Onufs

Onufs most often refers to Onuf's nucleus, a distinct cluster of motor neurons located in the ventral horn of the sacral spinal cord, typically at segments S2 to S4 in humans. This nucleus innervates the external anal and urethral sphincters and is therefore important for voluntary control of the pelvic floor, continence, and aspects of micturition and defecation. It receives descending input from higher motor centers and interacts with brainstem and spinal networks that regulate pelvic floor function. Onuf's nucleus is characterized by its specialized motor neuron population and its distinct neurochemical and anatomical properties that set it apart from neighboring motor pools.

In clinical and neuroanatomical literature, Onuf's nucleus is noted for its relatively robust resistance to degeneration in certain motor neuron diseases, such as amyotrophic lateral sclerosis, where other motor neuron groups may be affected earlier. This differential vulnerability has been of interest in studies of motor neuron biology, spinal cord organization, and the mechanisms underlying continence and pelvic floor control. The concept of Onuf's nucleus has also contributed to broader discussions of how specialized motor neuron pools support distinct functional systems within the human nervous system.

The term Onufs may also appear in historical or anatomical discussions as a reference to the eponym associated with Onuf's nucleus. In most contemporary neuroscience contexts, however, Onuf's nucleus is the primary meaning connected with the name Onufs.