Maximus Gage
The detrusor muscle, or detrusor urinae muscle, is a smooth muscle that forms the muscular layer of the urinary bladder wall. It is responsible for the contraction of the bladder during urination. The detrusor muscle is innervated by the pelvic nerve, which stimulates its contraction and initiates micturition. This process is regulated by both the parasympathetic and sympathetic nervous systems, with the former promoting contraction and the latter inhibiting it. The coordination of these systems ensures the proper filling and storage of urine in the bladder, and abnormalities in this process can lead to incontinence or voiding dysfunction.
| Characteristics | Values |
|---|---|
| Nerve | Pelvic nerve (S2-S4) |
| Muscle type | Smooth muscle |
| Muscle location | Wall of the bladder |
| Muscle function | Contracts during urination to release urine |
| Muscle state during urination | Contracted |
| Muscle state when storing urine | Relaxed |
| Muscle structure | Interlacing bundles of smooth muscle |
| Muscle fibres | Arise from the posterior surface of the body of the pubis in both sexes |
| Muscle receptors | Stretch receptors |
| Muscle contraction | Stimulated by efferent parasympathetic impulses |
Explore related products
What You'll Learn
The pelvic nerve contracts the detrusor muscle
The detrusor muscle, also known as the detrusor urinae muscle, is a smooth muscle that forms the muscular layer of the urinary bladder wall. It is responsible for facilitating bladder contraction during urination, allowing the release of urine. The detrusor muscle contracts to empty the bladder, and it relaxes to allow the bladder to store urine.
The pelvic nerve, specifically the parasympathetic pelvic nerve (S2-S4), innervates the detrusor muscle and causes its contraction. This nerve signal increases in response to a full bladder, stimulating the need to urinate or micturition. The pelvic nerve's role in contracting the detrusor muscle is essential for bladder function and maintaining urinary control.
During urination, or micturition, the pelvic nerve activates spinobulbospinal reflex pathways. This activation stimulates the parasympathetic outflow to the bladder and the urethral smooth muscle, which is part of the urethral sphincter. The urethral sphincter muscles envelop the urethra and work in conjunction with the detrusor muscle to control the flow of urine during urination.
The pudendal nerve (S2-4), a somatic nerve, also plays a role in the process. It innervates the external urethral sphincter, providing voluntary control over urination. The coordination between the pelvic nerve's activation of the detrusor muscle and the pudendal nerve's control of the external urethral sphincter ensures effective urination.
Abnormalities in the detrusor muscle or its innervation by the pelvic nerve can lead to issues such as incontinence or voiding dysfunction. It is important to understand the nerve distribution patterns in the bladder to develop effective treatments for such conditions and improve bladder function.
Muscle Recovery and Sleep: Friends or Foes?
You may want to see also
Explore related products
The pudendal nerve controls micturition
The pudendal nerve is the main nerve of the perineum, pelvic floor muscles, and external genitalia. It is a mixed nerve with sensory, motor, and autonomic functions. It is one of the primary nerves originating from the sacral plexus following the sciatic nerve. The pudendal nerve carries movement (motor) and sensation information from the genital area.
The pudendal nerve has two types of functions: motor and sensory. The motor function controls the movement of the anal sphincter muscles and urethral sphincter muscles. The urethral sphincter muscles help to hold in or release urine. The pudendal nerve innervates the external urethral sphincter, providing voluntary control over micturition. The somatic axons in the pudendal nerve release acetylcholine (ACh), which produces a contraction of the external sphincter striated muscle by activating nicotinic cholinergic receptors. During periods of increased acetylcholine release, the skeletal muscle in the external urethral sphincter contracts, causing urinary retention. In periods of decreased acetylcholine release, the skeletal muscle in the external urethral sphincter relaxes, allowing voiding of the bladder to occur.
The sensory function of the pudendal nerve provides sensory information about touch, pleasure, pain, and temperature to the penis, vagina, perineum, anal canal, and anus. The pudendal nerve also carries sympathetic autonomic fibers (but not parasympathetic fibers). It supplies sensation to the penis in males and the clitoris in females, which travel through the branches of the dorsal nerve of the penis and the dorsal nerve of the clitoris.
The pudendal nerve is crucial for sensation and function in the pelvic region, including the genitals and anus. It is also responsible for ejaculation. The pudendal nerve may be tested by elicitation of the anocutaneous reflex ("anal wink").
Muscle Enzymes: Unlocking Energy and Performance
You may want to see also
Explore related products
Muscarinic receptors in parasympathetic nerves
The detrusor 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 pelvic nerve acts to contract the detrusor muscle and stimulate micturition.
Muscarinic acetylcholine receptors are present throughout the local nervous system, in post-synaptic and pre-synaptic positions. They are also present on parasympathetic nerve terminals at the neuromuscular junction and in the parasympathetic ganglia. Muscarinic receptors form the principal receptors on the innervated tissue. Acetylcholine is used as a neurotransmitter, and muscarinic receptors are involved in the regulation of acetylcholine release.
