Tibialis Anterior

Original Editor - Daniele Barilla

Top Contributors - Daniele Barilla, Joao Costa, Kim Jackson, Ahmed Nasr, Nikhil Benhur Abburi, George Prudden, Simisola Ajeyalemi, Evan Thomas, Oyemi Sillo and WikiSysop;

Description

The Tibialis anterior (Tibialis anticus) is situated on the lateral side of the tibia; it is thick and fleshy above, tendinous below. The fibers run vertically downward, and end in a tendon, which is apparent on the anterior surface of the muscle at the lower third of the leg. This muscle overlaps the anterior tibial vessels and deep peroneal nerve in the upper part of the leg.

Variations.—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. The Tibiofascialis anterior, a small muscle from the lower part of the tibia to the transverse or cruciate crural ligaments or deep fascia.

Origin

It arises from:

• Lateral condyle and upper half or two-thirds of the lateral surface of the body of the tibia;
• Adjoining part of the interosseou
• s membrane;
• Deep surface of the fascia;
• Intermuscular septum between it and the Extensor digitorum longus.

Insertion

Medial and under surface of the first cuneiform bone, and the base of the first metatarsal bone.

Nerve

Deep Pereonal Nerve (L4, L5, S1)

Artery

Anterior Tibial Artery

Function

• Tibialis anterior is the primary dorsiflexor n of the ankle with synergistic action of extensor hallicus longus, extensor digitorium longus and peroneous tertius.
• Inversion of the foot.
• Adduction of the foot.
• Contributor of maintaining the medial arch of the foot.
• At anticipatory postural adjustment (APA) phase during gait initiation tibialis anterior favor knee flexion at the stance limb by causing forward displacement of tibia.
• Eccentric deceleration of foot planterflexion and eversion and foot pronation.

Integreated anatomy

Tibialis anterior is one of the muscles that tend to be inhibited and underactive this leads to overactive of synergestic muscles; extensor hallicus longus, extensor digitorium longus and peroneous tertius.

At people with inhibited or weak Tibialis anterior as people with hemiplegia or parkinsonsm they will have an abnormality in their anticipatory postural adjustment (APA) phase during gait initiation at their affected limb and they will try to compensate weakness of Tibialis anterior by overacting of the contralateral tensor fascia latae (TFL)

Clinical relevance

Pain along the path of this muscle is often referred to as "Shin splints". Also called medial tibial stress syndrome (MTSS)

Assessment

Palpation

The client is supine. Place your resistance hand on the medial side of the distal foot.

Resist the client from dorsiflexing and inverting the foot. Look the distal tendon of the tibialis anterior on the medial side of the ankle joint and foot; it is usually visible.

Palpate the distal tendon by strumming perpendicular across it. Continue palpating the tibialis anterior proximally to lateral tibial condyle by strumming perpendicular to the fibers.

Once the tibialis anterior has been located, have the client relax it and palpate to asses its baseline tone.

Power

The action of the tibialis anterior muscle is considerably superior that others three dorsal flextor muscles of the foot, both for the size and for its function that affects the entire foot.

See also

Shin Splints
Ankle and Foot
Strength