Tibialis anterior muscle
Encyclopedia
In human anatomy, the tibialis anterior is a muscle
that originates in the upper two-thirds of the lateral surface of the tibia
and inserts into the medial cuneiform
and first metatarsal
bones of the foot
. Its 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.
. The tibialis anterior is responsible for dorsiflexing
and inverting the foot. The muscle has two origins, one being the lateral tibial condyle and the other being the upper lateral surface of the tibia, and inserts on the medial surface of the medial cuneiform and adjoining part of base of the first metatarsal of the foot allowing the toe to be pulled up and held in a locked position. It also allows for the ankle to be inverted giving the ankle horizontal movement allowing for some cushion if the ankle were to be rolled. It is innervated by the deep fibular nerve
and acts as both an antagonist and a synergist of the tibialis posterior
. However, the most accurate antogonist of the tibialis anterior is the peroneus longus. The tibialis anterior aides in the activities of walking, running, hiking, kicking a ball, or 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
(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.
Antagonists are plantar-flexors
of the posterior compartment such as soleus and gastrocnemius.
Essentially, the movements of tibialis anterior are dorsiflexion
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.
and upper half or two-thirds of the lateral surface of the body of the tibia
; from the adjoining part of the interosseous membrane
; from the deep surface of the fascia; and from the intermuscular septum
between it and the extensor digitorum longus
.
The fibers of this fusiform muscle are relatively parallel to the plane on insertion, ending in a tendon, apparent on the anteriomedial dorsal aspect of the foot close to the ankle.
After passing through the most medial compartments of the transverse
and cruciate crural ligaments, it is inserted into the medial and under surface of the medial cuneiform bone
and the base of the first metatarsal
bone.
, 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
.
The tibiofascialis anterior, a small muscle from the lower part of the tibia to the transverse or cruciate crural ligaments or deep fascia
.
Muscle
Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...
that originates in the upper two-thirds of the lateral surface of the tibia
Tibia
The tibia , shinbone, or shankbone is the larger and stronger of the two bones in the leg below the knee in vertebrates , and connects the knee with the ankle bones....
and inserts into the medial cuneiform
Cuneiform (anatomy)
There are three cuneiform bones in the human foot:* the medial cuneiform* the intermediate cuneiform also known as the middle* the lateral cuneiform...
and first metatarsal
Metatarsus
The metatarsus or metatarsal bones are a group of five long bones in the foot located between the tarsal bones of the hind- and mid-foot and the phalanges of the toes. Lacking individual names, the metatarsal bones are numbered from the medial side : the first, second, third, fourth, and fifth...
bones of the foot
Foot
The foot 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 up of one or more segments or bones, generally including claws...
. Its 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
Anterior tibial artery
The anterior tibial artery of the lower limb carries blood to the anterior compartment of the leg and dorsal surface of the foot, from the popliteal artery.It is accompanied by a deep vein, the anterior tibial vein, along its course....
vessels and deep peroneal nerve
Common fibular nerve
The common fibular nerve , about one-half the size of the tibial nerve, is derived from the dorsal branches of the fourth and fifth lumbar and the first and second sacral nerves.It descends obliquely along the lateral side of the popliteal fossa to the head of the fibula,...
in the upper part of the leg.
Function
The tibialis anterior muscle is the most medial muscle of the anterior compartment of the legAnterior compartment of leg
-Muscles:The muscles of the compartment are* tibialis anterior* extensor hallucis longus* extensor digitorum longus* fibularis tertius -Nerve supply:...
. The tibialis anterior is responsible for dorsiflexing
Dorsiflexion
Dorsiflexion is the movement which decreases the angle between the dorsum of the foot and the leg, so that the toes are brought closer to the shin. The movement moving in opposite directions is called plantarflexion...
and inverting the foot. The muscle has two origins, one being the lateral tibial condyle and the other being the upper lateral surface of the tibia, and inserts on the medial surface of the medial cuneiform and adjoining part of base of the first metatarsal of the foot allowing the toe to be pulled up and held in a locked position. It also allows for the ankle to be inverted giving the ankle horizontal movement allowing for some cushion if the ankle were to be rolled. It is innervated by the deep fibular nerve
Deep fibular nerve
The deep fibular 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 extensor digitorum longus, to the anterior surface of the interosseous membrane, and comes into relation with the anterior...
and acts as both an antagonist and a synergist of the tibialis posterior
Tibialis posterior muscle
The Tibialis posterior is the most central of all the leg muscles, and is located in the posterior compartment of the leg.It is the key stabilizing muscle of the lower leg....
