L8: Lower Leg Muscles

Question 1

Anterior/Lateral Group (8)

Answer 1

Tibialis Anterior

Fibularis Tertius
Fibularis Brevis
Fibularis Longus

Extensor Hallucis Longus
Extensor Digitorum Longus
Extensor Digitorum Brevis
Extensor Hallicus Brevis

Question 2

Tibialis Anterior
dont need to know insertion

Answer 2

Origin:
Lateral condyle and upper two-thirds of the tibia, interosseous membrane.

Insertion:
Inferomedial surface of the medial cuneiform and base of the first metatarsal.

Function:
Dorsiflexes and inverts the foot. Supports medial longitudinal arch

Nerve Supply:
Deep fibular nerve (L4-L5).
Blood Supply: Anterior tibial artery.

Question 3

Fibularis Tertius
135

Answer 3

Origin:
Distal third of the anterior surface of the fibula.

Insertion:
Dorsal surface of the base of the fifth metatarsal.

Function:
Weak dorsiflexion and eversion of the foot.

Nerve Supply: Deep peroneal nerve (L5-S1).
Blood Supply: Anterior tibial artery.

Question 4

Fibularis Brevis
138

Answer 4

Origin: Distal two-thirds of lateral surface of fibula.

Insertion: Tuberosity of the base of the fifth metatarsal.

Function: Eversion and plantarflexion of the foot.

Nerve Supply: Superficial Fibular nerve (L5-S1).

Blood Supply: Fibular artery.

Question 5

Fibularis Longus
137

Answer 5

Origin:
Head and upper two-thirds of the lateral surface of the fibula.

Insertion:
The plantar surface of the medial cuneiform and the base of the first metatarsal.

Function:
Eversion and plantarflexion of the foot; supports the transverse arches.

Nerve Supply:
Superficial peroneal nerve (L5-S1).

Blood Supply: Fibular artery

Question 6

Extensor Hallucis Longus
136

Answer 6

Origin:
Middle part of the anterior surface of the fibula and the interosseous membrane.

Insertion:
Dorsal surface of the base of the distal phalanx of the great toe.

Function:
Extends the great toe; dorsiflexion of foot.

Nerve Supply: Deep peroneal nerve (L5-S2).
Blood Supply: Anterior tibial artery.

Question 7

Extensor Digitorum Longus
134

Answer 7

Origin:
Lateral condyle of the tibia and upper three-quarters of the fibula.

Insertion:
Middle and distal phalanges of the lateral four toes.

Function:
Extends the lateral four toes; dorsiflexion of the foot.

Nerve Supply: Deep peroneal nerve (L5-S1).
Blood Supply: Anterior tibial artery.

Question 8

Extensor Digitorum Brevis
dorsal intrinsic
146

Answer 8

Origin:
Superior and lateral surfaces of calcaneus.

Insertion:
Middle and distal phalanges of the lateral four toes.

Function:
Extends the lateral four toes.

Nerve Supply: Deep peroneal nerve (L5-S1).
Blood Supply: Dorsalis pedis artery

Question 9

Extensor Hallucis Brevis:
dorsal intrinsic
145

Answer 9

Origin:
Anterior part of the inferior surface of the calcaneus.

Insertion:
Proximal phalanx of the great toe.

Function:
Extends the great toe.

Nerve Supply: Deep peroneal nerve (L5-S1).
Blood Supply: Dorsalis pedis artery.

Question 10

Posterior group (8)

Answer 10

Medial Gastrocnemius
Lateral Gastrocnemius

Popliteus
Soleus

Flexor Hallucis Longus
Flexor Digitorum Longus

Plantaris
Tibialis Posterior

Question 11

Medial Gastrocnemius (S)
139 A

Answer 11

Origin:
Medial head: Medial femoral condyle.
Lateral head: Lateral femoral condyle.

Insertion: Posterior surface of the calcaneus via the Achilles tendon.

Function:
Plantarflexion of the foot; assists in knee flexion.

Nerve Supply: Tibial nerve (S1-S2).
Blood Supply: Sural arteries

Question 12

Lateral Gastrocnemius (S)
139 B

Answer 12

Origin:
Lateral head: Lateral femoral condyle.

Insertion:
The posterior surface of the calcaneus via the Achilles tendon.

Function:
Plantarflexion of the foot; assists in knee flexion.

Nerve Supply: Tibial nerve (S1-S2).
Blood Supply: Sural arteries.

Question 13

Popliteus (D)
141

Answer 13

Origin:
Lateral condyle of the femur.

Insertion:
Posterior proximal tibia.

Function:
Unlocks the knee joint (initiates knee flexion); medially & laterally rotates the femur on the tibia.

Nerve Supply: Tibial nerve (L4-S2).
Blood Supply: Popliteal artery

Question 14

Soleus (S)
slow twitch for standing, contracts to help send blood up through veins

Answer 14

Origin:
Soleal Line, medial border of tibia, head of fibula

Insertion:
Posterior surface of the calcaneus via the Achilles tendon.

Function:
Plantarflexion of the foot.

Nerve Supply: Tibial nerve (S1-S2).
Blood Supply: Posterior tibial artery

Question 15

Flexor Hallucis Longus (D)

Answer 15

Origin: Lower 2/3 of Posterior fibula and INTNS membrane
Insertion: The distal phalanx of the great toe.

Function: Flexes the great toe; plantarflexion of the foot; supports the medial longitudinal arch.

Nerve Supply: Tibial nerve (S2-S3).

Question 16

Flexor Digitorum Longus (D)

Answer 16

Origin:
Middle third of Posterior tibia.

Insertion:
Distal phalanges of the lateral four toes.

Function:
Flexes the lateral four toes; plantarflexion of the foot; supports the longitudinal arch.

Nerve Supply: Tibial nerve (S2-S3).
Blood Supply: Posterior tibial artery.

Question 17

Plantaris (S)

Answer 17

Origin:
Lateral supracondylar ridge of the femur.

Insertion:
Posterior surface of the calcaneus via the Achilles tendon.

Function:
Weakly assists in knee flexion; may assist in plantarflexion.

Nerve Supply: Tibial nerve (L5-S2).
Blood Supply: Sural arteries.

Question 18

Tibialis Posterior (D)
142

Answer 18

Origin:
Posterior tibia and fibula, interseseous membrane

Insertion:
Tuberosity of the navicular, cuneiforms, and bases of the metatarsals.

Function:
Inversion and plantarflexion of the foot; supports the medial longitudinal arch.

Nerve Supply: Tibial nerve (L4-L5).
Blood Supply: Posterior tibial artery