sympathetic ganglion

Examples of sympathetic ganglion in the following topics:

• Sympathetic Nervous System

  • This response is also known as the sympathetico-adrenal response because the pre-ganglionic sympathetic fibers that end in the adrenal medulla—like all sympathetic fibers—secrete acetylcholine.
  • An example of a sympathetic ganglion in a thoracic nerve is shown in . ganglia contain approximately 20000–30000 nerve cell bodies and are located close to and on either side of the spinal cord in long chains.
  • The chain extends from the upper neck down to the coccyx, forming the unpaired coccygeal ganglion.
  • There are usually 21 or 23 pairs of these ganglia: 3 in the cervical region, 12 in the thoracic region, 4 in the lumbar region, 4 in the sacral region and a single, unpaired ganglion lying in front of the coccyx called the ganglion impar.
  • This intercostal nerve shows the sympathetic ganglion at the top left.

• Parasympathetic (Craniosacral) Division

  • Nerves that supply 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 (no named ganglion); and the pelvic splanchnic nerves (no named ganglion).
  • These paired ganglia supply all parasympathetic innervation to the head and neck: ciliary ganglion (spincter pupillae, ciliary muscle), pterygopalatine ganglion (lacrimal gland, glands of nasal cavity), submandibular ganglion (submandibular and sublingual glands), and otic ganglion (parotid gland).
  • Each has three roots entering the ganglion (motor, sympathetic, and sensory roots) and a variable number of exiting branches.
  • The sympathetic root carries postsynaptic sympathetic fibers (general visceral efferent fibers) that traverse the ganglion without creating a synapse.
  • Because of its location, the parasympathetic system is commonly referred to as having craniosacral outflow, in contrast to the sympathetic nervous system, which is said to have thoracolumbar outflow.

• Postganglionic Neurons

  • In the sympathetic division, most are adrenergic, meaning they use norepinephrine as their neurotransmitter.
  • The activation of target tissue receptors causes the effects associated with the sympathetic system.
  • The chromaffin cells of the adrenal medulla are analogous to post-ganglionic neurons—the adrenal medulla develops in tandem with the sympathetic nervous system and acts as a modified sympathetic ganglion.
  • After this, it can then either create a synapse in this ganglion, ascend to a more superior ganglion, or descend to a more inferior paravertebral ganglion and make a synapse there, or it can descend to a prevertebral ganglion and create a synapse there with the postsynaptic cell.
  • This differs from the sympathetic nervous system, where synapses between pre- and post-ganglionic efferent nerves in general occur at ganglia that are farther away from the target organ.

• Autonomic Ganglia

  • The two main categories are: sympathetic ganglia and parasympathetic ganglia.
  • An example of parasympathetic ganglion is the ciliary ganglion, involved in pupil constriction and accommodation.
  • Sympathetic ganglia are the ganglia of the sympathetic nervous system.
  • Sympathetic ganglia are the tissue from which neuroblastoma tumors arise.
  • The pathways of the ciliary ganglion include sympathetic neurons (red), parasympathetic neurons (green), and sensory neurons (blue).

• Divisions of the Autonomic Nervous System

  • Sympathetic and parasympathetic divisions typically function in opposition to each other.
  • The sympathetic division typically functions in actions requiring quick responses.
  • Many think of sympathetic as fight or flight and parasympathetic as rest and digest or feed and breed.
  • In the autonomic nervous system, preganglionic neurons connect the CNS to the ganglion.
  • Distinguish between the parasympathetic and sympathetic subsystems of the autonomic nervous system

• Autonomic Interactions

  • Sympathetic and parasympathetic divisions typically function in opposition to each other.
  • The sympathetic division typically functions in actions requiring quick responses.
  • Consider sympathetic as fight or flight and parasympathetic as rest and digest or feed and breed.
  • Some typical actions of the sympathetic and parasympathetic systems are listed below.
  • In the autonomic nervous system, preganglionic neurons connect the CNS to the ganglion.

• Preganglionic Neurons

  • In the autonomic nervous system (ANS), fibers from the central nervous system to the ganglion 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.
  • The sympathetic division has thoracolumbar outflow, meaning that the neurons begin at the thoracic and lumbar (T1–L2) portions of the spinal cord.
  • The prevertebral ganglia celiac ganglion, aorticorenal ganglion, superior mesenteric ganglion, inferior mesenteric ganglion.
  • Pre- and post-ganglionic fibers and targets are depicted.

• Autonomic Plexuses

  • Autonomic plexuses are formed from sympathetic and parasympathetic fibers that innervate and regulate the overall activity of visceral organs.
  • Autonomic plexuses are formed from sympathetic postganglionic axons, parasympathetic preganglionic axons, and some visceral sensory axons.
  • A small ganglion, the cardiac ganglion of Wrisberg, is occasionally found connected with these nerves at their point of junction.
  • The pulmonary plexus is an autonomic plexus formed from pulmonary branches of vagus nerve and the sympathetic trunk.
  • This section of the sympathetic trunk shows both the celiac and the hypogastric plexus.

• Parasympathetic Responses

  • Its action is described as being complementary to that of one of the other main branches of the ANS, the sympathetic nervous system, which is responsible for stimulating activities associated with the fight-or-flight response.
  • The sympathetic and parasympathetic divisions typically function in opposition to each other.
  • The sympathetic nervous system can be considered a quick response, mobilizing system; and the parasympathetic system is a more slowly activated, dampening system.
  • When stimulated, the preganglionic nerve releases ACh at the ganglion, which acts on nicotinic receptors of the postganglionic neurons.

• Clusters of Neuronal Cell Bodies

  • In the peripheral nervous system, a cluster of neurons is called a ganglion.
  • 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.