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Muscles of the Lower Limbs Leg and Foot UoM T&O SocwLearning outcomes Slides & cert of attendance will be available after completion of feedback form at the end By the end of this lecture and private study, you should be able to 1. Describe the boundaries and the contents of the popliteal fossa 2. List the muscles in the posterior, lateral and anterior compartments of the leg, their circulation and nerve supply 3. Explain the functions of muscles acting on the ankle, foot and toes 4. Describe the intrinsic muscles of the foot, their functions, circulation and nerve supply 5. Describe the arches of the foot and their supports 6. Describe Tarsal TunnelPopliteal fossa Diamond shaped region behind the knee joint Borders: • Superomedial – semimembranosus • Superolateral – biceps femoris • Inferomedial – medial head of gastrocnemius • Inferolateral – lateral head of gastrocnemius Floor – popliteus, posterior surface of the knee joint capsule and the posterior surface of the femur Roof – popliteal fascia (continuous with fascia lata of the leg) and skinPopliteal fossa Contents: (medial to lateral) • Popliteal artery (deepest structure and continuation of femoral artery) • Popliteal vein - Small saphenous vein pierces the popliteal fascia of the popliteal fossa to enter the diamond and empty into the popliteal vein • Tibial nerve • Common fibular nerve • Posterior cutaneous nerve of the thigh • Lymph nodes • Fat Popliteus • During flexion of the femur must initially be rotated laterally • Popliteus laterally rotates the femur and unlocks the knee • Deep muscle of posterior compartment of leg Muscle Origin Insertion Innervation Movement Lateral surface of Weakly flexes the knee and lateral condyle of Posterior surface of unlocks it by rotating the femur Popliteus femur and lateral tibia, superior to Tibial nerve 5° on flexed tibia; medially meniscus soleal line rotates tibia of unplanted legRecap: Locking/unlocking of the knee When standing, the knee joint is “locked” into position • Ligaments are tightened • Flat surface of the femoral condyles are in contact with the tibia plateaus → joint surfaces become larger • Amount of muscle work needed to maintain the standing position is reduced • Vastus medialis locks the knee, aided by Gluteus maximus, tensor fascia lataClinical relevance: Swelling in the popliteal fossa • Baker’s cyst • Popliteal aneurysm • Compression on tibial nerve • Others? • deep vein thrombosis, adventitial cyst of the popliteal artery MRI of Baker’s cyst • Popliteal abscess, tumourCompartments of the leg Muscles in the leg are separated into 4 compartments by layers of fascia bones and ligaments Anterior, Lateral, Deep posterior, Superficial posterior Extensions of the deep fascia • Form intramuscular septa that compartmentalize groups of muscles with similar functions and innervations • Surround individual muscles and groups of vessels and nervesPosterior compartment 2 compartments: Superficial and Deep flexor compartments Superficial flexor compartment: • Gastrocnemius, Soleus, Plantaris • Superficial group muscles primarily flex the ankle, but gastrocnemius also flexes the knee • Gastrocnemius and soleus (sometimes plantaris) are collectively called triceps surae • Triceps surae • propels the body forward off the planted foot during walking • elevates the body upward onto the toes when standing • Supplied by the posterior tibial arteryPosterior compartment 2 compartments: Superficial and Deep flexor compartments Deep flexor compartment • Flexor hallucis longus, flexor digitorum longus, tibialis posterior, popliteus • Popliteus – unlocking of knee • TP – flexes (plantarflexes) ankle • FHL, FDL – flexes (plantarflexes) toes Posterior compartment • Sural nerve is formed by the • Small (short) saphenous vein • Posterior tibial artery, lateral cutaneous sural branch penetrates the deep fascia of accompanied by the tibial from the common fibular nerve the leg between the heads of nerve, descends to the soleus and medial cutaneous sural gastrocnemius muscle – muscle towards the medial branch from the tibial nerve – merges with deep veins to malleolus may be used as a nerve graft form the popliteal vein FLEXORS of the ANKLE Muscles Origin Insertion Innervation Movement Posterior surface of