Onuf’s nucleus

Onuf's Nucleus

Onuf's nucleus, also known as the Onufrowicz's nucleus, is a group of neurons located in the sacral spinal cord. Named after the Polish-American neurologist Bronislaw Onuf-Onufrowicz, this nucleus is unique in its preservation in certain neurodegenerative diseases, such as ALS and MSA.

Function

Onuf's nucleus is primarily involved in the control of the pelvic floor muscles and certain sphincter muscles. It plays a crucial role in the regulation of micturition, defecation, and sexual function. The neurons in Onuf's nucleus are somatic, meaning they control voluntary muscle movements.

Anatomy

Onuf's nucleus is located in the anterior horn of the sacral spinal cord, specifically in the second, third, and fourth sacral segments (S2-S4). It is composed of small, densely packed neurons. The neurons of Onuf's nucleus are unique in that they are resistant to degeneration in certain neurodegenerative diseases.

Clinical Significance

The preservation of Onuf's nucleus in diseases such as ALS and MSA is of significant clinical interest. In ALS, a disease characterized by the degeneration of motor neurons, the neurons of Onuf's nucleus are notably spared. This results in the preservation of urinary and bowel function in ALS patients. Similarly, in MSA, a disease that affects autonomic and motor systems, Onuf's nucleus is typically preserved.

Onuf's nucleus is also of interest in the study of Parkinson's disease. While it is not typically affected in Parkinson's disease, its involvement can lead to symptoms such as urinary incontinence and sexual dysfunction.

See Also

• Neuron
• Sacral spinal cord
• Amyotrophic lateral sclerosis
• Multiple system atrophy
• Parkinson's disease