Muscarinic receptors mediate autonomic function in all major organ systems. They are present on various organs throughout the body, including the neuronal, cardiac, musculoskeletal, pulmonary, digestive, and urinary systems. The overall function of the receptors is to achieve the "rest and digest" function of the parasympathetic nervous system. The parasympathetic nervous system functions as the unconscious restorative and energy-conserving system, in contrast to the sympathetic nervous system, which readies the body for "fight or flight".
Activation of muscarinic receptors on the nerve terminals can enhance (through M1 receptors) or suppress (through M4 receptors) transmitter release, depending on the intensity of neural firing. Muscarinic receptors also play a role in the dopamine reward system pathway. Abnormal muscarinic receptor function has been correlated with diseases such as Alzheimer's disease, Parkinson's disease, schizophrenia, and epilepsy.
Cardiac Muscle Contractions: Unconscious, Voluntary, or Both?
You may want to see also
Explore related products
Somatic axons in the pudendal nerve
The pudendal nerve is a major nerve in the pelvic region, carrying motor and sensory axons from the ventral rami of the sacral spinal nerves S2-S4. It is a mixed nerve with sensory, motor, and autonomic functions. The pudendal nerve is crucial for sensation and function in the pelvic region, including the genitals and anus. It provides sensory information about touch, pleasure, pain, and temperature to the penis, vagina, perineum, anal canal, and anus.
The pudendal nerve is involved in controlling somatic muscles, including penile and clitoral erection, and ejaculation in males. It innervates the external anal and urethral sphincters, allowing for the voluntary control of defecation and micturition. The somatic axons in the pudendal nerve release acetylcholine (ACh), which produces a contraction of the external sphincter striated muscle by activating nicotinic cholinergic receptors.
The pudendal nerve has several branches, including the inferior rectal nerve and the perineal nerve. The inferior rectal nerve carries somatic motor fibers to the external anal sphincter and sensory information to the anal canal. The perineal nerve supplies motor and sensory fibers to the structures in the urogenital triangle, including the external urethral sphincter, and provides sensory information to the perineum and the labia or scrotum.
Damage to the pudendal nerve can result in sexual dysfunction, urinary incontinence, and fecal incontinence. Pudendal nerve entrapment syndrome is a rare type of nerve compression syndrome that can cause chronic stabbing pain. This condition can be caused by various factors, including accidents, trauma, complications from pelvic surgeries, diabetes, difficult labor and delivery, prolonged pressure on the nerve, radiation therapy, tumors, or cysts.
Tracheal Muscle: Where Does It Originate?
You may want to see also
Explore related products
The detrusor muscle is smooth muscle
The detrusor muscle, also known as the detrusor urinae muscle, is a smooth muscle found in the wall of the bladder. It is responsible for the contraction of the bladder during urination, allowing for the release of urine. The detrusor muscle remains relaxed when the bladder is storing urine.
The muscle fibres of the detrusor are arranged in a swirl or whorl pattern, enabling them to work together to produce a powerful contraction of the bladder. The detrusor muscle is continuous with the internal urethral sphincter, which controls the flow of urine. These fibres originate from the posterior surface of the pubis and pass longitudinally up the inferior surface of the bladder, over its apex, and then down to attach to the prostate in males or the front of the vagina in females. At the sides of the bladder, the fibres intersect each other obliquely.
The detrusor muscle is innervated by the pelvic nerve (S2-S4), which is a parasympathetic nerve. Increased signalling from this nerve leads to contraction of the detrusor muscle and stimulation of micturition. Additionally, the somatic pudendal nerve (S2-4) provides voluntary control over micturition by innervating the external urethral sphincter. The bladder also contains sensory (afferent) nerves that signal the need to urinate when the bladder is full.
Abnormalities in the detrusor muscle or bladder innervation can result in incontinence or voiding dysfunction. The detrusor muscle plays a crucial role in maintaining bladder function and ensuring the smooth elimination of urine.
Developing Elbow Muscles: Strategies for Success
You may want to see also
Frequently asked questions
The detrusor muscle, also known as the detrusor urinae muscle, is the smooth muscle component of the urinary bladder.
The detrusor muscle remains relaxed to allow the bladder to store urine, and contracts during urination to release urine.
The detrusor muscle is innervated by the parasympathetic and sympathetic autonomic fibres of the pelvic and hypogastric nerve plexuses, respectively.
The nerve that innervates the detrusor muscle plays a role in stimulating micturition. Increased signals from this nerve cause contraction of the detrusor muscle, stimulating urination.
Abnormalities in the detrusor muscle or its innervation can result in incontinence or voiding dysfunction.
