The muscle peroneus longus is an extrinsic muscle of the foot that runs along the outside of the leg. Together with the peroneus brevis muscle, it forms the lateral muscle compartment of the lower limbs.
Your muscular body is directed downward, running through the entire fibula bone. It has a considerable tendinous portion that passes behind the outer part of the ankle joint until it reaches its final insertion in the foot.
Anatomy of the Peroneus longus. By DiademaProductions - Own work, CC BY-SA 4.0, Its main function is to perform the plantar flexion movement of the foot, that is, it flexes the foot downward. In addition to this, it fulfills accessory functions such as eversion and external rotation of the foot and stabilization of the plantar arches.
The functions of the peroneus longus are essential for gait and balance. He is very active, especially when running or climbing stairs.
The tendon of this muscle is one of the most susceptible to injuries that cause pain and instability of the ankle. For this reason, high-performance runners and athletes are dedicated to exercising the peroneus longus muscle to strengthen it and avoid disabling injuries.
Embryology
From the fifth week of gestation, the organization of the first cells that will form the muscles and bones of the lower limbs begins. These come together to form two nuclei that are differentiated into cartilage, bone and soft tissues, such as muscles and ligaments.
The peroneus longus muscle originates around the eighth week from the posterior cell nucleus, along with the rest of the flexor muscles of the leg and foot. By this time there is already a primitive version of the skeleton that is developed.
After birth, when the child begins crawling and standing movements, physiological muscle strengthening begins.
During this stage, the peroneus longus aids in the formation of the plantar arch. In fact, lack of activity or weakness is one of the causes of flat feet.
Origin and insertion
The peroneus longus is one of the three peroneal muscles of the leg. Together with the peroneus brevis, it forms the lateral compartment of the lower limb.
It is considered an extrinsic muscle of the foot since, although its origin is in the leg, its final insertion is in the tarsal bones and its main function is to mobilize the ankle.
Also known as fibular longus, it originates superficially on the lateral aspect of the head and proximal third of the fibula. A normal anatomical variant has a second point of origin, located on the lateral shoulder of the tibia, the lateral condyle, which is attached to the fibula muscle fibers.
By Henry Vandyke Carter - Henry Gray (1918) Anatomy of the Human Body (See «Book» section below) Bartleby.com: Gray's Anatomy, Plate 258, Public Domain, https://commons.wikimedia.org/w/index. php? curid = 792113
The muscular body runs along the lateral aspect of the fibula together with the peroneus brevis muscle, with which it shares a sheath of loose tissue that covers them.
At the end of its journey, the muscle becomes a strong, thick tendon that descends behind the lateral aspect of the ankle. At this point it passes through a fibrous structure called the superior peroneal retinaculum, which stabilizes it and holds it in position.
The tendon continues its route to the foot, traveling laterally through the body of the cuboid bone to finally insert into the lateral aspect of the medial cuneiform bone and the first metatarsal bone.
Muscle anatomy of the foot and ankle. By Henry Vandyke Carter - Henry Gray (1918) Anatomy of the Human Body (See «Book» section below) Bartleby.com: Gray's Anatomy, Plate 441, Public Domain, https://commons.wikimedia.org/w/index. php? curid = 561494
Irrigation and innervation
The blood supply of the peroneus longus muscle is through the anterior tibial artery and the fibular or fibular artery.
The tibialis anterior is a branch of the popliteal artery, whereas the peroneal artery originates from the tibio-peroneal troque that comes from the posterior tibial artery.
Regarding its innervation, the superficial peroneal nerve is responsible for emitting the neurological branches that provide movement to this muscle.
The superficial peroneal nerve is one of the two terminal branches of the common peroneum, and is responsible for providing branches for the movement of the muscles of the lateral compartment of the leg, and sensory branches for the dorsum of the foot.
Features
The main function of the peroneus longus muscle is plantar flexion of the foot, which is the downward movement of the ankle. This movement is performed in conjunction with the gastrocnemius, the calf muscle.
In addition to this, its contraction performs the eversion movement of the foot. This is the outward movement of the ankle.
Anatomical terms of movement. By Connexions - http://cnx.org, CC BY 3.0, As accessory functions, the peroneus longus helps stabilize the sole of the foot. When standing on one foot, this muscle helps maintain balance.
It is also one of the muscles that helps in the formation and maintenance of the arch of the foot. Although it is not the only cause of flat feet, patients with this condition generally have muscle weakness.
Injuries
Injuries to the peroneus longus tendon are relatively common, with young patients with a lot of activity or athletes being the most affected.
The main injuries to the peroneal longus tendon are peroneal tendonitis, peroneal subluxation, and tendon tear.
Tendon tear is an injury that occurs acutely, either from direct trauma or overload at the insertion point.
In contrast, subluxation and tendonitis occur chronically. They are generally seen in very physically active people, who may have inflammation in the tendon due to friction with the ankle joint.
Another cause of tendinitis is inadequate tread when running or jogging, due to the use of unfavorable footwear for this sport.
All these conditions present with pain in the lateral aspect of the ankle and instability in gait and standing. In turn, the instability causes there to be more and more friction between the tendon and the bone, perpetuating the pathology.
Treatment
Once the injury is diagnosed from the physical evaluation and imaging exams, an appropriate treatment plan can be planned.
In most cases, non-invasive therapy is started that includes rest and oral analgesics. The injection of steroids directly into the tendon is also of great help for inflammatory processes.
In case these treatments fail, surgery is chosen, which will be planned depending on the type and degree of the injury.
References
- Lezak, B; Varacallo, M. (2019). Anatomy, Bony Pelvis and Lower Limb, Calf Peroneus Longus Muscle. StatPearls. Treasure Island (FL). Taken from: ncbi.nlm.nih.gov
- Hallinan, J; Wang, W; Pathria, M; Smitaman, E; Huang, B. (2019). The peroneus longus muscle and tendon: a review of its anatomy and pathology. Skeletal Radiology. Taken from: researchgate.net
- Carvallo, P; Carvallo, E; Coello, R; del Sol, M. (2015). Fibular Muscles Long, Short… and Minimal: Why not ?. International Journal of Morphology. Taken from: scielo.conicyt.cl
- Bavdek, R; Zdolšek, A; Strojnik, V; Dolenec, A. (2018). Peroneal muscle activity during different types of walking. Journal of foot and ankle research. Taken from: ncbi.nlm.nih.gov
- Walt, J; Massey, P. (2019). Peroneal Tendon Syndromes. StatPearls. Treasure Island (FL). Taken from: ncbi.nlm.nih.gov
- Davda, K; Malhotra, K; O'Donnell, P; Singh, D; Cullen, N. (2017). Peroneal tendon disorders. EFORT open reviews. Taken from: ncbi.nlm.nih.gov