Rectum and Anal Canal Flashcards
Where does the rectum being?
At S3 as a proximal continuation of the sigmoid colon
Where does the rectosigmoid junction lie?
Anterior to S3
Where does the rectum end?
It ends at the inferior part of the coccyx anterior and pubic symphysis anterior to continue as the anal canal
Which muscle does the rectum pass through?
Puborectalis muscle
What forms as the rectum follows the curve of the sacrum and coccyx?
Sacral flexure of the rectum
What is the anorectal flexure of the rectum?
The approximately 90 degree angle formed as the rectum ends at the tip of the coccyx after taking a sharp posteroinferior angle
At which muscle does the anorectal flexure occur at?
Puborectalis muscle
What is the function of the puborectalis muscle on the anorectal flexure?
It enforces the angle of the flexure and prevents the process of defaecation through contraction
What is the shape of the rectum?
S-shaped
What forms as a result of the s-shape of the rectum?
Lateral flexures of the rectum
What is opposite the lateral flexures of the rectum internally?
Transverse rectal folds or Valves of Houston
What is the dilated, lower third of the rectum?
The rectal ampulla
How is the rectum covered by peritoneum?
Superior third = anteriorly and laterally
Middle third = anteriorly only
Inferior third = no covering and is subperitoneal
What septum exits anteriorly in the lower third of the rectum in males?
Rectovesical septum
What septum exists anteriorly in the lower third of the rectum in females?
Rectovaginal septum
