Ano Rectum

The rectum, endodermal in origin, is the dorsal component of the cloaca, which is partitioned by the anorectal septum. The anal canal is an invagination of ectodermal tissue. The anorectum develops from fusion of the rectum and the anal canal, which occurs at 8 weeks, when the anal membrane ruptures. The dentate line marks the point of fusion and the transition from endodermal to ectodermal tissue.


The rectum is 12–15 cm long. It extends from the rectosigmoid junction, marked by the fusion of the tenia, to the anal canal, marked by the passage into the pelvic floor musculature (Figure 31–1). The rectum lies in the sacrum and forms three distinct curves, creating folds known as the valves of Houston. The proximal and distal curves are convex to the left and the middle curve is convex to the right. The middle curve roughly marks the anterior peritoneal reflection, which is 6–8 cm above the anus. The rectum gradually undergoes transition from intraperitoneal to extraperitoneal beginning 12–15 cm from the anus and becoming completely extraperitoneal 6–8 cm from the anus. The rectum is fixed posteriorly, laterally, and anteriorly by the presacral (Waldeyer) fascia, the lateral ligaments, and Denonvilliers fascia, respectively.

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Dhanvandhiri Vaidyasala

Dhanvandhiri Vaidyasala is a traditional Herbal Hospital located in Theni. Dhanvandhiri Vaidyasala provides 'Holistic' Methods of Treatments like Ayurvedha, Siddha and Homeopathy.

Contact Information

Theni-Kandamanur Road,

Aranmanai Pudhur,

Theni - 625531

(+91) 98427 75242

Opposite to Vivekananda School,

School Road, Sakthivel Nagar,


Chennai - 600082

(+91) 7358560776