The Menace Response

One hand should cover up an eye and a threatening gesture should be made to the contralateral eye with the other hand. A lateral and medial visual field should be assessed in each eye. The normal response is a blink and or retraction of the eye

The visual stimulus is relayed contralaterally in CN II to the occipital cortex via the thalamus. The response to this stimulation is initiated via the motor cortex which ultimately stimulates the ipsilateral facial nerve (CN VII) to cause eyelid closure. The pathway can be seen to pass through the cerebellum which coordinates the response

Following a visual threat, the optic nerve (CN II) relays the stimulation and the blink response is completed by the ipsilateral facial nerve.

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Three cross sections are demonstrated illustrating the initial stimulus crossing over to the contralateral cortex; the pathway then crosses back over in the pons leading to stimulation of the ipsilateral CN VII.

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