Muscles - Posterior Leg

Question 1

Gastrocnemius

Answer 1

O: Lateral head: lateral side of lateral femoral condyle
Medial head: popliteal surface of femur, superior to medial condyle (larger head)
I: Posterior suface of calcaneus via calcaneal (achilles) tendon
NS: Tibial nerve (S1-S2)
A: Plantarflexion of ankle when knee is extended, raises heel during walking, flexes knee

Question 2

Soleus

Answer 2

O: Posterior head and superior 1/4 of fibula, soleal line and middle 1/3 of the medial border of tibia, tendinous arch extending between bony attachments
I: Posterior surface of calcaneus via calcaneal (achilles) tendon
NS: Tibial nerve (S1-S2)
A: Plantarflexes ankle

Question 3

Plantaris

Answer 3

O: Inferior part of lateral supracondylar line of the femur, oblique popliteal ligament
I: Posterior surface of calcaneus via calcaneal (achilles) tendon (or separate tendon)
NS: Tibial nerve (S1-S2)
A: Weakly assists gastrocnemius in plantarflexing ankle and flexing knee

Question 4

Popliteus

Answer 4

O: Lateral surface of lateral femoral condyle and lateral meniscus
I: Posterior surface of the tibia, superior to soleal line
NS: Tibial nerve (L4-S1)
A: Knee flexion, lateral rotation of femur, medial rotation of tibia when knee is flexed

Question 5

Flexor Digitorum Longus

Answer 5

O: Medial part of posterior tibia, inferior to soleal line and by broad tendon to the fibula
I: Bases of the distal phalanges of lateral 4 digits
NS: Tibial nerve (S2-S3)
A: Flexes lateral 4 digits, plantarflexes ankle, supports longitudinal arches of the foot

Question 6

Flexor Hallucis Longus

Answer 6

O: Inferior 2/3 of posterior surface of the fibula, some adjacent interosseous membrane
I: Base of the distal phalanx of the great toe
NS: Tibial nerve (S2-S3)
A: Flexes great toe, weak ankle plantarflexor, supports medial longitudinal arch of the foot

Question 7

Tibialis Posterior

Answer 7

O: Posterior tibia (inferior to soleal line); posterior fibula; interosseous membrane
I: Tuberosity of the navicular; cuneiforms; cuboid; sustentaculum tali of calcaneus; bases of the 2nd-4th metatarsals
NS: Tibial nerve (L4-L5)
A: Plantarflexes the ankle and inverts the foot, supports medial longitudinal arch