optic tract

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Related to Optic tracts: Optic nerves

tract

 [trakt]
a longitudinal assemblage of tissues or organs, especially a number of anatomic structures arranged in series and serving a common function, such as the gastrointestinal or urinary tract; also used in reference to a bundle (or fasciculus) of nerve fibers having a common origin, function, and termination within the central nervous system.
alimentary tract alimentary canal.
biliary tract the organs, ducts, and other structures that participate in secretion (the liver), storage (the gallbladder), and delivery (hepatic and bile ducts) of bile into the duodenum. See illustration.
Anatomy of the gallbladder and biliary tract. From Aspinall and Taylor-Robinson, 2002.
corticospinal t's two groups of nerve fibers (the anterior and lateral corticospinal tracts) that originate in the cerebral cortex and run through the spinal cord.
digestive tract alimentary canal.
dorsolateral tract a group of nerve fibers in the lateral funiculus of the spinal cord dorsal to the posterior column.
extrapyramidal tract extrapyramidal system.
gastrointestinal tract the stomach and intestine in continuity; see also digestive system.
iliotibial tract a thickened longitudinal band of fascia lata extending from the tensor muscle downward to the lateral condyle of the tibia.
intestinal tract see intestinal tract.
optic tract the nerve tract proceeding backward from the optic chiasm, around the cerebral peduncle, and dividing into a lateral and medial root, which end in the superior colliculus and lateral geniculate body, respectively.
pyramidal t's collections of motor nerve fibers arising in the brain and passing down through the spinal cord to motor cells in the anterior horns.
respiratory tract respiratory system.
urinary tract the organs and passageways concerned in the production and excretion of urine from the kidneys to the urinary meatus; see also urinary system.
uveal tract the vascular tunic of the eye, comprising the choroid, ciliary body, and iris.

op·tic tract

[TA]
the continuation of the optic nerve fibers beyond (behind) the latter's hemidecussation in the optic chiasm; each of the two symmetric optic tracts is composed of fibers originating from the temporal half of the retina of the ipsilateral eye and a nearly equal number of fibers from the nasal half of the contralateral retina; it forms a compact, somewhat flattened fiber band passing caudolaterally alongside the base of the hypothalamus and over the basal surface of the crus cerebri; most of its fibers terminate in the lateral geniculate body; a smaller number of fibers enter the brachium of the superior colliculus, to terminate in the superior colliculus and the pretectal region.
Synonym(s): tractus opticus

op·tic tract

(op'tik trakt) [TA]
The continuation of the optic nerve fibers beyond their hemidecussation in the optic chiasm; each of the two symmetric optic tracts is composed of fibers originating from the temporal half of the retina of the ipsilateral eye and a nearly equal number of fibers from the nasal half of the contralateral retina; it forms a compact, somewhat flattened fiber band passing caudolaterally along the base of the hypothalamus and over the basal surface of the crus cerebri; most of its fibers terminate in the lateral geniculate body; a smaller number of fibers enter the brachium of the superior colliculus, to terminate in the superior colliculus and the pretectal region.
Synonym(s): tractus opticus [TA] .

optic tract

The part of the nerve pathway for visual impulses lying between the OPTIC CHIASMA and the first set of connections (SYNAPSES) in the brain—the lateral geniculate body. If an optic tract is destroyed half of the field of vision of each eye is lost. The field loss in each eye is on the side opposite to the damaged tract.
References in periodicals archive ?
(4) Habu et al found a pituitary stalk mass in 63.7% of patients, a hypothalamic mass lesion in 17.4%, loss of hyperintensity at the neurohypophysis in 82.3%, intratumoral hemorrhage in 8.5%, constriction of the tumor at the diaphragmatic hiatus resulting in a dumbbell shape in 44.7%, hyperintensity around the optic tract in 11.5%, and contrast enhancement of the dura mater around the pituitary fossa in 17.1%.
MR Imaging Study of Edema-Like Change along the Optic Tract in Patients with Pituitary Region Tumors.
Lateral view of the brain: A= cerebrum, B= optic lobe, C= cerebellum, D= medulla oblongata, E= spinal cord, 1=wulst, 2= vallecula, 3= olfactory nerve, 4= olfactory lobe, 5= orbital print, 6= lateral part of transverse fissure, 7= optic tract, 8= optic chiasm, 9= optic nerve, 10= infundibulum, 11= hypothysis,12= midbrain, 13= pons, 14= trigeminal nerve, 15= cerebellar fissures, 16= cerebellar lobe.
Items Length (mm) Width (mm) (Mean [+ or -] SE) (Mean [+ or -] SE) Total brain 58.48 [+ or -] 0.44 (a) 42.63 [+ or -] 0.63 (b) Wulst 28.75 [+ or -] 0.32 (a) 10.88 [+ or -] 0.43 (b) Cerebral hemisphere 31.88 [+ or -] 0.43 (a) 20.50 [+ or -] 0.46 (b) Olfactory lobe 15.15 [+ or -] 0.67 (a) 8.75 [+ or -] 0.32 (b) Optic lobe 16.38 [+ or -] 0.43 (a) 8.48 [+ or -] 0.48 (b) Pineal body 6.93 [+ or -] 0.22 (a) 6.40 [+ or -] 0.22 (a) Cerebellum 26.75 [+ or -] 0.32 (a) 18.70 [+ or -] 0.34 (b) Medulla oblongata 18.85 [+ or -] 0.43 (a) 12.78 [+ or -] 0.34 (b) Hypophysis 8.23 [+ or -] 0.34 (a) 9.13 [+ or -] 0.43 (a) Optic tract 7.98 [+ or -] 0.21 (a) 3.35 [+ or -] 0.25 (b) Infundibulum 4.25 [+ or -] 0.32 (a) 3.48 [+ or -] 0.21 (a)
Rupture of intra cranial aneurysm--since the circle of Willis is closely related to optic chiasma, optic tracts, these rupture giving rise to characteristic visual field defects
Homonymous hemianopia-posterior portion of tumor involving the beginning of optic tracts. Visual field improvement following resection of the pituitary tumor occurs in three stages.
Lesions in anterior part of optic tract produce incongruous visual field defects.
Generally, central visual field programmes are considered adequate to reveal the majority of visual field defects that one is likely to encounter arising from intracranial lesions, including those at the optic chiasm or optic tract. There are however some exceptions that involve only the peripheral retinal fibres, the temporal crescent represented region of the occipital lobe or associated with a state-kinetic dissociation.
Retrochiasmal Lesions (affecting the optic tract, lateral geniculate body, optic radiation) cause a partial or complete homonymous hemianopia.