. However, the most accurate antogonist of the tibialis anterior is the peroneus longus. The tibialis anterior aides in the activities of walking, running, hiking, kicking a ball, or 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
Walking is one of the main gaits of locomotion among legged animals, and is typically slower than running and other gaits. Walking is defined by an 'inverted pendulum' gait in which the body vaults over the stiff limb or limbs with each step...
(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.
Antagonists are plantar-flexors
Plantarflexion
Plantarflexion is the movement which increases the approximate 90 degree angle between the front part of the foot and the shin, as when depressing an automobile pedal...
of the posterior compartment such as soleus and gastrocnemius.
Essentially, the movements of tibialis anterior are dorsiflexion
Dorsiflexion
Dorsiflexion is the movement which decreases the angle between the dorsum of the foot and the leg, so that the toes are brought closer to the shin. The movement moving in opposite directions is called plantarflexion...
and inversion
Inversion (kinesiology)
Inversion is the movement of the sole towards the median plane .Tibialis anterior and tibialis posterior invert. Some sources also state that the triceps surae and extensor hallucis longus invert....
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.
Origin and insertion
It arises from the lateral condyleLateral condyle
Lateral condyle can refer to:* Lateral condyle of tibia* Lateral condyle of femur* Lateral condyle on metatarsal...
and upper half or two-thirds of the lateral surface of the body of the tibia
Body of tibia
- Borders :The anterior crest or border, the most prominent of the three, commences above at the tuberosity, and ends below at the anterior margin of the medial malleolus...
; from the adjoining part of the interosseous membrane
Interosseous membrane
An interosseous membrane is a broad and thin plane of fibrous tissue that separates many of the bones of the body. It is an important component of many joints.Interosseous membranes in the human body:* Interosseous membrane of the forearm...
; from the deep surface of the fascia; and from the intermuscular septum
Intermuscular septum
Intermuscular septum can refer to:* medial intermuscular septum of arm* medial intermuscular septum of thigh* lateral intermuscular septum of arm* lateral intermuscular septum of thigh...
between it and the extensor digitorum longus
Extensor digitorum longus muscle
The Extensor digitorum longus is a pennate muscle, situated at the lateral part of the front of the leg.-Origin and insertion:It arises from the lateral condyle of the tibia; from the upper three-fourths of the anterior surface of the body of the fibula; from the upper part of the interosseous...
.
The fibers of this fusiform muscle are relatively parallel to the plane on insertion, ending in a tendon, apparent on the anteriomedial dorsal aspect of the foot close to the ankle.
After passing through the most medial compartments of the transverse
Superior extensor retinaculum of foot
The superior extensor retinaculum of the foot of the ankle is the upper part of the anterior annular ligament....
and cruciate crural ligaments, it is inserted into the medial and under surface of the medial cuneiform bone
Medial cuneiform bone
The medial cuneiform is the largest of the cuneiforms.It is situated at the medial side of the foot, anterior to the navicular and posterior to the base of the first metatarsal....
and the base of the first metatarsal
First metatarsal bone
The first metatarsal bone is the bone in the body of the foot just behind the big toe.It is remarkable for its great thickness, and is the shortest of the metatarsal bones.The body is strong, and of well-marked prismoid form....
bone.
Variations
A deep portion of the muscle is rarely inserted into the talusTalus bone
-External links:* *...
, 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
Hallux
In tetrapods, the hallux is the innermost toe of the foot. Despite its name it may not be the longest toe on the foot of some individuals...
.
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
Deep fascia is a layer of fascia which can surround individual muscles, and divide groups of muscles into compartments....
.
External links
- http://www.wheelessonline.com/ortho/tibialis_anterior