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StatPearls . Endowment Island (FL): StatPearls Publishing; 2021 Jan-.


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Anatomy, Bony Pelvis and Lower Limb, Tibialis Anterior Muscles

Pallavi Juneja; john B. Hubbard.

Author Information

Introduction

The tibialis anterior muscle, likewise known together the tibialis anticus, is the biggest of 4 muscle in the anterior compartment of the leg. Its thick muscle ship arises indigenous its proximal attachments at the lateral tibia; the tibialis anterior tendon (TAT) inserts distally on the medial border the the foot. The muscle is generally responsible because that dorsiflexion and also inversion of the foot.<1><2>


Structure and also Function

Anatomy

The tibialis anterior muscle, particularly its fleshy muscle belly, has a confluence the proximal attachments. These include the lateral condyle of the tibia, the proximal two-thirds the the lateral surface ar of the tibial shaft, the anterior surface of the interosseous membrane in between the tibia and also fibula, the deep surface of the fascia cruris, and the intermuscular septum between it and also the extensor digitorum longus. The tibialis anterior tendon (TAT) starts at the distal one-third that the tibia. It travels across the anterior ankle and also dorsum of the foot to insert vertically on the medial cuneiform and also the base of the first metatarsal. The is the many medial tendon the the ankle and also foot.

The extensor retinaculum (ER), a transverse aponeurotic band comprised of superior and inferior components, consist of the anterior ankle and foot. In many cases, the TAT passes beneath the extensor retinaculum, so the extensor retinaculum holds the TAT in place. In 25% the cases, however, the superficial and deep great of the superior extensor retinaculum form a separate tunnel because that the TAT. The synovial tendon sheath that the TAT extend from above the superior extensor retinaculum, inferiorly come the level the the talonavicular joint. The main synovial bursa is between the tendon and the cuneometatarsal joint and also the medial cuneiform.

Function

The tibialis anterior (TA) is the the strongest dorsiflexor the the foot. Dorsiflexion is vital to gait due to the fact that this movement clears the foot off the ground during the waver phase. 

The tibialis anterior, together with the tibialis posterior, is likewise a primary inverter of the foot. Due to the fact that the TA arises from the lateral tibia and the tendon inserts ~ above the medial border of the foot, muscle convulsion lifts frameworks of the medial arch (medial cuneiform, an initial metatarsal, navicular, talus) right into adduction-supination or inversion. The activity of inversion occurs at 2 synovial joints in the foot: the subtalar joint, between the talus and also calcaneus, and the midtarsal joint, in between the talus and also navicular bone. The tibialis anterior is together a powerful inverter that muscles that the lateral compartment need to be engaged in eversion for the TA come dorsiflex the foot without inversion. 

Due to its insertion on the medial foot, the tibialis anterior additionally supports the medial longitudinal arch of the foot. The medial arch is greater than the lateral arch and is created by the following bones: calcaneus, talus, navicular, 3 cuneiforms, and also the first three metatarsals.<3><4>


Embryology

The tibialis anterior muscle, a muscle the the lower limb, occurs from the myotome the the paraxial mesoderm (somites). At 4 gestational weeks, limb buds develop; through 8 weeks, the bones and muscle groups within the limbs are well-established.


Blood Supply and also Lymphatics

The anterior tibial artery offers the muscle proximally. The medial tarsal arteries, which are branches that the dorsalis pedis artery, supply the tendon distally. The anterior tibial artery is 1 that 2 terminal branches at the bifurcation that the popliteal artery. The various other branch is the tibioperoneal trunk, which more divides into the posterior tibial and also fibular arteries. The anterior tibial artery overcome from the posterior popliteal fossa come the anterior leg with an opened in the interosseous membrane between the tibia and fibula. That travels under the leg, supplying the anterior compartment, and into the foot, continuing as the dorsalis pedis artery. The dorsalis pedis artery then gives rise to the medial tarsal arteries in ~ the level of the medial cuneiform, which gives the tibialis anterior tendon distally.<2>


