The detrusor muscle, also detrusor urinae muscle, muscularis propria of the urinary bladder and (less precise) muscularis propria, is

smooth muscle Smooth muscle is one of the three major types of vertebrate muscle tissue, the others being skeletal and cardiac muscle. It can also be found in invertebrates and is controlled by the autonomic nervous system. It is non- striated, so-called bec ...

found in the wall of the

bladder The bladder () is a hollow organ in humans and other vertebrates that stores urine from the kidneys. In placental mammals, urine enters the bladder via the ureters and exits via the urethra during urination. In humans, the bladder is a distens ...

. 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 The urethra (: urethras or urethrae) is the tube that connects the urinary bladder to the urinary meatus, through which Placentalia, placental mammals Urination, urinate and Ejaculation, ejaculate. The external urethral sphincter is a striated ...

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

, over its

apex The apex is the highest point of something. The word may also refer to: Arts and media Fictional entities * Apex (comics) A-Bomb Abomination Absorbing Man Abraxas Abyss Abyss is the name of two characters appearing in Ameri ...

, 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 The autonomic nervous system (ANS), sometimes called the visceral nervous system and formerly the vegetative nervous system, is a division of the nervous system that operates viscera, internal organs, smooth muscle and glands. The autonomic nervo ...

. During urination,

parasympathetic The parasympathetic nervous system (PSNS) is one of the three divisions of the autonomic nervous system, the others being the sympathetic nervous system and the enteric nervous system. The autonomic nervous system is responsible for regulat ...

pelvic splanchnic nerves Pelvic splanchnic nerves or nervi erigentes are splanchnic nerves that arise from sacral spinal nerves S2, S3, S4 to provide parasympathetic innervation to the organs of the pelvic cavity. Structure The pelvic splanchnic nerves arise from th ...

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 Urinary retention is an inability to completely empty the bladder. Onset can be sudden or gradual. When of sudden onset, symptoms include an inability to urinate and lower abdominal pain. When of gradual onset, symptoms may include urinary incont ...

. The bladder also contains β₃ adrenergic receptors, and pharmacological agonists of this receptor are used to treat

overactive bladder Overactive bladder (OAB) is a common condition where there is a frequent feeling of needing to urinate to a degree that it negatively affects a person's life. The frequent need to urinate may occur during the day, at night, or both. Loss of bl ...

. 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.

References

External links

* * {{Authority control Urinary system Muscles of the torso

Structure

Nerve supply

Clinical significance

See also

References

External links