ganglion
(gang'glē-ŏn 
, gang'glē-ă)
Plural: ganglia
[Gr. ganglion, tumor, cystic tumor]
- Either of two types of groups of nerve cells (sympathetic ganglion, parasympathetic ganglion) in the autonomic nervous system.
SEE: autonomic ganglion; parasympathetic ganglion; sympathetic ganglion.
- A dorsal root (spinal) ganglion.
SEE: dorsal root ganglion.
- A benign cystic tumor developing on a tendon or aponeurosis. It sometimes occurs on the back of the wrist.
SEE: illus.
abdominal g.Any autonomic ganglion located in the abdomen.
aorticorenal g.Either of the paired prevertebral autonomic ganglia in the nerve plexus surrounding the aortic roots of the renal arteries. They receive preganglionic sympathetic axons via the thoracic splanchnic nerves.
autonomic g.A ganglion of postganglionic autonomic neurons in the peripheral nervous system that are surrounded by a capsule of loose connective tissue. Dendrites of the neurons can be limited to the neuropil inside the ganglion, or they can pierce the capsule and extend into the surrounding regions. Each preganglionic autonomic axon usually synapses on the dendrites of many ganglionic neurons. The autonomic ganglia develop from the neural crest during embryonic development.
SEE: basal ganglion.
SEE: under Bochdalek, Vincent.
cardiac g.Any of the ganglia of autonomic (mainly postganglionic parasympathetic) neurons clumped in the superficial and deep cardiac plexuses. These ganglia are a meshwork of visceral afferent, sympathetic, and parasympathetic axons that coat the lower part of the trachea, its bifurcation, the aorta, the pulmonary trunk, and the coronary arteries. SYN: Wrisberg ganglion.
carotid g.A ganglion formed by filaments from the carotid plexus beneath the carotid artery.
celiac g.Either of a pair of connected prevertebral autonomic ganglia in the celiac plexus. The celiac ganglia are the largest of the prevertebral ganglia; they receive preganglionic sympathetic innervation primarily from the greater thoracic splanchnic nerves.
cephalic g.Any of the four parasympathetic ganglia (ciliary ganglion, otic ganglion, pterygopalatine ganglion, submand ibular ganglion) of the head.
SEE: inferior cervical ganglion; middle cervical ganglion; superior cervical ganglion.
cervicothoracic g.Stellate ganglion.
ciliary g.A small autonomic ganglion lying on the outside of the optic nerve in the rear portion of the orbit. This ganglion receives preganglionic parasympathetic axons from the midbrain via the oculomotor nerve (CN III). It sends postganglionic parasympathetic axons into the eye, via the short ciliary nerves, to innervate the ciliaris and the pupillary sphincter.
coccygeal g.A ganglion located in the coccygeal plexus and found at the inferior junction of the sympathetic trunks. This ganglion is sometimes absent.
collateral g.Any of several ganglia of the sympathetic nervous system. They are in the mesenteric nervous plexuses near the abdominal aorta and include the celiac and mesenteric ganglia.
SEE: under Corti, Alfonso Giacomo Gaspare.
dorsal root g.A roughly spherical ganglion of unipolar neuronal cell bodies in the posterior roots of each spinal nerve near the intervertebral foramina. This ganglion is enclosed in a capsule that is a continuation of the epineurium of the spinal nerve. Besides neuronal cell bodies, the ganglion contains satellite cells, Schwann cells, axonal processes, and blood vessels. The neurons of the ganglion are part of the primary visceral or somatic sensory pathways; the peripheral processes of these pathways extend into the peripheral nerve and terminate in sensory endings; their central processes follow the dorsal roots into the central nervous system and synapse in sensory areas. Microscopically, the peripheral processes of dorsal root ganglion neurons look identical to axons. Dorsal root ganglia develop from neural crest cells during embryonic development.SYN: intervertebral ganglion; posterior root ganglion; spinal ganglion.
SEE: Ehrenritter ganglion.
g. of the facial nerve Geniculate ganglion.
false g.An enlargement on a nerve that does not contain neuronal cell bodies and is therefore not a true ganglion.
