The extensor hallucis longus muscle is a thin
skeletal muscle, situated between the
tibialis anterior
The tibialis anterior muscle is a muscle in humans that originates along the upper two-thirds of the lateral (outside) surface of the tibia and inserts into the medial cuneiform and first metatarsal bones of the foot. It acts to dorsiflex and inve ...
and the
extensor digitorum longus. It extends the big toe and
dorsiflects the foot. It also assists with foot
eversion and
inversion
Inversion or inversions may refer to:
Arts
* , a French gay magazine (1924/1925)
* ''Inversion'' (artwork), a 2005 temporary sculpture in Houston, Texas
* Inversion (music), a term with various meanings in music theory and musical set theory
* ...
.
Structure
The extensor hallucis longus muscle arises from the anterior surface of the
fibula for about the middle two-fourths of its extent, medial to the origin of the
extensor digitorum longus muscle. It also arises from the
interosseous membrane of the leg to a similar extent.
The anterior tibial vessels and deep fibular nerve lie between it and the tibialis anterior.
The fibers pass downward, and end in a
tendon, which occupies the anterior border of the muscle, passes through a distinct compartment in the
cruciate crural ligament
The inferior extensor retinaculum of the foot (cruciate crural ligament, lower part of anterior annular ligament) is a Y-shaped band placed in front of the ankle-joint, the stem of the Y being attached laterally to the upper surface of the calc ...
, crosses from the lateral to the medial side of the anterior tibial vessels near the bend of the ankle, and is inserted into the base of the distal
phalanx
The phalanx ( grc, φάλαγξ; plural phalanxes or phalanges, , ) was a rectangular mass military formation, usually composed entirely of heavy infantry armed with spears, pikes, sarissas, or similar pole weapons. The term is particularly ...
of the great toe.
Opposite the
metatarsophalangeal articulation, the tendon gives off a thin prolongation on either side, to cover the surface of the joint.
An expansion from the medial side of the tendon is usually inserted into the base of the proximal phalanx.
Nerve supply
The extensor hallucis longus muscle is supplied by the
deep fibular nerve, a branch of
common fibular nerve
The common fibular nerve (also known as the common peroneal nerve, external popliteal nerve, or lateral popliteal nerve) is a nerve in the lower leg that provides sensation over the posterolateral part of the leg and the knee joint. It divides at ...
, which includes
L4,
L5, and
S1 spinal nerve roots.
Variations
Occasionally united at its origin with the
extensor digitorum longus.
The
extensor ossis metatarsi hallucis, a small muscle, sometimes found as a slip from the extensor hallucis longus, or from the tibialis anterior, or from the extensor digitorum longus, or as a distinct muscle; it traverses the same compartment of the transverse ligament with the extensor hallucis longus.
Function
The extensor hallucis longus muscle extends the
big toe
Toes are the digits (fingers) of the foot of a tetrapod. Animal species such as cats that walk on their toes are described as being ''digitigrade''. Humans, and other animals that walk on the soles of their feet, are described as being ''plan ...
,
dorsiflects the
foot
The foot ( : feet) is an anatomical structure found in many vertebrates. It is the terminal portion of a limb which bears weight and allows locomotion. In many animals with feet, the foot is a separate organ at the terminal part of the leg made ...
, and also assists with foot
eversion and
inversion
Inversion or inversions may refer to:
Arts
* , a French gay magazine (1924/1925)
* ''Inversion'' (artwork), a 2005 temporary sculpture in Houston, Texas
* Inversion (music), a term with various meanings in music theory and musical set theory
* ...
.
Additional Images
File:Gray440_color.png, Cross-section through middle of leg. (Extensores longi digitorum et hallucis labeled at upper left.)
File:Slide1ABBAA.JPG, Dorsum of Foot. Deep dissection.
File:Slide2ABBAA.JPG, Dorsum of Foot. Deep dissection.
File:Slide2wewe.JPG, Ankle joint. Deep dissection. Medial view
File:Slide2WIKI.JPG, Ankle joint. Deep dissection. Lateral view.
References
External links
* - "The Leg: Muscles"
University of Washington
{{Authority control
Calf muscles
Muscles of the lower limb