Q: Answer it A: Reflex closure of eyelid corneal blink reflex a Any 5 facial muscles 1. Orbicularis oculi 2. Orbicularis oris 3. Buccinator 4. Frontalis frontal belly of occipitofrontalis 5. Platysma b Pathway of corneal reflex - Stimulus: Touch of cornea - Afferent limb: Nasociliary nerve branch of ophthalmic division, V1 of trigeminal nerve - First-order neuron: Trigeminal semilunar/Gasserian ganglion - Central connections: Spinal trigeminal nucleus interneurons project bilaterally to facial motor nuclei in pons - Efferent limb: Facial nerve CN VII to orbicularis oculi muscle - Response: Bilateral eyelid closure direct and consensual blink c Different types of taste buds taste receptor cell types 1. Type I cells supporting/glia-like; salt handling 2. Type II cells receptor cells for sweet, bitter, umami 3. Type III cells presynaptic cells; mainly sour 4. Type IV cells basal/progenitor cells Traditional taste modalities: sweet, salty, sour, bitter, umami. d Define Bell’s palsy Bell’s palsy is an acute, idiopathic, unilateral lower motor neuron LMN paralysis of the facial nerve CN VII, causing weakness of all muscles of facial expression on the affected side, typically including inability to close the eye and forehead involvement. --- Difference between UMN and LMN facial palsy Feature UMN facial palsy LMN facial palsy --------- Site of lesion Corticobulbar pathway above facial nucleus Facial nucleus/nerve after nucleus Forehead involvement Forehead spared upper face usually preserved Forehead affected Side of lower face weakness Contralateral lower face Ipsilateral whole face upper + lower Eye closure Usually preserved Weak/absent on affected side Bell’s phenomenon Usually not prominent Often seen Common causes Stroke, cortical lesions Bell’s palsy, otitis media, parotid lesions, temporal bone trauma If you want, I can also format this as a 20-mark structured answer exactly how examiners prefer introduction, diagram-ready pathway, and clinical correlation points.
