What is the effector in the pupillary light reflex?
What is the receptor and effector in the pupillary reflex? The retina is the receptor and the effector is the smooth muscle of the iris. They both work together to restrict or enlarge the pupil according to how bright the light it.
What nerves are involved in pupillary light reflex?
The pupillary light reflex pathway involves the optic nerve and the oculomotor nerve and nuclei. Parasympathetic Innervation of the Eye.
What is the stimulus in the pupillary reflex?
Light is the stimulus; impulses reach the brain via the optic nerve; and the response is conveyed to the pupillary musculature by autonomic nerves that supply the eye.…
What is the afferent nerve in pupillary reflex?
The optic nerve, or more precisely, the photosensitive ganglion cells through the retinohypothalamic tract, is responsible for the afferent limb of the pupillary reflex; it senses the incoming light.
Which cranial nerve controls pupillary response?
The pupillary control provided by CN III is located along the periphery of the nerve. By contrast, the CN III control of eye movement and eyelid opening runs deep in the centre of the nerve.
What causes pupillary dilation?
Pupils are supposed to dilate under normal circumstances due to light changes and emotional variables. Most of the time, dilated pupils will go back to normal size on their own. If pupils dilate suddenly, occur after a traumatic injury or cause headaches and confusion, seek medical attention immediately.
Why does sympathetic cause pupil dilation?
The iris dilator muscle is controlled by the sympathetic nervous system, the part of the autonomic nervous system that is involved in arousal, wakefulness, and the fight-or-flight response; the link between pupil dilation and the sympathetic nervous system explains why pupils are relatively large when someone is …
What branch of the nervous system controls pupillary response?
parasympathetic nervous system
The parasympathetic nervous system is the main system responsible for pupil constriction in response to light.
Is the pupillary reflex sympathetic or parasympathetic?
The pupillary dilation pathway is a sympathetically driven response to stimuli and is a three-neuron pathway. [1] The first-order neuron begins in the hypothalamus and descends through the midbrain to synapse onto the spinal cords ciliospinal center of Budge, found between C8 to T2.
What cranial nerve dilates pupil?
oculomotor cranial nerve
Pupillary response is a physiological response that varies the size of the pupil, via the optic and oculomotor cranial nerve….Pupillary response.
Constriction (Parasympathetic) | Dilation (Sympathetic) | |
---|---|---|
Cause in pupillary light reflex | Increased light | Decreased light |
What is the function of cranial nerve 6?
Cranial nerve six (CN VI), also known as the abducens nerve, is one of the nerves responsible for the extraocular motor functions of the eye, along with the oculomotor nerve (CN III) and the trochlear nerve (CN IV).
What nerve controls pupillary constriction or dilation?
Oculomotor nerve (III)
Oculomotor nerve (III) is responsible for the control of the pupil (constriction) via parasympathetic fibres (this is opposed by dilator tone controlled by sympathetic pathways).
What is mydriatic agent?
Definition. Agent that dilates the pupil. Used in eye diseases and to facilitate eye examination. It may be either a sympathomimetic or parasympatholytic.
What nerve controls pupillary dilation?
Oculomotor nerve (III) is responsible for the control of the pupil (constriction) via parasympathetic fibres (this is opposed by dilator tone controlled by sympathetic pathways).
What function is associated with the nerve III?
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.
What is the 4th cranial nerve?
The fourth cranial nerve controls the actions of one of the external eye muscles, the superior oblique muscle. This muscle runs from the back of the eye socket to the top of the eye. It passes through a loop of tissue near the nose known as the trochlea. It turns the eye inward and downward.