Peroneal: Definition, Anatomy, Functions, Origins, Innervation and Clinical Aspects

They are a group of muscles located in the legs.

They are found within the peroneal compartment located in the lateral region of the fibula.

Fibula Anatomy


The fibula and tibia are the skeletons of the leg, an anatomical region located between the knee and the ankle.

The fibula is located laterally and behind the tibia.


The long, thin bone, the fibula, is made up of:

  • One end, or epiphysis, is proximal to the tibial condyle.
  • A body called the diaphysis has many muscle attachment sites.
  • A more comprehensive, distal end or epiphysis that allows articulation with the slope to form a part of the ankle joint at the ankle.

Muscle insertions

The fibula is the seat of various muscle attachments, including the feet and ankle movements.

It is connected to the tibia by an interosseous membrane.


Fibula functions

Hold the ankle

The fibula helps maintain the slope of the bone present in the ankle.

Shock absorber

The fibula is not involved in supporting the body, but it has a role as a shock absorber during walking.

Thanks to the interosseous membrane that connects the fibula to the tibia, this role is allowed.

Muscle insertion zone

The fibula has a fixing role for many muscles in the leg, some of which are involved and extend to the foot.

Ankle dynamics

Ankle dynamics pass through the talocrural joint and allow dorsiflexion (flexion) and plantarflexion (extension) movements.

Anatomy of the peroneal muscles

The peroneal muscles are a group of muscles that originate from the fibula (lower part of the leg bone), and for this reason, these are also known as fibularis muscles.

These muscles attach to the bones of the middle foot called the tarsal and metatarsals, which are present between the ankle bones and the toes.

The peroneus longus and brevis muscles are present on the lateral side of the leg, while the peroneal plexus is present on the anterior side.

Origins and insertions

The peroneus longus is present on the lateral part of the leg. It is the most superficial of the three muscles.

The peroneus brevis is also present on the lateral side of the leg, just inside the peroneus longus muscle.

Since it is much shorter, it is attached to the fibula much lower than the fibula long.

Both muscles run on the lateral side of the leg; At the lower end, these muscles develop into tendons, running side by side, passing behind the outer ball of the ankle, the lateral malleolus, and then ventrally along the lateral border of the foot.

There they are led by two canal-like peroneal reticules.

The retinaculum of the superior fibula extends between the lateral malleolus and the calcaneus.

The inferior fibula retinaculum runs between the inferior extensor retinaculum of the anterior leg muscles and the calcaneus.

The peroneus longus tendon attaches to the first metatarsal (related to the big toe). The peroneus brevis attaches to the fifth metatarsal (the fifth or most minor toe).

Both tendons attach to the lower surface of these metatarsals.


The peroneus long and the short are innervated by the superficial fibular nerve and the artery.

External popliteal sciatica yields into the canal that provides it with the lateral peroneus longus, a nerve thread carried vertically down the center of the muscle threads.

This nerve sometimes also comes from the musculocutaneous nerve.

The peroneus brevis receives its nerve either from the cutaneous muscle or from the branch that goes to the peroneus longus.

Both peroneal muscles are supplied by the superficial fibular nerve (L5-S1).

Long lateral peroneal action

The peroneus longus has a triple role:

  • First, spread your foot over your leg.
  • Second, it causes the foot to twist out.
  • Third, it maintains the concavity of the arch.

The extension movement occurs in the tibiotarsal, is poorly extended, and is not very energetic.

The peroneus lateralis longus is, like an extensor proper, only a weak auxiliary of the triceps surae.

The torsional movement can be schematically decomposed into a rotational motion. The inner edge of the foot is lowered, and the outer edge is raised along the plantar surface facing the outside, and an adduction movement, below which the toe comes off.

This movement takes place in the three torsion joints: talo-navicular, talocalcaneal and calcaneocuboid.

The lateral peroneus longus imparts movement to these joints opposite to that imparted by the anterior tibia.

The movable joint surfaces move upward, outward, and backward around the axis common to these three joints.

In this movement, the dorsal surface of the foot tends to be superior, and the delicate texture of the incredible process of the calcaneus fills the outer part of the talus sinus.

Contraction of the lateral peroneus longus exaggerates the concavity of the arch.

This muscle action is because it brings the inner edge of the foot down and out.

This results in an increase in arch concavity in the transverse direction and the anteroposterior direction.

These two movements of the inner edge of the foot combine to produce a complex twisting motion, as evidenced by the curvilinear skin folds that appear on the plantar surface during the contraction of the peroneus longus muscle.

This twisting motion of the inside of the forefoot, not to be confused with the twisting motion outside of the entire foot, is because there are no longer movements in the three twisted joints but sliding motions that seat the small ones—joints of the inner part of the forefoot.

These movements are carried out first in the first metatarsal joint with the first wedge shape, the navicular, and a little in the talonavicular joint with the first wedge shape.

The head of the first metatarsal is lowered one and a half centimeters in the first joint movement and one centimeter in the second; the latter has less scope.

At the same time, the head of the first metatarsal is lowered; it is worn, making a kind of opposition movement and will cover only the head of the second metatarsal.

In a more advanced stage of muscle contraction, the movement is extended to the other two cuneiforms, and these three bones come together against each other on their underside.

This arch support function is the critical function of the peroneus lateralis longus.

The lateral peroneus longus is not very involved in the actual extension of the foot, that is, in the movement that takes place in the tibiotarsal joint.

But, thanks to its role in pressing the inner forefoot, it is an indispensable auxiliary of the sural triceps.

The calf muscle is a solid rear part of the extensor foot and the outside of the forefoot; however, it only has minimal work on the inside of the forefoot.

Peroneus brevis action

The lateral peroneus brevis twists the foot outward; it raises its outer edge and brings the sole to look outward.

He does not act as an expander, nor as a flexor; he produces a movement in the tibiotarsal only when the foot has previously been placed in forced flexion or extension, then returns it to the middle position.

The twisting motion takes place at all three twist joints.

Also, the peroneus brevis involves the small joint of the fifth metatarsal at the cuboid, printing it from the bottom up.


The thin thigh muscles help keep the legs firm on the feet. The action of the peroneus longus is especially significant when standing on one leg.

The lateral pull of this muscle prevents it from falling to the side of the raised leg.

The long and short fibular muscles move the upper and lower ankle joints.

In the upper ankle joint, they force a depression of the foot (plantar flexion) as their tendons go behind the flexion-extension axis.

At the lower ankle joint, its contraction leads to eversion (pronation), which reduces the medial foot edge while the lateral foot edge is raised.

Clinical aspects

When the superficial fibular nerve is paralyzed, pronation of the foot is severely restricted.

Therefore, supination predominates so that it is simultaneously displaced medially during the lifting of the foot (equinovarus position).

When affected patients try to walk, it hits the way they place the lateral edge of the foot with each step of the affected leg.

Additionally, a lateral calf contraction may be observed due to atrophy of the peroneal muscles.

Common causes of a superficial fibular nerve injury include:

  • Injury to the head of the fibula.
  • Too tight a cast or improper leg splint placement.
  • Polio disease (infantile paralysis).