Week 13 Leg - Muscles.pdf

The Leg Muscles of the Posterior Compartment  superficial group:  gastrocnemius  soleus  plantaris  deep group:  flexor digitorum longus  flexor hallucis longus  tibialis posterior...

The Leg Muscles of the Posterior Compartment  superficial group:  gastrocnemius  soleus  plantaris  deep group:  flexor digitorum longus  flexor hallucis longus  tibialis posterior  popliteus  superficial and deep muscles are separated by transverse intermuscular septum  all muscles are supplied by tibial nerve  Gastrocnemius  Origin:  medial and lateral heads originate from distal end of femur  medial head: popliteal surface, above medial condyle  lateral head: lateral surface of lateral condyle and distal end of lateral supracondylar line  Insertion: both heads join a common tendon (together with soleus) transition into the calcaneal tendon (Achilles tendon) and inserts into posterior surface of calcaneus  Nerve supply: tibial nerve  Action:  plantar flexion of foot at ankle joint  assists with flexion of leg at knee joint  Soleus   located anterior (deep) to gastrocnemius  Origin: soleal line and medial border of tibia, posterior surfaces of head and shaft of fibula and tendinous arch between tibial and fibular attachments  Insertion: posterior surface of calcaneus via calcaneal tendon  soleus and gastrocnemius together are known as triceps surae  Nerve supply: tibial nerve  Action: plantar flexion of foot at ankle joint  Plantaris  has a small muscle belly and a long tendon  Origin: lateral supracondylar line of femur, immediately above origin of lateral head of gastrocnemius  Insertion: tendon passes inferiorly and medially between gastrocnemius and soleus and descends along medial border of calcaneal tendon and inserts into posterior surface of calcaneus (plantaris tendon may fuse with calcaneal tendon)  Nerve supply: tibial nerve  Action: assists with plantar flexion of foot at ankle joint and flexion of leg at knee joint  Flexor Digitorum Longus  most medially located of deep posterior muscles  Origin: posterior surface of shaft of tibia, inferior to soleal line  Insertion: tendon passes posterior to medial malleolus, under flexor retinaculum and enters sole of foot and divides into 4 tendons for lateral 4 toes and tendons pass through openings in corresponding tendons of flexor digitorum brevis and insert into bases of distal phalanges of lateral 4 toes (similar to flexor digitorum profundus in hand)  Nerve supply: tibial nerve  Action:  flexion of lateral 4 toes (distal, middle and proximal phalanges)  plantar flexion of foot at ankle joint  Flexor Hallucis Longus  most laterally located of deep posterior muscles  Origin: posterior surface of shaft of fibula  Insertion: tendon passes posterior to medial malleolus, under flexor retinaculum and it grooves posterior process of talus (divides it into medial and lateral tubercles) and inferior aspect of sustentaculum tali and runs anteriorly in sole of foot to insert into base of distal phalanx of great toe  tendons of flexor hallucis longus and flexor digitorum longus cross each other on medial side of sole of foot (FDL tendon passes superficial [inferior] to FHL tendon)  Nerve supply: tibial nerve  Action:  flexion of big toe (distal and proximal phalanges)  plantar flexion of foot at ankle joint  Tibialis Posterior  most deeply placed muscle of deep posterior group  Origin: posterior surface of shaft of tibia (inferior to soleal line), posterior surface of shaft of fibula and interosseous membrane  Insertion: in lower leg its tendon passes anterior (deep) to flexor digitorum longus and passes posterior and directly in contact with medial malleolus, under flexor retinaculum and inserts into tuberosity of navicular, and via small tendinous slips it also inserts into cuboid, cuneiforms and bases of 2nd to 4th metatarsals  Nerve supply: tibial nerve  Action:  plantar flexion of foot at ankle joint  inversion of foot at subtalar and transverse tarsal joints  Popliteus  Origin: within capsule of knee joint, from lateral surface of lateral condyle of femur (a few fibers also originate from lateral meniscus of knee joint)   Insertion: emerges from