Leg Muscles

OBJECTIVES Identify and name the contents of the muscular compartments of the leg. Name the muscles causing plantar flexion, dorsiflexion, eversion, inversion, flexion of digits and extension of digits. Identify the neurovasculature behind the knee and in the leg

LEG. Tibia and fibula: -held together by an interosseuos membrane. -anterior border of tibia is subcutaneous from the tibial condyles to its distal end. [Shin] -only the distal ¼ of fibula is subcutaneous The distal ends are held together to form the proximal articular surface of ankle. Each ends subcutaneously as a Malleolus (medial – tibial and lateral - fibular). Proximal and distal tibio-fibular joints interosseous membrane Medial malleolus Lateral malleolus

Inversion / eversion: Complex twisting movement at transverse tarsal and subtalar jts. [inter-tarsal joints] Plantarflexion / dorsiflexion: (ankle jt) Flexion / extension: (digits)

Fascia of the Leg The deep fascia surrounds the leg and attached to Anterior & Medial borders of Tibia. Three Intermuscular Septa Pass from the deep aspect of this fascia to be attached to : Anterior border of fibula (Anterior fascial septum) Posterior border of fibula (Posterior fascial septum) Transverse intermuscular septum Interosseous membrane: A thin & strong membrane, that binds the interosseous borders of tibia & fibula. It binds the two bones and provides attachment for muscles.

Fascial Compartments of Leg Together with the interosseus membrane, the septa divide the leg into (3) Compartments : 1-Anterior 2-Lateral (peroneal) 3-Posterior Each has its own Muscles, Blood and Nerve supply.

Anterior Compartment MUSCLES NERVE SUPPLY TIBIALIS ANTERIOR DEEP PERONEAL Extensor Digitorum Longus PERONEUS TERTIUS Extensor Hallucis LONGUS

Anterior compartment of leg: -tibialis anterior -extensor hallucis longus -extensor digitorum longus (fibularis tertius) All supplied by the deep fibular (peroneal) nerve. Hallux = big toe [hallucis] Tendons are bound down by extensor retinaculum as they cross the ankle jt. Function: -dorsiflexion (ankle) -extension (digits) -inversion tibialis anterior extensor digitorum longus extensor hallucis longus extensor retinaculum

Tibialis Anterior & Extensor Digitorum Longus Muscle Origin Insertion Action Tibialis anterior Lateral surface of shaft of tibia and interosseous membrane Medial cuneiform and base of first metatarsal bone Extends foot at ankle joint; Inverts foot at subtalar & transverse tarsal joints & Holds up medial longitudinal arch of foot Extensor digitorum longus Anterior surface of shaft of fibula Extensor expansion of lateral four toes Extends toes; Extends foot at ankle joint

Peroneus Tertius, & Extensor Hallucis Longus Muscle Origin Insertion Action Peroneus tertius Anterior surface of shaft of fibula Base of 5th metatarsal bone 1-Extends foot at ankle joint; 2-Everts foot at subtalar and transverse tarsal joints Extensor hallucis longus Anterior surface of shaft of fibula Base of distal phalanx of great toe Extends big toe, Extends foot at ankle joint; Inverts foot at subtalar and transverse tarsal joints

Common Fibular n. Deep Fibular n. Superficial Fibular n. Tibialis Anterior Deep dissection Anterior view: Note vulnerability of common fibular (peroneal) nerve as it winds around the neck of fibula. extensor digitorum longus extensor hallucis longus DROP FOOT??????

Lateral Compartment of Leg MUSCLES NERVE PERONEUS LONGUS Superficial Peroneal BREVIS

Peroneus Longus Origin Lateral surface of shaft of fibula Insertion Action Lateral surface of shaft of fibula Base of first metatarsal and the medial cuneiform Plantar flexes foot at ankle joint; Everts foot at subtalar and transverse tarsal joints; Supports Lateral longitudinal & Transverse arches

Insertion Action Origin Peroneus Brevis Insertion Action Origin Lateral surface of shaft of fibula Base of fifth metatarsal bone Plantar flexes foot at ankle joint; Everts foot at subtalar and transverse tarsal joint; Supports Lateral longitudinal arch of foot

Peroneal Retinacula Superior peroneal retinaculum Connects the lateral malleolus to calcaneum & holds the tendons of peroneus longus & brevis Inferior peroneal retinaculum Synovial Sheaths of Peroneal Longus & Brevis: Tendons of peronei are surrounded by a single common tubular synovial sheath, deep to inferior peroneal retinaculum, they have separate sheaths

Popliteal Fossa Diamond-shaped region Posterior to knee bounded: Sup.Medially: semimembranosus / semitendinosus Sup.Laterally: -biceps femoris Inferiorly: -medial & lateral heads of gastrocnemius.