SEE: Frankenhäuser ganglion.
gasserian g.Trigeminal ganglion.
geniculate g.The sensory ganglion of the facial nerve (CN VII). The ganglion lies inside a bend in the facial canal (at the geniculum of the facial nerve) where the preganglionic parasympathetic axons leave the facial nerve and form the greater petrosal nerve. The geniculate ganglion contains the cell bodies of the bipolar neurons that receive taste information from the palate and the anterior two thirds of the tongue via the chorda tympani. The axons of the neurons of the ganglion run in the nervus intermedius component of the facial nerve and synapse in the nucleus of the fasciculus solitarius. SYN: ganglion of the facial nerve.
inferior cervical g.The lowest (most caudal) of the cervical ganglia, adjacent to vertebra C7 or T1. Postganglionic sympathetic axons from the inferior cervical ganglion join spinal nerves C7–T1 and the pulmonary nerves.
SEE: stellate ganglion.
inferior g. of the glossopharyngeal nerve Petrosal ganglion.
inferior mesenteric g.A prevertebral sympathetic ganglion in the inferior mesenteric plexus.
intervertebral g.Dorsal root ganglion.
jugular g.The smaller of the two sensory ganglia of the vagus nerve (CN X). The jugular ganglion lies in the jugular foramen. Neurons in the ganglion send somatic sensory fibers to the dura of the posterior cranial fossa, to the skin behind the ear, and to the skin along the inferior portion of the tympanic membrane and the adjacent floor of the external auditory canal. The axons of these neurons follow the vagus nerve into the brainstem where they join the spinal trigeminal tract. SYN: superior ganglion of the vagus nerve.
lateral g.Any of a chain of ganglia forming the sympathetic trunk.
SEE: Lee ganglion.
lumbar g.Any of the three or four pairs of paravertebral ganglia in the lumbar section of the sympathetic trunk. The lumbar ganglia send postganglionic sympathetic axons, via lumbar splanchnic nerves, to the superior hypogastric plexus. From there the axons are distributed to the pelvic viscera.
SEE: under Meckel, Johann Friedrich (the elder).
middle cervical g.The central and smallest of the cervical ganglia. It is adjacent to vertebra C6. Approximately 40% of people lack this ganglion. In some people, it merges with the superior cervical ganglion, forming one elongated ganglion. Postganglionic sympathetic axons from the middle cervical ganglion join cervical nerves C5–C6.
nodose g.The larger of the two sensory ganglia of the vagus nerve, located in the nerve below the jugular foramen. The ganglion contains a mix of somatic and visceral sensory neurons. Somatic neurons send their axons into the spinal trigeminal tract in the brainstem; visceral neurons send their axons into the fasciculus solitarius. SYN: inferior vagus of the vagus nerve.
otic g.A small parasympathetic ganglion located deep in the infratemporal fossa immediately below the foramen ovale. It receives preganglionic parasympathetic axons from the inferior salivatory nucleus via the glossopharyngeal nerve (CN IX); it sends postganglionic parasympathetic axons to innervate the parotid gland via the auriculotemporal nerve. SYN: auricular ganglion.
parasympathetic g.An autonomic ganglion containing postganglionic parasympathetic neurons.
paravertebral g.Any of the pairs of sympathetic ganglia lying on either side of the vertebral column and forming the thickened nodes of the sympathetic trunk. The usual complement of paravertebral ganglia includes 2–3 cervical, 11–12 thoracic, 3–4 lumbar, and 4–5 sacral ganglia.
peripheral g.An accumulation of neuronal cell bodies outside the central nervous system.
petrosal g.The larger of the two sensory ganglia in the glossopharyngeal nerve (IX). The ganglion lies on the outer surface of the base of the skull in a groove in the petrous portion of the temporal bone just outside the jugular foramen. The petrosal ganglion contains cell bodies of unipolar neurons that receive taste and tactile sensation from the posterior third of the tongue and the oropharynx. Axons of these neurons follow the glossopharyngeal nerve into the hindbrain. SYN: inferior of the glossopharyngeal nerve.
pharyngeal g.A ganglion in contact with the glossopharyngeal nerve.
phrenic g.Any of several ganglia joining the phrenic plexus.
posterior root g.Dorsal root ganglion.
prevertebral g.Any of the sympathetic ganglia in one of the nerve plexuses along the abdominal aorta or its major branches. Major prevertebral ganglia include the celiac, aorticorenal, and the superior and inferior mesenteric.
pterygopalatine g.Sphenopalatine ganglion.
