Fibularis longus

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Fibularis Longus (previously known as the peroneus longus) is a muscle located in the lateral compartment of the leg. It plays a crucial role in foot movement and stability, particularly in eversion of the foot and supporting the arch.

Anatomy[edit | edit source]

The Fibularis Longus originates from the head and upper two-thirds of the lateral surface of the fibula, one of the two bones in the lower leg. It descends down the leg, posterior to the Fibularis Brevis, and passes behind the lateral malleolus. The muscle then runs under the foot to insert at the base of the first metatarsal bone and the medial cuneiform.

This muscle is innervated by the superficial fibular nerve, which branches from the sciatic nerve. Its blood supply comes from the fibular artery, a branch of the posterior tibial artery.

Function[edit | edit source]

The primary function of the Fibularis Longus is to evert the foot, which means it helps to turn the sole of the foot outward. Additionally, it plays a significant role in maintaining the transverse arch of the foot. By contracting, it also assists in plantarflexion of the foot at the ankle joint.

Clinical Significance[edit | edit source]

Injury to the Fibularis Longus can result from direct trauma, overuse, or ankle sprains. Symptoms typically include pain along the course of the muscle, weakness in foot eversion, and difficulty in walking or running. Treatment often involves rest, physical therapy, and in some cases, surgery.