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.