A camel rider sustained an injury to the lateral side of his right leg just below the knee caused by the camel stick. The site is slightly bruised and tender to touch. He is unable to either dorsiflex or evert the foot. There is loss of sensation over the front and outer half of the leg and dorsum of the foot. What is the SINGLE most likely anatomical structure to be affected?
A. Sural nerve
B. Common peroneal nerve
C. Tibia nerve
D. Lateral plantar nerve
E. Medial plantar nerve
This is actually called a peroneal strike. A peroneal strike is a temporarily disabling blow to the common peroneal nerve of the leg, just above the knee which causes a temporary loss of motor control of the leg, accompanied by numbness and a painful tingling sensation from the point of impact all the way down the leg, usually lasting anywhere from 30 seconds to 5 minutes in duration.
Common peroneal nerve
The common peroneal nerve innervates the short head of the biceps femoris muscle (part of the hamstring muscles, which flex at the knee). In addition, its terminal branches also provide innervation to muscles:
Motor Functions
Superficial fibular nerve: Innervates the muscles of the lateral compartment of the leg. These muscles act to evert the foot.
Deep fibular nerve: Innervates the muscles of the anterior compartment of the leg. These muscles act to dorsiflex the foot, and extend the digits. It also innervates some intrinsic muscles of the foot.
If the common fibular nerve is damaged, the patient may lose the ability to dorsiflex and evert the foot, and extend the digits.
Sensory Functions
There are two cutaneous branches that arise directly from the common fibular nerve as it moves over the lateral head of the gastrocnemius.
Sural communicating nerve: This nerve combines with a branch of the tibial nerve to form the sural nerve. The sural nerve innervates the skin over the lower posterolateral leg.
Lateral sural cutaneous nerve: Innervates the skin over the upper lateral leg.
In addition to these nerves, the terminal branches of the common fibular nerve also have a cutaneous function: