rubbing together. A bursa also enables pressure to be distributed better. Joints are encased in a joint capsule.

An inflammation can be caused by overwork, injuries or pathogens, for example. An inflammation may be painful. The pain may make moving your leg more difficult than usual.