What are the five basic components of pupillary light reflex pathway?
What are the five basic components of pupillary light reflex pathway?
It consists of a pupillary accommodation reflex, lens accommodation reflex, and convergence reflex. Afferent pathway for pupillary constriction, lens accommodation, and convergence: Afferent input from the retina is sent to the lateral geniculate nucleus via the optic tract.
What are the components of pupillary light reflex?
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 is the pupillary reflex arc?
The pupillary light reflex (PLR) or photopupillary reflex is a reflex that controls the diameter of the pupil, in response to the intensity (luminance) of light that falls on the retinal ganglion cells of the retina in the back of the eye, thereby assisting in adaptation of vision to various levels of lightness/ …
What is the main stimulus for the pupillary reflex?
…the best-known reflex is the pupillary light reflex. If a light is flashed near one eye, the pupils of both eyes contract. 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.…
How do you do pupillary light reflex?
Gently point the focal light into one eye, this is known as the direct pupillary light reflex. Then, withdraw the light for few seconds, followed by stimulating the same eye again but this time observe the indirect, or consensual, PLR in the opposite eye.
What is the receptor in pupillary reflex?
:Pupillary Reflexes test both, the retina of the eye is the receptor, the optic nerve holds the afferent fibers, the oculomotor nerve contains the efferent fibers, and the smooth muscle of the iris is the effector organ.
Which of the following components is the integration center of the patellar reflex arc?
Which of the following components is the integration center of the patellar reflex arc? synapses in the L2-L4 segments. Reflex testing is an important diagnostic tool for assessing the condition of the NS.
What is the interneuron in the pupillary light reflex arc?
The RGC axons form the first interneuron arm of the PLR arc and carry the neuronal signal from the photoreceptors [2]. The parasympathetic nervous system is the main system responsible for pupil constriction in response to light. The pupillary RGC axons exit the optic tract and synapse at the pretectal olivary nucleus.
What is reverse Argyll Robertson pupil?
Inverse Argyll Robertson Pupil (IARP), absence of pupillary constriction to near stimuli with retention of pupillary light reflex, has rarely been described. Chrousos and colleagues (1985) reported a child with absence of complete near reflex triad.
How does the pupillary reflex work?
The pupillary light reflex pathway. The pupils normally dilate (increase in size) when it is dark (i.e., when light is removed). This response involves the relaxation of the iris sphincter and contraction of the iris dilator. The iris dilator is controlled by the sympathetic nervous system.
What is the function of the pupillary light reflex?
Eyes allow for visualization of the world by receiving and processing light stimuli. The pupillary light reflex constricts the pupil in response to light, and pupillary constriction is achieved through the innervation of the iris sphincter muscle. Eyes allow for visualization of the world by receiving and processing light stimuli.
How are pupil reflexes tested with a pen torch?
The pupillary reflexes are tested clinically using a pen torch ( Fig. 3.28 ). Illumination of one eye causes reflexive constriction of both pupils: via the direct and indirect pupillary light reflexes. This is mediated by projections from the retina to the pretectal nucleus of the midbrain, just rostral to the superior colliculus.
What causes an uneven pupillary light reflex RAPD?
RAPDs can occur due to ischemic retinal diseases such as BRVO, CRVO, BRAO, and CRAO secondary to the death of photoreceptors and viable retina, ultimately leading to an uneven pupillary response. Via the same mechanism of significant retinal cell death, retinal detachments can cause RAPDs.
How are neurons involved in the reflex arc?
If the neurons had to travel all the way to the brain, it would cause a longer delay and could result in injury to tissues by the time the reflex is carried out. Efferent, or motor, neuron: This is the nerve that travels from the central nervous system back out to the body to carry out the response.
