Nerve fiber in the context of "Group B nerve fiber"

A nerve fascicle is a bundle of nerve fibers belonging to a nerve in the peripheral nervous system. A nerve fascicle is also called a fasciculus, as is a nerve tract in the central nervous system.

A nerve fascicle is enclosed by perineurium, a layer of fascial connective tissue. Each enclosed nerve fiber in the fascicle is enclosed by a connective tissue layer of endoneurium. Bundles of nerve fascicles are called fasciculi and are constituents of a nerve trunk. A main nerve trunk may contain a great many fascicles enclosing many thousands of axons.

Group C nerve fibers are one of three classes of nerve fiber in the central nervous system (CNS) and peripheral nervous system (PNS). The Group C fibers are unmyelinated and have a small diameter and low conduction velocity, whereas Groups A and B are myelinated. Group C fibers include postganglionic fibers in the autonomic nervous system (ANS), and nerve fibers at the dorsal roots (IV fiber). These fibers carry sensory information.

Damage or injury to nerve fibers causes neuropathic pain. Capsaicin activates C fibre vanilloid receptors, providing the burning sensation associated with chili peppers.

In physiology, nociception /ˌnəʊsɪˈsɛpʃ(ə)n/, also nocioception; from Latin nocere 'to harm/hurt') is the sensory nervous system's process of encoding noxious stimuli. It deals with a series of events and processes required for an organism to receive a painful stimulus, convert it to a molecular signal, and recognize and characterize the signal to trigger an appropriate defensive response.

In nociception, intense chemical (e.g., capsaicin present in chili pepper or cayenne pepper), mechanical (e.g., cutting, crushing), or thermal (heat and cold) stimulation of sensory neurons called nociceptors produces a signal that travels along a chain of nerve fibers to the brain. Nociception triggers a variety of physiological and behavioral responses to protect the organism against an aggression, and usually results in a subjective experience, or perception, of pain in sentient beings.

The endoneurium (also called endoneurial channel, endoneurial sheath, endoneurial tube, or Henle's sheath) is a layer of delicate connective tissue around the myelin sheath of each myelinated nerve fiber in the peripheral nervous system. Its component cells are called endoneurial cells. The endoneuria with their enclosed nerve fibers are bundled into groups called nerve fascicles, each fascicle within its own protective sheath called a perineurium. If sufficiently large, nerves containing multiple fascicles, each with its blood supply and fatty tissue, may be bundled within yet another sheath, the epineurium.

The endoneurium contains a liquid known as endoneurial fluid, which contains little protein. In the peripheral nervous system the endoneurial fluid is notionally equivalent to cerebrospinal fluid in the central nervous system. Peripheral nerve injuries commonly release increased amounts of endoneurial fluid into surrounding tissues; these can be detected by magnetic resonance neurography, thereby assisting in locating injuries to peripheral nerves.

Anticholinergics (anticholinergic agents) are substances that block the action of the acetylcholine (ACh) neurotransmitter at synapses in the central and peripheral nervous system.

These agents inhibit the parasympathetic nervous system by selectively blocking the binding of ACh to its receptor in nerve cells. The nerve fibers of the parasympathetic system are responsible for the involuntary movement of smooth muscles present in the gastrointestinal tract, urinary tract, lungs, sweat glands, and many other parts of the body.

In neuroscience, an internodal segment (or internode) is the portion of a nerve fiber between two nodes of Ranvier. The neurilemma or primitive sheath is not interrupted at the nodes, but passes over them as a continuous membrane.

The anterior white commissure (ventral white commissure) is a bundle of nerve fibers which cross the midline of the spinal cord just anterior (in front of) to the gray commissure (Rexed lamina X). A delta fibers (Aδ fibers) and C fibers carrying pain sensation in the spinothalamic tract contribute to this commissure, as do fibers of the anterior corticospinal tract, which carry motor signals from the primary motor cortex.

Two of the five sensory modalities, pain and temperature, cross sides at the anterior white commissure, reaching the contralateral side about two vertebral levels rostral to their origin. The spinothalamic tract thus decussates very soon after entering the spinal cord, ascending in the spinal cord, contralateral to the side from where it provides (pain and temperature) sensory information. Therefore, a lesion that is caudal to the sensory decussation where the remaining three-fifths modalities decussate (at the superior medulla) will result in contralateral (opposite sided) pain and temperature loss (as this has already crossed over at the anterior white commissure), whereas loss of crude touch, pressure, and proprioception will be ipsilateral (same sided) as these have not yet crossed over.