Foot Anatomy

Sole/plantar aspect: the bottom of the foot

}}Plantar aponeurosis}}

a thick band of fibrous tissue which extends from heel to toes

@@Posteriorly@@: attached to medial tubercle of calcaneus

@@Anteriorly@@: divides into 5 slips that pass to all toes

@@Laterally@@: on each side, attached to metatarsal bones by %%medial and lateral plantar intermuscular septa%%

}}Sole muscles}}

2 groups of muscles:

• @@extrinsic muscles:@@ found in the lower leg, act to dorsiflex, plantarflex, invert and evert the foot
• @@intrinsic muscles:@@ found within the foot and primarily act to ==move the toes and support foot arches to maintain foot structure==

}}Intrinsic muscles}}

Divided into 4 layers:

First layer

• most superficial
• immediately underneath plantar fascia

Contains 3 muscles:

1. ^^Abductor hallucis^^
2. ^^Flexor digitorum brevis^^
3. %%Abductor digiti mini%%

All the muscles are supplied by ^^medial plantar nerve^^, except abductor digiti minimi (supplied by %%lateral plantar nerve%%)

Second layer

• deep to 1st layer

Contains 2 muscles and 2 tendons:

1. %%Quadratus plantae%% (flexor digitorum accessories)
2. %%4 Lumbrical muscles%% (^^1st lumbrical muscle supplied by medial plantar nerve^^)
3. Tendon of flexor digitorum longus (crosses superficial to FHL to reach insertion)
4. Tendon of flexor hallucis longus

All the muscles are supplied by %%lateral plantar nerve,%% except 1st lumbrical muscle (supplied by ^^medial plantar nerve^^ )

Third layer

• deep to 2nd layer
• 2 sesamoid bones develop in tendon of adductor hallucis

Contains 3 muscles:

1. ^^Flexor hallucis brevis^^
2. %%Adductor hallucis%% (originates by 2 heads: oblique and transverse)
3. %%Flexor digiti minimi brevis%%

All the muscles are supplied by %%lateral plantar nerve,%% except flexor hallucis brevis (supplied by ^^medial plantar nerve^^ )

Fourth layer

• deepest layer

Contains 2 muscles and 2 tendons:

1. %%Plantar interossei%%
2. %%Dorsal interossei%%
3. Tendon of fibularis longus
4. Tendon of tibialis posterior

All muscles are supplied by %%lateral plantar nerve%%

}}Sole Nerves and Vessels}}

{{Plantar nerves{{

The sole is innervated by ==2 terminal branches of tibial nerve:==

• @@medial plantar nerve@@: largest and accompanies medial plantar artery
• @@lateral plantar nerve@@: smallest and accompanies lateral plantar artery

Medial plantar nerve

• arises beneath the flexor retinaculum
• passes forward deep to the abductor hallucis muscle

Branches:

1. Muscular:
   • abductor hallucis
   • flexor digitorum brevis
   • 1st lumbrical muscle
   • flexor hallucis brevis
2. Cutaneous
   • medial 2/3 of the sole

Lateral plantar nerve

• arises beneath the flexor retinaculum
• passes forward deep to the abductor hallucis muscle
• reachs base of 5th metatarsal bone, and divides into 2 branches:
  • superficial
  • deep

Branches:

1. Muscular:
   • abductor digiti minimi
   • 2nd, 3rd, 4th lumbrical muscle
   • adductor hallucis
   • flexor digiti minimi brevis
   • all interossei (4th layer)
2. Cutaneous
   • lateral 1/3 of the sole

<<Plantar vessels<<

Medial plantar artery

• smallest
• terminal branch of ==posterior tibial artery==
• arises beneath flexor retinaculum
• passes forward deep to abductor hallucis muscle

Lateral plantar artery

• largest
• terminal branch of ==posterior tibial artery==
• arises beneath flexor retinaculum
• passes forward deep to abductor hallucis and flexor digitorum brevis muscles
• on reaching base of 5th metatarsal bone, it curves medially to form ==deep plantar arch==

}}Arches of Foot}}

• 3 arches:
  • 2 longitudinal (medial + lateral)
  • 1 transverse
• main function: to support body weight and act as a lever to propel the body

Medial longitudinal arch

@@Formed by:@@

• calcaneus
• talus
• navicular
• 3 cuneiform bones
• medial 3 metatarsal bones

@@Keystone bone@@: ==talus==

@@Supporting structures:@@

• plantar aponeurosis

• muscles:

  • tendons of tibialis anterior
  • tibialis posterior
  • flexor hallucis longus
  • fibularis longus
  • intrinsic muscles

• ligaments:

  • spring
  • deltoid
  • long and short
  • plantar and interosseous

  

Lateral longitudinal arch

• flatter than medial arch
• lies on the ground during standing position

@@Formed by:@@

• calcaneus
• cuboid
• lateral 2 metatarsal bones

@@Keystone bone:@@ ==cuboid==

@@Supporting structures:@@

• muscles:

  • tendons of fibularis longus, brevis, and tertius
  • intrinsic muscles

• ligaments:

  • long and short
  • plantar and interosseous

  

Transverse arch

@@Formed by:@@

• cuboid
• 3 cuneiforms
• bases of metatarsal bones

@@Keystone bone:@@ ==intermediate cuneiform==

@@Supporting structures:@@

• muscles:

  • tendons fibularis longus (most important)
  • slips of tibialis posterior tendon (pulling tarsal bone together)
  • transverse head of adductor hallucis (drawing metatarsal bones)

• ligaments:

  • long and short
  • plantar and interosseous