Popliteal Fossa Contents: 2. Small saphenous vein 3. Tibial nerve. 1. Popliteal vessels 2. Small saphenous vein 3. Tibial nerve. 4. Common peroneal nerve. 5. Posterior cut. nerve of thigh. 6. Connective tissue & popliteal lymph nodes.

CONTENTS OF THE POSTERIOR FASCIAL COMPARTMENT OF THE LEG The transverse intermuscular septum of the leg is a septum divides the muscles of the posterior compartment into superficial and deep groups. Contents: Superficial group of muscles Deep group of muscles Posterior tibial artery Tibial nerve

SUPERFICIAL GROUP Gastrocnemius 2. Plantaris 3. Soleus

SUPERFICIAL GROUP Muscle Origin Insertion Nerve Action Gastrocnemius Lateral head from lateral condyle of femur & medial head from above medial condyle Posterior surface of calcaneum via tendo calcaneus Tibial Plantar flexes foot at ankle joint; flexes knee joint Plantaris Lateral supracondylar ridge of femur Posterior surface of calcaneum Soleus Shafts of tibia and fibula Together with gastrocnemius and plantaris is powerful plantar flexor of ankle joint; provides main propulsive force in walking and running

DEEP GROUP Popliteus 2. Flexor digitorum longus 3. Flexor hallucis longus 4. Tibialis posterior

DEEP GROUP Popliteus Lateral surface of lateral condyle of femur (Intracapsular) Post surface of shaft of tibia above soleal line Tibial Flexes leg at knee joint; Unlocks knee joint by lateral rotation of femur on tibia Flexor digitorum longus Posterior surface of shaft of tibia Bases of distal phalanges of lateral four toes Flexes distal phalanges of lateral four toes; plantar Flexes foot at ankle joint; Supports medial and lateral longitudinal arches Flexor hallucis longus Posterior surface of shaft of fibula Base of distal phalanx of big toe Flexes distal phalanx of big toe; plantar flexes foot at ankle joint; supports medial longitudinal arch Tibialis posterior Posterior surface of shafts of tibia and fibula and interosseous membrane Tuberosity of navicular bone and other neighboring bones. Plantar flexes foot at ankle joint; inverts foot at subtalar and transverse tarsal joints; supports medial longitudinal arch

Posterior (deep) compartment of leg: -Tibialis posterior -Flexor digitorum longus -Flexor hallucis longus Tendons are bound down by flexor retinaculum as they pass into foot behind the medial malleolus. Functions: -plantarflexion -flexion -inversion Innervated by Tibial nerve. flexor digitorum longus flexor hallucis longus tibialis posterior flexor retinaculum

Blood supply to the lower limb: Thigh: Femoral artery and branches: (profunda, medial & lateral circumflex) Behind knee: Popliteal artery Leg: divides into anterior and posterior tibial arteries. to supply these compartments. The posterior tibial artery gives off the fibular (peroneal) artery to supply the lateral compartment. popliteal a. posterior tibial a. anterior tibial a. fibular artery

Cutaneous innervation of thigh and Leg Anterior Posterior Anterior, lateral, medial thigh ( lumbar plexus). - branches of femoral n. - lateral femoral cutaneous n.) Posterior thigh – from sacral plexus. Anteromedial leg – branch of femoral n. (Saphenous nerve). Posterolateral leg – from Sciatic n. (Sural nerve). Anterior leg: - From Sciatic n. (Superficial fibular n.) Post. femoral cutaneous n. saphenous nerve sural nerve L4 S1

Superficial drainage of the lower limb FYI - varicose veins Great Saphenous vein: Drains into femoral vein in femoral triangle Small Saphenous vein: Drains into popliteal vein