Muscles of the Leg - Lecture Notes PDF

MUSCLE OF THE LEG Course Lecturer: OVIOSUN, AUGUSTINE Department of Anatomy Faculty of Basic Medical Science Edo State university, Uzairue.  LEARNING OUTCOMES By the end of this class, students should be able to 1. Describe the anatomy of the leg 2. List and...

MUSCLE OF THE LEG Course Lecturer: OVIOSUN, AUGUSTINE Department of Anatomy Faculty of Basic Medical Science Edo State university, Uzairue.  LEARNING OUTCOMES By the end of this class, students should be able to 1. Describe the anatomy of the leg 2. List and explain the muscles of the leg and their compartment 3. state their point of origin, insertion, innervation and action.  THE LEG The leg is that part of the lower limb between the knee and ankle joints Proximally, most major structures pass between the thigh and leg through the popliteal fossa. Distally, most structures pass between the leg and foot through the tarsal tunnel  COMPARTMENTS OF THE LEG The interosseous membrane, intermuscular septa and deep fascia of the leg divide the leg into three compartments: Anterior/extensor (dorsiflexor and foot Inverter) lateral (fibular), foot everters Posterior/flexor (plantarflexor and foot everters) 4  COMPARTMENTS OF THE LEG Muscles of each compartment produce different kinds of movements thus: Anterior compartment --dorsiflex the ankle, extend the toes and invert the foot. Lateral compartment muscles 5  ANTERIOR COMPARTMENT OF THE LEG Located anterior to the interosseous membrane Between the lateral surface of the tibial shaft and the medial surface of the fibular shaft Bounded anteriorly by the deep fascia of the leg and skin. 6  THE LEG Inferiorly, two band-like thickenings of the fascia form retinacula Bind the tendons of the anterior compartment muscles before and after they cross the ankle joint  They are the superior extensor retinaculum (SER) Prevent them from bowstringing anteriorly during dorsiflexion of the The inferior extensor joint. retinaculum (IER) 7  MUSCLES OF THE ANTERIOR COMPARTMENT They include:  Tibialis anterior (TA) Extensor digitorum longus (EDL) Extensor hallucis longus (EHL) Fibularis tertius (FT) All innervated by the deep fibular nerve, a branch of the common fibular nerve. 8  TIBIALIS ANTERIOR Most anterior and medial of the muscles in anterior compartment of leg. Origin Upper two-thirds of the lateral surface of tibia Interosseous membrane. Also from deep fascia overlying it. 9  TIBIALIS ANTERIOR The muscle fibers converge in the lower one-third of the leg Forms a tendon, which descends into the medial side of the foot Attachments: medial and inferior surfaces of the medial cuneiform bone adjacent parts of first metatarsal (associated with the great toe). 10  TIBIALIS ANTERIOR Action: Dorsiflexion of the ankle joint inverts the foot at the intertarsal joints. During walking, it provides dynamic support for the medial arch of the foot. TEST: When the foot is dorsiflexed against resistance; the tendon can be seen and felt. 11  EXTENSOR HALLUCIS LONGUS Lies next to and is overlapped by the tibialis anterior muscle. Origin Middle two-forths of the medial surface of the fibula adjacent interosseous membrane. 12  EXTENSOR HALLUCIS LONGUS Insertion: The base of the distal phalanx of great toe. Action: extends the great toe. Because it crosses anterior to the ankle joint, it also dorsiflexes the foot at the ankle joint. TEST: When the big toe is dorsiflexed against resistance, the tendon can be seen and felt 13  EXTENSOR DIGITORUM LONGUS the most posterior and lateral of the muscles in the anterior compartment of leg. Origin  upper three-quarter of the medial surface of the fibula extends superiorly  lateral condyle of the tibia.  deep fascia. 14  EXTENSOR DIGITORUM LONGUS Descends to form a tendon which passes under the SER Beneath the IER the tendon divides into four Enclosed with the tendon of fibularis tartius in a common synovial sheath. Insertion: on the dorsal surfaces of the bases of the middle and distal phalanges of the lateral four toes. 15  EXTENSOR DIGITORUM LONGUS Action: extends the lateral four digit and dorsiflexes the foot at the ankle joint, TEST: when the four lateral toes are dorsiflexed against resistance, the tendons can be seen and felt, with some assistance in dorsiflextion of the ankle 16  FIBULARIS TERTIUS Origin  The lower third of the anterior surface of the fibula Its tendon descends into the foot with the tendon of extensor digitorum longus. On the dorsal aspect of the foot, it deviates laterally Insertion: the base of the fifth metatarsal Action: assists in dorsiflexion and possibly eversion of the foot 17 LATERAL COMPARTMENT OF THE LEG The lateral compartment of the leg lies between the peroneal surface of the fibula and deep fascia of the leg. It is bounded in front and behind by the anterior and posterior intermuscular septa. 18 LATERAL COMPARTMENT OF THE LEG It contains the peroneal longus and brevis muscles and the superficial peroneal nerve. The blood supply of the lateral compartment of the leg are derived from branches of the peroneal artery and the veins drain into the small saphenous vein. 19  Peroneus longus ORIGIN It arises from the head and the upper two-third of the peroneal surface of the fibula and from intermuscular septa. INSERTION The lateral side of the base of the first metatarsal and the adjoining part of the medial cuneiform. 20  PERONEUS LONGUS…..contd NERVE SUPPLY: Superficial peroneal nerve (L5 S1). ACTIONS It everts and plantarflexes the foot. The peroneal longus is a factor in maintaining the lateral longitudinal and transverse arches of the foot. TEST The foot is everted and the tendon can be seen and felt below the lateral malleolus. 21  PERONEUS BREVIS ORIGIN It arises from the lower two-third of the fibula. In the middle third of the fibula bone, peroneus brevis lies in front of that of peroneus longus. INSERTION The tendon of peroneus brevis passes above the peroneal trochlea to be inserted into the tubercle at the base of the fifth metatarsal bone. 22  PERONEUS BREVIS…… contd NERVE SUPPLY Superficial peroneal nerve (L5, S1) ACTIONS It everts and weakly plantarflexes the foot. TEST The foot is everted and the tendon can be seen and felt below the lateral malleolus. 23  FIBULAR RETINACULUM Fibular retinacula bind the tendons of the peroneus longus and peroneus brevis muscles to the lateral side of the foot a superior fibular retinaculum extends between the lateral malleolus and the calcaneus; 24