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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 ...
All the fibers from the corticopontine system terminate in the pontine nuclei.The fibers descend through the sublenticular and retrolenticular of internal capsule, then traverse the midbrain through the basis pedunculi (i.e. ventral part of cerebral peduncle) to reach the pontine nuclei and synapse with neurons that give rise to pontocerebellar fibers.
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 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]
The cerebral crus (crus cerebri.crus means ‘leg’ in Latin.) is the anterior portion of the cerebral peduncle which contains the motor tracts, traveling from the cerebral cortex to the pons and spine.
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]
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]