knee joint and passes inferiorly and medially and inserts into posterior surface of shaft of tibia, superior to soleal line  Nerve supply: tibial nerve  Action:  medial rotation of tibia (if foot is o ground) or lateral rotation of femur (if foot is on ground) and this action occurs at beginning of flexion from a fully extended (“locked”) knee joint and is referred to as “unlocking” knee joint Muscles of the Anterior Compartment of the leg  tibialis anterior  extensor digitorum longus  extensor hallucis longus  fibularis (peroneus) tertius  All muscles are innervated by deep fibular (peroneal) nerve Tibialis Anterior  superficial and medially located in anterior compartment  Origin: lateral condyle of tibia, lateral surface of shaft of tibia and interosseous membrane  Insertion: tendon passes under extensor retinacula and inserts into medial cuneiform and base of 1st metatarsal  Nerve supply: deep fibular nerve  Action:  dorsiflexion of foot at ankle joint  inversion of foot at subtalar and transverse tarsal joints  Extensor Digitorum Longus  superficial and laterally located in anterior compartment  Origin: lateral condyle of tibia, medial surface of shaft of fibula and interosseous membrane   Insertion: tendon passes under extensor retinacula and divides into 4 tendons (for lateral 4 toes). Each tendon divides into 3 slips  central slip inserts into base of middle phalanx  2 lateral slips join and insert into base of distal phalanx (similar to extensor digitorum in hand)  extensor expansions are formed by tendons of extensor digitorum longus on dorsal aspects of proximal phalanges  similar, but shorter, to those of the tendons of extensor digitorum over fingers  Nerve supply: deep fibular nerve  Action: extension of lateral 4 toes (distal, middle and proximal phalanges), dorsiflexion of foot at ankle joint  Extensor Hallucis Longus  its upper part is deeply located, covered by tibialis anterior and extensor digitorum longus muscles and in lower leg it becomes superficial  Origin: medial surface of shaft of fibula and interosseous membrane  Insertion: tendon passes under extensor retinacula and inserts into base of distal phalanx of great toe  Nerve supply: deep fibular nerve  Action:  extension of great toe (distal and proximal phalanges)  dorsiflexion of foot at ankle joint  Fibularis Tertius  it is essentially a lateral slip of extensor digitorum longus, from which it is rarely completely separated  Origin: medial surface of shaft of fibula and interosseous membrane  Insertion: tendon passes under extensor retinacula and inserts into dorsal aspects of shaft and base of 5th metatarsal  Nerve supply: deep fibular nerve  Action:   dorsiflexion of foot at ankle joint  eversion of foot at subtalar and transverse tarsal joints Muscles of the Lateral Compartment of the leg  fibularis longus  fibularis brevis  The two muscles are supplied by superficial fibular (peroneal) nerve  Fibularis Longus  superficial muscle of lateral compartment  Origin: lateral surfaces of head and shaft of fibula  Insertion: tendon passes posterior to lateral malleolus (under superior fibular retinaculum) and runs anteriorly and inferiorly on lateral surface of calcaneus (under inferior fibular retinaculum) and curves around cuboid and enters a groove on its inferior surface (groove is transformed into an osteofibrous tunnel by long plantar ligament) and crosses sole of foot from lateral to medial and inserts into medial cuneiform and base of 1st metatarsal  Nerve Supply: superficial fibular nerve  Action:  plantar flexion of foot at ankle joint  eversion of foot at subtalar and transverse tarsal joints  Fibularis Brevis  lies deep to fibularis longus muscle  Origin: lateral surface of shaft of fibula  Insertion: tendon passes posterior and directly in contact with lateral malleolus (under superior fibular retinaculum) and runs anteriorly and inferiorly on lateral surface of calcaneus (under inferior fibular retinaculum) and inserts into tuberosity (styloid process) of base of 5th metatarsal  Nerve supply: superficial fibular nerve  Action:  plantar flexion of foot at ankle joint  eversion of foot at subtalar and transverse tarsal joints