Anterior Leg, Dorsum of Foot & Lateral Leg Anatomy PDF

Anterior leg, dorsum of foot & lateral leg Paul Fletcher  Outline Tibia & fibula osteology Anterior compartment of the leg Dorsum of the foot Lateral compartment of the leg Surface anatomy session Motion of the foot Sagittal plane: dorsiflexion and plantarflexion Fronta...

Anterior leg, dorsum of foot & lateral leg Paul Fletcher  Outline Tibia & fibula osteology Anterior compartment of the leg Dorsum of the foot Lateral compartment of the leg Surface anatomy session Motion of the foot Sagittal plane: dorsiflexion and plantarflexion Frontal plane: inversion and eversion Transverse plane: abduction and adduction Triplanar motion of the foot: pronation and supination  Osteology & surface anatomy Tibia Fibula Foot bones  The tibia Largest leg bone Proximal end articulates with femur, distal end known as medial malleolus (forms part of ankle joint) Proximal end: medial/lateral condyles, tibial tuberosity Triangular shaft of bone: anterior, medial & interosseous borders  The fibula Lateral leg bone Head, (common peroneal n.) shaft, lateral malleolus (ankle joint) syndesmosis at lower end of shaft joints to tibia 3 surfaces of shaft: anterior/extensor, lateral/peroneal, posterior/flexor  Compartments of the leg There are 3 compartments of the leg: anterior lateral posterior Each has its own muscles, blood supply and nerve supply Interosseous membrane: connects the interosseous border of the tibia and fibula Anterior compartment of the leg Tibialis anterior Extensor hallucis longus Extensor digitorum longus Peroneus tertius  Tibialis anterior (TA) origin/insertion: lateral shaft of tibia, IoM, intermuscular septa --> (under extensor retinaculum) --> medial cuneiform & base of 1st MT innvervation: deep peroneal n. action: AJ dorsiflexor, foot supinator (STJ and long axis of MTJ) function: decelerates pronation and plantarflexion from HC, toe clearance during swing phase pathology: weak: foot drop, excessive foot pronation; contracture: supinated foot  Extensor Hallucis Longus (EHL) origin/insertion: middle half of medial surface of fibula, IoM (under extensor retinaculum) --> dorsal surface of base of distal phalanx of the hallux (extensor expansion into the extensor hood) innveration: deep peroneal n. action: AJ dorsiflexion, extends/stabilises hallux phalanges Extensor digitorum longus (EDL) origin/insertion: lateral tibial condyle, upper medial fibula, IoM (under retinaculum) --> divide into 4 slips --> base of distal phalanx of the lesser 4 toes (also base of intermediate phalanx) contributes to extensor hood innervation: deep peroneal n. action: AJ dorsiflexion, extends lesser toe phalanges Digital musculature Long flexors/extensors: insert into DISTAL phalanx and produce motion at the distal interphalangeal joint (DIPJ) Short flexors/extensors: insert into INTERMEDIATE phalanx and produce motion at the proximal interphalangeal joint (PIPJ)  Peroneus tertius Closely related to EDL (almost 5th tendon) origin/insertion: distal 1/4 of fibula and IoM (deep to ext retinaculum) --> dorsal surface of base of 5th MT innervation: deep peroneal action: foot eversion, AJ dorsiflexion, weak foot pronator  Arterial supply to anterior leg Anterior tibial artery smaller of the branches of the popliteal artery enters anterior compartment through an opening in the interosseous membrane accompanies the deep peroneal nerve passes behind the superior extensor retinaculum (between EHL and EDL) becomes dorsalis pedis in front of the AJ  The retinacula Important deep fascia around ankle joint: keep long tendons in position & act as modified pulleys The superior extensor retinaculum anterior border of fibula - anterior border of tibia continuous with deep fascia of leg The inferior extensor retinaculum Y-shaped band: calcaneus - tibia/plantar aponeurosis  The retinacula... The flexor retinacula (lacinate ligament) medial malleolus - medial tuberosity of calcaneus protects/supports medial tendons, vessels, nerve Peroneal retinacula superior peroneal retinaculum (lateral malleolus - lateral calcaneus inferior peroneal retinaculum (continuous with inferior extensor retinaculum) (peroneal tubercle - plantar aponeurosis) Nerve of the