What is optical radiation?

The optic radiations, or the geniculocalcarine tract, are a projection tract that connects the lateral geniculate nucleus to the primary visual cortex in the occipital lobe. It functions to transmit visual input coming from the retina, the optic nerve, and the optic tract.

Where is dorsal optic radiation?

The optic radiation (or geniculocalcarine tract) is part of the visual pathway, forming the connection between the lateral geniculate nucleus of the pulvinar of the thalamus with the primary visual cortex of the occipital lobe. This pathway carries third order neurons correlating to the contralateral visual field.

What are the two optic radiations?

Anatomical terms of neuroanatomy The optic radiation (also known as the geniculocalcarine tract, the geniculostriate pathway, and posterior thalamic radiation) are axons from the neurons in the lateral geniculate nucleus to the primary visual cortex.

What Fibres are conveyed via Meyer’s loop?

These fibers, known as optic radiations, Gratiolet radiations, or the inferior longitudinal fasciculus, constitute the geniculocalcarine tract (Fig. 1). The anterior extension of these fibers in relation to the temporal horn is known as Meyer’s loop.

Why is there macular sparing?

Macular sparing may be caused by collateral vascular supply to the macular region or by the very large macular representation in the occipital cortex; additionally, bilateral representation of macular vision has been suspected.

What happens when left optic radiation is damaged?

Damage to the retina or one of the optic nerves before it reaches the chiasm results in a loss of vision that is limited to the eye of origin. In contrast, damage in the region of the optic chiasm—or more centrally—results in specific types of deficits that involve the visual fields of both eyes (Figure 12.8).

What causes Quadrantanopia?

A superior quadrantanopia results from an insult to the optic radiation inferiorly in the temporal lobe, resulting in a ‘pie in the sky’ type of visual field defect (Figure 1d), while an inferior quadrantanopia is caused by damage to the parietal lobe optic radiation (Figure 1e).

What is the visual pathway of the eye?

The Visual Pathway. The visual pathway consists of the retina, optic nerves, optic chiasm, optic tracts, lateral geniculate bodies, optic radiations, and visual cortex. The pathway is, effectively, part of the central nervous system because the retinae have their embryological origins in extensions of the diencephalon.

Where is Meyer’s loop located?

temporal lobe
The Meyer loop is part of the inferior optic radiation that sweeps back on itself into the temporal lobe, just lateral to the temporal horn of the lateral ventricle. It can be injured in temporal lobectomy, resulting in a superolateral field cut, the so called pie-in-the-sky field cut.

What is meant by macular sparing?

Macular sparing is visual field loss that preserves vision in the center of the visual field, otherwise known as the macula. It appears in people with damage to one hemisphere of their visual cortex, and occurs simultaneously with bilateral homonymous hemianopia or homonymous quadrantanopia.

What is right homonymous Hemianopsia?

Homonymous hemianopsia is a condition in which a person sees only one side ― right or left ― of the visual world of each eye. The condition results from a problem in brain function rather than a disorder of the eyes themselves.

What would happen if you cut the optic chiasm?

Damage to the retina or one of the optic nerves before it reaches the chiasm results in a loss of vision that is limited to the eye of origin. In contrast, damage to the optic chiasm results in visual field deficits that involve noncorresponding parts of the visual field of each eye.

What is the function of the optic radiation?

Function. The optic radiation contains tracts which transmit visual information from the retina of the eye to the visual cortex. Lesions of the optic radiations are usually unilateral and commonly vascular in origin. Field defects therefore develop abruptly, in contrast to the slow progression of defects associated with tumors.

What happens to the right side of the optic tract?

A lesion on the right side of the optic tract may lead to left homonymous hemianopia. Partial injury to the optic tract may affect only one quadrant of the visual field.

Where do the fibres of the optic tract terminate?

The remaining fibres of the optic tract terminate in the pretectal nuclei and superior colliculus. Optic tract and optic chiasm in relation to anterior and middle cerebral arteries.

Where does the tapetum and optic radiation meet?

This posterior bundle is relatively superior to both anterior and central bundles and terminates in the superior lip of the calcarine sulcus. In their relation to the posterior horn of the lateral ventricle, the tapetum and optic radiation together make up the sagittal striatum, which runs in a craniocaudal direction.