What is the consequence of a facial nerve injury at the stylomastoid foramen?

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Impaired taste sensation on the anterior two-thirds of the tongueWeakness or paralysis of the orbicularis oculi muscleAbsence of innervation to the stapedius muscleReduced tear production from the lacrimal glandLoss of sensation in the external ear

Explanation

A lesion of the facial nerve at the stylomastoid foramen affects the motor fibers to the muscles of facial expression, including the orbicularis oculi. However, taste fibers and parasympathetic fibers to the lacrimal gland branch off before this point, so taste and lacrimal secretion remain intact. Similarly, the stapedius muscle is innervated by branches proximal to the lesion. Therefore, paralysis of the orbicularis oculi muscle is the primary deficit.