Gastrocnemius Lateral: lateral condyle of femur calcaneus via calcaneal Tibial Nerve Plantarflexes ankle when Medial: medial condyle of femur knee is extended tendon Posterior aspect of head of fibula, superior quarter of Posterior surface of Plantarflexes ankle Soleus calcaneus via calcaneal Tibial Nerve independent of position of posterior surface of fibula, soleal tendon knee; steadies leg on foot line and medial border of tibia Inferior end of lateral Posterior surface of Weakly assists Plantaris supracondylar line of femur and calcaneus via calcaneal Tibial Nerve gastrocnemius in oblique popliteal ligament tendon plantarflexing ankle Interosseous membrane, Tibalis posterior (deep posterior surface of tibia inferior Tubersoity of navicular, Plantarflexes ankle; inverts Tibial Nerve compartment) to soleal line, and posterior medial cuneiform foot surface of fibula • All flexors of the ankle are supplied by the tibial nerve • The primary function of tibialis posterior is to support the medial longitudinal plantar arch • Tibialis posterior is the main inverter of the foot (when the foot is off the groundEXTRINSIC FLEXORS of the TOES Muscle Origin Insertion Innervation Movement Medial part of posterior surface of tibia inferior to Base of distal phalanges of Flexes lateral 4 digits; Flexor digitorum longus Tibial Nerve Plantarflexes ankle; supports soleal line and by a broad lateral four toes longitudinal arches of foot tendon to fibula Inferior two thirds of Flexes great toe at all joints; posterior surface of fibula Base of distal phalanx of weakly plantarflexes ankle; Flexor hallucis longus Tibial Nerve and inferior part of hallux supports medial longitudinal interosseous membrane arch of foot • All muscles in the posterior compartment of the leg are supplied by the tibial nerve • Flexor hallucis longus has a very important function in walking and supports the medial longitudinal plantar arch • Flexor digitorum longus supports both the medial and lateral longitudinal plantar arches • Flexor digitorum longus, flexor hallucis longus – have other primary functions. Once the primary action has been achieved, they can flex the ankleClinical relevance: Calcaneal tendon Gastrocnemius, soleus, plantaris inserts onto the posterior surface of calcaneus via calcaneal tendon • Ankle reflex • Elicited by striking the calcaneal tendon briskly • Tests the S1 and S2 nerve roots • Ruptured calcaneal tendon • history of calcaneal tendinitis • unable to plantarflex the foot against resistance • affected foot permanently dorsiflexed • soleus and gastrocnemius can contract to form a lump in the calf regionAnterior compartment • Tibialis anterior, Extensor hallucis longus and Extensor digitorum longus • TA – extends (dorsiflexes) ankle • EHL and EDL – extend (dorsiflex) toes • Fibularis [peroneus] tertius • Arises from inferior part of EDL • (some texts eg Moore’s) part of EDL • Supplied by the anterior tibial artery Anterior compartment • Deep fibular nerve arises between fibularis longus • Anterior tibial artery passes anterior to the interosseal membrane and neck of fibula • Descends between the tibialis anterior and extensor digitorum longus. • Dhallucis longus on the interosseal membranesor • Supplies the muscles in the anterior compartment of the leg (dorsiflexors). • Accompanied by anterior tibial artery • At ankle, it becomes the dorsalis pedis arteryEXTENSORS of the ANKLE Muscle Origin Insertion Innervation Movement Lateral condyle and Dorsiflexes ankle and Tibialis anterior superior-lateral surface of Medial cuneiform and Deep fibular nerve inverts foot, supports the tibia and interosseous base of 1st metatarsal medial longitudinal arch membrane • Extensor of the ankle = Dorsiflexor of the ankle • Tibialis anterior, as with all muscles in the anterior compartment of the leg, is supplied by the deep fibular [peroneal] nerve EXTRINSIC EXTENSORS of the TOES Muscle Origin Insertion Innervation Movement Middle part of anterior Dorsal aspect of base of Extensor hallucis longus surface of fibular and distal phalanx of great toe Deep fibular [peroneal] Extends great toe and interosseous membrane (hallux) nerve dorsiflexes ankle Lateral condyle of tibia and Extensor digitorum longus superior 2/3 of anterior Middle and distal Deep fibular [peroneal] Extends lateral 4 