Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0002736 (amyotrophic lateral sclerosis)
 19,048 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Onuf's nucleus is a small motoneuron group in S2 anterior horn, which was described by Onufrowicz in 1900. He suggested that the motoneurons in the nucleus innervated striated muscles involved in election and ejaculation. The nucleus is readily shown by the K-B stain on account of its pale staining background which is sharply demarcated from the surrounding network of fine myelinated fibers. However, neuropathological descriptions of the nucleus are very rare. Pons-Tortella et al reported the sparing of this nucleus in acute anterior poliomyelitis. In 1977. We reported that Onuf's nucleus were well preserved in cases with ALS, in which the function of bladder and rectal sphincters is often intact until the latest stage of the illness. On the control , Shy-Drager syndrome showed severe degeneration of Onuf's nucleus. The patients with Shy-Drager syndrome showed clinically evident urinary and/or fecal incontinence. Combination of these clinical and pathological findings led to conclusion that Onuf's nucleus innervates the striated muscles of the sphincters. In 1990, Iwatsubo et al studied corticofugal projections to the motoneurons with Nauta-Gygax's technique in a patient with cerebral infarction. They verified that the oculomotor and abducens nuclei and Onuf's nucleus do not receive direct cortical projections. These motoneurons are characteristically spared in ALS. For the studies on ALS, it is important to know what differences between Onuf's nucleus and other motoneuron groups in anterior horn are biochemically and physiologically.
 ...
PMID:[Neuropathology of Onuf's nucleus]. 181 91

Neurobiological aspects of the organization of pelvic floor musculature are reviewed. Evolutionary considerations on the origin of these muscles indicate that they develop with specific attachments and function, i.e., do not derive from preexisting muscles such as the ones from the tail. Anatomically, pelvic floor muscles can be divided into 1) true sphincters and related muscles and 2) muscles which flank the visceral outlets. While in quadrupedal mammals the EAS behaves as a fast twitch muscle, in man this muscle has slow twitch characteristics. Like some epaxial muscles the EAS has a strong connectivity with its surrounding skin. In further analogy with some epaxial muscle the EAS, although endowed with muscle spindles, is devoid of the phasic, monosynaptic component of the stretch reflex. Onuf's nucleus which innervates pelvic floor muscles receives an important group of suprasegmental afferents including, probably, direct corticospinal fibers. Pelvic floor muscles play a fundamental role in signaling arrival of feces to the perineum. While sphincteric activity is important for continence, other mechanisms such as the anorectal angle and anal cushions are also of relevance. Although emphasis has been put on motor factors, fecal incontinence can also result from impairments in sensory mechanisms of the anorectal system. In diseases like amyotrophic lateral sclerosis, Werdnig Hoffman's and others there is selective sparing of neuropathology in Onuf's nucleus. In contrast, the nucleus is affected in some autonomic visceromotor neuronal disorders, e.g., Shy Drager syndrome, Fabry's disease. It has been suggested that Onuf's nucleus occupies an intermediate position between visceral and somatic nuclei.
 ...
PMID:Neurobiological aspects of the pelvic floor muscles involved in defecation. 219 Jan 15