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In neuroanatomy, the pretectal area, or pretectum, is a midbrain structure composed of seven nuclei and comprises part of the subcortical visual system.Through reciprocal bilateral projections from the retina, it is involved primarily in mediating behavioral responses to acute changes in ambient light such as the pupillary light reflex, the optokinetic reflex, and temporary changes to the ...
The auguraculum (pl.: auguracula) was a roofless temple oriented to the cardinal points, in which the priests of ancient Rome practiced augury and ornithomancy. [1] The priest observer was positioned at the center of the temple, in a tent or a hut, and watched portions of the sky from which came the birds, which were marked out by stones placed along the perimeter of the temple.
In primates, eye movements can be divided into several types: fixation, in which the eyes are directed toward a motionless object, with eye movements only to compensate for movements of the head; smooth pursuit, in which the eyes move steadily to track a moving object; saccades, in which the eyes move very rapidly from one location to another ...
The umbo is the center of the foveola which in turn is located at the center of the fovea. The fovea is located near the center of the macula. It is a small pit that contains the largest concentration of cone cells. The retina's receptor layer contains two types of photosensitive cells, the rod cells and the cone cells.
It projects to the nucleus raphe magnus, and also contains descending autonomic tracts. The ascending pain and temperature fibers of the spinothalamic tract send information to the PAG via the spinomesencephalic pathway (so-named because the fibers originate in the spine and terminate in the PAG, in the mesencephalon or midbrain).
The tegmentum area includes various different structures, such as the rostral end of the reticular formation, several nuclei controlling eye movements, the periaqueductal gray matter, the red nucleus, the substantia nigra, and the ventral tegmental area. [3] The tegmentum is the location of several cranial nerve nuclei. The nuclei of CN III and ...
In neuroanatomy, the lateral geniculate nucleus (LGN; also called the lateral geniculate body or lateral geniculate complex) is a structure in the thalamus and a key component of the mammalian visual pathway. It is a small, ovoid, ventral projection of the thalamus where the thalamus connects with the optic nerve. There are two LGNs, one on the ...
The locus coeruleus (LC) is located in the posterior area of the rostral pons in the lateral floor of the fourth ventricle. It is composed of mostly medium-size neurons. Melanin granules inside the neurons contribute to its blue colour. Thus, it is also known as the blue nucleus, or the nucleus pigmentosus pontis (heavily pigmented pontine ...