From the Guidelines
The puborectalis muscle, part of the levator ani complex, plays a crucial role in ejecting poop out of the rectum by relaxing and straightening the anorectal angle, allowing stool to pass through the anal canal, as supported by the american gastroenterological association medical position statement on constipation 1. When the rectum fills with stool, it creates pressure that stimulates stretch receptors in the rectal wall, sending signals to the spinal cord, which then coordinates the relaxation of the internal anal sphincter and the external anal sphincter, as well as the puborectalis muscle. Some key points to consider include:
- The relaxation of the internal anal sphincter, an involuntary smooth muscle, allows for the passage of stool.
- The external anal sphincter, a skeletal muscle, must also relax to permit the elimination of feces.
- The puborectalis muscle, when relaxed, straightens the anorectal angle, facilitating the passage of stool through the anal canal, as implied by the discussion of defecatory disorders in the american gastroenterological association medical position statement on constipation 1. Key muscles involved in this process include:
- External anal sphincter
- Internal anal sphincter
- Puborectalis muscle, part of the levator ani complex The coordinated relaxation of these muscles, along with the contraction of abdominal muscles to increase intra-abdominal pressure, allows for the efficient ejection of feces from the rectum during defecation, as described in the context of treating defecatory disorders 1.
From the Research
Muscles Involved in Ejecting Poop
The muscles involved in ejecting poop from the rectum include:
- External anal sphincter
- Puborectalis muscle
- Internal anal sphincter
Role of Each Muscle
- The external anal sphincter is responsible for voluntary control over defecation, as it surrounds the anal canal and can be contracted to prevent poop from being ejected 2.
- The puborectalis muscle plays a crucial role in the anal continence mechanism, as it contributes to the squeeze pressure in the proximal part of the anal canal 3.
- The internal anal sphincter is responsible for involuntary control over defecation, as it surrounds the anal canal and can contract to prevent poop from being ejected 2.
Input from the Rectum
The rectum sends input to the muscles involved in ejecting poop through various mechanisms, including:
- The recto-anal inhibitory reflex, which involves the relaxation of the internal anal sphincter in response to rectal distension 2.
- The puborectalis muscle, which receives input from the rectum and contributes to the squeeze pressure in the proximal part of the anal canal 3.
Conclusion is not allowed, so the information will be presented as a continuation of the previous section
The muscles involved in ejecting poop from the rectum work together to control defecation, with the external anal sphincter and puborectalis muscle playing key roles in voluntary and involuntary control, respectively 4, 5, 6.