The foot

• Transverse tarsal joint


  Calcaneocuboid joint + talonavicular (part of the talocalcaneonavicular joint)

  • Augments inversion & eversion of the foot (axis 3)

  
• Bifurcate ligament


  Calcaneocuboid + Calcaneonavicular

  • Resists Inversion of the foot

  
• Plantar calcaneonavicular ligament


  Spring ligament

  Function to

  • Maintain longitudinal arches of the foot

  • Absorb load
• Long + short plantar ligament


  Two plantar ligaments

  Function to

  • Maintain longitudinal arches of the foot

  • Absorb load
• PLANTAR FASCIA = PLANTAR APONEUROSIS


  Supports arches of foot
• Intrinsic foot muscles - dorsal

  extensor digitorum brevis

  extensor hallucis brevis

  • innervated by deep fibular nerve
• Intrinsic foot muscles - plantar (4 layers)


  Abductor hallucis (M)

  Flexor digitorum brevis (M)

  Abductor digiti minimi (L)

  Quadratus plantae (L)

  Lumbricals 1‐4 (M1, L3)

  Flexor hallucis brevis (M)

  Adductor hallucis (L)

  Flexor digiti minimi (L)

  Dorsal Interossei (L)

  Plantar interossei (L)

  • innervated by tibial nerve
• Intrinsic foot muscles - layer 1


  FDB, abd hallucis, abd digiti minimi

  • FDB splits for FDL tendons at distal attachment (similar to hand)
  • First layer hallux and 4th toe move MTPJs
• Intrinsic foot muscles - layer 2


  Lumbricals 1-4, FHL tendon, FDL tendons, quandratus plantae

  • 1st and 2nd layers assist FDL. i.e. quadratus plantae inserts into side of FDL tendon to align the line of pull to aid toe flexion.
  • Lumbricals flex MTPJ, extend IPJs (similar to hand)
• Intrinsic foot muscles - layer 3

  add hallucis, FHB, flexor digiti minimi brevis

  • move MTPJs
• Intrinsic foot muscles - layer 4


  dorsal interossei: 1st, 2nd, 3rd, 4th

  • Plantar interossei Adduct the toes PAD
  • Dorsal interossei Abduct the toes DAB
  • Both flex MTPJs
  • Same in the hand
• primary function of the muscles of the foot

  to maintain the arches of the foot
• What is the function of the arches of the foot?


  distribute weight over the foot

  absorb shock

  act as springs during walking & jumping
• Superficial fibular nerve L4‐S2: course & distribution


  supplies muscles in lateral compartment of leg:

  – fibularis longus – fibularis brevis

  • Cutaneous supply

  • The yellow portion

  
• Deep fibular nerve L4-S1: course and distribution

  Muscular deep fibular nerve branches supply:

  • tib ant
  • EDL
  • EHL
  • fibularis tertius
  • Extensor digitorum brevis and extensor hallucis brevis
  • Sensory (cutaneous) branches: − cutaneous branch of deep fibular nerve (in blue below)
  • Also supplies: − proximal tibiofibular joint
• Medial and plantar nerves

  Arise from the tibial nerve deep to the flexor retinaculum
• Medial and lateral plantar nerves: distribution

  • Muscular branches supply:

  supplied by medial plantar nerve:

  – abductor hallucis

  – flexor digitorum brevis

  – flexor hallucis brevis

  – 1st lumbrical

  supplied by lateral plantar nerve:

  – quadratus plantae

  – abductor digiti minimi

  – plantar & dorsal interossei

  – 2nd 3rd and 4th lumbricals

  – adductor hallucis
• Medial and lateral plantar nerves: distribution

  Sensory (cutaneous) branches:

  – cutaneous distribution of medial plantar nerve

  – cutaneous distribution of lateral plantar nerve
• The foot - Sensory role

  the only point of contact with the ground in typical standing

  critical for balance and weight distribution

  brain devotes a lot of space to foot sensation

  
  

  Many sensory (ie pressure) receptors that relay information about weight distribution, uneven ground, surface texture that is relayed up to the spinal cord and brain and used in functional tasks.
• The foot - Adaptive role

  • When in contact with uneven ground, the tarsals and metatarsals have accessory movements that mould to the surface.

  • The toes do this as well – typically using the lumbrical action.

  • The extrinsic foot muscles flex the toes and are not built for maximising good contact with the floor.
• Where are the tarsometatarsal joints?

  Joint between the cuboid and the three cuneiforms (2)

  
• Which one of these is the proximal interphalangeal joint (PIPJ)


  Joint between the base of the proximal phalanges and head of distal phalanges (4)

  
• Which one of these is a metatarsophalangeal joint?

  (3)

  
• Medial Plantar Nerve


  Supplies: abductor hallucis, flexor digitorum brevis, flexor hallucis brevis, and 1st lumbrical muscles.
• Lateral Plantar Nerve


  Supplies: quadratus plantae, abductor digiti minimi, plantar and dorsal interossei, 2nd, 3rd, and 4th lumbricals, and adductor hallucis muscles.