There are two muscles in the lateral compartment of the leg; the fibularis longus and brevis (also known as peroneus longus and brevis). The common function of the muscles is eversion – turning the sole of the foot outwards. They are both innervated by the superficial fibular nerve. In this article, we shall look at the anatomy of the muscles in the lateral compartment of the leg – their attachments, innervation and actions. Note: From the anatomical position, only a few degrees of eversion are possible. In reality, the job of these muscles is to ‘fix’ the medial margin of the foot during running, and prevent excessive inversion. Pro Feature - 3D Model You've Discovered a Pro Feature Access our 3D Model Library Explore, cut, dissect, annotate and manipulate our 3D models to visualise anatomy in a dynamic, interactive way. Learn More Fibularis Longus The fibularis longus is the larger and more superficial muscle within the compartment. Attachments The fibularis longus originates from the superior and lateral surface of the fibula and the lateral tibial condyle. The fibres converge into a tendon, which descends into the foot, posterior to the lateral malleolus. The tendon crosses under the foot, and attaches to the bones on the medial side, namely the medial cuneiform and base of metatarsal I. Actions: Eversion and plantarflexion of the foot. Also supports the lateral and transverse arches of the foot. Innervation: Superficial fibular (peroneal) nerve. Adobe Stock, Licensed to TeachMeSeries Ltd Fig 1The fibularis longus and brevis muscles Pro Feature - Dissection Images Prosection of the muscles of the anterior and lateral compartments of the leg. The deep fibular is deep to this layer, and not visible on this prosection. Prosection of the muscles of the anterior and lateral compartments of the leg. The deep fibular is deep to this layer, and not visible on this prosection. You've Discovered a Pro Feature Access our Dissection Image Library Enhance your understanding with high-resolution dissection images showcasing real-life anatomy. Learn More Fibularis Brevis The fibularis brevis muscle is deeper and shorter than the fibularis longus. Attachments: Originates from the inferolateral surface of the fibular shaft. The muscle belly forms a tendon, which descends with the fibularis longus into the foot. It travels posteriorly to the lateral malleolus, passing over the calcaneus and the cuboidal bones. The tendon then attaches to a tubercle on the 5th metatarsal. Actions: Eversion of the foot. Innervation: Superficial fibular (peroneal) nerve. By TeachMeSeries Ltd (2025) Fig 2Lateral view of the tendons of the foot. Note the fibularis longus tendon, as it moves underneath the foot. Clinical Relevance Locating the Common Fibular Nerve The common fibular nerve can be a difficult structure to identify. However, it can be located using the fibularis longus as an anatomical landmark. There is a small space between the parts of the fibularis longus that originate from the head of the fibula, and the neck of the fibula. The common fibular nerve passes through this gap, and is easily identified. After passing through the gap, the nerve terminates by bifurcating into two terminal branches; the deep and superficial fibular nerve. Do you think you’re ready? Take the quiz below Pro Feature - Quiz Muscles in the Lateral Compartment of the Leg Question 1 of 3 Submitting... Skip Next Rate question: You scored 0% Skipped: 0/3 1800 More Questions Available Upgrade to TeachMeAnatomy Pro Challenge yourself with over 1800 multiple-choice questions to reinforce learning Learn More Print Article Rate This Article