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Central Muscles of sole of the Foot - want to learn more about it?

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Central Muscles of sole of the Foot

The plantar muscles of the foot are traditionally studied in either layers or groups. If studying by layers, we can organise these muscles into four primary layers:

  • 1st layer: abductor hallucis, flexor digitorum brevis, abductor digiti minimi
  • 2nd layer: quadratus plantae, lumbricals
  • 3rd layer: flexor hallucis brevis, adductor hallucis, flexor digiti minimi brevis
  • 4th layer: plantar and dorsal interossei

The plantar muscles of the foot can alternatively be considered by medial, central and lateral groups. This article will discuss the central plantar muscles

Anatomy and supply

Central plantar muscles

The central muscles of the foot sole lie within the central compartment between the muscles of the big and little toe.

The compartment comprises numerous short foot muscles in different layers. Together they form the central surface of the foot sole.

Muscular branches of the tibial nerve (L5-S2) are responsible for the innervation of the central muscles.

Flexor digitorum brevis muscle

The FBD originates at the calcaneal tuberosity and plantar aponeurosis. Distally it divides into four tendons moving towards the second to fifth toes. At the proximal phalanges these tendons separate further into two smaller tendons, which finally insert along the medial and lateral aspects of the  middle phalanges.

(Innervation: medial plantar nerve)

Quadratus plantae muscle

This muscle runs from the calcaneus to the tendon of the flexor digitorum longus muscle.

(Innervation: lateral plantar nerve)

Quadratus plantae (left), lumbrical muscles (left) - inferior view

Lumbrical muscles (I-IV)

The group of muscles originate at the tendons of the flexor digitorum longus muscle and insert medially into the bases of the second through fifth proximal phalanges as well as the dorsal aponeurosis.

(Innervation: medial plantar nerve (I), lateral plantar nerve (II-IV)) 

Plantar interossei muscles I-III

The plantar interossei extend from the third through fifth metatarsal bones to the medial side of the proximal phalanx of the respective toe.

(Innervation: lateral plantar nerve)

Dorsal interossei - superior view (left), Plantar interossei - inferior view (right)

Dorsal interossei muscles I-IV

The four dorsal interossei are two-headed, or bipennate muscles found interposed between the five metatarsal bones of the foot.  

The first lumbrical inserts into the medial aspect of the base of the second proximal phalanx. The second through fourth lumbricals however, have their insertions along the lateral aspects of the bases of the proximal phalanges of the second through fourth toes.

(Innervation: lateral plantar nerve)

Recommended video: Central muscles of the sole of the foot
Origins, insertions, innervation and functions of the central muscles of the sole of the foot.

Anatomical relations

The flexor digitorum brevis muscle lies relatively superficially under the plantar aponeurosis and marks the largest muscle in the central compartment. The quadratus plantae muscle runs immediately deep to it. The origins of the lumbrical muscles are located at the distal end of the quadratus plantae muscle.

In comparison the plantar and dorsal interossea muscles lie deeper within the plantar aspect of the foot. 

In addition to the above mentioned muscles, the central compartment of the foot sole comprises the oblique head of the adductor hallucis muscle, the posterior tibial artery and vein and the tibial nerve.

Medial plantar nerve - inferior view

However the vessels and nerves divide quite early into a medial and lateral bundle entering the medial and lateral compartment of the foot sole. Distally the branches meet again in the central compartment forming an arterial and venous arcade (plantar arch and plantar venous arch).

Function

The muscles of the central compartment fulfill various tasks.

  • The flexor digitorum brevis muscle is involved in flexion of the second to fifth toes and actively supports the longitudinal arch of the foot.
  • The quadratus plantae muscle does not move any joints but has a rather special function: By pulling at the tendon of the flexor digitorum longus muscle it shifts the tendon’s force effect to the longitudinal direction increasing the effectiveness of the plantar flexion of the muscle.
  • The lumbricals, as well as the plantar interossei muscles flex and adduct the toes (closing the spread toes).
  • The dorsal interossei muscles flex the toes as well but in contrast cause an abduction (spreading of the toes).

Clinical note

The plantar aponeurosis passively contributes to the longitudinal arch of the foot. If it is chronically strained (e.g. in athletes and elderly people) a plantar fasciitis may develop.

Longitudinal arch of the foot - lateral view

This is a degenerative change of the plantar aponeurosis at the origin at the calcaneus. Typically the X-ray shows a dense ossification (calcaneal or heel spur).

Being overweight, having metabolic and rheumatic diseases are the most important risk factors. The affected people experience a slow and subtle, stress-dependent pain at the heel and the sole of the foot.

In addition to orthopedic insoles, physiotherapy and pain medication (if required) good results are achieved with shock wave therapy.

Central Muscles of sole of the Foot - want to learn more about it?

Our engaging videos, interactive quizzes, in-depth articles and HD atlas are here to get you top results faster.

Sign up for your free Kenhub account today and join over 921,002 successful anatomy students.

“I would honestly say that Kenhub cut my study time in half.” – Read more. Kim Bengochea Kim Bengochea, Regis University, Denver

Show references

References:

  • M. Schünke/E. Schulte/U. Schumacher: Prometheus – LernAtlas der Anatomie – Allgemeine Anatomie und Bewegungssystem, 2.Auflage, Thieme Verlag (2007), S.488-489
  • W. Graumann/D.Sasse: CompactLehrbuch der gesamten Anatomie – Band 2 – Bewegungsapparat, Schattauer Verlag (2003), S.222-229
  • J. W. Rohen: Topographische Anatomie, 10.Auflage, Schattauer Verlag (2008), S.171-173
  • D. Drenckhahn/J. Waschke: Taschenbuch Anatomie, Urban & Fischer Verlag/Elsevier (2008), S.100-101
  • C. J. Wirth/L. Zichner: Fuss – das Standardwerk für Klinik und Praxis, Thieme Verlag (2002), S.490-493

Author:

  • Achudhan Karunaharamoorthy

Illustrators:

  • Central plantar muscles - Liene Znotina 

  • Flexor digitorum brevis  - inferior view - Liene Znotina 
  • Quadratus plantae - inferior view - Liene Znotina 
  • Lumbrical muscles - inferior view - Liene Znotina 
  • Dorsal interossei/ plantar interossei - Liene Znotina 

  • Medial plantar nerve - inferior view - Liene Znotina 

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Calcaneus

Main muscles of the lower extremity

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