| Fibularis tertius | |
|---|---|
 Animation | |
| Details | |
| Origin | Distal anterior surface of thefibula also the interosseous membrane |
| Insertion | Dorsal surface ofmetatarsal 5 |
| Artery | Anterior tibial artery |
| Nerve | Deep fibular nerve |
| Actions | Dorsiflexion andeversion of the foot |
| Identifiers | |
| Latin | musculus fibularis tertius |
| TA98 | A04.7.02.039 |
| TA2 | 2649 |
| FMA | 22538 |
| Anatomical terms of muscle | |
In human anatomy, thefibularis tertius (also known as theperoneus tertius) is amuscle in theanterior compartment of the leg. It acts to tilt the sole of the foot away from the midline of the body (eversion) and to pull the foot upward toward the body (dorsiflexion).
The fibularis tertius arises from the lower third of the front surface of thefibula, the lower part of theinterosseous membrane, andseptum, or connective tissue, between it and thefibularis brevis.[1] The septum is sometimes called the intermuscular septum of Otto.
The muscle passes downward and ends in a tendon that passes under thesuperior extensor retinaculum and theinferior extensor retinaculum of the foot in the same canal as theextensor digitorum longus muscle.[1] It may be mistaken as a fifth tendon of the extensor digitorum longus.[1] The tendon inserts into the medial part of the posterior surface of the shaft of the fifthmetatarsal bone.[1]
The fibularis tertius is supplied by thedeep fibular nerve.[2][3] In rare cases, it may also be supplied by thecommon fibular nerve.[2] This is unlike the otherfibularis muscles, which are located in thelateral compartment of the leg and are supplied by thesuperficial fibular nerve, since the fibularis tertius is found in the anterior compartment of the leg.
The fibularis tertius may be absent inhumans.[1][4] It may be absent in as few as 5% of people,[4] or as many as 72%, depending on the population surveyed.[1] It is rarely found in otherprimates, which is one reason its function has been linked to efficientbipedalism.[4]
As a weakdorsiflexor of the ankle joint, the fibularis tertius assists in pulling the foot upward toward the body. It also assists in tilting the sole of the foot away from midline of the body at the ankle (eversion). It is likely to be helpful though not essential inbipedal walking.[4]
The fibularis tertius may be involved in ankle injuries[1] and may rupture.[5] This is caused byhyperextension.[6]
The fibularis tertius may be imaged usingmedical ultrasound.[6]
Terminologia Anatomica designates "fibularis" as the preferred word over "peroneus.".[7]
The word "peroneus" comes from the Greek word "perone," meaning pin of a brooch or a buckle. In medical terminology, the word refers to being of or relating to the fibula or to the outer portion of the leg.
The fibularis tertius muscle inhorses originates from the near thelateral condyle of the femur, passes through the extensor sulcus on the head of thetibia, and inserts onto the thirdmetatarsal bone, the third and fourthtarsal bones, and thecalcaneus.[8] Rupture of the muscle may cause theAchilles tendon to have a slight dip.[8]
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This article incorporates text in thepublic domain frompage 482 of the 20th edition ofGray's Anatomy(1918)