SEE: under Remak, Robert.
renal g.Any of a group of ganglia within the renal plexus.
sacral g.Any of the four small ganglia located in the sacral portion of the sympathetic trunk that lie on the anterior surface of the sacrum and are connected to the spinal nerves by gray rami.
semilunar g.Trigeminal ganglion.
sensory g.Any ganglion (such as the trigeminal ganglion or dorsal root ganglion) containing neurons that receive afferent (sensory) signals.
simple g.A cystic tumor in a tendon sheath. SYN: wrist ganglion.
sphenopalatine g.An accumulation of postanglionic parasympathetic cell bodies located in the pterygopalatine fossa that innervate the palate, nasal and oral cavities, and the lacrimal gland . SYN: Merkel ganglion; pterygopalatine ganglion.
spinal g.Dorsal root ganglion.
spiral g.A chain of tiny sensory ganglia that winds through the cochlea of the inner ear. These ganglia contain the cell bodies of the neurons that receive auditory signals from the organ of Corti. The axons of these neurons form the cochlear component of the vestibulocochlear nerve and synapse in the cochlear nuclei in the brainstem. SYN: acoustic ganglion; auditory ganglion; cochlear ganglion.
stellate g.The merger of the inferior cervical ganglion and the first thoracic ganglion, which occurs in many people. SYN: cervicothoracic ganglion.
submand ibular g.An autonomic ganglion suspended from the lingual nerve between the mylohyoid and hyoglossus muscles. It receives preganglionic parasympathetic axons from the superior salivatory nucleus via the facial nerve (CN VII). It sends postganglionic parasympathetic axons to innervate the submand ibular and sublingual salivary gland s and the mucosa of the floor of the mouth.
superior cervical g.The most superior (rostral) cervical ganglion and the largest paravertebral autonomic ganglion. It is adjacent to vertebra C2 or C3. It is the sole source of sympathetic fibers to the head and sends postganglionic sympathetic axons cervical nerves C1–C4, and the pharyngeal, carotid, and cardiac nerves.
superior mesenteric g.Either of the paired prevertebral autonomic sympathetic ganglia in the lower celiac plexus and adjacent to the superior mesenteric artery. They receive preganglionic sympathetic axons via the major splanchnic nerves.
superior g. of the vagus nerve Jugular ganglion.
suprarenal g.A ganglion in the suprarenal plexus.
sympathetic g.Any of the paravertebral or prevertebral autonomic ganglia innervated by preganglionic axons from the intermediolateral column of neurons in spinal cord segments T1–L2.
temporal g.A tiny ganglion joining the anterior branches of the superior cervical ganglion.
terminal g.A ganglion of the autonomic division of the nervous system that lies close to or within the organ innervated.
thoracic g.Any of 11 or 12 pairs of paravertebral ganglia in the thoracic section of the sympathetic trunk. They contain postganglionic sympathetic cell bodies that are destined to send their fibers into the thoracic wall. The first few thoracic ganglia send postganglionic sympathetic axons to the cardiac and thoracic visceral nerves.
trigeminal g.The somatic sensory ganglion of the trigeminal nerve (CN V). It is semilunar and flattened along the front and medial surfaces of the floor of the middle cranial fossa. The ophthalmic, the maxillary, and the sensory portion of the mand ibular nerves emerge from the front of the ganglion; the motor portion of the mand ibular nerve runs under the ganglion.SYN: gasserian ganglion; semilunar ganglion.
tympanic g.An enlargement on the tympanic portion of the glossopharyngeal nerve.
SEE: Valentin ganglion.
inferior g. of the vagus nerve Nodose ganglion.
vestibular g.A two-part ganglion in the vestibular branches of the vestibulocochlear nerve (CN VIII) inside the internal auditory meatus. The ganglion contains the cell bodies of bipolar neurons that receive equilibrium information from the membranous labyrinth of the semicircular canals in the inner ear. The axons of these neurons form the vestibular component of the vestibulocochlear nerve and synapse in the vestibular nuclei in the brainstem. SYN: Scarpa ganglion.