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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 .
Each layer contains a topographic map of the surrounding world in retinotopic coordinates, and activation of neurons at a particular point in the map evokes a response directed toward the corresponding point in space. In primates, the superior colliculus has been studied mainly with respect to its role in directing eye movements.
The inferior colliculi of the midbrain are located just below the visual processing centers known as the superior colliculi. The inferior colliculus has three subdivisions – the central nucleus, the dorsal cortex by which it is surrounded, and an external cortex which is located laterally. [1]
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]
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In humans, the tectospinal tract (or colliculospinal tract) is a decussating extrapyramidal tract that coordinates head/neck and eye movements. [1]It arises from the superior colliculus of the mesencephalic (midbrain) tectum, and projects to the cervical and upper thoracic spinal cord levels. [2]