Alec Titan
The detrusor muscle, also known as the detrusor urinae muscle, is a smooth muscle found in the wall of the bladder. Its primary function is to contract during urination to push urine out of the bladder and into the urethra. The detrusor muscle is innervated by the pelvic nerve, which stimulates its contraction and causes micturition. This process is controlled by the autonomic system, specifically the parasympathetic nervous system, which acts through the pelvic nerve fibres. The pudendal nerve also plays a role in innervating the external urethral sphincter, providing voluntary control over micturition. The microstructure and function of the detrusor muscle are crucial in understanding voiding dysfunctions and incontinence, particularly in the elderly population.
| Characteristics | Values |
|---|---|
| Location | Wall of the bladder |
| Composition | Smooth muscle fibres |
| Function | Contracts during urination to push urine out of the bladder and into the urethra |
| Control | Autonomic system |
| Innervation | Parasympathetic nervous system, Pelvic nerve, Hypogastric nerve |
| Pathologies | Detrusor areflexia, bladder atony, voiding dysfunctions, incontinence |
Explore related products
What You'll Learn
The pelvic nerve innervates the detrusor muscle
The detrusor muscle is a smooth muscle located within the walls of the bladder. It contracts during urination to push urine out of the bladder and into the urethra. At other times, the detrusor muscle remains relaxed to allow the bladder to store urine. The detrusor muscle is under autonomic control.
The pelvic nerve is also involved in the bladder stretch reflex. This reflex is a primitive spinal reflex that stimulates micturition in response to the stretching of the bladder wall. During toilet training in infants, this reflex is overridden by higher centres of the brain, allowing for voluntary control over micturition. However, in spinal cord injuries or neurodegenerative diseases, the bladder stretch reflex can result in involuntary micturition due to the loss of descending inhibition.
The pelvic nerve is not the only nerve involved in the functioning of the detrusor muscle. The pudendal nerve, a somatic nerve, innervates the external urethral sphincter, providing voluntary control over micturition. Additionally, sensory (afferent) nerves are present in the bladder wall, signalling the need to urinate when the bladder becomes full. These afferent nerves transmit information about bladder fullness to the brain, which then initiates the micturition process.
The functioning of the detrusor muscle is crucial for maintaining normal bladder function. Any abnormalities or pathologies of the detrusor muscle can lead to urinary retention, incontinence, or a combination of both. Understanding the microstructure and innervation of the detrusor muscle is essential for managing and treating voiding dysfunctions and incontinence, especially in the elderly population.
Tendon and Muscle: What's the Difference?
You may want to see also
Explore related products
The pudendal nerve is involved in detrusor muscle innervation
The detrusor muscle is a smooth muscle that forms the wall of the bladder. It contracts during urination to push urine out of the bladder and into the urethra, and relaxes to allow the bladder to store urine. The muscle is under autonomic control, with the parasympathetic nervous system playing a key role in stimulating contraction.
The pudendal nerve is a somatic nerve that plays a role in the innervation of the detrusor muscle. Specifically, it is involved in the somatic innervation of the urethralis muscle, which is a striated muscle of the urethra. The pudendal nerve carries somatic afferent information from the urethralis muscle, as well as from the genitalia, anal canal, and skin of the perineum. This information includes sensory and pain signals.
The pudendal nerve releases acetylcholine at neuromuscular junctions, targeting nicotinic ion channel receptors. This process increases cation permeability, which is important for muscle function.
In addition to the pudendal nerve, the detrusor muscle receives innervation from the pelvic nerve, which is a parasympathetic nerve. The pelvic nerve innervates all regions of the bladder and relays information from various receptors. It plays a crucial role in stimulating the contraction of the detrusor muscle during urination.
The detrusor muscle is also influenced by the sympathetic nervous system, which provides inhibitory input. This input comes from preganglionic neurons in the intermediolateral nucleus of the lumbar spinal cord, and it results in smooth muscle contraction of the bladder neck and urethra, as well as inhibition of the detrusor muscle.
The Strength of Muslim Men: Unlocking Physical Power
You may want to see also
Explore related products
The hypogastric nerve plays a role in detrusor muscle innervation
The detrusor muscle is a smooth muscle that forms the walls of the bladder. It contracts during urination to push urine out of the bladder and into the urethra and remains relaxed to allow the bladder to store urine. The detrusor muscle is under autonomic control.
The hypogastric nerve also plays a role in the normal physiology of lubrication and orgasm. Patients with spinal cord lesions at the level of the origin of the hypogastric nerves have disturbed fantasy-induced lubrication and anorgasmia. During a dissection of the uterosacral ligament, special care should be taken to prevent damage to the hypogastric nerves.
