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The ventral nerve cord is a major structure of the invertebrate central nervous system. It is the functional equivalent of the vertebrate spinal cord . [ 2 ] The ventral nerve cord coordinates neural signaling from the brain to the body and vice versa, integrating sensory input and locomotor output. [ 1 ]
The ventral nerve cord (formed by nerve cells and nerve fibers) begins at the sub-pharyngeal ganglia and extends below the alimentary canal to the most posterior body segment. The ventral nerve cord has a swelling, or ganglion, in each segment, i.e. a segmental ganglion, which occurs from the fifth to the last segment of the body.
The rest of the central nervous system, the ventral nerve cord, is generally "ladder-like", consisting of a pair of nerve cords that run through the bottom part of the body and have in each segment paired ganglia linked by a transverse connection.
Arthropods, such as insects and crustaceans, have a nervous system made up of a series of ganglia, connected by a ventral nerve cord made up of two parallel connectives running along the length of the belly. [30] Typically, each body segment has one ganglion on each side, though some ganglia are fused to form the brain and other large ganglia.
Each nerve lies within a cord of connective tissue lying beneath the cuticle and between the muscle cells. The ventral nerve is the largest, and has a double structure forward of the excretory pore. The dorsal nerve is responsible for motor control, while the lateral nerves are sensory, and the ventral combines both functions. [44]
Central nervous system of a nectiopod remipede, showing the presence of both deutocerebrum (dc) and ventral nerve cord (vnc) organized by segmented ganglia. Living arthropods have paired main nerve cords running along their bodies below the gut, and in each segment the cords form a pair of ganglia from which sensory and motor nerves run to ...
The nervous system consists of two ventral nerve cords, which are usually fused into a single structure, and three or four pairs of smaller nerves per body segment. Only a few aquatic oligochaetes have eyes, and even then they are only simply ocelli. Nonetheless, their skin has several individual photoreceptors, allowing the worm to sense the ...
The ventral nerve cord extends from the suboesophageal ganglion posteriorly. [4] A layer of connective tissue called the neurolemma covers the brain, ganglia, major peripheral nerves and ventral nerve cords. The head capsule (made up of six fused segments) has six pairs of ganglia.