What 2 cranial nerves are responsible for the menace response?
Technique. The optic nerve is tested in conjunction with the oculomotor nerve (CN III), which provides the motor pathway for the pupillary light reflex, and the facial nerve, which provides the motor pathway for the menace reflex.
What cranial nerves are involved in Palpebral reflex?
The sensory fibers for the palpebral and corneal reflexes are in CN V. The three branches of this CN (ophthalmic, maxillary and mandibular) should all be tested. Touching the medial canthus of the eye evaluates the ophthalmic branch. Touching the lateral canthus of the eye evaluates the maxillary branch.
Which nerves are involved in the corneal reflex?
The corneal blink reflex is caused by a loop between the trigeminal sensory nerves and the facial motor (VII) nerve innervation of the orbicularis oculi muscles. The reflex activates when a sensory stimulus contacts either free nerve endings or mechanoreceptors within the epithelium of the cornea.
Do humans have a menace response?
The menace reflex (blink reflex to visual threat) tests visual processing at the bedside in patients who cannot participate in normal visual field testing.
What does the menace reflex test?
A menace response tests the continuity of a neurologic pathway initiating at the medial retina (optic nerve); continuing through the contralateral geniculate nucleus, motor cortex, and pontine nucleus; to the cerebellum; and terminating at both facial nerves.
What does an absent menace response mean?
The menace response is one of three forms of blink reflex. The presence or absence of the menace reflex, in combination with other reflexes, indicates a locus of damage. For example, an animal with polioencephalomalacia will lack the menace reflex, but will still have the pupillary light reflex.
What does the menace response test?
What does absent menace mean?
The presence or absence of the menace reflex, in combination with other reflexes, indicates a locus of damage. For example, an animal with polioencephalomalacia will lack the menace reflex, but will still have the pupillary light reflex.
What controls corneal reflex?
The reflex is mediated by: the nasociliary branch of the ophthalmic branch (V1) of the trigeminal nerve (CN V) sensing the stimulus on the cornea only (afferent fiber). the temporal and zygomatic branches of the facial nerve (CN VII) initiating the motor response (efferent fiber).
What does a positive menace reflex mean?
A blink is considered a positive menace response. If a reponse is not elicited the intactness of palpebral responses are tested by palpation of the face. It is important to note that the menace response is a learned response that is not consistently present in dogs and cats under 3 to 4 months in age.
Why is menace response not a reflex?
The entire peripheral and central visual pathway must be intact for a response to occur. This is a learned response, not a reflex, to a perceived threat. Normal function is demonstrated by a blink or retraction of the globe in response to the threat or even an aversive head movement.
Where does the menace reflex take place in the body?
The neural pathway of the menace reflex comprises the optic (II) and facial (VII) nerves. It is mediated by tectobulbar fibres in the rostral colliculi of the midbrain passing from the optic tract to accessory nuclei, and thence to the spinal cord and lower motor neurones that innervate the head, neck,…
How is the menace reflex used in veterinary medicine?
Stimulating the menace reflex is used as a diagnostic procedure in veterinary medicine, in order to determine whether an animal’s visual system, in particular the cortical nerve, has suffered from nerve damage. Cortical damage, particularly cerebral lesions, can cause loss of the menace reflex while leaving the other blink reflexes,…
How is the menace reflex elicited in Crias?
Assessment of vision is similar to that of other domestic species. The menace reflex is elicited by advancing a closed fist quickly toward the eye and observing a blink, globe retraction, head retraction, or all of these. The menace response is learned and is therefore not present in newborn crias.
Can a waving object demonstrate a menace reflex?
Waving an object close to an animal’s eyes or face does not necessarily demonstrate a functioning menace reflex, in part because the animal can sense such objects and react to them via senses other than sight.