Lower leg and foot: Extrinsic muscles (Posterior compartment)

Question 1

All posterior muscles are….?

Answer 1

Plantar flexors

Question 2

What are the 4 deep posterior muscles of the lower leg?

Answer 2

Tibialis posterior muscle
Flexor hallucis longus muscle
Flexor digitorum longus muscle
Popliteus

Question 3

What is the function, origin, insertion and innervation of the tibialis posterior muscle?

Answer 3

Function – Inverts foot at subtalar and transverse tarsal joints; plantarflexes foot at ankle joint
Origin – Posterior surface of tibia, inferior to soleal line, posterior surface of fibula, and adjacent interosseous membrane of leg
Insertion – Tuberosity of navicular bone, plantar aspects of medial, intermediate and lateral cuneiform bones, and plantar aspects of 2nd-4th metatarsal bones
Innervation – Tibial nerve (L4-L5)

Question 4

What is the function, origin, insertion and innervation of the flexor hallucis longus muscle?

Answer 4

Function – Flexes great toe; plantarflexes foot at ankle joint
Origin – Distal two thirds of posterior surface of fibula and adjacent interosseous membrane of leg
Insertion -Plantar aspect of base of distal phalanx of great toe
Innervation – Tibial nerve (L5-S2)

Question 5

What is the function, origin, insertion and innervation of the flexor digitorum longus muscle?

Answer 5

Function – Flexes 2nd, 3rd, 4th and little toes; plantarflexes foot at ankle joint
Origin – Posterior surface of tibia, inferior to soleal line
Insertion – Plantar aspects of bases of the distal phalanges of the 2nd, 3rd, 4th, and little toes
Innervation – Tibial nerve (L5-S2)

Question 6

What is the function, origin, insertion and innervation of the popliteus muscle?

Answer 6

Function – Medially rotates leg at knee joint; ‘unlocks’ knee joint at beginning of knee flexion
Origin – Groove for popliteus muscle
Insertion – Posterior surface of tibia, superior to soleal line
Innervation – Tibial nerve (L4-S1)

Question 7

What are the 4 superficial posterior muscles of the lower leg?

Answer 7

Soleus muscle
Medial head of gastrocnemius muscle
Lateral head of gastrocnemius muscle
Plantaris muscle

Question 8

What is the function, origin, insertion and innervation of the soleus muscle?

Answer 8

Function – Plantarflexes foot at ankle joint
Origin – Head of fibula, posterior surface of fibula, soleal line, and medial border of tibia
Insertion – Posterior surface of calcaneus, via calcaneal tendon
Innervation – Tibial nerve (S1-S2)

Question 9

What is the function, origin, insertion and innervation of the medial head of gastrocnemius muscle?

Answer 9

Function – Plantarflexes foot at ankle joint; flexes leg at knee joint
Origin – Medial condyle and popliteal surface of femur
Insertion – Posterior surface of calcaneus, via calcaneal tendon
Innervation – tibial nerve (S1-S2)

Question 10

What is the function, origin, insertion and innervation of the lateral head of gastrocnemius muscle?

Answer 10

Function – Plantarflexes foot at ankle joint; flexes leg at knee joint
Origin – Lateral condyle and lateral supracondylar line of femur
Insertion -Posterior surface of calcaneus, via calcaneal tendon
Innervation – Tibial nerve (S1-S2)

Question 11

What is the function, origin, insertion and innervation of the plantaris muscle?

Answer 11

Function – Assists in plantarflexion of foot at ankle joint; assists in flexion of leg at knee joint
Origin – Lateral supracondylar line of femur
Insertion – Posterior surface of calcaneus
Innervation – Tibial nerve (S1-S2)