digits and surface if fibula and phalanges of lateral 4 digits nerve dorsiflexes ankle interosseous membrane Inferior third of anterior Dorsum of base of 5th Deep fibular [peroneal] Dorsiflexes ankle and aids Fibularis tertius surface of fibula and metatarsal nerve in eversion of foot interosseous membrane • All are supplied by the deep fibular [peroneal] nerve • Extensor hallucis longus, extensor digitorum longus, fibularis [peroneus] tertius: they have other primary functions. Once the primary action has been achieved, they can extend the ankleLateral compartment • Fibularis longus, fibularis brevis • Supplied by the posterior tibial arteryLateral compartment • Superficial fibular nerve arises between fibularis longus and neck of fibula • Descends in lateral compartment of the leg • At distal 1/3 of leg, becomes superficialINVERSION and EVERSION Inversion = tibialis anterior and posterior Eversion = fibularis longus and brevis Anterior Deep posterior LateralINVERSION and EVERSION Inversion = tibialis anterior and posterior Eversion = fibularis longus and brevis Muscle Origin Insertion Innervation Movement Fibularis longus Fibula and Medial cuneiform and Superficial fibular Everts foot and intermuscular septum 1st metatarsal nerve weakly plantarflexes Fibularis brevis Fibula and 5th metatarsal Superficial fibular ankle intermuscular septum nerve • Peroneal muscles are supplied by superficial fibular [peroneal] nerve • Fibularis [peroneus] longus supports the lateral longitudinal plantar arch • Fibularis [peroneus] longus allows standing on one leg • Fibularis [peroneus] brevis acts against transverse plantar archFoot • The region of the lower limb distal to the ankle joint • It is subdivided into the ankle, the metatarsals, and the digits • The foot has a dorsum (superior surface) and a sole (inferior surface)Sole firmly attached to the plantar aponeurosisin, very Plantar aponeurosis • For grip and weight bearing • Thickens as 5 longitudinal bands that continue with the fibrous flexor sheaths • Sends septae to the metatarsals to create compartments and potential spacesPlantar muscles • Plantar muscles are arranged in layers (4 layers) • Their actions are implied by the names, important role in arch support, adjustment of balance and gait as well • Supplied by the medial or lateral plantar nerves • The extrinsic muscles arise from the anterior, posterior and lateral compartments of the leg. They are mainly responsible for actions such as eversion, inversion, plantarflexion and dorsiflexion of the foot. • The intrinsic muscles are located within the foot and are responsible for the fine motor actions of the foot, for example movement of individual digits.Plantar muscles • Plantar muscles are arranged in layers (4 layers) 1st 2nd 3rd 4th Plantar: Intrinsic muscles Muscles Origin Insertion Innervation Movement First layer Medial tubercle of tuberosity of Abductor hallucis calcaneus; flexor retinaculum; Medial side of base of Medial plantar nerve Abducts and flexes 1st digit proximal phalanx of 1st digit plantar aponeurosis Medial tubercle of tuberosity of Both sides of middle Flexor digitorum calcaneus; plantar aponeurosis; phalanges of lateral four Medial plantar nerve Flexes lateral four digits brevis intermuscular septa digits Medial tubercle of tuberosity of Abductor digit minimi calcaneus; plantar aponeurosis; Lateral side of base of Lateral plantar nerve Abducts and flexes little toe intermuscular septa proximal phalanx of 5th digit (5th digit) Second layer Posterolateral margin of Assists flexor digitorum Quadratus Plantae Medial surface and lateral margin tendon of flexor digitorum Lateral plantar nerve longus in flexing lateral four of plantar surface of calcaneus longus digits Medial one: medial plantar Flex proximal phalanges; Medial aspect of aspect of nerve extend middle and distal Lumbricals Tendons of flexor digitorum longus expansion over lateral four Lateral three: lateral plantar phalanges of lateral four digits nerve digits Plantar: Intrinsic muscles Muscles Origin Insertion Innervation Movement Third layer Plantar surfaces of cuboid and Both sides of base of Flexes proximal phalanx of Flexor hallucis brevis lateral cuneiforms proximal phalanx of 1st digit Medial plantar nerve 1st digit Tendons of both heads Oblique: bases of metatarsals 