The extensor hallucis longus muscle is a thin

skeletal muscle Skeletal muscle (commonly referred to as muscle) is one of the three types of vertebrate muscle tissue, the others being cardiac muscle and smooth muscle. They are part of the somatic nervous system, voluntary muscular system and typically are a ...

, situated between the

tibialis anterior The tibialis anterior muscle is a muscle of the anterior compartment of the lower leg. It originates from the upper portion of the tibia; it inserts into the medial cuneiform and first metatarsal bones of the foot. It acts to dorsiflex and invert ...

and the

extensor digitorum longus The extensor digitorum longus is a pennate muscle, situated at the lateral part of the front of the leg. Structure It arises from the lateral condyle of the tibia; from the upper three-quarters of the anterior surface of the body of the fibula; ...

. It extends the big toe and dorsiflects the foot. It also assists with foot eversion and inversion.

Structure

The muscle ends as a tendon of insertion. The tendon passes through a distinct compartment in the

inferior extensor retinaculum of foot 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 calca ...

. It crosses anterior tibial vessels lateromedially near the bend of the ankle. In the foot, its tendon is situated at along the medial side of the dorsum of the foot. 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.

Origin

The extensor hallucis longus muscle arises from the middle portion of the anterior surface of the

fibula The fibula (: fibulae or fibulas) or calf bone is a leg bone on the lateral side of the tibia, to which it is connected above and below. It is the smaller of the two bones and, in proportion to its length, the most slender of all the long bones. ...

and adjacent

interosseous membrane of the leg The interosseous membrane of the leg (middle tibiofibular ligament) extends between the interosseous crests of the tibia and fibula, helps stabilize the Tib-Fib relationship and separates the muscles on the front from those on the back of the leg. ...

. Its origin is medial to the origin of the

extensor digitorum longus muscle The extensor digitorum longus is a pennate muscle, situated at the lateral part of the front of the leg. Structure It arises from the lateral condyle of the tibia The tibia (; : tibiae or tibias), also known as the shinbone or shankbone, i ...

Insertion

The muscle inserts at the base of the

distal phalanx The phalanges (: phalanx ) are digital bones in the hands and feet of most vertebrates. In primates, the thumbs and big toes have two phalanges while the other digits have three phalanges. The phalanges are classed as long bones. Structur ...

of the great toe.

Nerve supply

The muscle receives motor innervation from the

deep fibular nerve The deep fibular nerve (also known as deep peroneal nerve) begins at the bifurcation of the common fibular nerve between the fibula and upper part of the fibularis longus, passes infero-medially, deep to the extensor digitorum longus, to the a ...

( L5) (a branch of common fibular nerve).

Relations

The anterior tibial vessels and deep fibular nerve pass between this muscle and the tibialis anterior muscle.

Variation

Occasionally united at its origin with the

. 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.

Actions/movements

The muscle extends/dorsiflects the

big toe Toes are the Digit (anatomy), digits 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 ' ...

(primary action), and 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 an organ at the terminal part of the leg made up o ...

(secondary action).

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