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The pupillary reflex results in the pupil constricting (left) and dilating (right) These include the pupillary light reflex and accommodation reflex . Although the pupillary response , in which the pupil dilates or constricts due to light is not usually called a "reflex", it is still usually considered a part of this topic.
The pupillary light reflex (PLR) or photopupillary reflex is a reflex that controls the diameter of the pupil, in response to the intensity 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/darkness.
Pupillary reflexes, particularly the pupillary light reflex, are a powerful diagnostic tool often employed in clinical and emergency medical practice. A lack of equal consensual pupillary constriction to a light stimulus, especially a Marcus Gunn pupil, can be indicative of optic nerve damage, brainstem death, or optic tract damage in between.
Pharyngeal reflex — also known as the gag reflex. Photic sneeze reflex — a sneeze caused by sudden exposure to bright light. Plantar reflex — in infants up to 1 year of age, a curling of the toes when something rubs the ball of the foot. Pupillary accommodation reflex — a reduction of pupil size in response to an object coming close to ...
In neuroanatomy, the pretectal area, or pretectum, is a midbrain structure composed of seven nuclei and comprises part of the subcortical visual system.Through reciprocal bilateral projections from the retina, it is involved primarily in mediating behavioral responses to acute changes in ambient light such as the pupillary light reflex, the optokinetic reflex, and temporary changes to the ...
The visual system also has several non-image forming visual functions, independent of visual perception, including the pupillary light reflex and circadian photoentrainment. This article describes the human visual system, which is representative of mammalian vision , and to a lesser extent the vertebrate visual system.
In people with diabetes and older than 50 years of age, an oculomotor nerve palsy, in the classical sense, occurs with sparing (or preservation) of the pupillary reflex. This is thought to arise due to the anatomical arrangement of the nerve fibers in the oculomotor nerve; fibers controlling the pupillary function are superficial and spared ...
The pupil constricts when the iris sphincter muscle is stimulated and contracts. In humans, it functions to constrict the pupil in bright light (pupillary light reflex) or during accommodation. [citation needed] In lower animals, the muscle cells themselves are photosensitive causing iris action without brain input. [5]