6. Nervous system


Spinal ganglia of spinal nerves (Ganglia spinalia nervorum spinalium); Image: Rebecca Betts

Spinal ganglia of spinal nervesGanglia spinalia nervorum spinalium1/4Synonyms: Dorsal root ganglia of spinal nerves, Sensory

Ganglia (sing. ganglion) are clusters of neuronal cell bodies outside of the CNS, meaning that they are the PNS equivalents to subcortical nuclei of the CNS. Ganglia can be sensory or visceral motor (autonomic) and their distribution in the body is clearly defined.

Dorsal root ganglia are clusters of sensory nerve cell bodies located adjacent to the spinal cord, They are a component of the posterior root of a spinal nerve.

Autonomic ganglia are either sympathetic or parasympathetic. Sympathetic ganglia are found in the thorax and abdomen, grouped into paravertebral and prevertebral ganglia. Paravertebral ganglia lie on either side of vertebral column (para- means beside), comprising two ganglionic chains that extend from the base of the skull to the coccyx, called sympathetic trunks. Prevertebral ganglia (collateral ganglia, preaortic ganglia) are found anterior to the vertebral column (pre- means in front of), closer to their target organ. They are further grouped according to which branch of abdominal aorta they surround; celiac, aorticorenal, superior and inferior mesenteric ganglia.

Parasympathetic ganglia are found in the head and pelvis. Ganglia in the head are associated with relevant cranial nerves and are the ciliary, pterygopalatine, otic and submandibular ganglia. Pelvic ganglia lie close to the reproductive organs comprising autonomic plexuses for innervation of pelvic viscera, such as prostatic and uterovaginal plexuses.

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