The detrusor muscle, also detrusor urinae muscle, muscularis propria of the urinary bladder and (less precise)
muscularis propria, is
smooth muscle found in the wall of the
bladder. The detrusor muscle remains relaxed to allow the bladder to store
urine
Urine is a liquid by-product of metabolism in humans and many other animals. In placental mammals, urine flows from the Kidney (vertebrates), kidneys through the ureters to the urinary bladder and exits the urethra through the penile meatus (mal ...
, and contracts during
urination
Urination is the release of urine from the bladder through the urethra in Placentalia, placental mammals, or through the cloaca in other vertebrates. It is the urinary system's form of excretion. It is also known medically as micturition, v ...
to release urine. Related are the
urethral sphincter
The urethral sphincters are two muscles used to control the exit of urine in the urinary bladder through the urethra. The two muscles are either the external sphincter muscle of male urethra, male or external sphincter muscle of female urethra, fe ...
muscles which envelop the
urethra to control the flow of urine when they contract.
Structure
The fibers of the detrusor muscle arise from the
posterior surface of the
body of the pubis in both sexes (musculi pubovesicales), and in the male from the adjacent part of the
prostate
The prostate is an male accessory gland, accessory gland of the male reproductive system and a muscle-driven mechanical switch between urination and ejaculation. It is found in all male mammals. It differs between species anatomically, chemica ...
. These fibers pass, in a more or less
longitudinal manner, up the
inferior surface of the
bladder, over its
apex, and then descend along its
fundus to become attached to the prostate in the male, and to the front of the
vagina
In mammals and other animals, the vagina (: vaginas or vaginae) is the elastic, muscular sex organ, reproductive organ of the female genital tract. In humans, it extends from the vulval vestibule to the cervix (neck of the uterus). The #Vag ...
in the female. At the sides of the bladder the fibers are arranged
obliquely and intersect one another.
The three layers of muscles are arranged longitudinal-circular-longitudinal from innermost to outermost.
Nerve supply
The detrusor muscle is innervated by the
autonomic nervous system.
During urination,
parasympathetic pelvic splanchnic nerves act primarily on postganglionic
M3 receptors to cause contraction of the detrusor muscle.
At other times, the muscle is kept relaxed via
sympathetic branches from the
inferior hypogastric plexus
Inferior may refer to:
* Inferiority complex
* An anatomical term of location
* Inferior angle of the scapula, in the human skeleton
* ''Inferior'' (book), by Angela Saini
* '' The Inferior'', a 2007 novel by Peadar Ó Guilín
* Inferior good: ...
to allow the bladder to fill.
Clinical significance
In older adults over 60 years in age, the detrusor muscle may cause issues in voiding the bladder, resulting in uncomfortable
urinary retention.
The bladder also contains
β3 adrenergic receptors, and pharmacological agonists of this receptor are used to treat
overactive bladder.
The mucosa of the urinary bladder may herniate through the detrusor muscle.
This is most often an acquired condition due to high pressure in the urinary bladder, damage, or existing connective tissue disorders.
See also
*
External sphincter muscle of female urethra
*
External sphincter muscle of male urethra
*
Internal urethral sphincter
References
External links
*
*
{{Authority control
Urinary system
Muscles of the torso