Muscles of Posterior Leg and Ankle

Question 0

soleus

Answer 0

Origin: posterior aspect of head of fibula, superior 1/4 of posterior surface of fibula, soleal line, and medial border of tibia
Insertion: posterior surface of calcaneus via calcaneal tendon
Innervation: tibial nerve (S1, S2)
Action: plantarflexes ankle; steadies led on foot

Question 1

Gastrocnemius

Answer 1

Origin: lateral head: lateral aspect of lateral condyle of femur
medial head: popliteal surface of femur, superior to medial condyle
Insertion: posterior surface of calcaneus via calcaneal tendon
Innervation: tibial nerve (S1, S2)
Action: plantarflexes ankle when knee is extended; raises heel during walking; flexes knee joint

Question 2

plantaris

Answer 2

Origin: inferior end of lateral supracondylar line of femur and oblique popliteal ligament
Insertion: posterior surface of calcaneus via calcaneal tendon
Innervation: tibial nerve (S1, S2)
Action: weakly assists gastrocnemius in plantarflexing ankle; function is probably mainly proprioceptive

Question 3

flexor digitorum longus (FDL)

Answer 3

Origin: medial part of posterior surface of tibia inferior to soleal line and by a broad tendon to fibula
Insertion: bases of distal phalanx of lateral 4 digits
Innervation: tibial nerve (S2, S3)
Action: flexes lateral four digits; plantar flexes ankle; supports longitudinal arches of foot

Question 4

Flexor hallucis longus

Answer 4

Origin: inferior 2/3s of posterior surface of fibula and inferior part of interosseous membrane
Insertion: base of distal phalanx of great toe (hallux)
Innervation: tibial nerve (S2, S3)
Action: flexes great toe at all joints; weakly plantarflexes ankle; supports medial longitudinal arch of foot

Question 5

tibialis posterior

Answer 5

Origin: interosseous membrane; posterior surface of tibia inferior to soleal line; posterior surface of fibula
Insertion: primarily to tuberosity of navicular; cuneiforms; bases of 2nd-4th metatarsals
Innervation: tibial nerve (L4, L5)
Action: plantarflexes ankle; inverts foot; supports medial longitudinal arch of foot

Question 6

popliteus

Answer 6

Origin: lateral surface of lateral condyle of femur and lateral meniscus (intra-articular; within cavity of knee joint)
Insertion: posterior surface of tibia, superior to soleal line
Innervation: tibial nerve (L4, L5, S1)
Action: weakly flexes knee and unlocks its by laterally rotating femur on fixed tibia, may also medially rotate tibia on unplanted limb