Nerves: medial (L4,5) and lateral (S1,2) plantar nerves: perforate aponeurosis centrally.
- terminal branches of tibial nerve
- medial and lateral supply like median & ulnar nerves of hand (sharing 4th digit)
- likewise supply nail bed and surrounding skin
See Pl 505: medial calcaneal branch of tibial supplies skin over calcaneus, sural (S1,2) has a lateral contribution and saphenous (L3,4) a medial contribution.
Blood: accompanies vessels: ie medial and lateral plantars, off posterior tibial.
Subcut tissues: more fibrous; septa divide tissue into loculi filled with fat under tension
- shock absorbent; especially over heel; anchor skin to underlying plantar aponeurosis
Plantar aponeurosis: dense collagen fibres, longitudinal (496)
- arises posteriorly from medial process of calcaneus ¨ fans out over sole
- five bands, one for each toe joined by superficial transverse metatarsal ligament just distal to the metatarsal heads
- the bands bifurcate for the flexor tendons to pass; ¨ insert into edges of fibrous flexor sheaths
- deep metacarpal ligament unites the insertions along adjacent metatarsophalangeal jts.
Septa arises from each aponeurosis edge, separates FDB from abductors of big and little toes
- ie they compartmentalise the first layer
- these abductors are not covered by aponeurosis, rather a thinner deep fascia.
Muscles are arranged in four layers:
- superficial: three short muscles covering sole under aponeurosis
- second: long tendons to digits
- third: short muscles of great / little toes
- fourth: both plantar and dorsal interossei; tendons of peroneus longus, tib posterior.
- Segmental supply to all is essentially S2
Arises: medial process of tuberosity of calcaneus & deep surface of central part of plantar aponeurosis
¨ four tendons that pass to the toes, each entering the fibrous flexor sheath
¨ divides and spirals around the long flexor tendons
¨ partially reunites in a chiasma before dividing again to insert into sides of middle phalanx
- ie identical to hand FDS
Nerve: medial plantar (cf FDS in hand which is a median nerve muscle)
Action: flex toes independent of ankle position
Arises: medial processes of calcaneus & flexor retinaculum (does the split thing)
Inserts: runs along medial margin to medial side of base of proximal phalanx of hallux.
Nerve: medial plantar
Action: abducts great toe
Arises: both medial and lateral processes of calcaneus deep to FDB
Inserts: runs along lateral margin ¨ base of proximal phalanx of 5th toe & tubercle of 5th metatarsal.
Nerve: branch from lateral plantar
Action: abducts little toe
Passes forward b/n medial longitudinal arch, crossed inferiorly by FDL tendon
¨ strong slip to medial two tendons of FDL
¨ groove b/n sesamoids beneath head of 1st metatarsal.
¨ base of distal phalanx of big toe
Invested in synovial sleeve throughout its course.
Enters sole medial to tendon of FHL, crosses it where it ¨ 4 tendons (and receives slips of support and flexor accessorius tendon.
¨ forward deep to FDB, give off lumbricals
¨ enter fibrous sheaths of lateral four toes, each perforating its FDB tendon
¨ base of distal phalanx.
Arises: large medial head from medial calcaneus, and small lateral head from lateral calcaneus
Inserts: into FDL tendon
Nerve: Lateral plantar
Action: assists flexion, independent of ankle position; also straightens FDL pull
Arises: tendons of FDL
Inserts: pass to medial side of MTP jts of lateral four toes; tendons lie on plantar surface of deep transverse ligament ¨ extensor expansions
Nerve: As in hand:
- medial n lumbricals unicipital, lateral n bicipital (two heads arise from adjacent tendons)
- only the first is medial in the foot (single head, only tendon); lateral three are lateral plantar supplied; each arising from adjoining side tendons.
Action: Maintain extension of digits at IP jts while FDL flexes; (so they donŐt buckle when walking).
Three muscles but short and confined to the metatarsal region: 2 big toe, 1 little.
