Extensor Hallucis Longus

Original Editor - Esraa Mohamed Abdullzaher

Top Contributors - Esraa Mohamed Abdullzaher, Mohit Chand, Patti Cavaleri, George Prudden, 127.0.0.1, WikiSysop, Simisola Ajeyalemi, Kim Jackson and Joao Costa

Introduction

The Extensor hallucis longus (EHL) muscle is a key muscle located in the anterior compartment of the lower leg. It is responsible for extending the big toe at both the metatarsophalangeal and interphalangeal joints.

Anatomy

Origin

From the middle two quarters of the anterior surface of fibula and the adjacent interosseous membrane.

Insertion

EHL passes deep to the extensor retinaculum before inserting at the base of the distal phalanx of the big toe.

Nerve Supply

Deep peroneal nerve L4 -L5.

Action

Extends the metatarsophalangeal and interphalangeal joints of the big toe and assist in the in the inversion of the foot and dorsiflexion of the ankle.

Artery

Anterior tibial artery

Manual Muscle test

Patient position: supine or sitting.

Test: extension of metatarsophalangeal and interphalangeal joints of the big toe.

Pressure: against dorsal surface of distal phalanges of the big toe in the direction of flexion.

Paralysis of EHL

In the paralysis of EHL, the action of EHB is dominant, the distal phalanx doesn't extend, and the proximal phalanx extend in the direction of adduction.

Effect of Weakness

Weakness of EHL decreases extension at the metatarsophalangeal and interphalangeal joints. As it is the only muscle for the extension of interphalangeal joint, decreased dorsiflexion of the great toe is diagnostic for EHL weakness.

During normal locomotion, an individual contacts the ground with the heel of the foot first. The ground reaction force applies a plantarflexion moment to the whole foot, which is resisted by all of the dorsiflexors. Weakness of the EHL diminishes an individual’s ability to control the descent of the medial portion of the foot, particularly the great toe.

Patients with weakness of the extensor hallucis longus also report that the toe tends to fold under the foot when they are pulling on socks or shoes and can cause tripping.

Effect of Tightness

Tightness of the EHL pulls the metatarsophalangeal joint of the great toe into extension, which, as in the fingers and thumb, tends to produce flexion at the interphalangeal joint, leading to a claw toe deformity.

Hyperextension of the great toe pulls the plantar plate distally, exposing the metatarsal head to excessive loads and producing pain. Similarly, hyperextension of the metatarsophalangeal joint pulls the interphalangeal joint into the toe box of a shoe, causing pain and calluses, or corns, on the dorsal surface of the interphalangeal joint.

Claw Deformities of the toes:
Claw toe deformities in a foot with sensation are quite painful. Claw deformities in a foot without sensation put the individual at risk of skin breakdown as the result of increased pressure under the metatarsal heads and between the dorsal surfaces of the toes and the shoe.

Trigger point referral

EHL refers pain to the distal aspect of the 1st metatarsal and great toe, as well as the dorsum of the foot. It may reach up the leg as far as the point. These points are located just distal to the junction between the middle and distal thirds of the leg, just anterior to the fibula. The patient may also complain of persistent dorsal foot pain.

Treatment

Strengthening

Here are some effective exercises to strengthen the big toe, backed by research evidence:

• Big Toe Lift- This exercise targets the extensor hallucis longus and brevis muscles. Raise your big toe while keeping the other toes flat on the floor. Avoid letting the foot roll out or scrunching the little toes. Practice this to improve isolation and range of motion.
• Big Toe Extension with Heel Raises- Perform heel raises while keeping the big toe extended. A towel roll under the toes can help with mobility. This strengthens the big toe extensor muscles in a functional, weight-bearing position.
• Short Foot Exercise- Pull the base of the big toe towards the heel to create an arch, keeping the toes flat. This activates the intrinsic foot muscles like the abductor hallucis that stabilize the big toe joint.
• Towel Curls- Sitting or standing, use your toes to slowly curl a towel or piece of paper under your foot. This strengthens the toe flexor muscles, including the flexor hallucis brevis.
• Resistance Band Big Toe Abduction- Loop a resistance band around your big toe and abduct it against the band's resistance. Keep the other toes relaxed. This isolates the abductor hallucis muscle. Performing these exercises 2-3 times per week can improve big toe strength and mobility. Start with 2-3 sets of 10-15 reps. Gradually increase difficulty by adding resistance bands or holding for longer. Proper technique is key to isolating the big toe muscles.