musculus sphincter ani internus

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Noun1.musculus sphincter ani internus - an internal ring of smooth muscle formed by circular fibers of the rectum
involuntary muscle, smooth muscle - a muscle that contracts without conscious control and found in walls of internal organs such as stomach and intestine and bladder and blood vessels (excluding the heart)
anal sphincter, musculus sphincter ani, sphincter ani - the sphincter muscle of the anus
References in periodicals archive ?
Hypertrophic myopathy of the internal anal sphincter: a rarely recognized cause of proctalgia.
Primary degeneration of the internal anal sphincter as a cause of passive faecal incontinence.
The recognition of organic nitrates as the non-adrenergic, non-cholinergic neurotransmitters mediating relaxation of the internal anal sphincter has initiated the wide-spread use of organic nitrates in the treatment of chronic anal fissure.
It has been shown that the resting tone of internal anal sphincter is higher in patients of chronic anal fissure.
Chronic tension in the internal anal sphincter -- the muscular ring that surrounds the anal canal -- is often an underlying factor because it reduces blood flow to the region.
It typically causes pain during defecation which may last for 12 hour afterwards.1 The finding on physical examination is spasm of the anal canal due to hypertonia of the internal anal sphincter. It has been postulated that this may either be due to or be the result of ischaemia.2
(1,7) Internal Sphincterotomy reduces post hemorrhoidectomy pain by abolishing the hypertonicity (spasm/pressure) of the internal anal sphincter and subsequently reduces the related post hemorrhoidectomy complications as well.
The treatment of chronic anal fissure has changed greatly during the past two decades with ongoing research directed at lowering the internal anal sphincter tone and avoiding the risk of fecal continence disturbance.
The low pass rate of 42.5% suggests lack of adequate training in repair and the satisfaction with the beef-tongue model was significantly higher with those who passed compared to those who failed (8.40 compared with 7.41; P=0.2).9 In our study, 84.6% consultants and 53.1% residents demonstrated similarity of anal canal with human anatomy, and 88.5% consultants and 93.7% residents were able to identify both external and internal anal sphincter in the goat model.
Current options for repair of the internal anal sphincter include grafts of skeletal muscle, injectable silicone material or implantation of mechanical devices, all of which have high complication rates and limited success.
Thus defined, the anal canal corresponds to the segment that is invested by the internal anal sphincter, and is about 4.0 cm in length.

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