anterior fascial compartment of the leg Deep peroneal one of the branches of the common peroneal nerve arises in PL near the neck of the fibula, extends deep to the anterior leg muscles passes behind the extensor retinacula has muscular branches to TA, EDL, Peroneus tertius and EHL articular branch to AJ Dermatom es The area of skin supplied by a single spinal nerve, and therefore a single spinal segment, is called a dermatome Cutaneous nerve distribution of the lower extremity  Dorsum of foot Dorsum considerably less complicated anatomically than plantar aspect of foot skin much thinner than plantar foot Extrinsic muscles of the foot: those muscles that have an origin outside of the foot, but an insertion into part of the foot Intrinsic muscles of foot: those muscles that have both an origin and insertion into part of the foot  Dorsum nerve supply Sensory nerve supply: superficial peroneal nerve (br. of common peroneal n.) (assisted by deep peroneal, saphenous and sural nerves) Superficial peroneal nerve divides into medial (dorsum, medial hallux, 2nd/3rd toes) and lateral (dorsum, adjacent sides of the 3-5th toes) cutaneous branches Deep peroneal nerve supplies the 1st/2nd toe web Saphenous nerve: medial foot as distal as head of first MTPJ Sural nerve: lateral foot and lateral 5th toe  Dorsal cutaneo us nerves Dorsal venous arch Lies in the subcutaneous tissue over the MT heads Drains into the great saphenous vein (medially) and the small saphenous vein (laterally) This arch is important as a large amount of blood from the foot drains into the arch via digital veins and communicating veins from the sole of the foot  Dorsalis pedis artery Continuation of anterior tibial artery passes deep into the sole of the foot between the first and second metatarsals it joins the lateral plantar artery (plantar arch) Superficial: usually easily able to be palpated Branches into: lateral tarsal artery, arcuate artery, first dorsal metatarsal artery Extensor digitorum brevis origin: anterior dorsal calcaneus and inferior extensor retinaculum --> splits into 4 tendons --> #1 (med) EHB base of proximal phalanx of hallux, --> #2-#4 (lat) lateral side of EDL tendons and into the middle and distal phalanges of 2/3/4 toes innervation: lateral branch of deep peroneal action: EHB: extension of hallux MTPJ, EDB: extension 2,3,4 MTPJs & IPJs  Arteries of the dorsal foot anterior tibial artery (smaller branch of popliteal a.) dorsalis pedis artery arcuate artery dorsal digital arteries  Lateral compartment of Contents: leg Muscles: Peroneus longus & Peroneus brevis Blood supply: branches from the peroneal artery Nerve supply: superficial peroneal nerve  Peroneus Longus origin/insertion: upper 2/3rd of lateal fibula and intermuscular septa --> passes behind lateral malleolus --> runs under cuboid and inserts in the base of the 1st MT and medial cuneiform innervation: superficial peroneal nerve Action: everts (pronates) foot, foot flexor, stabilises (plantarflexes) 1st ray and forefoot  Peroneus Brevis origin/insertion: lower 2/3rd of lateral fibula and intermuscular septa --> peroneal retinaculum - insert into base of 5th MT innervation: superficial peroneal nerve Action: everts (pronates) foot about STJ and oblique axis of MTJ Blood/nerve supply of the lateral fascial compartment of the leg Blood supply: a number of branches of the peroneal artery (which lies in the posterior compartment) supply the peroneal muscles Nerve supply: superficial peroneal nerve (branch of common peroneal), descends leg between PL and PB (supplying these), pierces deep fascia and becomes cutaneous (lower part anterior leg and dorsum of foot) Simple muscle testing QuickTime™ and a Video decompressor are needed to see this picture.  Surface Anatomy Please mark (or observe) on a partner: patella, tibial tuberosity, lateral collateral ligament, head of fibula (common peroneal nerve) anterior crest of tibia, lateral malleolus, medial malleolus Styloid process, 1-5 MTPJs (dorsally & plantarly), tuberosity of the navicular, insertion point of tendo achilles Palpate dorsalis pedis pulse Undertake simple muscle testing of anterior and lateral compartments of leg: try to differentiate TA/EHL/EDL and PL/PB Questions?