Muscles of the lateral leg Flashcards
How many muscles are in the lateral compartment of the leg?
There are two muscles in the lateral compartment of the leg; the fibularis longus and brevis. In older texts, they are referred to as the peroneal longus and brevis. As the fibularis longus and brevis are in the same muscular compartment, they have the same function and innervation.
What is the common function of the fibularis longus and brevis muscles?
The common anatomical function of the muscles is eversion – turning the sole of the foot outwards. You’ll notice that from the anatomical position, only a few degrees of eversion is possible. In reality, the job of these muscles is to fix the medial margin of the foot during running, and preventing excessive inversion.
Describe the fibularis longus muscle.
This is the longer and more superficial muscle of the two.
Attachments: The tendon of the fibularis longus has a slightly odd anatomical course:
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 the descends into the foot, posterior to the lateral malleolus.
The tendon then 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 tranverse arches of the foot.
Innervation: Superficial fibular (peroneal) nerve, L4-S1.
Describe the fibularis brevis muscle.
The fibularis brevis muscles is deeper and shorter than the fibularis longus.
Attachments: It originates from the inferior and lateral surface of the fibular shaft. The muscle belly forms a tendon, which descends with the fibularis longus tendon. It travels into the foot, posterior to the lateral malleolus, passing over the calcaneus and the cuboidal bones. The tendon of the fibularis brevis attaches to a tubercle on metatarsal 5.
Actions: Eversion of the foot.
Innervation: Superficial fibular (peroneal) nerve, L4-S1.
How do you locate the common fibular nerve during dissection?
The common fibular nerve is a difficult structure to identify. However, it can be located, using the fibularis longus as an anatomical landmark.
There is a gap between the parts of the fibularis longus that originate from the fibular head and neck. The common fibular nerve passes through this gap, and can be relatively easily identified.
After passing through the gap, the nerve terminates by bifurcating into two terminal branches; the deep and superficial fibular nerve.
