Maximus Gage
The urinary bladder is a reservoir for urine and is located in the pelvic cavity, behind the symphysis pubis. The bladder is surrounded by the muscles of the pelvic diaphragm, which support the bladder. The bladder wall is made up of three layers, with the detrusor muscle forming the walls of the bladder and allowing it to contract to excrete urine or relax to hold urine. The detrusor muscle is composed of smooth muscle fibres that are oriented in multiple directions. This muscle is controlled by the autonomic nervous system and its contraction, along with the relaxation of the urethral sphincter, leads to urination.
| Characteristics | Values |
|---|---|
| Name of muscle | Detrusor muscle |
| Location | Within the walls of the bladder |
| Composition | Smooth muscle fibres that are longitudinal and circular |
| Number of layers | 3 |
| Function | Contracts during urination to push urine out of the bladder and into the urethra; relaxes to allow the storage of urine in the bladder |
| Control | Autonomic system |
| Blood supply | Superior vesical artery (upper portion); vaginal artery (females) or inferior vesicular artery (males) (lower portion) |
| Venous drainage | Vesical veins |
| Lymphatic drainage | External iliac lymph nodes |
| Innervation | Parasympathetic, sympathetic, and somatic nerve fibres |
| Sensory function | Stretch receptors respond to the stretch of the muscle with distension, sending sensory information to the central nervous system |
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What You'll Learn
The detrusor muscle surrounds the bladder
The primary function of the detrusor muscle is to contract during urination to push urine out of the bladder and into the urethra. When the bladder is full of urine, sensory nerves communicate with autonomic nerves to control the release of urine through stimulation of the detrusor muscle. This stimulation causes the detrusor muscle to contract and the internal and external urethral sphincters to relax, allowing urine to be released.
The detrusor muscle is under the control of the autonomic system, which includes the parasympathetic and sympathetic nervous systems. The parasympathetic nervous system stimulates the bladder through pelvic nerve fibres, leading to the contraction of the detrusor muscle for urination. Simultaneously, the parasympathetic fibres inhibit the internal urethral sphincter, causing relaxation and allowing the bladder to empty. The sympathetic nervous system is stimulated when the bladder is empty, activating the beta-3 receptors through the adenylyl cyclase-cAMP pathway.
The detrusor muscle is essential for the proper functioning of the bladder as a reservoir and active excretory organ for urine. It contracts to expel urine from the bladder and relaxes to allow the storage of urine. The bladder receives its innervation through a network of parasympathetic, sympathetic, and somatic nerve fibres that control the release of urine. Abnormalities in the detrusor muscle can lead to urinary retention, incontinence, or deterioration of the upper urinary tracts if left untreated.
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The bladder is supported by the pelvic diaphragm
The bladder is a reservoir and active excretory organ for urine. It is located in the pelvic cavity, posterior to the symphysis pubis, and below the parietal peritoneum. The urinary bladder is a temporary storage reservoir for urine. The inner lining of the urinary bladder is a mucous membrane of transitional epithelium that is continuous with that in the ureters. The bladder is surrounded by venous, lymphatic, and nerve systems. The bladder is supported by the muscles of the pelvic diaphragm.
The bladder is a relatively free organ in the subcutaneous fat of the subperitoneum, except for some fixed ligamentous connections at the bladder neck. The superior and part of the posterior surfaces of the bladder are covered by peritoneum. The inferior portion and the inferolateral sides of the bladder are covered by endopelvic fascia. The bladder is well-protected in adults as it lies within the confines of the bony pelvis. The rigid pelvic ring and the rectus abdominis muscle guard it.
The bladder and urethra are supported caudally by the muscles of the pelvic floor. The pelvic diaphragm is a muscular partition separating the pelvic cavity from the perineum. The pelvic diaphragm is formed by the levator ani and the coccygeus muscles. The levator ani muscle is a broad, thin muscle that covers the lower part of the pelvic cavity. The coccygeus muscle is a triangular muscle that extends from the coccyx to the levator ani. These muscles work together to provide support and stability to the pelvic organs, including the bladder and urethra.
The bladder wall is made up of three main layers. The inner lining, called the urothelium or transitional epithelium, is composed of urothelial or transitional cells. The second layer, called the lamina propria or submucosa, is a thin layer of connective tissue that surrounds the urothelium. It contains blood vessels, nerves, and glands. The third layer, called the muscularis propria or detrusor muscle, is the thick, outer muscle layer of the bladder. It is composed of three layers of smooth muscle that contract during urination to expel urine from the bladder.
