pretectum


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pre·tec·tal ar·e·a

[TA]
a narrow, transversely oriented rostral zone of the mesencephalic tectum, bounded caudally by the superior colliculus, rostrally by the habenular trigone, and laterally by the pulvinar thalami; the pretectal area contains several nuclei that receive fibers from the optic tract; it has bilateral efferent connections with the Edinger-Westphal nucleus of the oculomotor nuclear complex by way of which it mediates the pupillary light reflex.

pretectum 

Either of the midbrain structures located anterior to the superior colliculus. Each pretectum contains several nuclei including the pretectal olivary nucleus, the nucleus of the optic tract and the anterior, medial and posterior pretectal nuclei. A small number of retinal fibres leave the optic tract before the lateral geniculate bodies and synapse mainly in the pretectal olivary nucleus and in the nucleus of the optic tract. Axons from the pretectal olivary nucleus project to the Edinger-Westphal nuclei. Neurons in the pretectal olivary nuclei are involved in pupillary constriction. See pupil light reflex; tectum of the mesencephalon.
References in periodicals archive ?
Nerve axons in the retina make synapses at the mesencephalon, lateral geniculate nucleus, pretectum, and hypothalamus.
These perforating arteries are of utmost importance and irrigate the posterior part of the thalamus, medial ventral thalami, the walls of the third ventricle, hypothalamus, and subthalamic-mesencephalic junctions (subthalamus, substantia nigra, red nucleus, oculomotor nucleus, trochlear nucleus, reticular formation of the midbrain, pretectum, rhomboid fossa, and the posterior part of the internal capsule) [7-17].
Lund, "Extent and duration of recovered pupillary light reflex following retinal ganglion cell axon regeneration through peripheral nerve grafts directed to the pretectum in adult rats," Experimental Neurology, vol.
The comparison revealed that the thalamus, pretectum, and midbrain regions now found in vertebrates correspond to a single region in the lancelet brain, suggesting a common evolutionary and developmental origin.
Supranuclear control of vertical eye movements is subserved by diffuse cortical projections from the frontal and supplementary eye fields reaching the rostral interstitial nuclei of the medial longitudinal fasciculus (riMLF) and the interstitial nuclei of Cajal (inC) at the level of the midbrain pretectum (7).
In addition, the rostral superior colliculus projects to the Edinger-Westphal nucleus via the primary, shorter route through the pretectum and also through a secondary, longer route through the nucleus reticularis tegmenti pontis (pons), cerebellar cortex, and cerebellar nuclei.
* Upward gaze palsy results from compression on the pretectum and superior colliculi
A direct OKN pathway from the retina to the pretectum (nucleus of the optic tract) as seen in other animals is either weak or non-existent in humans.
Neurons were also found in the pretectum, midbrain, and cerebellar nuclei that are, in all probability, correlated primarily with vertical eye movements and gaze (not illustrated).