The pupillary light reflex pathway involves the optic nerve and the oculomotor nerve and nuclei.
Which two cranial nerves are involved in the pupillary reaction?
The pupillary light reflex requires CN II, CN III, and central brain stem connections. Light shined in one eye stimulates retinal photoreceptors, and subsequently retinal ganglion cells, whose axons travel through the optic nerve, chiasm, and tract to terminate in the pretectum (pretectal nucleus).
What nerve is responsible for pupillary light reflex?
The optic nerve sends impulses to the brain for further processing and image recognition.  These are the first steps of the pupillary light reflex afferent pathway. The optic nerve then forms the optic chiasm, which diverges into a left and right optic tract.
What nerves are involved in pupil dilation?
These axons then enter the orbit upon the short and long ciliary nerves (branches of V1, the ophthalmic division of CN V – the trigeminal nerve) to synapse on the dilator pupillae muscle, causing pupillary dilation.
What nerves are involved in pupillary constriction and accommodation?
Since parasympathetic fibers of the oculomotor nerve mediate ciliary contraction and pupillary constriction, parasympatholytics like atropine results in loss of accommodation and parasympathomimetics like pilocarpine induce accommodation. Vision is not a prerequisite for accommodation reflex.
What cranial nerve is pupillary response?
The oculomotor nerve is responsible for the efferent limb of the pupillary reflex; it drives the iris muscles that constrict the pupil.
What is cranial nerve II?
The optic nerve is the second cranial nerve (CN II) responsible for transmitting visual information. The optic nerve contains only afferent (sensory) fibers, and like all cranial nerves is paired.
What branch of the nervous system controls pupillary response?
The parasympathetic nervous system is the main system responsible for pupil constriction in response to light.
What is the third nerve?
The oculomotor nerve is the third cranial nerve (CN III). It allows movement of the eye muscles, constriction of the pupil, focusing the eyes and the position of the upper eyelid. Cranial nerve III works with other cranial nerves to control eye movements and support sensory functioning.
Which nerve is detecting light on the retina?
Finally, the light reaches the retina. This is the light-sensitive nerve layer that lines the back of the eye. Here the image is inverted. The optic nerve is then responsible for carrying the signals to the visual cortex of the brain.
Which nerves are mostly involved in pupil dilation and other fight or flight responses?
The sympathetic nervous system (SNS) is part of the autonomic nervous system (ANS), which also includes the parasympathetic nervous system (PNS). The sympathetic nervous system activates what is often termed the fight or flight response.
Where are the cranial nerves?
Cranial nerves are the nerves that emerge directly from the brain (including the brainstem), in contrast to spinal nerves (which emerge from segments of the spinal cord). Cranial nerves relay information between the brain and parts of the body, primarily to and from regions of the head and neck.
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.
Which cranial nerve is responsible for accommodation?
It is dependent on cranial nerve II (afferent limb of reflex), superior centers (interneuron) and cranial nerve III (efferent limb of reflex). The change in the shape of the lens is controlled by ciliary muscles inside the eye.