Plantar Foot Anatomy PDF

Plantar Foot Paul Fletcher  Outline/housekeeping for today Lecture: plantar foot Dissection this afternoon: Posterior compartment of leg. Plantar Foot  Sole of foot superficial structures – compared to dorsum – loculated fat pads – plantar aponeurosis...

Plantar Foot Paul Fletcher  Outline/housekeeping for today Lecture: plantar foot Dissection this afternoon: Posterior compartment of leg. Plantar Foot  Sole of foot superficial structures – compared to dorsum – loculated fat pads – plantar aponeurosis muscles – compartments – 4 layers ligaments arches  Dorsum vs. sole Dorsum: Sole: Skin is thin, mobile, hairy --> Skin is thick, large number of deeper structures easily identified nerve endings, sweat glands. Glaborous (hairless) --> hard to distinguish deeper structures  Plantar aponeurosis thickening of deep fascia – dense fibrous CT – continuous with deep fascia medially and laterally – longitudinal septa form boundaries of muscle compartments attachments – medial tubercle of calcaneus – 5 slips to bases proximal phalanges – longitudinal septa to plantar aspect of tarsals and metatarsals  Plantar aponeurosis The function of the aponeurosis is to contain the plantar tissues and to anchor the skin to the skeleton – Form pockets for the loculated fat pads of the plantar foot – Provide channels for the neurovascular structures  Loculated fat pads specializations of superficial fascia – loose adipose CT – fibrous septa contain fat prevent dissipation with weightbearing under weightbearing (WB) areas – post calcaneus – heads of the metatarsals – distal phalanges attachments – dermis (superficially) – bone or DF (deep)  Loculated fat pads calcaneus fibrous septa skin  met distal heel phalanx head Weight distributio n when walking force gait cycle  Organization of sole muscles by compartments – medial, central, lateral & deep by layers – 4 layers from superficial to deep new principles – muscles lying in more superficial layers of the foot will originate more proximally – muscles of the sole insert just distal to the most distal joint upon which they act  Neurovascular components of the sole Lay between the 1st and 2nd layer of muscles Medial and lateral plantar nerves – Branches of the tibial nerve – Med: cutaneous: supplies the medial 3.5 toes – Lat: cutaneous: supplies the lateral 1.5 toes Medial and lateral plantar arteries – Branches of the posterior tibial artery – Med: supplies the medial side of the hallux – Lat: forms the plantar arch --> plantar digital arteries, supplies the adjacent sides of the lateral 4 toes and lateral side of the 5th toe – Medial and lateral plantar veins accompany the corresponding arteries 1  Layer 1 muscles Abductor hallucis (AbH) – Origin/Insertion: medial calc tuberosity/plantar aponeurosis/FDB --> tendon to FHB and base proximal hallux phalanx – Action: abduct & flex 1st MTPJ – Innervation: medial plantar n. Flexor digitorum brevis (FDB) – Origin/insertion: medial calc tub/PA --> divides into 4 tendons for lesser toes (prox phalanges) - divides into 2 slips either side FDL --> intermediate phalanx – Action: flex MTPJ & PIPJ – Innervation: medial plantar n.  Layer 1 muscles… Abductor digiti minimi (AbDM) – Origin/insertion:medial/lateral calc tuberosity, PA ---> tendon grooves base 5th MT --> lateral base of proximal phalanx of 5th toe – Action: flex & abduct 5th MTPJ – Innervation: lateral plantar n. Layer 1 muscles AbDM AbH FDB 2 Layer 2 muscles - extrinsic FDL FHL tendinous slip between them synovial tendon sheathes – under flexor retinaculum – under fibrous flexor sheathes of toes Synovial tendon sheathes in foot  Layer 2 muscles - intrinsic – Lumbricals Origin: FDL tendons Insertion: base proximal phalanx & ext hood (extensor expansion) of lateral 4 toes Actions: flex MPJ & extend IPJ’s, stabilise proximal phalanges Innervation: med. plantar (1st), lat. plantar (2-4th) – Quadratus Plantae (QP = flexor accesorius) Origin: body calcaneus Insertion: FDL tendon (lateral border) Action: flex MPJ & IPJ’s (straightens pull of FDL) Innervation: lat. Plantar n.  