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Flashcards in Deep Fibular nerve Deck (15):

Nerve roots, motor & sensory function?

L4 & L5
Motor: muscles in anterior compartment of leg & some intrinsic foot muscles
Sensory: triangle region between 1st & second toes (webbing)


What is it a terminal branch of?

deep fibular (peroneal) nerve is a terminal branch of common fibular nerve


Which branch does the deep fibular nerve arise from?

sciatic nerve --> popliteal fossa --> common fibular nerve (wraps around neck of fibula) --> moves anterolaterally --> superficial and deep fibular nerve


Where does the deep fibular nerve arise from anatomically?

superolateral aspect of leg - between fibularis longus muscle and neck of fibula


Describe the course of travel of the deep fibular nerve from the neck of the fibula

nerve moves from lateral to anterior compartment of the leg
follows anterior tibial artery
both passes through tibialis anterior and extensor digitoum longus in superior leg, passes between tibialis anterior and extensor hallucis longus in inferior leg


Describe what happens to the deep fibular nerve as it passes the ankle joint

passing anterior to distal tibia at the ankle joint, travelling deep into extensor retinaculum, terminating in the dorsum of the foot - divide into lateral & medial branch


what does the lateral branch of the deep fibular nerve supply?

motor innervation to some of intrinsic muscles of foot


What does the medial branch of the deep fibular nerve supply?

cutaneous branch innervating the skin between the 1st & 2nd toe


What does the deep fibular nerve innervate?

muscles in anterior compartment of the leg:
tibialis anterior
extensor hallucis longus
extensor digitorum longus
fibularis tertius


Which actions are the muscles innervated by the deep fibular nerve responsible for?

dorsiflexion of the foot esp. during gait cycle for walking:
1. when a person strikes their heel on the floor in stance phase
2. during swing phase - bring 1 foot forwards

also extensor hallucis brevis & extensor digitorum brevis - extend toes at metatarsophalangeal & interphalangeal joints


Sensory function of the deep fibular nerve

terminates in dorsum of foot as cutaneous nerve
innervates webbed space of skin between great toe (hallux) & 2nd toe


Clinical relevance - footdrop
what causes this?
What are the consequences?

deep fibular nerve becomes entrapped / compressed during its course through the anterior compartment of the leg
causing paralysis of the muscles in the anterior compartment of the leg - patient loses ability to dorsiflex foot - unopposed plantarflexion


How will footdrop affect a patient's gait?

unopposed plantarflexion - giving abnormal gait
1. difficult to clear the ground in the swing phase when walking
2. foot slap on ground as it can't be lowered in controlled manner


What does the patient do to compromise for their footdrop? How will their gait appear?

waddling gait: patient leans excessively onto NORMAL limb
swing-out gait: patient ABducts the ABnormal limb
high stepping gait: the patient flexes the hip and knee excessively on the ABnormal limb - to clear the dropped foot from the floor


What are the reasons as to why the deep fibular nerve could be compressed?

1. excessive use of the anterior leg muscles - compressing nerve - giving rise to pain in the anterior compartment
2. tight-fitting shoes: compressing the nerve beneath the extensor retinaculum e.g. tight ski boots - patient will experience pain in dorsum of foot