Difference between revisions of "Rectum - Anatomy & Physiology"
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**This is a short passage derived from the proctodeum (formed by invagination of the surface ectoderm). | **This is a short passage derived from the proctodeum (formed by invagination of the surface ectoderm). | ||
**Before joining the anal canal, the rectum becomes dilated to form the ''rectal ampulla''. | **Before joining the anal canal, the rectum becomes dilated to form the ''rectal ampulla''. | ||
− | *At the ''rectoanal'' junction, the lumen is constricted by longitudinal folds in the mucosa. | + | *At the '''rectoanal''' junction, the lumen is constricted by longitudinal folds in the mucosa. |
**These are normally pressed together to occlude the lumen. | **These are normally pressed together to occlude the lumen. | ||
Revision as of 15:00, 14 July 2008
Introduction
Structure
- Exists dorsal to the reproductive organs, bladder and urethra.
- The cranial portion of the rectum is attached to the dorsal body wall by a short mesorectum which is a continuation of the mesocolon.
- The mesorectum is reflected to continue with the parietal peritoneum of the pelvic cavity and to cover the urogenital organs ventrally.
- This forms the rectogenital pouch.
- Therefore the most distal part of the rectum is retroperitoneal.
- This distal, retroperitoneal part is directly attached to the vagina in the female and to the urethra in the male.
- The retroperitoneal space is filled with soft tissue rich in fat.
- The anal canal joins the bowel to the exterior.
- This is a short passage derived from the proctodeum (formed by invagination of the surface ectoderm).
- Before joining the anal canal, the rectum becomes dilated to form the rectal ampulla.
- At the rectoanal junction, the lumen is constricted by longitudinal folds in the mucosa.
- These are normally pressed together to occlude the lumen.
Function
Vasculature
Innervation
Lymphatics
Histology
Rectum
- Epithelium is columnar.
- Goblet cells are present in the mucosa.
Recto-Anal Junction
- Termination of the lamina muscularis and longitudinal layer of the tunica muscularis.
- The circular layer of the tunica muscularis forms the internal anal sphincter.
- The external anal sphincter is formed from skeletal muscle.
- Epithelium changes from columnar to stratified squamous non-keratinised.