Corpus: Fibularis longus muscle

The fibularis longus muscle is a skeletal muscle of the lower extremity. It is part of the lateral group of lower leg muscles.

2.1. Origin

The fibularis longus muscle originates from the capsule of the tibiofibular joint, the head of the fibula, and the proximal area of the fibula. It also uses the anterior and posterior intermuscular septum of the leg as areas of origin. The common fibular nerve runs through a small gap in its area of origin.

2.2. Attachment

The fibularis longus muscle ends in a long tendon that runs distally behind the lateral malleolus. It then processes ventrally in close approximaty to the tendon of the fibularis brevis muscle. It is situated beneath the superior and inferior peroneal retinacula.

The tendon then follows the outer edge of the foot. Upon reaching the cuboid bone, it moves medially through the plantar peroneal sulcus of the long plantar ligament to the opposite side of the foot, eventually inserting into the first metatarsal bone and the medial cuneiform bone. Due to the lateral pressure load at the contact point between the cuboid bone and the fibular longus tendon, a cartilage cover is present. Depending on the degree of strain, a sesamoid bone may also develop as a result of the additional bending load.

The fibularis longus muscle is innervated by the superficial fibular nerve.

The fibularis longus muscle causes plantar flexion at the talocrural joint and pronation (eversion) of the foot at the talotarsal joint. By supporting the midfoot along with the tibialis anterior muscle, the fibularis longus muscle helps tense the physiological transverse arch of the foot skeleton in interaction with the tibialis posterior muscle.