Nucleus of pudendal nerve

The nucleus of pudendal nerve (a.k.a. Onuf’s nucleus) is a cluster of motor neurons which are located in the anterior horns of the upper sacral spinal cord segments, primarily S2 and S3, with occasional extension into the S1 segment.

The nucleus of pudendal nerve or Onuf’s nucleus serves as the origin of the pudendal nerve, which innervates voluntary striated muscles in the pelvic and perineal regions. These include levator ani, ischiocavernosus, bulbospongiosus, external urethral sphincter, and external anal sphincter muscles. This innervation is essential for functions such as erection, urinary and fecal continence, and ejaculation, highlighting its pivotal role in pelvic and perineal physiology.

Supraspinal inputs to the nucleus of pudendal nerve originate from regions in the brainstem, hypothalamus, and cerebral cortex. These pathways regulate pelvic floor muscle contractions, adjust abdominal pressure, and harmonize the cortical emotional state of an individual with micturition and other physiological functions mentioned above.