Nerves

The deep peroneal nerve, likewise called the deep fibular nerve, innervates the tibialis anterior muscle. The deep peroneal nerve is one of two terminal branches at the bifurcation that the common peroneal (fibular) nerve. The other branch is the superficial peroneal (fibular) nerve, which innervates the muscle of the lateral compartment that the leg. The typical peroneal nerve itself derives native the end bifurcation of the sciatic nerve in ~ the apex that the popliteal fossa; the various other terminal branch is the tibial nerve. Spinal nerves L4 through S1 make up the usual peroneal nerve. This nerve wraps roughly the neck the the fibula and also passes between the attachments the the fibularis longus prior to giving increase to the superficial peroneal nerve and deep peroneal nerve. The deep peroneal nerve travels with the anterior tibial artery in one inferomedial direction to innervate every 4 muscles in the anterior compartment that the leg. Both the nerve and also the artery pass in between the tibialis anterior and also extensor digitorum longus proximally and between the tibialis anterior and extensor hallucis longus distally. The nerve then travels beneath the extensor retinaculum together it the cross the fish eye joint; the terminates in the dorsum the the foot, dividing into a lateral branch and a medial branch.<5>


Muscles

The tibialis anterior is one of four muscles in the anterior compartment that the leg. The others include extensor digitorum longus (EDL), extensor hallucis longus (EHL), and fibularis tertius. The deep peroneal nerve innervates every muscles and is perfused by the anterior tibial artery. Collectively, the muscle dorsiflex and invert the foot at the fish eye joint. The extensors (EDL and EHL) also extend the toes; the EDL expand the lateral four toes if the EHL extends the an excellent toe. The fibularis tertius occurs from the inferior EDL and also contributes to eversion. 

The antagonist muscle of the anterior compartment are the muscle of the posterior compartment. Collectively, the posterior muscles plantarflex the foot at the fishing eye joint.


Physiologic Variants

The tibialis anterior tendon (TAT) deserve to have varying insertion patterns. Instead of 1 tendon inserting top top the medial cuneiform and the base of the an initial metatarsal, the tendon can split into two bands that insert on every individually. The broad of this bands can be equal, or they have the right to differ; because that example, the TAT have the right to have a wide insertion top top the medial cuneiform however only a fine tape of insertion in ~ the base of the first metatarsal. It is also feasible for the tendon to insert at only 1 that the 2 sites: the medial picture writing or the basic of the an initial metatarsal. 

The muscle might likewise insert somewhere various altogether. Because that example, a deep section of the muscle have the right to insert more proximally right into the talus. Whereas the tendon may expand further and also insert into the head the the first metatarsal or the basic of the first phalanx.


Surgical Considerations

Rupture the the tibialis anterior tendon (TAT) is an uncommon pathology. However, in the event of a rupture, if the patient experiences significant loss that dorsiflexion and also inversion attach by gait disorder, the therapy of choice is surgical repair or reconstruction. In surgery, the tendon is reattached come the bone.


Clinical Significance

Foot Drop

Because the primary duty of the tibialis anterior is dorsiflexion, paralysis the this muscle outcomes in “foot drop,” or an i can not qualify to dorsiflex. This paralysis have the right to be led to by nerve injury, favor direct damages to the deep peroneal nerve, or a muscle disorder, choose ALS. “Foot drop” is regularly most obvious during gait when the patient cannot clear your foot throughout the waver phase.

Tendinitis

The tibialis anterior tendon (TAT), like any kind of tendon, can become irritated and also inflamed—a condition known together tibialis anterior tendinitis. Too much tension ~ above the tendon causes tendinitis, often due to repetitive, high-force activities, because that example, hill running or direct call with equipment, favor a shoe that is as well tight roughly the ankle and the tendon. Due to the fact that the tendon traverses the anterior ankle and also inserts top top the medial foot, many patients will complain of pain in ~ the front of the ankle or the medial midfoot. Pain will be aggravated through the stressful task and alleviated by rest. Symptom usually present gradually and get significantly worse.

