Learning objectives

  • Skin, superficial fascia and deep fascia of sole of foot
  • Different muscular layers of sole of foot
  • Neurovasculature of sole of foot
  • Lymphatics of sole of foot
  • Arches of foot
  • Clinicals

Sole of Foot

  • Skin:
  •  The skin of the sole of the foot is thick and hairless.
  • It is firmly bound down to the underlying deep fascia by numerous fibrous bands.
  • Sweat glands are present in large numbers.
  •  The sensory nerve supply to the skin of the sole of the foot is derived from
    •  Medial calcaneal branch of the tibial nerve, which innervates the medial side of the heel
    • Branches from the medial plantar nerve, which innervate the medial two thirds of the sole
    •  Branches from the lateral plantar nerve, which innervate the lateral third of the sole
  • Deep Fascia :
  • The plantar aponeurosis is a triangular thickening of the deep fascia that protects the underlying nerves, blood vessels, and muscles
  •   Apex is attached to the medial and lateral tubercles of the calcaneum.
  • Base of the aponeurosis divides into five slips that pass into the toes.

Muscles of the Sole

  • Four layers
    •  First layer: Abductor hallucis, flexor digitorum brevis, abductor digiti minimi
    •  Second layer: Quadratus plantae, lumbricals, flexor digitorum longus tendon, flexor hallucis longus tendon
    •  Third layer: Flexor hallucis brevis, adductor hallucis, flexor digiti minimi brevis
    •  Fourth layer: Interossei, peroneus longus tendon, tibialis posterior tendon

Muscles of foot

Arteries of the Sole

  • Medial Plantar Artery:
    •   Smaller of the terminal branches of the posterior tibial artery
    •  It arises beneath the flexor retinaculum and passes forward deep to the abductor hallucis muscle
    •  It ends by supplying the medial side of the big toe
    •  During its course, it gives off numerous muscular, cutaneous, and articular branches.

Arteries of the Sole

  • Lateral Plantar Artery :
    •  Larger of the terminal branches of the posterior tibial artery
    •  It arises beneath the flexor retinaculum and passes forward deep to the abductor hallucis and the flexor digitorum brevis
    •  On reaching the base of the 5th metatarsal bone, the artery curves medially to form the plantar arch  and at the proximal end of the first intermetatarsal space joins the dorsalis pedis artery
    •  During its course, it gives off numerous muscular, cutaneous, and articular branches. The plantar arch gives off plantar digital arteries to the toes.
    • Dorsalis Pedis Artery (The Dorsal Artery of the Foot)
      •  On entering the sole between the two heads of the first dorsal interosseous muscle, the dorsalis pedis artery immediately joins the lateral plantar artery
      • Branches
      • The first plantar metatarsal artery, which supplies the cleft between the big and second toes.

Arteries of foot

Veins & Nerves of  Sole  

  • Medial and lateral plantar veins accompany the corresponding arteries, and they unite behind the medial malleolus to form the posterior tibial venae comitantes.
  •  Nerves of the Sole of the Foot
    •  Medial Plantar Nerve
      •  It is a terminal branch of the tibial nerve
      •  It arises beneath the flexor retinaculum and runs forward deep to the abductorhallucis, with the medial plantar artery
      •  It comes to lie in the interval between the abductor hallucis and the flexor digitorum brevis.
    • Branches
      •  Muscular branches to the abductor hallucis, the flexor digitorum brevis, the flexor hallucis brevis, and the first lumbrical muscle.
      •  Cutaneous branches: Plantar digital nerves run to the sides of the medial three and a half toes
    •  The nerves extend onto the dorsum and supply the nail beds and the tips of the toes.

Nerves of the Sole of foot

  • Lateral Plantar Nerve:
  • It is a terminal branch of the tibial nerve
  •  It arises beneath the flexor retinaculum and runs forward deep to the abductor hallucis and the flexor digitorum brevis, in company with the lateral plantar artery
  •  On reaching the base of the fifth metatarsal bone, it divides into superficial and deep branches
  •  Branches
  • From the main trunk to the quadratus plantae and abductor digiti minimi
    •  Cutaneous branches to the skin of the lateral part of the sole.
  • From the superficial terminal branch to the flexor digiti minimi and the interosseous muscles of the fourth intermetatarsal space.
    •  Plantar digital branches pass to the sides of the lateral one and a half toes. The nerves extend onto the dorsum and supply the nail beds and tips of the toes.
  • From the deep terminal branch
    •  This branch curves medially with the lateral plantar artery and supplies the adductor hallucis; the second, third, and fourth lumbricals; and all the interossei, except those in the fourth intermetatarsal space

