MSK - Muscles of the Anterior Compartment of the Lower Leg

Question 1

What are the four muscles of the anterior leg?

Answer 1

• Tibialis anterior
• Extensor digitorum longus
• Extensor hallucis longus
• Fibularis tertius

Question 2

What are the collective actions of the anterior leg muscles?

Answer 2

• Dorsiflexion of the foot at the ankle

- Inversion of the foot at the ankle

Question 3

What are the extra movements of the extensor digitorum longus and extensor hallucis longus?

Answer 3

Extension of the toes

Question 4

What is the innervation of all the muscles in the anterior leg?

Answer 4

Deep fibular nerve (L4-L5)

Question 5

What is the arterial supply of all the muscles in the anterior leg?

Answer 5

The anterior tibial artery

Question 6

What is the origin of tibialis anterior?

Answer 6

The lateral surface of the tibia

Question 7

Where does tibialis anterior insert?

Answer 7

• Medial cuneiform

- Base of metatarsal 1

Question 8

What are the actions of tibialis anterior?

Answer 8

• Dorsiflexion of the foot

- Inversion of the foot

Question 9

How can the power of tibialis anterior be tested?

Answer 9

• Ask patient to stand on their heels

- (Tibialis anterior is the strongest dorsiflexor)

Question 10

What is the origin of extensor digitorum longus?

Answer 10

• Lateral condyle of the tibia

- Medial surface of the fibula

Question 11

Where does extensor digitorum longus insert?

Answer 11

• Fibres converge into a tendon which goes to the dorsal surface of the foot
• Tendon splits into four for one insertion per toe

Question 12

What are the actions of extensor digitorum longus?

Answer 12

• Extension of the lateral four toes

- Dorsiflexion of the foot

Question 13

Where can the extensor digitorum longus tendons be palpated?

Answer 13

Dorsal surface of the foot

Question 14

Where is the extensor hallucis longus?

Answer 14

Deep to the extensor digitorum longus and tibialis anterior

Question 15

What is the origin of extensor hallucis longus?

Answer 15

Medial surface of the fibular shaft

Question 16

Where does extensor hallucis longus insert?

Answer 16

• Base of the distal phalanx of the big toe (after the tendon crosses the ankle anteriorly)

Question 17

What is the action of extensor hallucis longus?

Answer 17

• Extension of the big toe

- Dorsiflexion of the foot

Question 18

What is the origin of fibularis tertius?

Answer 18

• Medial surface of the fibula (with extensor digitorum longus)

Question 19

Where does fibularis tertius insert?

Answer 19

• Metatarsal 5 after forming a tendon at the dorsal surface of the foot
• Descends with the EDL

Question 20

What are the actions of fibularis tertius?

Answer 20

• Eversion of the foot

- Dorsiflexion of the foot

Question 21

What is footdrop?

Answer 21

• Indicator of paralysis to anterior muscles

- Most commonly due to common fibular nerve damage

Question 22

How does footdrop manifest?

Answer 22

Permanent plantarflexion due to unopposed plantarflexor muscles

Question 23

How can footdrop affect a patient?

Answer 23

• Interferes with walking as affected limb can drag on the ground
• Tries to cancel out by flicking the foot outwards (eversion flick)