Onuf's nucleus: Difference between revisions
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In addition to its motor functions, Onuf's nucleus also performs autonomic functions by association with parasympathetic neurons in the sacral segment of the spinal cord.<ref name=":1" /><ref name=":3" /> | In addition to its motor functions, Onuf's nucleus also performs autonomic functions by association with parasympathetic neurons in the sacral segment of the spinal cord.<ref name=":1" /><ref name=":3" /> | ||
== Significance == | == Clinical Significance == | ||
Onuf's nucleus, interestingly, is the only motor neuron preserved in [[Amyotrophic Lateral Sclerosis (aka ALS or Lou Gehrig’s Disease)|Amyotrophic Lateral Sclerosis]]. Additionally, it is also spared in [[Spinal Muscular Atrophy (SMA)|Spinal Muscular Atrophy]], [[Duchenne Muscular Dystrophy]], and Poliomyelitis. In stark contrast, it is one of the most affected structures in [[Multiple System Atrophy]].<ref name=":2" /><ref name=":0" /><ref name=":1" /><ref name=":3">Marani, Enrico. (2015). The nucleus of Onuf. 10.13140/RG.2.1.2253.0401.</ref> | Onuf's nucleus, interestingly, is the only motor neuron preserved in [[Amyotrophic Lateral Sclerosis (aka ALS or Lou Gehrig’s Disease)|Amyotrophic Lateral Sclerosis]]. Additionally, it is also spared in [[Spinal Muscular Atrophy (SMA)|Spinal Muscular Atrophy]], [[Duchenne Muscular Dystrophy]], and Poliomyelitis. In stark contrast, it is one of the most affected structures in [[Multiple System Atrophy]].<ref name=":2" /><ref name=":0" /><ref name=":1" /><ref name=":3">Marani, Enrico. (2015). The nucleus of Onuf. 10.13140/RG.2.1.2253.0401.</ref> | ||
Revision as of 05:18, 14 February 2020
Introduction[edit | edit source]
Onuf's nucleus is a small group of motor neurons located in the anterior horn of the S2 segment of the spinal cord, specifically in Lamina IX. It is named after Bronislaw Onuf-Onufrowicz, a neurologist, who first discovered the structure in 1899. It is the site of origin of the pudendal nerve.[2][3]
Functions[edit | edit source]
Through the pudendal nerve, Onuf's nucleus innervates the external anal and urethral sphincters, as well as two perineal muscles: ischiocavernosus and bulbospongiosus. Hence, it maintains bowel and bladder continence through the voluntary control of both external sphincters and enables sexual functions like penile erection and ejaculation through perineal muscle contractions.[3][4][5]
In addition to its motor functions, Onuf's nucleus also performs autonomic functions by association with parasympathetic neurons in the sacral segment of the spinal cord.[4][5]
Clinical Significance[edit | edit source]
Onuf's nucleus, interestingly, is the only motor neuron preserved in Amyotrophic Lateral Sclerosis. Additionally, it is also spared in Spinal Muscular Atrophy, Duchenne Muscular Dystrophy, and Poliomyelitis. In stark contrast, it is one of the most affected structures in Multiple System Atrophy.[2][3][4][5]
Therefore, the presence or absence of incontinence and/or impotence allows clinicians to rule in or out the conditions mentioned above, from their differential diagnosis, subsequently saving a lot of time during a clinical examination.
References[edit | edit source]
- ↑ Jost, W., Marsalek, P. Duloxetine: mechanism of action at the lower urinary tract and Onuf’s nucleus. Clin Auton Res 14, 220– 227 (2004). https://doi.org/10.1007/s10286-004-0197-8
- ↑ 2.0 2.1 Watson C, Kayalioglu G. Chapter 1: The Organization of the Spinal Cord. The Spinal Cord. 2009. DOI: 10.1016/B978-0-12-374247-6.50005-5
- ↑ 3.0 3.1 3.2 Mannen T. Neuropathology of Onuf's nucleus. Rinsho Shinkeigaku. 1991 Dec;31(12):1281-5. Review. PubMed PMID: 1817791.
- ↑ 4.0 4.1 4.2 Mannen T. Neuropathological findings of Onuf's nucleus and its significance. Neuropathology. 2000 Sep;20 Suppl:S30-3. Review. PubMed PMID: 11037184.
- ↑ 5.0 5.1 5.2 Marani, Enrico. (2015). The nucleus of Onuf. 10.13140/RG.2.1.2253.0401.
