external anal sphincter การใช้

• This is most likely a denervation injury to the external anal sphincter.
• Hemorrhoid cushions are important for internal and external anal sphincter pressure may also be involved in hemorrhoid symptoms.
• Treatment depends on where the fistula lies, and which parts of the internal and external anal sphincters it crosses.
• Relaxation increases the angle between rectum and anus, allowing defecation in conjunction with relaxation of the internal and external anal sphincters.
• This means that the internal anal sphincter contributes more to the resting tone of the anal canal than the external anal sphincter.
• Anal fistulae originate from the anal glands, which are located between the internal and external anal sphincter and drain into the anal canal.
• The external anal sphincter, by contrast, is made up of skeletal ( or striated muscle ) and is therefore under voluntary control.
• This finding was shown to be absent in healthy subjects, and may be the cause of denervation-related atrophy of the external anal sphincter.
• The relevant anatomy includes : the rectum, the anal canal and the muscles of the pelvic floor, especially puborectalis and the external anal sphincter.
• The internal and external anal sphincters along with the puborectalis muscle allow the feces to be passed by muscles pulling the anus up over the exiting feces.
• In some cases, the fibers of the deeper layer of the external anal sphincter cross over in front of the anus and are continued into this muscle.
• It carries sensation from the external genitalia of both sexes and the skin around the anus and perineum, as well the female external urethral sphincter and the external anal sphincter.
• External anal sphincter ( EAS ) dysfunction is associated with impaired voluntary control, whereas internal anal sphincter ( IAS ) dysfunction is associated with impaired fine tuning of fecal control.
• As mentioned before, the motoneurons of the external urethral sphincter and the external anal sphincter are found in ventral horn of the second sacral segment known as Onuf s nucleus.
• The internal and external anal sphincters along with the puborectalis muscle allow the feces to be passed by pulling the anus up over the exiting feces in shortening and contracting actions.
• Alternatively, the intussuscepting rectum may lead to chronic stimulation of the rectoanal inhibitory reflex ( RAIR-contraction of the external anal sphincter in response to stool in the rectum ).
• These are the internal anal sphincter and the external anal sphincter, which are circular muscles that normally maintain constriction of the orifice and which relaxes as required by normal physiological functioning.
• Relaxation of the internal and external anal sphincters allows the feces to exit from the anus, finally, as the levator ani muscles pull the anus up over the exiting feces.
• Distension of the rectum normally causes the internal anal sphincter to relax ( rectoanal inhibitory response, RAIR ) and the external anal sphincter initially to contract ( rectoanal excitatory reflex, RAER ).
• In patients with anismus, the puborectalis and the external anal sphincter muscles fail to relax, with resultant failure of the anorectal angle to straighten out and facilitate evacuation of feces from the rectum.