Leg Muscles Flashcards
Tibialis Anterior
O: Lateral condyle of tibia, proximal 1/2 or lateral surface of tibial shaft, interosseous membrane
I: Medial and plantar surfaces of 1st cuneiform, Base of first metatarsal
Fx: Dorsiflexor of ankle and invertor of foot
nn: Deep peroneal nerve (L4, L5, S1)
Arterial Supply: Anterior tibial artery
Extensor Digitorum Longus
O: Lateral condyle of fibula, upper 3/4 of medial fibular shaft surface, upper part of interosseous membrane, fascia cruris, and anterior intermuscular septum
I: Splits into 4 tendon slips after inferior extensor retinaculum, each of which insert on dorsum of middle and distal phalanges as part of extensor expansion complex
Fx: Extend toes 2 - 5 and dorsiflexes ankle
nn: Deep peroneal nerve (L4, L5, S1)
Extensor Hallucis Longus
O: middle part of the anterior surface of the fibula interosseous membrane
I: Base and dorsal center of distal phalanx of great toe
Fx: Extends great toe and dorsiflexes ankle
nn: Deep peroneal nerve (L4, L5, S1)
Gastrocnemius
O: medial head from popliteal surface of femur and the superior surface of medial condyle; Lateral head from lateral surface of femoral lateral condyle
I: The two heads unite into a broad aponeurosis which eventually unites with the deep tendon of the soleus to form the Achilles tendon, inserting on the middle 1/3 of the posterior calcaneal surface
Fx: Powerful plantar flexor of anklle
nn: Tibial nerve (S1, S2)
Soleus
O: Posterior aspect of fibular head, upper 1/4 of posterior surface of fibula, soleal line and middle 1/3 of medial border of tibial shaft, and from posterior surface of a tendinous arch spanning the two sites of bone origin
I: Achilles tendon, inserting on the middle 1/3 of the posterior calcaneal surface
Fx: Powerful plantar flexor of ankle
nn: Tibial nerve (S1, S2)
Plantaris
O: Inferior aspect of lateral supracondylar line of distal femur
I: Middle 1/3 of the posterior calcaneal surface, just medial to Achilles tendon
Fx: Plantar flexor of ankle; also flexes knee
nn: Tibial nerve (L5, S1, S2)
Tibialis Posterior
O: Posterior aspect of interosseous membrane, superior 2/3 of medial posterior surface of fibula, superior aspect of posterior surface of tibia, inferior to soleal line
I: Splits into two: superficial slip inserts on the tuberosity of the navicular bone and sometimes medial cuneiform; deeper slip divides again into slips inserting on plantar surfaces of metatarsals 2 - 4 and second cuneiform
Fx: Principal invertor of foot; also adducts foot, plantar flexes ankle, and helps to supinate the foot
nn: Tibial nerve (L4, L5)
Flexor Digitorum Longus
O: Posterior surface of tibia distal to popliteal line
I: bases of 2nd - 5th distal phalanges
Fx: Flexes toes 2 - 5; also helps in plantar flexion of ankle
nn: Tibial nerve (S2, S3)
Flexor Hallucis Longus
O: Inferior 2/3 of posterior surface of fibula, lower part of interosseous membrane
I: distal phalanx of great toe
Fx: Flexes great toe, helps to supinate ankle, and is a very weak plantar flexor of ankle
nn: Tibial nerve (S2, S3)
Popliteus
O: Anterior part of the popliteal groove on lateral surface of lateral femoral condyle
I: Posterior surface of tibia, just superior to the popliteal line
Fx: Rotates knee medially and weakly flexes knee and unlocks it by rotating femur on fixed tibia
nn: Tibial nerve (L4, L5, S1)
Poroneus Tertius
O: medial fibular shaft surface
Anterior intramuscular septum (between the extensor digitorum longus and the tibialis anterior)
I: Dorsal surface of the base of the fifth metatarsal
Fx: Works with the extensor digitorum longus to dorsiflex, everts and abducts the foot
nn: Deep peroneal nerve (L5, S1)
Peroneus Brevis
O: Head of fibula, upper half of lateral fibular shaft surface, anterior and posterior intramuscular septa of leg
I: Lateral surface of styloid process of 1st metatarsal base
Fx: Everts foot and plantar flexes ankle
nn: Superficial peroneal nerve (L5, S1, S2)
Peroneus Longus
O: Head of fibula, upper 1/2 - 2/3 of lateral fibular shaft surface; also anterior and posterior intermuscular septa of leg
I: Plantar posterolateral aspect of medial cuneiform and lateral side of 1st metatarsal base
Fx: Everts foot and plantar flexes ankle; also helps to support the transverse arch of the foot
nn: Superficial peroneal nerve (L5, S1, S2); may also receive additional innervation from common or deep peroneal nerves (L5, S1, S2)
