Area pretectalis

The pretectal area or Area pretectal even pretectum called, is part of the Epithalamus in the midbrain . This region borders directly on the superior colliculi in the roof of the midbrain ( tectum mesencephali ) - to which it is sometimes assigned - and contains several differently delimited nuclei pr (a) etectales .

The area pretectalis is, among other things, an important subcortical center of the visual system and is involved in the interconnection of optokinetic reflexes, such as a physiological nystagmus , as well as in those of the accommodation response and the pupillary light reflex . Its core areas receive direct afferents from the retina , partly from photosensitive ganglion cells , via the optic nerves , the tractus opticus and the brachia colliculorum superiorum . In primates, non-visual afferents of the retina on one side also reach pretectal nuclei on both sides.

Within the nuclei praetectales, which are still vaguely differentiated or named differently, a distinction is usually made between five:

Nucleus tractus optici ( TA ), often abbreviated NOT
Nucleus pretectalis olivaris (TA), often abbreviated to PON
Nucleus pretectalis anterior (TA)
Nucleus pretectalis posterior (TA)
Nucleus pretectalis medialis

In addition, two further sub-nuclei are differentiated depending on the species,

the "comissural pretectal area" close to the commission
as well as the posterior delimiting area "posterior limitans".

Afferents are contained in the core complex , which is collectively known as the pretectal nucleus (TA), among others

from the retina of the eye via the optic tract and brachium colliculi superioris , mostly projecting onto NOT and OPN

from the corpus geniculatum laterale of the metathalamus of the diencephalon
from the thalamus of the diencephalon from (specific) posterior nuclei
from the colliculi superiores of the tectum of the midbrain
from the reticular formation in the area of the pons of the hindbrain
and from the visual cortex and the frontal eye field of the cerebrum

Core areas from the area pretectalis (TA) are related to each other via efferents

to the corpora geniculata lateralia in the diencephalon, thus reciprocal
to the pulvinar of the thalamus, specific nuclei
to the colliculi superiores , so alternating with the upper hills immediately behind the praetectum
to the nuclei accessorii nervi oculomotorii (Edinger-Westphal), the autonomous core areas of the cranial nerve III nervus oculomotorius in the midbrain on both sides, of which via ganglion ciliare u. a. the pupil-constricting inner eye muscles are parasympathetically influenced
to the interstitial nuclei (Cajal) in the midbrain, from which the medial longitudinal fasciculus of the brain stem originates
to the nuclei olivares inferiores in the medullary brain

In particular, the efferents of the pretectal nucleus on one side extend to the equilateral and, via the posterior commissure , to the contralateral Edinger-Westphal nucleus . Because the Edinger Westphal nuclei on both sides can be reached from each side, a consensual pupillary light reflex occurs , i.e. both pupils are narrowed even when light falls into only one of the eyes.

literature

Martin Trepel: Neuroanatomy with student consultancy access: structure and function . Elsevier, Urban & Fischer, 4th edition 2008, ISBN 9783437412981 , p. 212.