Internal anal sphincter is a apa of:
Correct Answer: Internal circular fibers
Description: Involuantry internal anal sphincter is formed by thickening of circular muscle layer (i.e. circular layer of muscularis externa, a smooth muscle) of upper end (2/3 or 3/4) of anal canal. This sphincter remains in the state of tonic contraction most of the time to maintain resting tone or pressures (-90 cm H20) & to prevent leakage of fluid or flatus. Its contraction (tonus) is maintained by sympathetic fibers from superior rectal (periaerial) and hypogastric plexuses; and inhibited (i.e. sphincter relaxed) by parasympathetic pelvic NERVES. Ref: Gray&;s anatomy text book of anatomy BD chaurasia 21st Ed.
Category:
Anatomy
Get More
Subject Mock Tests
Practice with over 200,000 questions from various medical subjects and improve your knowledge.
Attempt a mock test nowMock Exam
Take an exam with 100 random questions selected from all subjects to test your knowledge.
Coming SoonGet More
Subject Mock Tests
Try practicing mock tests with over 200,000 questions from various medical subjects.
Attempt a mock test now