parasympathetic ganglia

Examples of parasympathetic ganglia in the following topics:

• Parasympathetic (Craniosacral) Division

  • Parasympathetic ganglia are the autonomic ganglia of the parasympathetic nervous system which lie near or within the organs they innervate.
  • Parasympathetic ganglia are the autonomic ganglia of the parasympathetic nervous system, blue fibers).
  • Most are small terminal ganglia or intramural ganglia, so named because they lie near or within (respectively) the organs they innervate.
  • The exceptions are the four paired parasympathetic ganglia of the head and neck (shown in ).
  • Nerves supplying parasympathetic fibers to the parasympathetic ganglia of the head include the oculomotor nerve (ciliary ganglion), the facial nerve (pterygopalatine ganglion, submandibular ganglion), the glossopharyngeal nerve (otic ganglion), the vagus nerve, and the pelvic splanchnic nerves.

• Autonomic Ganglia

  • The two main categories are: sympathetic ganglia and parasympathetic ganglia.
  • A depiction of all the parasympathetic ganglia in the head and neck is shown in .
  • Parasympathetic ganglia are the autonomic ganglia of the parasympathetic nervous system.
  • The exceptions are the four paired parasympathetic ganglia of the head and neck.
  • Parasympathetic ganglia of the head (red circles) help supply all parasympathetic innervation to the head and neck.

• Preganglionic Neurons

  • In the autonomic nervous system (ANS), nerve fibers that connect the central nervous system to ganglia are known as preganglionic fibers.
  • Sympathetic preganglionic fibers tend to be shorter than parasympathetic preganglionic fibers because sympathetic ganglia are often closer to the spinal cord while parasympathetic preganglionic fibers tend to project to and synapse with the postganglionic fiber close to the target organ.
  • Paravertebral ganglia of the sympathetic chain (these run on either side of the vertebral bodies), Cervical Ganglia, Thoracic Ganglia and Rostral Lumbar Ganglia and Caudal Lumbar Ganglia and Pelvic Ganglia,
  • Prevertebral ganglia celiac ganglion, aorticorenal ganglion, superior mesenteric ganglion, inferior mesenteric ganglion
  • The site of synapse formation and this divergence for both the sympathetic and parasympathetic preganglionic neurons does however, occur within ganglia situated within the Peripheral nervous system.

• Clusters of Neuronal Cell Bodies

  • One exception is the basal ganglia which are located not in the periphery but rather in the forebrain.
  • Ganglia are composed mainly of neuron cell bodies (somata) and dendritic structures.
  • Satellite glial cells (SGCs) also surround neuron cell bodies within ganglia.
  • SGCs have been found to hold a variety of roles, including control over the microenvironment of sympathetic ganglia.
  • Satellite glial cells are expressed throughout the sympathetic and parasympathetic ganglia in their respective nervous system divisions.

• Postganglionic Neurons

  • In the parasympathetic division, they are cholinergic and use acetylcholine as their neurotransmitter.
  • Presynaptic nerves' axons terminate in either the paravertebral ganglia or prevertebral ganglia.
  • The parasympathetic fibers: The axons of presynaptic parasympathetic neurons are usually long: They extend from the CNS into a ganglion that is either very close to or embedded in their target organ.
  • As a result, the postsynaptic parasympathetic nerve fibers are very short.
  • In the cranium, preganglionic fibers (Cranial nerves III, VII, and IX) usually arise from specific nuclei in the Central Nervous System (CNS) and synapse at one of four parasympathetic ganglia: ciliary, pterygopalatine, otic, or submandibular.

• Enteric Nervous System

  • The neurons of the ENS are collected into two types of ganglia: myenteric (Auerbach's) and submucosal (Meissner's) plexuses.
  • These tissues also send information back to the sympathetic pre-vertebral ganglia, the spinal cord, and the brain stem .
  • It normally communicates with the central nervous system (CNS) through the parasympathetic (e.g., via the vagus nerve) and sympathetic (e.g., via the prevertebral ganglia) nervous systems.
  • The parasympathetic nervous system is able to stimulate the enteric nerves in order to increase enteric function.
  • The parasympathetic enteric neurons function in defecation, providing a rich nerve supply to the sigmoid colon, the rectum, and the anus.

• Sympathetic Nervous System

  • Sympathetic ganglia are the ganglia of the sympathetic nervous system that initiate "fight-or-flight" or stress-mediated responses.
  • Sympathetic ganglia are the ganglia of the sympathetic nervous system (see , red fibers).
  • The bilaterally symmetric sympathetic chain ganglia, also called the paravertebral ganglia, are located just ventral and lateral to the spinal cord.
  • These include the celiac ganglia, superior mesenteric ganglia, and inferior mesenteric ganglia.
  • The parasympathetic nervous system, shown in blue, is a division of the autonomic nervous system.

• Vagus (X) Nerve

  • The vagus nerve is the tenth of twelve paired cranial nerves and is responsible for parasympathetic output to heart and visceral organs.
  • The dorsal nucleus of vagus nerve - Sends parasympathetic output to the viscera, especially the intestines.
  • The nucleus ambiguus - Sends parasympathetic output to the heart (slowing it down).
  • The vagus nerve supplies motor parasympathetic fibers to all the organs, except the suprarenal (adrenal ) glands, from the neck down to the second segment of the transverse colon.
  • Parasympathetic innervation of the heart is partially controlled by the vagus nerve and is shared by the thoracic ganglia.

• Autonomic Nervous System (ANS)

  • It is classically divided into two subsystems: the parasympathetic nervous system (PSNS) and sympathetic nervous system (SNS).
  • The effect of parasympathetic stimulation is to increase activity in the entire enteric nervous system The proximal half of the nervous system is innervated from the cranial parasympathetic nerve fibers via the vagal nerve.
  • The distal half is innervated via the Sacral Parasympathetic nerves.
  • The fibers originate in the sympathetic ganglia of T-5 to L-2 and terminate mainly on the enteric plexuses, but also a few nerves terminate in the mucosa it self.

• Autonomic Plexuses

  • Autonomic plexuses are formed from both sympathetic and parasympathetic fibers and innervate visceral organs to regulate overall activity.
  • Autonomic plexuses are formed from sympathetic postganglionic axons, parasympathetic preganglionic axons, and some visceral sensory axons.
  • Abdominal: The abdominal aortic plexus (aortic plexus, shown in ) is formed by branches derived, on either side, from the celiac plexus and ganglia, and receives filaments from some of the lumbar ganglia.