The detrusor muscle surrounds the bladder and is responsible for its contraction and relaxation. It is composed of smooth muscle fibers that are oriented in multiple directions. These fibers allow the bladder to stretch in response to the presence of urine. The contraction of the detrusor muscle expels urine from the bladder, while its relaxation allows for the storage of urine. The detrusor muscle is under the control of the autonomic nervous system, which regulates its contraction and relaxation during the urination process.
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The bladder is protected by the rigid pelvic ring
The urinary bladder is a reservoir for urine located in the pelvic cavity, behind the pubic symphysis. The bladder is a relatively free organ in the subcutaneous fat of the subperitoneum, with some ligamentous connections at the bladder neck. The bladder is a mesodermal organ, with some endodermal components.
The bladder wall is made up of three main layers. The innermost layer, the urothelium, is a mucous membrane of transitional epithelium. This layer is covered by the lamina propria, a thin layer of connective tissue containing blood vessels, nerves, and glands. The final layer is the muscularis propria, or detrusor muscle, which is a thick, outer layer of smooth muscle. The detrusor muscle is composed of fibres oriented in multiple directions, providing the bladder with the ability to stretch in response to the presence of urine.
The detrusor muscle contracts during urination to push urine out of the bladder and into the urethra. This contraction is stimulated by the parasympathetic nervous system, which activates the bladder's stretch receptors. At the same time, the parasympathetic fibres cause the internal urethral sphincter to relax, allowing urine to pass through. When the bladder is empty, the mucosa of the bladder wall has numerous folds, called rugae, which allow the bladder to expand as it fills.
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The bladder is supplied by the superior vesical artery
The bladder is a muscular, hollow organ situated in the pelvis, just posterior to the pubic symphysis. The bladder functions as a reservoir for urine excreted by the kidneys, which passes through the ureters and the ureterovesical junction into the bladder. The bladder is surrounded by muscles of the pelvic diaphragm, which support it inferiorly. The bladder is also covered by peritoneum on its superior and part of its posterior surfaces, and by endopelvic fascia on its inferior portion and inferolateral sides.
The bladder receives innervation through a network of parasympathetic, sympathetic, and somatic nerve fibers. Parasympathetic fibers arise from sacral spinal nerves (S2-S4) and coalesce to form the pelvic splanchnic nerves. Sympathetic control arises from the lower thoracic and upper lumbar spinal levels (T10-L2) in the form of the superior and inferior hypogastric plexuses and nerves. The detrusor muscle, which forms the walls of the bladder, is under autonomic control. When the bladder fills with urine, sensory nerves communicate with somatic and autonomic nerves to control the release of urine through stimulation of the detrusor muscle and relaxation of the internal and external urethral sphincters.
The superior vesical artery exhibits anatomical variations in terms of occurrence and origin. Classical anatomical textbooks describe the presence of up to five superior vesical arteries, with two being the most common occurrence in 70-74% of cases. During embryonic development, the superior vesical artery arises from the umbilical artery, which serves as a vital conduit for oxygenated blood from the placenta.
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The bladder is drained by the vesical veins
The bladder is an organ of the urinary system, situated anteriorly in the pelvic cavity. It collects and acts as a temporary store for urine excreted by the kidneys. The bladder is surrounded by muscles known as the detrusor muscle, which allows the bladder to contract to excrete urine or relax to hold urine. The detrusor muscle is composed of smooth muscle fibres that are longitudinal and circular.
The process of urination involves the contraction of the detrusor muscle and relaxation of the internal urethral sphincter. The detrusor muscle is under control from the autonomic system and is composed of smooth muscle. The parasympathetic nervous system stimulates the bladder through the pelvic nerve fibres. When urine fills the bladder, the M3 receptors located within the bladder become stretched and stimulated, leading to the contraction of the detrusor muscle for urination.
The bladder receives its innervation through a network of parasympathetic, sympathetic, and somatic nerve fibres. The sympathetic response causes the relaxation of the detrusor muscle and the constriction of the internal urethral sphincter. The parasympathetic response is inhibited during this process. When the bladder is full, sensory fibres travel to the pontine micturition centre, stimulating the parasympathetic response and allowing for contraction of the detrusor muscle and relaxation of the internal sphincter.
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Frequently asked questions
The detrusor muscle surrounds the bladder. It is a thick smooth muscle tissue outside the lamina propria.
The detrusor muscle contracts during urination to push urine out of the bladder and into the urethra. It relaxes to allow the storage of urine in the bladder.
The detrusor muscle is located within the walls of the bladder and is composed of smooth muscle fibres that are longitudinal and circular. It is under autonomic control and allows the bladder to contract to excrete urine or relax to hold urine.
The blood supply to the detrusor muscle varies between males and females. The upper portion of the bladder receives supply primarily from the superior vesical artery, a branch of the hypogastric artery. The lower portion is supplied by the vaginal artery in females and the inferior vesicular artery in males.
