This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: ENT
Facial nerve palsy at sternomastoid canal can cause: 
Select and explain. 
A. Loss of corneal reflex at side of lesion, B. Loss of corneal taste sensation anterior 2/3 of ipsilateral tongue, C. Loss of lacrimation at side of lesion, D. Hyperacusis
A: Loss of corneal reflex at side of lesion
Answer: A: Loss of corneal reflex at side of lesion 
Explanation: Ans. A Loss of Corneal reflex at the side of lesionCourse of Facial NerveBelow stylomastoid formen, facial nerve gives following branches: Posterior auricular branch, muscular branches (stylohyoid and posterior belly of diagastric) and terminal (peripheral) branches.Lesion at sternomastoid forameni. Will spare:- Greater superficial petrosal nerve -7 Lacrimation present.- Nerve to stapedius -7 Normal stapedial reflex and no hyperacusis.- Chorda tympani -7 Normal salivation and taste sensation in anterior 2/3 of tongue.ii. Will involve:Terminal (peripheral) branches -7 Paralysis of muscles of facial expression. Corneal reflex will also be lost because efferent fibres of corneal reflex are derived from peripheral branches of facial nerve (it is a LMN type lesion).Remember:Corneal Reflex: Afferent: Trigeminal nerveEfferent: Peripheral branches of facial nerve