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Equine Urinary System - Horse Anatomy (view source)
Revision as of 16:10, 28 November 2012
, 16:10, 28 November 2012→Urethra
==Urethra==
==Urethra==
This muscular tube is the connection between the bladder and the external environment and plays a vital role in conscious urinary continence.
===The Layers of the Urethra===
The layers of the walls of the urethra are largely similar to those of the bladder apart from one significant difference; in both the male and the female the urethral submucosa has a network of veins which may contribute to continence by forming a kind of erectile tissue.
===Female===
The urethra empties at the external urethral orifice on the ventral wall of the [[Female Reproductive Tract - Horse Anatomy#Vagina and Vestibule|vagina]]. This is often at the vestibulo-vaginal junction. Only urine passes through the female urethra. In the horse, the urethra is short and wide.
===Male===
[[Image:maleluttri.jpg|right|thumb|250px|<small><center>A schematic overview of the path of the male urethra</center></small>]]
[[Image:sumbsbladurtri.jpg|right|thumb|250px|<small><center>A schematic overview of the blood supply to the bladder and urethra</center></small>]]
The urethra empties at tip of penis. The male urethra carries urine, semen and seminal secretions from the [[Male Reproductive Tract - Horse Anatomy#Accessory Sex Glands|accessory sex glands]]. The uretha is divided into 3 parts:
*Pre-prostatic - bladder neck to seminal hillock
*Prostatic portion - openings of deferant, vesicular and prostatic ducts
*Penile portion - ischial arch to penile tip
The combination of the pre-prostatic and prostatic portions are called the pelvic portion.
===Muscles of the Urethra===
The '''''urethralis''''' muscle runs the entire length of the urethra and forms the '''external urethral sphincter'''. Unlike the [[Urinary Bladder - Anatomy & Physiology#Internal Urethral Sphincter|internal sphincter]], the external sphincter is composed of striated muscle fibres which are under the voluntary control of the somatic nervous system.
=====Somatic Motor Supply - External Urethral Sphincter=====
* S1-S2
* Pudendal Nerve
* No synapse
* Innervates the urethral skeletal muscle - external urethral sphincter
* Function is to contract and retain urine
===Vascular Supply===
Blood Supply comes from the '''Urethral Artery''', which is a branch of the '''vaginal artery''' which in turn is a branch of the '''internal pudendal''' which is a branch of the '''internal iliac'''.