Dorsal root ganglion
Dorsal root ganglion | |
---|---|
Details | |
Precursor | neural crest |
Identifiers | |
Latin | ganglion sensorium nervi spinalis |
MeSH | D005727 |
TA98 | A14.2.00.006 |
TA2 | 6167 |
FMA | 5888 |
Anatomical terminology |
A dorsal root ganglion (or spinal ganglion; also known as a posterior root ganglion
The
Structure
The neurons comprising the dorsal root ganglion are of the
Unlike the majority of neurons found in the
Distal section
The distal section of the axon may either be a bare nerve ending or encapsulated by a structure that helps relay specific information to nerve. Two examples where the nerve ending of the distal process is encapsulated as such are,
Location
The dorsal root ganglia lie in the
Development
The dorsal root ganglia develop in the embryo from neural crest cells, not neural tube. Hence, the spinal ganglia can be regarded as gray matter of the spinal cord that became translocated to the periphery.
Function
Nociception
Proton-sensing G protein-coupled receptors are expressed by DRG sensory neurons and might play a role in acid-induced nociception.[4]
Mechanosensitive channels
The nerve endings of dorsal root ganglion neurons have a variety of sensory receptors that are activated by mechanical, thermal, chemical, and noxious stimuli.[5] In these sensory neurons, a group of ion channels thought to be responsible for somatosensory transduction have been identified. Compression of the dorsal root ganglion by a mechanical stimulus lowers the voltage threshold needed to evoke a response and causes action potentials to be fired.[6] This firing may even persist after the removal of the stimulus.[6]
Two distinct types of
High-threshold mechanosensitive channels
High-threshold channels have a possible role in nociception. These channels are found predominantly in smaller sensory neurons in the dorsal root ganglion cells and are activated by higher pressures, two attributes that are characteristic of nociceptors.[5] Also, the threshold of HT channels was lowered in the presence of PGE2 (a compound that sensitizes neurons to mechanical stimuli and mechanical hyperalgesia) which further supports a role for HT channels in the transduction of mechanical stimuli into nociceptive neuronal signals.[5][6][7]
Presynaptic control
The presynaptic regulation of the dorsal nerve ending discharge in the spinal cord can occur through certain types of GABAA receptors but not through the activation of glycine receptors which are absent from these types of terminals. Thus GABAA receptors but not glycine receptors can presynaptically control nociception and pain transmission.[8]
See also
- Anterior root of spinal nerve
- Knee jerk
- Sensory neuronopathy (also known as sensory ganglionopathy): A heterogenous group of causes leading to nerves in the dorsal root ganglion being destroyed causing sensory symptoms.
References
- ^ "Ganglion". Physiopedia. Retrieved 2021-05-15.
- ^ Purves, Dale; Augustine, George J.; Fitzpatrick, David; Katz, Lawrence C.; LaMantia, Anthony-Samuel; McNamara, James O.; Williams, S. Mark (2001). "The Major Afferent Pathway for Mechanosensory Information: The Dorsal Column-Medial Lemniscus System". Neuroscience. 2nd edition. Retrieved 30 May 2018.
- ISBN 0-8385-7701-6
- S2CID 38351962.
- ^ PMID 11850451.
- ^ S2CID 23961565.
- S2CID 31565617.
- PMID 24920633.
Additional images
-
Medulla spinalis
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The formation of the spinal nerve from the posterior and anterior roots
-
Scheme showing structure of a typical spinal nerve.
External links
- Anatomy figure: 02:04-09 at Human Anatomy Online, SUNY Downstate Medical Center
- Histology image: 04401loa – Histology Learning System at Boston University
- Photo of model at Ohio State University
- Diagram at webanatomy.net
- Photo at uwlax.edu