A policemen found a person lying unconscious in right lateral position on the road with superficial injury to the face, bruises on the right arm, and injury to the lateral aspect of right knee. Nerve most probably injured:

Ans. c. Common peroneal nerve (Ref: BDC 4th/Vol-II/174)'Common peroneal nerve (L4, L5, S1, S2) is the smaller terminal branch of sciatic nerve. The larger terminal branch of sciatic nerve is the tibial nerve. The common peroneal nerve is relatively unprotected as it traverses the lateral aspect of the head of fibula and is easily compressed at this site.'- BDC 4th/Vol-II/174Common Peroneal Nerve InjuryCommon peroneal nerve (L4, L5, S1, S2) is the smaller terminal branch of sciatic nerve.The larger terminal branch of sciatic nerve is the tibial nerve.The common peroneal nerve is relatively unprotected as it traverses the lateral aspect of the head of fibula and is easily compressed at this site.Common Modes of InjuryFracture of neck of fibulaPlaster on the legLathi injury on the lateral side of knee jointClinical Features:Injury to common peroneal nerve results in paralysis of all muscles in the anterior and lateral compartment of the leg (dorsiflexors of the ankle and evertors of the foot) which results in:Loss of eversion of foot and dorsiflexion of the ankle causes foot dropFoot drop and toes drags on the floor while walkingFoot comes down suddenly producing a distinctive plopVariable loss of sensation on the anterolateral aspect of the leg and dorsum of the footArticular loss the lateral side of the knee jointIn common peroneal nerve injury, only eversion and dorsiflexion is lost, while inversion and plantar flexion remains normal, therefore ankle reflex is intact.