Week 10 - The Anterior and Lateral Compartments of the Leg Flashcards

1
Q

What are the general actions of the anterior compartment of the leg?

A

Dorsiflexion and inversion of the foot at the ankle

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2
Q

Which nerve innervates all the muscles in the anterior compartment of the leg?

A

Deep fibular (peroneal) nerve

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3
Q

Which muscle in the anterior compartment of the leg is the strongest dorsiflexor of the foot?

A

Tibialis anterior

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4
Q

What are the actions of tibialis anterior?

A

Dorsiflexion and inversion of the foot at the ankle

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5
Q

What are the actions of extensor digitorum longus?

A

Dorsiflexion of the foot and extension of the lateral 4 toes

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6
Q

What are the actions of extensor hallucis longus?

A

Dorsiflexion of the foot at the ankle

Extension of the great toe

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7
Q

What muscles make up the lateral compartment of the leg?

A

Fibularis longus and fibularis brevis

aka peroneal longus and brevis

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8
Q

What is the general action of the lateral compartment of the leg?

A

Eversion of the ankle, or more importantly, prevention of excessive inversion of the ankle.

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9
Q

Which is more superficial - fibularis longus or brevis?

A

Fibularis longus

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10
Q

What are the actions of fibularis longus?

A

Eversion and plantarflexion of the foot

Also supports the lateral and transverse arches of the foot

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11
Q

Which nerve innervates both muscles in the lateral compartment of the leg? Give its nerve roots.

A

Superficial fibular nerve, L4 - S1

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12
Q

What are the actions of fibularis brevis?

A

Eversion of the foot only

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13
Q

Why is fibularis longus an important anatomical landmark for dissection?

A

Common fibular nerve passes through the gap between its two parts (1 originates from the head of the fibula, and the other from the neck).

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14
Q

What happens to the common fibular nerve once it has passed between the two parts of fibularis longus?

A

It bifurcates into the deep and superficial fibular nerves

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15
Q

How might the common fibular nerve be damaged?

A

Fracture of the fibula

Tight plaster cast

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16
Q

What happens if the common fibular nerve is damaged?

A

Footdrop, due to paralysis of the muscles in the anterior leg, as they are supplied by the deep fibular nerve which branches off from the common fibular nerve.

17
Q

What is footdrop, and why does it occur as a result of damage to the common fibular nerve?

A

Footdrop = permanent plantarflexion of the foot
This is because the muscles in the anterior leg, which perform dorsiflexion, are paralysed, leaving the posterior leg muscles, which perform plantarflexion, unopposed.

18
Q

How may someone with footdrop present?

A

Permanent plantarflexion
“Eversion flick” - foot flicks outwards
Loss of sensation over lateral leg and dorsum of foot

19
Q

Which muscles make up the anterior compartment of the leg?

A

Tibialis anterior
Extensor digitorum longus
Extensor hallucis longus