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If talking about the skull, the dorsal side is the top. [38] The ventral (from Latin venter 'belly') surface refers to the front, or lower side, of an organism. [38] For example, in a fish, the pectoral fins are dorsal to the anal fin, but ventral to the dorsal fin. The terms are used in other contexts; for example dorsal and ventral gun ...
Ascidian larvae have a dorsal mouth, as one would expect from inversion. [7] The amphioxus has an odd feature: its mouth appears on the left side and migrates to the ventral side. [8] Biologist Thurston Lacalli speculates that this may be a recapitulation of the migration of the mouth from the dorsal to the ventral side in a protochordate. [9]
Dorsal and ventral: In animals with linear nervous systems, the term dorsal (from the Latin dorsum, meaning "back") is synonymous with superior and the term ventral (from the Latin venter, meaning "belly") is synonymous with inferior. In humans, however, the terminology differs on either side of the midbrain-diencephalic junction.
The ventral spinocerebellar tract will cross to the opposite side of the body first in the spinal cord as part of the anterior white commissure and then cross again to end in the cerebellum (referred to as a "double cross"), as compared to the dorsal spinocerebellar tract, which does not decussate, or cross sides, at all through its path.
Ventral and dorsal, which describe structures derived from the front (ventral) and back (dorsal) of the embryo, before limb rotation. Rostral and caudal, which describe structures close to (rostral) or farther from (caudal) the nose. For example, the eyes are rostral to the back of the skull, and the tailbone is caudal to the chest.
Early inductive effects of the axial mesoderm upon the overlying neural ectoderm is the mechanism that establishes the length dimension upon the brain primordium, jointly with establishing what is ventral in the brain (close to the axial mesoderm) in contrast with what is dorsal (distant from the axial mesoderm). Apart from the lack of a causal ...
The optic tract grows from the retina to the optic tectum. Because dorsal and ventral are inverted in the anterior head region, the tracts grow at first toward the ventral side, to meet in the midline to form a chiasma. Since the optic tectum lies on the dorsal midbrain, each tract then continues dorsally to the contralateral optic tectum. [10]
The parvo- and magnocellular fibers were previously thought to dominate the Ungerleider–Mishkin ventral stream and dorsal stream, respectively. However, new evidence has accumulated showing that the two streams appear to feed on a more even mixture of different types of nerve fibers. [8]