Lower Leg Muscles

Question 1

What muscles are innervated by the Tibial nerve (S1, S2)?

Answer 1

Gastrocnemius, Soleus, Plantaris

Question 2

Flexor digitorum longus

Answer 2

O: Medial part of posterior surface of tibia inferior to soleal line

I: Bases of distal phalanges of lateral four digits

N: Tibia nerve (S2, S3)

A: Flexes lateral four digits; plantarflexes ankle

Question 3

Extensor hallucis longus

Answer 3

O: Middle part of anterior surface of fibula and interosseous membrane

I: Dorsal aspect of base of distal phalanx of great toe (hallux)

N: Deep fibular nerve (L5, S1)

A: Extends great toe and dorsiflexes ankle

Question 4

Extensor digitorum longus

Answer 4

O: Lateral condyle of tibia, superior-medial surface of fibula, and interosseous membrane

I: Middle and distal phalanges of lateral four digits

N: Deep fibular nerve (L5, S1)

A: Extends lateral four digits and dorsiflexes ankle

Question 5

Fibularis longus

Answer 5

O: Head and superior two-thirds of lateral surface of fibula

I: Base of 1st metatarsal and medial cuneiform

N: Superficial fibular (L5, S1, S2)

A: Everts foot and weakly plantarflexes ankle

Question 6

What muscle(s) are innervated by the Deep fibular nerve (L4, L5)?

Answer 6

Tibialis anterior

Question 8

Plantaris

Answer 8

O: Inferior end of lateral superacondylar line of femur; oblique popliteal ligament

I: Posterior surface of calcaneus via calcaneal/Achilles’ tendon

N: Tibial nerve (S1, S2)

A: Weakly assists in plantarflexing ankle

Question 9

Which muscle(s) are innervated by the Superficial fibular nerve (L5, S1, S2)?

Answer 9

Fibularis Longus, Fibularis Brevis

Question 10

Tibialis Anterior

Answer 10

O: Lateral condyle and superior-lateral surface of tibia, and interosseous membrane

I: Medial inferior surfaces of medial cuneiform and base of the 1st metatarsal

N: Deep fibular nerve (L4,L5)

A: Dorsiflexes ankle and inverts foot

Question 11

Soleus

Answer 11

O: Fibular head, superior-posterior fibula, soleal line, and middle part of medial tibia

I: Posterior surface of calcaneus via calcaneal/Achilles’ tendon

N: Tibial nerve (S1, S2)

A: Plantarflexes ankle; control progression of leg on foot during gait

Question 12

Tibialis posterior

Answer 12

O: Interosseous membrane; posterior surface of tibia inferior to soleal line; posterior surface of fibula

I: Tuberosity of navicular, cuneiform, cuboid, and sustentaculum tali of calcaneus; bases of 2nd, 3rd, and 4th metatarsals

N: Tibial nerve (L4, L5)

A: Plantarflexes ankle; inverts foot

Question 13

Lateral Leg

Answer 13

Muscles:
- Fibularis Longus
- Fibularis Brevis

General functions: Eversion and aids in plantar flexion; arch support

Blood Supply: Fibular Artery

Innervation: Superficial Fibular Nerve

Question 14

Flexor hallucis longus

Answer 14

O: Inferior-posterior surface of fibula; inferior part of interosseous membrane

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

N: Tibial nerve (S2, S3)

A: Flexes great toe; weakly plantarflexes ankle

Question 15

Fibularis brevis

Answer 15

O: Inferior two-thirds of lateral surface of fibula

I: Dorsal surface of base of 5th metatarsal

N: Superficial fibular nerve (L5, S1, S2)

A: Everts foot and weakly plantarflexes ankle

Question 16

Fibularis tertius

Answer 16

O: Anterior-inferior surface of fibula and interosseous membrane

I: Dorsum of base of 5th metatarsal

N: Deep fibular nerve (L5, S1)

A: Dorsiflexes ankle and aids in eversion of foot

Question 17

Popliteus

Answer 17

O: Lateral surface of lateral condyle of femur and lateral meniscus

I: Posterior surface of tibia and superior to soleal line

N: Tibial nerve (L4, L5, S1)

A: Assists in knee flexion; unlocks knee by laterally rotating femur (in closed chain) or medially rotating tibia (in open chain)

Question 18

Superficial Posterior Leg

Answer 18

Muscles:
- Gastrocnemius
- Soleus
- Plantaris
- Popliteus

General functions: Plantar flexion

Blood supply: Posterior Tibial Artery

Innervation: Tibial Nerve

Question 19

Which muscle(s) are innervated by the Deep fibular nerve (L5, S1)?

Answer 19

Extensor digitorum longus, extensor hallucis longus, fibularis tertius

Question 20

What muscles insert on the “posterior surface of calcaneus/Achilles’ tendon”?

Answer 20

Gastrocnemius, Soleus, Plantaris

Question 21

What muscles insert on the “posterior surface of calcaneus via calcaneal/Achilles’ tendon”?

Answer 21

Gastrocnemius, Soleus, Plantaris

Question 22

Anterior Leg

Answer 22

Muscles:
- Tibialis Anterior,
- Extensor digitorum longus,
- Extensor Hallucis Longus,
- Fibularis Tertius

General functions: Dorsiflexion, extension of toes

Blood Supply: Anterior Tibial Artery

Innervation: Deep Fibular Nerve (peroneal)

Question 23

Gastrocnemius

Answer 23

O: Lateral Head - Lateral aspect of lateral condyle of femur

Medial Head - Popliteal surface of femur, superior to medial condyle

I: Posterior surface of calcaneus via cancaneal/Achilles’ tendon

N: Tibial nerve (S1, S2)

A: Plantarflexes ankle when knee is extended; flexes leg at knee joint

Question 24

What muscles are innervated by the Tibial Nerve (S1, S2)?

Answer 24

Gastrocnemius, Soleus, Plantaris

Question 25

Deep Posterior Leg

Answer 25

Muscles:
- Tibialis posterior
- Flexor digitorum longus
- Flexor hallucis longus

General functions: Plantar flexion, flexion toes, arch support

Blood supply: Posterior tibial artery

Innervation: Tibial Nerve