Nerves of foot

Lymphatic drainage of Foot

  • Superficial  lymphatics
    •  medial and lateral
  • Medial superficial lymphatics
    • Drain the medial side of the dorsum and sole of foot
    • Converge on great saphenous vein
    • Then to vertical group of superficial inguinal lymph nodes
    • Terminate at deep inguinal lymph nodes
  • Lateral superficial lymphatics
    • Drain the lateral side of dorsum and sole of foot
    • These vessels pass post. To lateral mallolus and then with small saphenous vein enter the popliteal lymph nodes
  • Deep lymphatics
    • These follow the main vessels ( fibular, anterior and posterior tibial popliteal and femoral veins
    • From these lymph is carried to deep inguinal lymph nodes
  • Then in the end all the lymph from lower limb goes to iliac lymph nodes

The Foot as a Functional Unit

  • Arches of the Foot:
    • The foot is composed of numerous bones connected by ligaments, it has considerable flexibility that allows it to deform with each ground contact, thereby absorbing much of the shock.
  • The foot has three arches,
    • the medial longitudinal, lateral longitudinal, and transverse arches
  • The arches distribute
    • weight over the foot,
    • Act as  shock absorbers and also helps during walking, running, and jumping.
    • Arches add to the foot’s ability to adapt to changes in surface contour.

Arches of Foot

Mechanisms of Arch Support

The Bones of the Arches

  • Medial longitudinal arch:
    • This consists of the calcaneum, the talus, the navicular bone, the three cuneiform bones, and the first three metatarsal bones
  • Lateral longitudinal arch:
    • This consists of the calcaneum, the cuboid, and the 4th and 5th metatarsal bones
  •  Transverse arch:
    •  This consists of the bases of the metatarsal bones and the cuboid and the three cuneiform bones

Maintenance of the Medial Longitudinal Arch

  • Shape of the bones:
    • The sustentaculum tali holds up the talus
    • The concave proximal surface of the navicular bone receives the rounded head of the talus; the slight concavity of the proximal surface of the medial cuneiform bone receives the navicular.
    • The rounded head of the talus is the keystone in the center of the arch 
  • The inferior edges of the bones are tied together by
    •  the plantar ligaments, which are larger and stronger than the dorsal ligaments.
    •  The most important ligament is the plantar calcaneonavicular ligament
    •   The tendinous extensions of the insertion of the tibialis posterior muscle play an important role in this respect.
  • Tying the ends of the arch together are the plantar aponeurosis, the medial part of the flexor digitorum brevis, the abductor hallucis, the flexor hallucis longus, the medial part of the flexor digitorum longus, and the flexor hallucis brevis
  •  Suspending the arch from above are the tibialis anterior and posterior and the medial ligament of the ankle joint.

Maintenance of the Lateral Longitudinal Arch

  • Shape of the bones:
    • The distal end of the calcaneum and the proximal end of the cuboid. The cuboid is the keystone.
  •  The inferior edges of the bones are tied together by the long and short plantar ligaments and the origins of the short muscles from the forepart of the foot 
  •  Tying the ends of the arch together are the plantar aponeurosis, the abductor digiti minimi, and the lateral part of the flexor digitorum longus and brevis.
  •  Suspending the arch from above are the peroneus longus and the brevis

Maintenance of the Transverse Arch

  • Shape of the bones:
    •  The marked wedge shaping of the cuneiform bones and the bases of the metatarsal bones
  •  The inferior edges of the bones are tied together by the deep transverse ligaments, the strong plantar ligaments, and the origins of the plantar muscles from the forepart of the foot; the dorsal interossei and the transverse head of the adductor hallucis are particularly important in this respect.
  • Tying the ends of the arch together is the peroneus longus tendon.
  •  Suspending the arch from above are the peroneus longus tendon and the peroneus brevis

The Foot as a Weight Bearer

  • The weight of the body is transmitted to the talus from the tibia. Then it is transmitted posteriorly to the calcaneus and anteriorly to the “ball of the foot” (the sesamoids of the 1st metatarsal and the head of the 2nd metatarsal), and that weight/pressure is shared laterally with the heads of the 3rd–5th metatarsals.
  •  Between these weight-bearing points are the relatively elastic arches of the foot, which become slightly flattened by body weight during standing. They normally resume their curvature (recoil) when body weight is removed.

clinical

  • Pes cavus (clawfoot):
    • it is a condition in which the medial longitudinal arch is unduly high. Most cases are caused by muscle imbalance, in many instances resulting from poliomyelitis.
  • Pes planus (flat foot):
    • It is a condition in which the medial longitudinal arch is depressed or collapsed. As a result, the forefoot is displaced laterally and everted. The head of the talus is no longer supported, and the body weight forces it downward and medially between the calcaneum and the navicular bone. When the deformity has existed for some time, the plantar, calcaneonavicular, and medial ligaments of the ankle joint become permanently stretched, and the bones change shape. The muscles and tendons are also permanently stretched. The causes of flat foot are both congenital and acquired
  • Clubfoot (Talipes equinovarus):
    • Congenital condition
    • Involves the subtalar joint
    • Foot is inverted,ankle is plantar flexed,forefoot is adducted
    • Person bears the weight on lateral surface of forefoot
    • Walking is painful
    • There is shortness and tightness of muscles and tendons,ligaments and joint capsules on the medial side and posterior aspect of ankle

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