Week 10 - The Anterior and Lateral Compartments of the Leg Flashcards
What are the general actions of the anterior compartment of the leg?
Dorsiflexion and inversion of the foot at the ankle
Which nerve innervates all the muscles in the anterior compartment of the leg?
Deep fibular (peroneal) nerve
Which muscle in the anterior compartment of the leg is the strongest dorsiflexor of the foot?
Tibialis anterior
What are the actions of tibialis anterior?
Dorsiflexion and inversion of the foot at the ankle
What are the actions of extensor digitorum longus?
Dorsiflexion of the foot and extension of the lateral 4 toes
What are the actions of extensor hallucis longus?
Dorsiflexion of the foot at the ankle
Extension of the great toe
What muscles make up the lateral compartment of the leg?
Fibularis longus and fibularis brevis
aka peroneal longus and brevis
What is the general action of the lateral compartment of the leg?
Eversion of the ankle, or more importantly, prevention of excessive inversion of the ankle.
Which is more superficial - fibularis longus or brevis?
Fibularis longus
What are the actions of fibularis longus?
Eversion and plantarflexion of the foot
Also supports the lateral and transverse arches of the foot
Which nerve innervates both muscles in the lateral compartment of the leg? Give its nerve roots.
Superficial fibular nerve, L4 - S1
What are the actions of fibularis brevis?
Eversion of the foot only
Why is fibularis longus an important anatomical landmark for dissection?
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).
What happens to the common fibular nerve once it has passed between the two parts of fibularis longus?
It bifurcates into the deep and superficial fibular nerves
How might the common fibular nerve be damaged?
Fracture of the fibula
Tight plaster cast
What happens if the common fibular nerve is damaged?
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.
What is footdrop, and why does it occur as a result of damage to the common fibular nerve?
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.
How may someone with footdrop present?
Permanent plantarflexion
“Eversion flick” - foot flicks outwards
Loss of sensation over lateral leg and dorsum of foot
Which muscles make up the anterior compartment of the leg?
Tibialis anterior
Extensor digitorum longus
Extensor hallucis longus