Extensor hood Discussed in MTPJ lecture next week Layer 2 muscles QP FDL FHL Lumbricals 3  Layer 3 muscles flexor hallucis brevis (FHB) – Origin: plantar aspect midfoot – Insertion: two heads to base 1st prox. phalanx via med. & lat. sesamoids – Action: flex 1st MTPJ – Innervation: med. plantar n. flexor digiti minimi (FDM) – Origin: base 5th met – Insertion: lat base 5th prox. phalanx – Action flex 5th MTPJ – Innervation: lat. plantar n.  Layer 3 muscles … adductor hallucis – Origin: bases 2-4 metatarsals (oblique head), 3-5 plantar plates (transverse head) – Insertion: base 1st prox phalanx via lateral sesamoid – Action: flex & adduct 1st MTPJ – Innervation: lat. Plantar n. Layer 3 muscles AdH FHB FDMB 4  Layer 4 muscles - extrinsic peroneus longus – grooves cuboid – to base 1st metatarsal – synovial sheath in tunnel tibialis posterior – extensive insertion beyond navicular  Layer 4 muscles - intrinsic plantar interossei (PI-O) Origin: unipennate from shafts 3-5th mets Insertion: base prox. phalanx and extensor hoods 3-5 toes Action: flex & adduct MPJ (‘PAD’) and extend IPJ’s Innervation: lat. Plantar n. (deep br.) dorsal interossei (DI-O) Origin: bipennate from shafts metatarsals Insertion: base prox. phalanx and extensor hoods 2-4 toes Action: flex & abduct MPJ (‘DAB’) and extend IPJ’s Innervation: lat. plantar (deep br.) Layer 4 muscles interossei TP PL  Plantar ligts. Plantar calcaneonavicular ligt (‘spring’ ligt.) – Thick band that attaches sustentaculum tali [prominent medial process of calc.] to the navicular Short plantar ligt. – Connects calc. to cuboid Long plantar ligt. – Connects calc. To a ridge on the cuboid then to the bases of the 2nd-5th MT Ligaments of sole ‘spring’ short plantar long plantar  Arches of foot longitudinal – medial – lateral transverse new principle – anchoring the ends of an arched structure will prevent distortion of the arch on loading Medial longitudinal arch talus N calc. Cun met. Lateral longitudinal arch calc. cub. met.  Functions of arches weight distribution – posteriorly to calcaneus – anteriorly to metatarsal heads shock absorption – some ‘give’ at joints between components of arch protection – muscles, nerves and vessels of sole Medial longitudinal arch body weight  Mechanisms of arch ‘keystone’ support – wedge shape of bones near apex of arch ‘tiebeam’ – structure linking two ends of arch and preventing separation ‘staples’ – structure linking individual components of arch and preventing separation ‘suspension’ structures – structure holding up apex of arch from above  Arch head of talus suppor keystone t plantar lig’s staples FHL tiebeam PL suspension  MLA support keystone – head of talus tiebeams – PA, FHL, FDL, AbH, FDB staples – FHB – spring ligament suspension – TP, TA – deltoid ligament  LLA support keystone – cuboid tiebeams – PA, FDL, AbDM, FDB staples – FDM – long and short plantar ligaments suspension – PL, PB  Transverse arch support keystone – bases metartarsals & cuneiforms tiebeams – PL staples – transverse head AdH – Deep Transverse Metatarsal Ligament (DTML) suspension – TA Transverse arch support metatarsal bases  Arch support: general passive structures (standing) – bones – ligaments – fascia active structures (locomotion) – muscles Plantar aponeurosis (PA) & arches of foot PA supports longitudinal arches of foot at rest windlass effect of PA – MPJ extension raises height of longitudinal arches Windlas s effect calc arch height pp  Summary Plantar aspect of the foot is complex! – Try and simplify by remembering the most important structures