Arises: cuboid, lateral cuneiform, tendon of tibialis posterior
Inserts: splits into two parts ¨ each by way of a sesamoid ¨ medial & lateral prox phalanx great toe
Nerve: medial plantar
Action: flex prox phalanx great toe
Arises: 2 heads: oblique head from long plantar ligament roofing peroneus longus tendon and bases of 2nd-4th metatarsals; transverse head from deep transverse ligament and plantar ligaments 2-5
Inserts: unites into a short tendon ¨ with lateral FHB ¨ lateral base of proximal phalanx
Nerve: deep branch of lateral plantar
Action: adducts hallucis and maintains transverse arch
Arises: base of 5th metatarsal & fibrous sheath of peroneus longus adjoining
Inserts: base of proximal phalanx medial to insertion of abductor digiti minimi
Nerve: superficial branch of lateral plantar
Action: flexes little toe
Interossei and intermetatarsal spaces, with tendons of tibialis posterior and peroneus longus deep.
Arises: as in hand: plantar interossei arise from metatarsals of own toe; dorsal from two heads of two metatarsals between them. (Infer which from PAD / DAB action)
- there are 3 plantar adducting interossei (great toe has its own adductors)
- 4 dorsal interossei, big and little each have their own abductors, second requires one on each side while 3rd and 4th need one each have a single one to pull them laterally.
Inserts: plantar ¨ medial sides of third, fourth and fifth digits: tendons pass dorsal to deep transverse ligament to bases of proximal phalanges
- dorsal: 1st ¨ tibial side of second toe, rest ¨ fibular side of toes, chiefly ¨ bases of proximal phalanges, but also to the dorsal extensor expansions.
Nerve: All by lateral plantar nerve; 4th space = superficial branch; rest = deep branch
Action: PAD and DAB; but note long axis of foot shifted to lie along second toe.
- actually these actions are of less significance in the foot; more importantly they assist lumbricals in extending interphalangeal jts; flex metatarsophalangeal jts
Tendon of Peroneus Longus (5000
Crosses sole obliquely, under posterior ridge of groove under cuboid
- contains a sesamoid at the lateral margin of the foot which may be ossified
Crosses groove of cuboid, held in position there by long plantar ligament
¨ emerges from this tunnel to insert at base of first metatarsal
¨ and adjoining area on lateral surface of medial cuneiform
Synovial sheath accompanies it throughout its course.
Tendon of Tibialis Posterior
Lies above sustentaculum tali & spring ligament
¨ inserts into navicular tubercle, and fans out as a series of ligaments ¨ cuneiforms, sustentaculum tali, floor in groove in cuboid and bases of 2nd Đ 4th metatarsals.
Derived from posterior tibial neurovascular bundle in calf
- posterior tibial artery and tibial nerve divide ¨ medial and lateral plantar branches
- artery lies outside nerve; has a pair of venae comitantes
- where they cross, nerve is nearer skin.
- Lie between 1st and 2nd layers, inferior to long tendons.
Smaller, supplies big toe only. There is only one plantar arch in foot, from the lateral.
¨ abductor hallucis, FDB, FHB, first lumbrical.
- in addition gives digital cutaneous branches that supply medial 3 1/2 toes.
- Communicates with lateral branch across 4th MTP jt; pressure here ¨ metatarsalgia.
Crosses sole obliquely deep to first layer ¨ toward base of 5th metatarsal.
¨ small superficial branch with superficial branch of lateral plantar nerve
¨ main branch ¨ deep plantar arch: curves across bases of 4th-2nd metatarsals under third layer
- joined in proximal part of 1st interspace by dorsalis pedis
- plantar metatarsal arteries run forward from it, bifurcate ¨ four webs & digits
- perforating branches from it reinforce dorsal arteries
Veins: accompany perforating arteries from sole (muscles act as a pump) ¨ dorsal venous arch.
Crosses sole obliquely medial to the lateral plantar artery
Similar to ulnar nerve in hand
¨ flexor accessorius, abductor digiti minimi
¨ perforators through plantar aponeurosis to skin on lateral side of sole.
¨ superficial and deep branches near base of 5th metatarsal:
- superficial ¨ 4th cleft and communicates with medial plantar by lateral branch to lateral side (and distal dorsum of little toe)
- deep ¨ in concavity of plantar arch ¨ deep surface of oblique head of adductor hallucis ¨ branches to remaining interossei, to transverse head of adductor hallucis and 3 lateral lumbricals.