Difference between revisions of "Urethra - Anatomy & Physiology"

Revision as of 15:03, 2 September 2008

()Map URINARY SYSTEM (Map)

This is the connection between the bladder and the external environment.

Female

Empties at the external urethral orifice on the ventral wall of the vagina
This is often at the vestibulo vaginal junction
Only urine passes through it
The urethral submucosa has a network of veins which may contribute to continence by forming a kind of erectile tissue.
Length and diameter is species specific
- Short and wide - mare
- 2 fossa - bitch
- Suburethral diverticulum - cow and sow

Male

Empties at tip of penis
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
- Note the first 2 combined 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 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 retain urine

Blood Supply

Blood Supply comes from the Urethral Artery

@@ Line 30: / Line 30: @@
 ==Muscles of the Urethra==
-The urethralis muscle runs the entire length of the urethra and forms the external urethral sphincter.
+The '''urethralis''' muscle runs the entire length of the urethra and forms the external urethral sphincter.
-Unlike the [[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. It is often called the '''urethralis''' muscle and runs the entire length of the urethra.
+Unlike the [[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=====