World Library  
Flag as Inappropriate
Email this Article

Internal sphincter muscle of urethra

Article Id: WHEBN0014099084
Reproduction Date:

Title: Internal sphincter muscle of urethra  
Author: World Heritage Encyclopedia
Language: English
Subject: Urethra, Urethral sphincter, Medullary interstitium, External sphincter muscle of female urethra, Ureteropelvic junction
Collection:
Publisher: World Heritage Encyclopedia
Publication
Date:
 

Internal sphincter muscle of urethra

Internal sphincter muscle of urethra
Coronal section of anterior part of pelvis, through the pubic arch. Seen from in front. (Region visible, but muscle not labeled.)
Urinary bladder (Region visible, but muscle not labeled.)
Details
Latin Musculus sphincter urethrae internus
The inferior ramus of the pubic bone
Perineal raphe
Sympathetics from L1-L2 through lumbar splanchnic nerves and inferior hypogastric plexus
Actions Sympathetic contracts and parasympathetic relaxes the muscle
Dorlands
/Elsevier
m_22/13540450
Anatomical terms of muscle

The internal sphincter muscle of urethra is a urethral sphincter muscle which constricts the internal urethral orifice. It is the junction of the urethra with the urinary bladder. The muscle is made of smooth muscle, so therefore it is under involuntary control. It is kept tonically contracted by Lumbar plexus of the sympathetic nervous system.

Function

During micturition it is relaxed via branches from the pelvic plexus (S2-S4) parasympathetic nervous system. This is the primary muscle for maintenance of continence of urine. Its two major roles are:

  1. Prevent urine leakage as the muscle is contracted via sympathetic stimulation (via the Inferior hypogastric plexus).
  2. During ejaculation, the contraction of the muscle prevents reflux of semen in the urinary bladder.


This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and USA.gov, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for USA.gov and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
 
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
 
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.
 


Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.