The detrusor muscle is innervated by both sympathetic and parasympathetic nerves. The sympathetic nerves stimulate the urethral sphincter and inhibit the detrusor muscle of the bladder, while the parasympathetic nerves relax the urethral sphincter and stimulate the detrusor muscle. The pelvic nerve, which is parasympathetic, causes detrusor contraction and internal sphincter relaxation necessary for bladder emptying.
Cardio and Muscle Loss: What's the Real Deal?
You may want to see also
Explore related products
Preganglionic neurons innervate the detrusor muscle
The detrusor muscle, or detrusor urinae muscle, is a smooth muscle found in the wall of the bladder. It contracts during urination to release urine and remains relaxed to allow the bladder to store urine. The detrusor muscle is under autonomic control, with the parasympathetic nervous system playing a key role in stimulating contraction.
The role of preganglionic neurons in innervating the detrusor muscle is crucial for maintaining normal bladder function. When the bladder fills with urine, the parasympathetic nervous system stimulates muscarinic stretch receptors in the bladder wall through pelvic nerve fibres. This activation causes the detrusor muscle to contract and the internal urethral sphincter to relax, allowing for urination.
In addition to preganglionic neurons, postganglionic neurons also play a role in detrusor muscle innervation. These neurons release neurotransmitters that generate excitatory or inhibitory junction potentials. Excitatory potentials lead to muscle contraction, while inhibitory potentials result in muscle relaxation. This complex interplay between different neuronal circuits ensures the proper functioning of the detrusor muscle during urination and urine storage.
Furthermore, it is important to note that the detrusor muscle is not solely dependent on neuronal innervation for its function. The muscle's interwoven smooth muscle fibres provide the bladder with the ability to stretch in response to the presence of urine. This inherent elasticity allows the bladder to accommodate varying volumes of urine before triggering the neuronal signals associated with micturition.
Icing for Muscle Swelling: Effective Remedy or Myth?
You may want to see also
Explore related products
Postganglionic neurons are involved in detrusor muscle innervation
The detrusor muscle, or detrusor urinae muscle, is a smooth muscle that forms the wall of the bladder. It contracts during urination to release urine and remains relaxed to allow the bladder to store urine. The detrusor muscle is under autonomic control.
The process of urination involves the coordination of the detrusor muscle and the urethral sphincter muscles. The detrusor muscle contracts to push urine out of the bladder, while the urethral sphincter muscles relax to allow urine to flow through the urethra. This coordination is regulated by the autonomic nervous system, specifically the parasympathetic and sympathetic nervous systems.
The parasympathetic nervous system stimulates the detrusor muscle to contract during urination through the release of acetylcholine. This process is mediated by the pelvic nerve (S2-S4), which originates from preganglionic neurons in the sacral spinal cord (S1-3). The preganglionic axons travel through the pelvic nerve to the pelvic plexus, where they synapse on postganglionic neurons within the pelvic ganglia. These postganglionic neurons release acetylcholine, leading to detrusor contraction and internal sphincter relaxation via nitric oxide release.
The sympathetic nervous system, on the other hand, inhibits the detrusor muscle and stimulates the urethral sphincter muscles. This inhibition is mediated by preganglionic neurons in the intermediolateral nucleus of the lumbar spinal cord (L2-L4). The preganglionic axons travel through the lumbar splanchnic nerves to the caudal mesenteric ganglion and then continue as postganglionic axons through the hypogastric nerve and pelvic plexus to reach the bladder and urethra. These postganglionic axons release norepinephrine, resulting in smooth muscle contraction of the bladder neck and urethra, as well as inhibition of the detrusor muscle.
In summary, postganglionic neurons are indeed involved in detrusor muscle innervation as part of the parasympathetic and sympathetic nervous systems. They play a crucial role in mediating the contraction of the detrusor muscle during urination and its relaxation during bladder storage.
Preventing Muscle Injuries: Strategies for Staying Injury-Free
You may want to see also
Frequently asked questions
The detrusor muscle, also known as the detrusor urinae muscle, is a smooth muscle found in the wall of the bladder. It contracts during urination to push urine out of the bladder and into the urethra.
The detrusor muscle is under autonomic control. When the bladder fills with urine, the M3 receptors located within the bladder become stretched and stimulated, leading to the contraction of the detrusor muscle for urination. At the same time, the parasympathetic fibres inhibit the internal urethral sphincter, causing relaxation and allowing for bladder emptying.
The detrusor muscle is innervated by the pelvic nerve, which acts to contract the muscle and stimulate micturition. The pudendal nerve also plays a role in innervating the external urethral sphincter, providing voluntary control over micturition.
