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The axial twist theory was designed to explain how the pattern of contralateral organization, [10] decussations and chiasmas develops, and why this pattern is so evolutionarily stable, [25] having no known exceptions throughout the 500 million years of vertebrate evolution. According to the theory, the contralateral organization develops as ...
The origin of the contralateral organization, the optic chiasm and the major decussations on the nervous system of vertebrates has been a long standing puzzle to scientists. [2] The visual map theory of Ramón y Cajal has long been popular [ 3 ] [ 4 ] but has been criticized for its logical inconsistence. [ 5 ]
This article is about the optic chiasm of vertebrates, which is the best known nerve chiasm, but not every chiasm denotes a crossing of the body midline (e.g., in some invertebrates, see Chiasm (anatomy)). A midline crossing of nerves inside the brain is called a decussation (see Definition of types of crossings).
Pictured here is a cross-section showing the gross anatomy of the human brain. Neuroanatomy is the study of the structure and organization of the nervous system . In contrast to animals with radial symmetry , whose nervous system consists of a distributed network of cells, animals with bilateral symmetry have segregated, defined nervous systems.
Axial or "transverse" or "horizontal", the plane that is horizontal and parallel to the ground with the body standing in the standard anatomical position. It contains (and thus is defined by) the lateral and the medial axes of the brain.
In the mid-19th century scientists first began to make discoveries regarding lateralization of the brain, or differences in anatomy and corresponding function between the brain's two hemispheres. Franz Gall, a German anatomist, was the first to describe what is now known as the Doctrine of Cerebral Localization. Gall believed that, rather than ...
The paramedian pontine reticular formation (PMPRF) is involved in coordinating horizontal conjugate eye movements and saccades. To do so, besides projecting to the ibsilateral abducens nucleus, the PMPRF projects fibers through the MLF to the contralateral oculomotor nucleus (specifically, those of its motor neurons that innervate the medial rectus muscle).
Cross-section of the midbrain. Tectum. 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 ...