Deep Fibular Nerve Flashcards
What is the deep fibular nerve?
One of the terminal branches of the common fibular nerve
What are the nerve roots of the deep fibular nerve?
L4 and L5
What are the motor functions of the deep fibular nerve?
Innervates the muscles in the anterior compartment of the leg, as well as some of the intrinsic muscles of the foot
What are the sensory functions of the deep fibular nerve?
Supplies the triangular region of skin between the 1st and 2nd toes
How does the deep fibular nerve originate?
The sciatic nerve bifurcates into the common fibular and the tibial nerves at the apex of the popliteal fossa, at the back of the knee. The common fibular nerve wraps around the neck of the fibula, moving anterolaterally, and gives rise to the two terminal branches- superficial and deep fibular nerve
Where does the deep fibular nerve arise?
In the superolateral aspect of the leg, between the fibularis longus muscle and the neck of the fibula
What is the anatomical course of the deep fibular nerve?
The nerve moves from the lateral compartment to the anterior compartment of the leg. It then follows the course of the anterior tibial artery, in an inferomedial direction. Together, the two structures pass between the tibialis anterior and the extensor digitorum longus in the superior portion of the leg, and between the tibialis anterior and the extensor hallucis longus in the inferior leg
The deep fibular nerve crosses the ankle joint, passing anterior to the distal tibia, and travels deep to the extensor retinaculum
Where does the deep fibular nerve terminate?
In the dorsum of the foot
How does the deep fibular nerve terminate?
It divides into a lateral branch and a medial branch do
What does the lateral branch of the deep fibular nerve do?
Supplies motor innervation to some of the intrinsic muscles of the foot
What does the medial branch of the deep fibular nerve do?
Innervates the skin between the 1st and 2nd toes
Where are the muscles that the deep fibular nerve innervates found?
In the anterior compartment of the leg
Some intrinsic muscles of foot
What muscles of the anterior leg does the deep fibular nerve innervate?
Tibialis anterior
Extensor halucis longus
Extensor digitorum longus
Fibularis tertius
What are the muscles of the anterior leg innervated by the deep fibular nerve responsible for?
Dorsiflexion of the foot
When is dorsiflexion of the foot required during the gait cycle for walking?
When a person strikes their heel on the floor in the stance phase
During the swing phase
Which intrinsic muscles of the foot are innervated by the deep fibular nerve?
The extensor digitorum brevis and extensor hallucis brevis
What are the intrinsic foot muscles innervated by the deep fibular nerve responsible for?
Extending the toes at the metatarsophalangeal joints and interphalangeal joints
Where does the deep fibular nerve terminate?
In the dorsum of the foot as the cutaneous nerve
What does the cutaneous nerve of the deep fibular nerve innervate?
The webbed space of skin between the great toe (hallux) and second toe
When can the deep fibular nerve become entrapped or compressed?
During its course through the anterior compartment of the leg
What does entrapment or compression of the deep fibular nerve cause?
Paralysis of the muscles in the anterior compartment of the leg, and so a patient loses the ability to dorsiflex the foot
What happens with unopposed plantarflexion?
The foot drops
What does footdrop give?
The patien’t foot difficulty in clearing the ground during the swing phase of walking, and the limb looks too long
The foot will slap down on the floor when the patient walks, because it can’t be lowered in a controlled manner
How is footdrop compensated for when walking?
The patient develops an abnormal gait
What abnormal gaits may arise from footdrop?
Waddling gait
Swing-out gait
High steppage gait
What happens in waddling gait?
The patient leans excessively onto the normal limb
What is swing-out gait?
The patient abducts the abnormal limb
What is high-steppage gait?
The patient flexes the hip and knee excessively on the abnormal limb, so as to clear the dropped foot from the floor
What are the main reasons that the deep fibular nerve could be compressed?
Anterior leg muscles may have been excessively used, and so are compressing the nerve within the anterior compartment
Tight-fitting shoes may compress the nerve beneath the extensor retinaculum
What will the patient experience when the deep fibular nerve is compressed because of excessive anterior leg muscle usage?
Pain the anterior leg
What will the patient experience when the deep fibular nerve is compressed because tight fitting shoes?
Pain in the dorsum of the foot
