preganglionic neuron

(noun)

The nerve fibers that supply a ganglion.

Related Terms

Examples of preganglionic neuron in the following topics:

  • Preganglionic Neurons

    • The ANS is unique in that it requires a sequential two-neuron efferent pathway; the preganglionic neuron must first cross a synapse onto a postganglionic neuron before innervating the target organ.
    • The preganglionic, or first neuron will begin at the outflow and will cross a synapse at the postganglionic, or second neuron's cell body.
    • These cell bodies are GVE (general visceral efferent) neurons and are the preganglionic neurons.
    • There are several locations where preganglionic neurons create synapses with their postganglionic neurons:
    • These are the preganglionic neurons that synapse with the postganglionic neurons in these locations :

  • Autonomic Nervous System

    • A preganglionic neuron (originating in the CNS) synapses to a neuron in a ganglion that, in turn, synapses on the target organ .
    • Most preganglionic neurons in the sympathetic nervous system originate in the spinal cord.
    • Parasympathetic preganglionic neurons have cell bodies located in the brainstem and in the sacral (toward the bottom) spinal cord.
    • The axons of the preganglionic neurons release acetylcholine on the postganglionic neurons, which are generally located very near the target organs.
    • In the autonomic nervous system, a preganglionic neuron of the CNS synapses with a postganglionic neuron of the parasympathetic nervous system.

  • Autonomic Reflexes

    • The ANS is unique in that it requires a sequential two-neuron efferent pathway; the preganglionic neuron must first creat a synapse to a postganglionic neuron before innervating the target organ.
    • The preganglionic, or first neuron will begin at the outflow and will cross a synapse at the postganglionic, or second neuron's cell body.
    • The postganglionic neuron will then create a synapse at the target organ.

  • Divisions of the Autonomic Nervous System

    • In the autonomic nervous system, preganglionic neurons connect the CNS to the ganglion.

  • Postganglionic Neurons

    • At the synapses within the ganglia, the preganglionic neurons release acetylcholine, a neurotransmitter that activates nicotinic acetylcholine receptors on postganglionic neurons.
    • The axons of presynaptic parasympathetic neurons are usually long.
    • The pelvic splanchnic efferent preganglionic nerve cell bodies reside in the lateral gray horn of the spinal cord at the S2–S4 spinal levels.
    • Most transmissions occur in two stages: When stimulated, the preganglionic nerve releases ACh at the ganglion, which acts on the nicotinic receptors of the postganglionic neurons.
    • In the autonomic nervous system, preganglionic fibers (shown in light blue) carry information from the CNS to the ganglion.

  • Submucosa

    • Tiny parasympathetic ganglia are scattered around forming the submucosal plexus (or "Meissner's plexus") where preganglionic parasympathetic neurons synapse with postganglionic nerve fibers that supply the muscularis mucosae.

  • Autonomic Ganglia

    • The axons of dorsal root ganglion neurons are known as afferents.
    • Preganglionic nerves from the spinal cord create a synapse end at one of the chain ganglia, and the postganglionic fiber extends to an effector, typically a visceral organ in the thoracic cavity.
    • The first neuron in this pathway is referred to as the preganglionic or presynaptic neuron.
    • This second neuron is referred to as the postganglionic or postsynaptic neuron.
    • The pathways of the ciliary ganglion include sympathetic neurons (red), parasympathetic neurons (green), and sensory neurons (blue).

  • Parasympathetic Responses

    • When stimulated, the preganglionic nerve releases ACh at the ganglion, which acts on nicotinic receptors of the postganglionic neurons.

  • Sympathetic Nervous System

    • Preganglionic nerves from the spinal cord create a synapse at one end of the chain ganglia and the postganglionic fiber extends to an effector, typically a visceral organ, in the thoracic cavity.
    • Neurons of the collateral ganglia, also called the prevertebral ganglia, receive input from the splanchnic nerves and innervate organs of the abdominal and pelvic region.

  • Facial (VII) Nerve

    • It also functions in the conveyance of taste sensations from the anterior two-thirds of the tongue and oral cavity, and it supplies preganglionic parasympathetic fibers to several head and neck ganglia.
    • In an upper motor neuron lesion, called central seven (central facial palsy), only the lower part of the face on the contralateral side will be affected due to the bilateral control to the upper facial muscles (frontalis and orbicularis oculi).
    • Lower motor neuron lesions can result in a cranial nerve VII palsy (Bell's palsy is the idiopathic form of facial nerve palsy), manifested as both upper and lower facial weakness on the same side of the lesion.