- Optic radiation
Brain: Optic radiation Colour coded diagram showing radiations in quadrants from retinal disc through the brain Latin radiatio optica NeuroNames ancil-529
The optic radiation (also known as the geniculo-calcarine tract or as the geniculostriate pathway) is a collection of axons from relay neurons in the lateral geniculate nucleus of the thalamus carrying visual information to the visual cortex (also called striate cortex) along the calcarine fissure.
There is one such tract on each side of the brain.
A distinctive feature of the optic radiations is that they split into two parts on each side:
Source Path Information Damage Fibers from the inferior retina (also called "Meyer's loop" or "Archambault's loop") must pass through the temporal lobe by looping around the inferior horn of the lateral ventricle. Carry information from the superior part of the visual field A lesion in the temporal lobe that results in damage to Meyer's loop causes a characteristic loss of vision in a superior quadrant (quadrantanopia.) Fibers from the superior retina (also called "Baum's loop") travel straight back through the parietal lobe to the occipital lobe in the retrolenticular limb of the internal capsule to the visual cortex. Carry information from the inferior part of the visual field Taking the shorter path, these fibers are less susceptible to damage.
- Optic+radiation at eMedicine Dictionary
- Kier LE, Staib LH, Davis, LM, Bronen, RA (1 May 2004). "MR Imaging of the Temporal Stem: Anatomic Dissection Tractography of the Uncinate Fasciculus, Inferior Occipitofrontal Fasciculus, and Meyer’s Loop of the Optic Radiation". Am J Neuroradiology 25 (5): 677–691. PMID 15140705. http://www.ajnr.org/cgi/content/abstract/25/5/677. Retrieved 2007-12-19.
Sensory system: Visual system and eye movement pathways Visual perception Muscles of orbitTrackingHorizontal gazeVertical gaze Pupillary reflexPupillary dilation Circadian rhythm
Human brain: diencephalon (TA A14.1.08, GA 9.807) EpithalamusSurface ThalamusSurface
Mammillothalamic fasciculus · Pallidothalamic tracts (Ansa lenticularis, Lenticular fasciculus, Thalamic fasciculus) · PCML (Medial lemniscus, Trigeminal lemniscus) · Spinothalamic tract · Lateral lemniscus · Dentatothalamic tract · Acoustic radiation · Optic radiation · Subthalamic fasciculus · Anterior trigeminothalamic tractMedullary laminae
HypothalamusSurfaceAutonomic zonesAnterior (parasympathetic/heat loss) · Posterior (sympathetic/heat conservation) Subthalamus Ventricular system:
Human brain, cerebrum, Interior of the cerebral hemispheres—Rostral Basal ganglia and associated structures (TA A14.1.09.321–552, GA 9.832–837) Basal gangliaVentral striatumOther Rhinencephalon Other basal forebrainDiagonal band of Broca · Stria terminalis Archicortex:
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