A patient presents with inability to close the left eye, drooping of the left angle of the mouth, and loss of the left nasolabial fold. There is no forehead sparing. The lesion is most likely at:

• A Right internal capsule (upper motor neuron)
• B Left facial nerve after exiting the stylomastoid foramen
• C Left facial nerve nucleus in the pons (lower motor neuron) ✓
• D Right motor cortex (upper motor neuron)

Explanation

Complete ipsilateral facial paralysis including the forehead (no forehead sparing) indicates a lower motor neuron (LMN) lesion of the facial nerve, either at its nucleus in the pons or along its peripheral course. The upper part of the face (frontalis, orbicularis oculi) receives bilateral cortical input, so an upper motor neuron lesion spares the forehead. The absence of forehead sparing here localizes the lesion to the left LMN pathway, most likely at the facial nerve nucleus in the pons (e.g., in Bell's palsy or Millard-Gubler syndrome).

Reference: BD Chaurasia's Human Anatomy, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.