2-4 attach to lateral side of base Deep branch of lateral Adduct 1st digit; assists in Adductor hallucis Transverse: plantar ligaments of of proximal phalanx of 1st plantar nerve transverse arch of foot by metatarsophalangeal (MTP) joints metatarsals medially digit Flexor digiti minimi brevis Base of 5th metatarsal Base of proximal phalanx of Superficial branch of lateral Flexes proximal phalanx of 5th digit planatr nerve 5th digit Fourth layer Plantar aspect of medial sides of Medial sides of bases of Adduct digits 3-5 and flex Plantar interossei shafts of metatarsals 3-5 phalanges of 3rd-5th digits Lateral plantar nerve metatarsophalangeal joints 1st: medial side of proximal Adjacent sides of shafts of phalanx of 2nd digit Abduct digits 2-4 and flex Dorsal interossei metatarsals 1-5 2nd-4th : lateral sides of Lateral plantar nerve metatarsophalangeal joints 2nd-4th digitsPlantar arteries • Posterior tibial artery becomes the medial and lateral plantar arteries after running posterior to the medial malleolus • Pmalleolusbe felt behind the medialPlantar nerves • Tmalleolus, deep to the flexor retinaculumedial • Divides into the medial and lateral plantar nervesPlantar arches • Medial longitudinal arch: • calcaneus, talus, navicular, all cuneiforms and medial 3 metatarsals • Lateral longitudinal arch: • calcaneus, cuboid and 4th-5th metatarsals • Transverse arch: • cuneiforms and cuboid; disappears near the heads of the metatarsalsPlantar arches Passive supporters of arches 1. Shape of bones 2. Strong ligaments • Calcaneonavicular plantar ligament: support the keystone • Long plantar ligament • Plantar aponeurosis • Deltoid ligament • Calcaneocuboid (short plantar) ligament Active supporters of the arches: Muscles (effective when contracting) Supporters of the medial arch: Deltoid ligament, Plantar aponeurosis, Spring ligament Supporter of the lateral arch: Flexor digitorum longus, Lateral ligamentDorsum: Intrinsic muscles Muscle Origin Insertion Innervation Movement Calcaneus (floor of tarsal sinus); Aids the extensor interosseous talocalcaneal digitorum longus in ligament; stem of inferior Long extensor tendons Deep fibular nerve extending the four medial Extensor digitorum brevis extensor retinaculum; attaches to of four medial digits toes at the proximal phalanx of the great toe and the long extensor tendons of metatarsophalangeal and toes 2-4 interphalangeal joints Calcaneus (floor of tarsal sinus); Dorsal aspect of the Aids the extensor hallucis interosseous talocalcaneal base of the proximal Deep fibular nerve longus in extending the Extensor hallucis brevis ligament; stem of inferior extensor retinaculum; base of the phalanx of the great toe great toe at the proximal phalanx of the great toe metatarsophalangeal jointDorsum: Arteries and nerves • Deep fibular nerve enters the dorsum of the foot passing under the extensor retinaculum • Give rise to dorsal digital nerve to toes 1-2 • Anterior tibial artery passes under the inferior extensor retinaculum and becomes dorsalis pedis • Phallucis longuss pedis is felt in the first intermetatarsal space, between the tendon of extensor digitorum longus and extensorT arsal tunnel • Bony floor, connective tissue roof Floor • Concave surface • medial aspect of the tibia, talus and calcaneus. Roof • Flexor retinaculum between medial malleolus and medial tubercle of calcaneus Contents (posterior to anterior) • Tibialis posterior tendon • Flexor digitorum longus tendon • Posterior tibial artery and vein • Tibial nerve • Flexor hallucis longus tendon structures and the other three containing the muscle tendonsneurovascularClinical relevance: Tarsal tunnel syndrome • Entrapment and compression of the tibial nerve as it passes through the tarsal tunnel • Altered sensation in the sole of the foot • Severe disease, motor function can also be affected à weakness and wasting of the intrinsic foot muscles • Management: conservatively (Physiotherapy, NSAIDs, corticosteroid injections) or surgically (tarsal tunnel release)References • My own notes • TeachMeAnatomy • Moore et al. Clinically Oriented Anatomy • Hansen JT. Netter's Clinical Anatomy • Putz & Pabst. Sobotta Atlas of Human Anatomy With special thanks to Dr. Enis Cezayirli Scan me J Thank you for listening! 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