Exploring the fibularis longus muscle
This is the second muscle that we’ll cover which is part of the lateral compartment on the outside of the foreleg. Interestingly, the fibularis longus muscle (peroneus longus muscle) forms one half of our anatomical stirrup. And, the tibialis anterior forms the other half. Specifically, the anatomical stirrup is created by the way in which the tendon from this muscle goes under the foot and then attaches to the same two bones as the tibialis anterior. The effect is a “stirrup” for your foot. For this reason, these two muscles are critically important for our balance and the health and maintenance of the arch on the medial side of the foot.
What does the name of this muscle mean?
This is one of those muscles that actually has more than one name. In anatomical references, you’ll find this muscle listed both by its older name, fibularis longus muscle, and also by its current name, peroneus longus. Fibularis refers to one of the lower leg bones, the fibula. And, peroneus also means “relating to the outer leg” or fibula. The word “longus” refers to this muscle being the longest of the fibularis or peroneal muscles.
Where does the fibularis longus muscle attach?
This muscle originates on the head and proximal two-thirds of the fibula.
From the origin, the long tendon of this muscle comes down behind the lateral malleolus (lateral ankle bone), then dips under the foot to cut across and get to its insertion point. It inserts on the first, or medial, cuneiform and base of the first metatarsal.
What actions does the fibularis longus muscle do?
The fibularis longus muscle functions to do eversion of the ankle. Additionally, it assists in plantarflexion of the ankle because its tendon is behind the lateral malleolus.