The peroneal muscles, though often overlooked, play an important role in the lower leg’s overall function and stability. These muscles contribute to everyday movements and dynamic sports activities. They help maintain balance and coordination, integral to confident movement. Understanding these muscles illuminates their impact on lower limb health and performance.
Anatomy of the Peroneal Muscles
The peroneal muscles are located on the outside of the lower leg. This muscle group includes two primary muscles: the peroneus longus and the peroneus brevis. The peroneus longus originates higher on the fibula, the smaller lower leg bone. Its tendon extends behind the lateral malleolus (the prominent bony bump on the outside of the ankle), then crosses underneath the foot to insert on the first metatarsal and medial cuneiform bones.
The peroneus brevis begins lower on the fibula, just below the peroneus longus. Its tendon also travels behind the lateral malleolus, but unlike the longus, it inserts onto the base of the fifth metatarsal bone on the outside of the foot. Both tendons pass through a groove behind the lateral malleolus, held by the superior peroneal retinaculum. This arrangement allows them to exert leverage on the foot and ankle.
Function of the Peroneal Muscles
The peroneal muscles perform two main actions. Their primary action is eversion, turning the sole of the foot outward. This movement helps the foot adapt to uneven surfaces. They also assist in plantarflexion, pointing the foot downward, working with the calf muscles.
Beyond these movements, an important role of the peroneal muscles is ankle stabilization. They provide dynamic support to the ankle joint, preventing excessive inversion (the inward rolling of the ankle). This stabilizing function is important during activities like walking, running, or sudden changes in direction, where the ankle is susceptible to sprains. Their action helps maintain balance and prevent the foot from collapsing inward, protecting the ankle from injury.
Common Peroneal Muscle Injuries
Injuries to the peroneal muscles or their tendons cause pain along the outside of the ankle and foot. Peroneal tendonitis, an inflammation of these tendons, often results from overuse, repetitive activities, or sudden increases in activity levels. This condition causes a dull ache that worsens with physical activity, especially those involving ankle eversion or standing. Swelling and tenderness along the tendon path behind the lateral malleolus are also common symptoms.
Tendinosis, a chronic condition, involves the degeneration of the peroneal tendons, often without significant inflammation. This can result from prolonged stress or inadequate healing after an initial injury. Acute strains, or muscle tears, can occur during sudden, forceful movements, leading to immediate pain, swelling, and sometimes bruising in the lateral lower leg. These injuries can range from mild pulls to more severe ruptures.
Peroneal tendon subluxation or dislocation occurs when the tendons slip out of their normal position behind the lateral malleolus. This can present as a snapping or popping sensation with ankle movement, accompanied by pain and instability. Many peroneal injuries are associated with ankle sprains, especially inversion sprains, as the tendons are stretched or damaged during the forceful inward roll of the ankle. Weakness or instability in the ankle often accompanies these conditions, making everyday activities challenging.
Strengthening and Rehabilitation Exercises
Rehabilitation for peroneal muscle injuries involves exercises to restore strength and stability. Resistance band eversions directly target the peroneal muscles. To perform this, sit with legs extended, loop a resistance band around the affected foot, and anchor the other end to a sturdy object or the opposite foot. Slowly turn the foot outward against the band’s resistance, keeping the heel on the floor. Hold for about five seconds before returning to the start. This rebuilds muscle power and improves ankle control.
Calf raises, performed with both feet or single-leg, also engage the peroneal muscles indirectly while strengthening the lower leg. Stand with support if needed, then slowly raise the heels as high as possible onto the balls of the feet. This exercise improves ankle stability and strength. Balance exercises, such as standing on one leg for 10-30 seconds, challenge the peroneal muscles to maintain stability and proprioception (the body’s sense of its position in space). Gently stretching the peroneal muscles can also be beneficial. For example, cross one foot over the other and gently pull the toes back towards the shin to improve flexibility.