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The corpora quadrigemina are reflex centers involving vision and hearing. It consists of groups of nerve cells-grey matter scattered in white matter. It basically connects the forebrain and the hind brain. It has four corpora quadrigemina which are the reflex centres of eye movement and auditory responses.
Corpora quadrigemina. Inferior colliculi; Superior colliculi; Pretectum; Tegmentum. Periaqueductal gray; Rostral interstitial nucleus of medial longitudinal fasciculus; Midbrain reticular formation; Dorsal raphe nucleus; Red nucleus; Ventral tegmental area. Parabrachial pigmented nucleus; Paranigral nucleus; Rostromedial tegmental nucleus ...
The corpora quadrigemina are four mounds, called colliculi, in two pairs – a superior and an inferior pair, on the surface of the tectum. The superior colliculi process some visual information, aid the decussation of several fibres of the optic nerve (some fibres remain ipsilateral), and are involved with saccadic eye movements .
The inferior colliculi together with the superior colliculi form the eminences of the corpora quadrigemina, and also part of the midbrain tectum. The inferior colliculus lies caudal to its counterpart - the superior colliculus - above the trochlear nerve, and at the base of the projection of the medial geniculate nucleus and the lateral ...
In mammals, the superior colliculus forms a major component of the midbrain. It is a paired structure and together with the paired inferior colliculi forms the corpora quadrigemina. The superior colliculus is a layered structure, with a pattern that is similar in all mammals. [4]
The descending upper fibers from the internal capsule continue on through the midbrain and are then seen as the fibers in the cerebral peduncles. [5] The corticopontine fibers are found in the outer and inner third of the cerebral peduncle, these are the cortical input to the pontine nuclei. [6]
Stimulation of the periaqueductal gray matter of the midbrain activates enkephalin-releasing neurons that project to the raphe nuclei in the brainstem. 5-HT released from the raphe nuclei descends to the dorsal horn of the spinal cord where it forms excitatory connections with the inhibitory interneurons located in Laminae II (aka the substantia gelatinosa).
The cerebral aqueduct (aqueduct of the midbrain, aqueduct of Sylvius, Sylvian aqueduct, mesencephalic duct) is a small, narrow tube connecting the third and fourth ventricles of the brain.