Abductor Hallucis

Abductor Hallucis (AH): Origin, Function, and Pain

The abductor hallucis (AH) is the most superficial muscle in the medial compartment of the first layer of the foot’s sole. An abductor hallucis muscle runs diagonally to the flexor hallucis brevis muscle. The plantar aponeurosis covers the plantar surface of the muscle, and the dorsal surface is covered by the tendon of the flexor digitorum longus, the medial plantar artery, and the medial plantar nerve.

Porta pedis is a space created by the fibers that makes up the abductor hallucis and calcaneus. This space acts as a tunnel through which nerves and vessels from the lateral and medial sides of the foot pass. 

AH: Origin and Insertion

The abductor hallucis is a powerful, petite and slender muscle that has three origin points and one insertion point. It arises from the medial process of the calcaneal tuberosity, the plantar aponeurosis, and the superficial layer of the flexor retinaculum.

A tendon is formed at the metatarsal bone where the muscle fibers run anteriorly and medially in the shape of two parallel lines. After being inserted to the base of the proximal phalanx of the great toe, the tendon runs along the medial border of the first metatarsophalangeal joint. 

AH: Blood Supply and Innervation

There are two arteries which supply blood to abductor hallucis;

  • The medial artery, a branch of the posterior tibial artery.
  • Plantar metatarsal artery, a branch of the lateral plantar artery.

AH: Functions

Tibialis anterior is the most significant muscle on the first metatarsophalangeal joint of the foot that is mainly responsible for the abduction of the big toe. If this action is hindered, it may result in deformities of the toes, such as hallux valgus, since it preserves the central position of the big toe while walking.

This muscle assists the flexion of the big toe in conjunction with the flexor hallucis longus and the flexor hallucis brevis muscles. While walking, this muscle also maintains the medial longitudinal arch of the foot by providing support to the arch. In addition, this muscle also plays a vital role in posture and gait.

AH: Pain and Strain

Injuries to this muscle tend to cause severe foot pain and overpronation of the foot. Abductor Hallucis strain is the most common type of injury caused to this muscle.

Causes of AH Strain

The following activities can cause abductor Hallucis Muscle damage or strain;

  • Walking or running on uneven surfaces.
  •  Wearing shoes that are too small for a person.
  • High heel wearers are also prone to straining and injuring their abductor hallucis muscles.
  • People who have previously injured their ankles and have a weak ankle can also strain the Abductor Hallucis Muscle.

Symptoms of AH Strain

  • The pain along the inner arch of the foot. The pain and tenderness in foot while pressing into the sole.
  • Overpronation is the most common symptom found in athletes when their feet roll inwards too much during the gait cycle.

Treatment of AH Strain

Listed below are some methods for treating a strained abductor hallucis muscle;

  • Rest is essential to healing the Abductor Hallucis strain.
  • Taping the strained Abductor Hallucis helps to take off the load of   foot’s arch and it heals quickly.
  • Wearing insoles can also prevent the overpronation.
  • Cold Therapy: Several gels and cold packs are available in the market that can help to treat Strained Abductor Hallucis Muscle. Gels are usually applied soon after an injury or strain to keep the injured area cool and prevent swelling. It has been proven that such gels or coolants have healed injuries to the Abductor Hallucis Muscle faster than regular ice application that provides long-lasting pain relief. 
  • Warm Therapy: Abductor Hallucis Strain can also be treated with warm therapy. The gel used for this therapy provides adequate warmth without burning the injured area and it works wonderfully to relieve pain and stiffness. The gel should be applied to the bottom of the foot and rubbed into the ankle for best results. It is important to point out here that warm therapy should never be used when using ice packs or heat packs as that may result in blisters forming.
  • Foot Wrap: Strained Abductor Hallucis Muscles can be compressed using foot wraps. Compression helps reduce inflammation and pain and prevents swelling in the foot and ankle region caused by the Abductor Hallucis Strain.
  • Medication: Pain and inflammation can be decreased by NSAIDs such as ibuprofen and naproxen.
  • Massage: Professionals can perform sports massage on your foot to speed up the healing process.

Abductor Hallucis Tendinopathy (AHTs):

The term abductor hallucis tendinopathy (AHT) refers to damage to the abductor hallucis muscle caused by overload. The symptoms of this condition are very similar to plantar fasciitis caused by pain in the arch of the foot.

AHTs Causes

In general, AHTs are caused by overuse. As the tendon is overloaded from excessive or repetitive strain and pressure, tiny tears form, causing the tendon to suffer damage and develop painful symptoms. There are several causes of tendon overuse, including:

  • Bio mechanical abnormalities of the feet.
  • Flat feet (pronated feet).
  • Wearing unsupportive shoes.
  • Increased physical activity or intensity.
  • Particular activities such as climbing stairs that strain the arch.
  • Injuries to the insertion of the AHT at the heel, such as falling from a height
  • Poor training techniques.
  • Excessive weight.

AHTs Symptoms

This condition is characterized by:

  •  Inflammation of the heel.
  •  Pain that travels through the arch of the foot.
  •  Feel pain in the morning after waking up.
  •  Pain when you stand up after rest.

AHTs Treatment

Usually, the treatment begins with relieving the painful symptoms through the PRICE principle (protection, rest, ice, compression, and elevation). After that, the focus is on facilitating the healing, repairing of the damaged tendon and reducing the likelihood of future recurrence. Some of the treatments are:

  • Orthotics: Wearing orthotics will relieve pressure and strain on the AHT and correct any irregular foot biomechanics, including reducing pronation.
  • Footwear assessment: Footwear examination is required to ensure the shoes are assisting and not hindering the patient’s recovery.
  • Tapping/Strapping: By temporarily tapping/strapping the AHT, you can reduce the strain until symptoms settle down and repairs begin.
  • Stretches: It helps to lose the tight muscles, which may have contributed to overexertion of the tendon. They are also strengthening weak muscles after the tendon has healed. Moreover, it reduces the load on the AHT from high-stress activities until it is fully recovered.

References:

  • https://www.epainassist.com/sports-injuries/foot-and-heel-injuries/abductor-hallucis-strain retrieved on March 12, 2022.
  • https://www.performpodiatry.co.nz/footproblems/abductor-hallucis-tendinopathy/ retrieved on March 12, 2022.
  • https://www.kenhub.com/en/library/anatomy/abductor-hallucis-muscle?__cf_chl_rt_tk=wXLKC.Qz62IQ3Fiyy60j3s4llKA9FU2ocaph3FPgOFI-1647285889-0-gaNycGzNCeU retrieved on March 12, 2022.
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