Posterior Leg and Ankle

Question 1

Gastrocnemius

Superficial Muscle Group

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; and flexes knee joint

Question 2

Soleus

Superficial Muscle Group

Answer 2

Origin:
Posterior aspect of head of fibula, superior quarter 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 leg on foot

Question 3

Plantaris

Superficial Muscle Group

Answer 3

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 4

Flexor Digitorum Longus

Deep Muscle Group

Answer 4

Origin:
Medial part of posterior surface of tibia inferior to soleal line and by a broad tendon to fibula

Insertion:
Bases of distal phalanges of lateral four digits

Insertion:
Tibial Nerve (S2, S3)

Action:
Flexes lateral four digits; plantarflexes ankle; supports longitudinal arch of foot

Question 5

Flexor Hallucis Longus

Deep Muscle Group

Answer 5

Origin:
Inferior two thirds of posterior surface of fibula and inferior part of interosseous membrane

Insertion:
Base of distal phalanx of great toe (hallux)

Innervation:
Tibial Nerve (S2, S4)

Action:
Flexes great toe at all joints; weakly plantarflexes ankle; supports medial longitudinal arch of foo

Question 6

Tibialis Posterior

Deep Muscle Group

Answer 6

Origin:
Interosseous membrane, posterior surface of tibia inferior to soleal line, and posterior surface of fibula

Insertion:
Primarily to tuberosity of navicular; also to cuneiforms, cuboid, and bases of 2nd–4th metatarsals

Innervation:
Tibial nerve (L4, L5)

Action:
Plantarflexes ankle; inverts foot; supports medial longitudinal arch of foot