On exam, the patient will have tenderness end the tendon and also maybe even swelling. Loading the tendon, as in dorsiflexion, will exacerbate the pain. Therapy is conservative. Since the injury is as result of exertion, the primary treatment is limiting activity. NSAIDs can be provided for analgesia. The is likewise important to stretch the calf, decreasing the resistance to dorsiflexion. A stabilizing or restricting ankle brace may additionally decrease the pack through the tendon.<6>

Tibial anxiety Syndrome (Shin Splints)

The tibialis anterior muscle is regularly overused, bring about a tibial tension syndrome the is more commonly known as shin splints. Anterior tibial tension syndrome (ATSS) is acute and also experienced by new runners or walkers; medial tibial tension syndrome (MTSS) is more chronic and also occurs through athletes. The tibialis anterior muscle is much more commonly affiliated in the former, while the tibialis posterior muscle is much more commonly involved in the latter, despite the tibialis anterior can likewise cause MTSS. Both syndromes are led to by repetitive stress and also strain top top the tibia, often because of training errors or miscellaneous biomechanical abnormalities. Maintain errors include the current onset of boosted activity, intensity, or expression (doing “too much, as well fast”) or running/walking on difficult or uneven surfaces. Biomechanical abnormalities encompass hyperpronation of the subtalar joint (eversion) and tibial torsion. Tibial tension syndrome, particularly MTSS, have the right to progress come a anxiety fracture the the tibia. This is an ext common in females 보다 males due to a higher incidence of reduced bone density and also osteoporosis.

In ATSS, the patient will current with tightness or tenderness in the anterior muscle of the leg the is aggravated by running or walking and also alleviated through rest. The pains may begin as a dull ache yet often progresses come sharper pain. Together the injury progresses, pain may be existing even in ~ rest.

Since tibial stress syndrome results from overuse and repetitive stress, the most crucial treatment in the acute step is rest. Ice and also NSAIDs can administer analgesia. Long-term, that is crucial to change the training program and include in stretching and strengthening exercises. Extending helps avoid muscle fatigue and subsequent strain on the tibia wherein muscles attach; increase muscles, like the tibialis anterior, helps manage movement to minimize stress top top the tibia. The is also important to exactly underlying biomechanical abnormalities.<7>

Anterior Compartment Syndrome

Compartment syndrome occurs as soon as tissue pressure within a closed, non-extensible muscle compartment over the perfusion pressure. Pressure greater than 30 mm Hg (in relaxed muscles, common tissue press is 10 come 12 mm Hg) compromises circulation and can bring about necrosis and/or ischemia. In acute compartment syndrome, the boosted pressure is brought about by bleeding or edema, usually as result of fracture or trauma. In chronic compartment syndrome (CCS), the boosted pressure in skeletal muscle is due to overexertion. Unlike various other exertional injuries, prefer ATSS or MTSS, chronic compartment syndrome won’t respond come NSAIDs or physics therapy. In the leg, the anterior compartment is most frequently affected by compartment syndrome. 

Patients through compartment syndrome often present with ischemic pain, defined as greater pain 보다 one can expect provided the clinical situation. The pain deserve to be reproduced by passively stretching the muscles in the influenced compartment. For example, in anterior compartment syndrome, plantarflexion will rise pain. In CCS, like various other exertional injuries, the pain is aggravated by task and alleviated through rest. Patients may also develop paresthesia due to nerve ischemia or paralysis that the impacted muscles; however, neurological symptoms may likewise be due to a concurrent nerve injury. Ischemia may likewise lead to pallor and pulselessness, though the last may be a sign of arterial injury instead. Finally, swelling is common and can make the leg feeling firm and “wooden” ~ above palpation.

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Early diagnosis the compartment syndrome is an important to preventing poor outcomes, such as infection, contracture, and amputation. Diagnosis needs awareness of the syndrome and also appropriate examination. Intra-compartmental press can also be measured to diagnose compartment syndrome. Fasciotomy is the typical treatment; the referral is come decompress all 4 compartments. Chronic compartment syndrome can be cure nonoperatively with finish cessation of all causative tasks and massage therapy. In general, nonoperative treatment is unsuccessful.<8>