The tibialis anterior muscle is a

muscle Muscle is a soft tissue, one of the four basic types of animal tissue. There are three types of muscle tissue in vertebrates: skeletal muscle, cardiac muscle, and smooth muscle. Muscle tissue gives skeletal muscles the ability to muscle contra ...

of the anterior compartment of the lower leg. It originates from the upper portion of the

tibia The tibia (; : tibiae or tibias), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two Leg bones, bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outsi ...

; it inserts into the medial

cuneiform Cuneiform is a Logogram, logo-Syllabary, syllabic writing system that was used to write several languages of the Ancient Near East. The script was in active use from the early Bronze Age until the beginning of the Common Era. Cuneiform script ...

and first

metatarsal The metatarsal bones or metatarsus (: metatarsi) are a group of five long bones in the midfoot, located between the tarsal bones (which form the heel and the ankle) and the phalanges ( toes). Lacking individual names, the metatarsal bones are ...

bones of 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 ...

. It acts to dorsiflex and invert the foot. This muscle is mostly located near the shin. It is situated on the lateral side of the tibia; it is thick and fleshy above, tendinous below. The tibialis anterior overlaps the anterior tibial vessels and deep peroneal nerve in the upper part of the leg.

Structure

The tibialis anterior muscle is the most medial muscle of the anterior compartment of the leg. The muscle ends in a

tendon A tendon or sinew is a tough band of fibrous connective tissue, dense fibrous connective tissue that connects skeletal muscle, muscle to bone. It sends the mechanical forces of muscle contraction to the skeletal system, while withstanding tensi ...

which is apparent on the anteriomedial dorsal aspect of the foot close to the ankle. Its tendon is ensheathed in a synovial sheath. The tendon passes through the medial compartment superior and inferior extensor retinacula of the foot.

Origin

The tibialis anterior muscle arises from the upper 2/3 of the lateral surface of the tibia and the adjoining part of the

interosseous membrane An interosseous membrane is a thick dense fibrous sheet of connective tissue that spans the space between two bones, forming a type of syndesmosis joint. Interosseous membranes in the human body: * Interosseous membrane of forearm * Interosseo ...

and deep fascia overlying it, and the intermuscular septum between this muscle and the extensor digitorum longus.

Insertion

It is inserted into the medial and inferior surface of the medial cuneiform bone, and adjacent portion of the

first metatarsal bone The first metatarsal bone is the bone in the foot just behind the big toe. The first metatarsal bone is the shortest of the metatarsal bones and by far the thickest and strongest of them. Like the four other metatarsals, it can be divided into ...

Nerve supply

The tibialis anterior muscle is innervated by 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 ...

, and recurrent genicular nerve (L4).

Variation

A deep portion of the muscle is rarely inserted into the talus, or a tendinous slip may pass to the head of the first metatarsal bone or the base of the first phalanx of the

great toe Toes are the 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 ''plantigrade''; ...

. The tibiofascialis anterior, a small muscle from the lower part of the tibia to the transverse or cruciate crural ligaments or

deep fascia Deep fascia (or investing fascia) is a fascia, a layer of dense connective tissue that can surround individual muscles and groups of muscles to separate into fascial compartments. This fibrous connective tissue interpenetrates and surrounds the m ...

Actions/movements

The muscle acts to dorsiflex and invert the foot. It is the largest dorsiflexor of the foot. The muscle also contributes to deceleration.

Function

The muscle helps maintain the medial longitudinal arch of the foot. It draws up and holds the toe in a locked position. The tibialis anterior aids in any activity that requires moving the leg or keeping the leg vertical. It functions to stabilize the ankle as the foot hits the ground during the contact phase of

walking Walking (also known as ambulation) is one of the main gaits of terrestrial locomotion among legged animals. Walking is typically slower than running and other gaits. Walking is defined as an " inverted pendulum" gait in which the body vaults o ...

(eccentric contraction) and acts later to pull the foot clear of the ground during the swing phase (concentric contraction). It also functions to 'lock' the ankle, as in toe-kicking a ball, when held in an isometric contraction. The movements of tibialis anterior are

dorsiflexion Motion, the process of movement, is described using specific anatomical terms. Motion includes movement of organs, joints, limbs, and specific sections of the body. The terminology used describes this motion according to its direction relativ ...

and inversion of the ankle. However, actions of tibialis anterior are dependent on whether the foot is weight bearing or not (closed or open kinetic chain). When the foot is on the ground, the muscle helps to balance the leg and talus on the other tarsal bones so that the leg is kept vertical even when walking on uneven ground.

Clinical significance

A tibialis anterior hernia is a rare type of

hernia A hernia (: hernias or herniae, from Latin, meaning 'rupture') is the abnormal exit of tissue or an organ (anatomy), organ, such as the bowel, through the wall of the cavity in which it normally resides. The term is also used for the normal Devel ...

in which fat or other material protrudes through a defect in the tibialis anterior muscle. It may be caused by trauma, such as an inadvertent kick to the lower leg from an opposing player in a

football Football is a family of team sports that involve, to varying degrees, kick (football), kicking a football (ball), ball to score a goal (sports), goal. Unqualified, football (word), the word ''football'' generally means the form of football t ...

match.

Additional images

medial view of dissected ankle has two muscles File:Gray1240.png, Lateral aspect of right leg. File:Tibialis anterior 2.png, Tibialis anterior muscle File:Braus 1921 293.png, Cross-section through top third and second third of right leg. File:Slide9DDDD.JPG, Tibialis anterior muscle File:Slide2WIKI.JPG, Ankle joint. Deep dissection. Lateral view *This has some structures labelled incorrectly e.g. tibialis anterior, extensor hallucis longus and cuboid bone

References

External links

*
Tibialis Anterior
from Wheeless' Textbook of Orthopaedics {{Authority control Calf muscles Muscles of the lower limb