The external urethral sphincter originates at the ischiopubic ramus and inserts into the intermeshing muscle fibers from the other side. It is controlled by the deep perineal branch of the pudendal nerve.
Do you have voluntary control over the external urethral sphincter?
The internal urethral sphincter and the external urethral sphincter both provide muscle control for the flow of urine. The internal sphincter is involuntary. It surrounds the opening of the bladder to the urethra and relaxes to allow urine to pass. The external sphincter is voluntary.
What are the two reflexes that control urination?
The micturition reflex is a bladder-to-bladder contraction reflex for which the reflex center is located in the rostral pontine tegmentum (pontine micturition center: PMC). There are two afferent pathways from the bladder to the brain. One is the dorsal system and the other is the spinothalamic tract.
What is the guarding reflex?
The term Guarding Reflex refers to a progressive, involuntary increase in the external urethral sphincter activity during bladder filling. This is a mechanism of continence, preventing from unwanted urine leakage in situation of stress.
What do you mean by micturition?
urination
Definition of micturition : the act or process of micturating : urination As the bladder fills, spinal sensory afferents relay this information to a region in the pons that coordinates micturition.
What happens when the external urethral sphincter is voluntary relaxed?
At an appropriate time and place, the external urethral sphincter can then be voluntarily relaxed, allowing the passing of urine. A secondary function of the urethral sphincter complex is to prevent retrograde ejaculation of semen into the bladder. In males, semen and urine share the urethra as a passageway.
Which muscle controls the urethral sphincter?
A layer of muscle called the urogenital diaphragm supplies support for the contents of the pelvis and acts as the external urethral sphincter. It provides a second means of stopping the escape of urine from the body. This sphincter is under voluntary control.
What do you mean by micturition reflex?
micturition reflex. contraction of the walls of the bladder and relaxation of the trigone and urethral sphincter in response to a rise in pressure within the bladder; the reflex can be voluntarily inhibited and the inhibition readily abolished to control micturition.
What is micturition reflex process?
The micturition reflex involves a coordinated and sustained contraction of the detrusor muscle (the detrusor reflex) along with simultaneous relaxation of the urethra. Detrusor contraction without urethral relaxation is called reflex dyssynergia.
What happens in micturition reflex?
The micturition reflex is ultimately generated from the level of the spinal cord after it receives reflexes from the pontine region in the brain. Once the bladder and the urethra receive the signals to empty the bladder, the two sphincters relax and the detrusor muscle causes the contractions of the bladder.
How does the urethral sphincter prevent involuntary bladder emptying?
Throughout bladder filling, the parasympathetic innervation of the detrusor is inhibited and the smooth and striated parts of the urethral sphincter are activated, preventing involuntary bladder emptying. This process is organized by urethral reflexes known collectively as the ‘guarding reflex’.
What is the filling phase of the urethral detrusor?
-The filling phase is characterized by voluntary contraction of the external urethral sphincter, with sympathetic contraction of the inner urethral sphincter. -The sympathetic nervous system also enables the detrusor to distend without reflex contractions, unlike that which happens in most voluntary muscles.
What part of the brain controls the external urethral sphincter?
In addition, the motor cortex controls the voluntary muscle of the external urethral sphincter. The decision to void implies that the prefrontal cortex suppresses the tonic inhibition of the afferents from the PAG to the PMC.
What are the two types of urethral sphincters?
In simple terms we can divide this complex into two urethral sphincters; an internal urethral sphincter and an external urethral sphincter. The internal urethral sphincter is located at the junction of the urethra and the urinary bladder. It is made of smooth muscle, and is under autonomic or involuntary control.
