Answer: Rectum.

Rectum: The last section of the intestine, connected to the sigmoid colon above and the anus below.

The rectum is located in the pelvic cavity and is the end of the large intestine. It descends along the front of the sacrum and coccyx, passes through the pelvic diaphragm, and terminates at the anus. The rectum above the pelvic diaphragm is called the pelvis, and the parts below are called the anus and anal canal. The lower end of the basin sometimes expands in a fusiform shape and is called the rectal ampulla. The rectum has two curves in the anteroposterior direction.

The upper curve is called the rectosacral flexure, which bulges toward the back, and the lower curve, which bulges toward the front, is called the recto-perineal flexure. When performing sigmoidoscopy, the colon must be inserted slowly along these two curves to avoid damaging the intestinal wall. In front of the male rectum are the bladder, seminal vesicles and prostate, and in front of the female rectum are the uterus and vagina, so these organs can be palpated through the rectum.

Extension:

The rectum is the last section of the digestive tube, located in the pelvic cavity. Its course is not a straight line but has several bends. It has three transverse folds, two of which are in One on the left, one on the right, with different heights. Viewed from below, the three folds overlap each other, surrounding the rectum and supporting feces.

The section of the rectum near the anus expands into the rectal ampulla, which contains 6 to 10 vertical folds called anal columns, and a venous plexus above the anal columns. The rectum ends with the anus. The anus has the external anal sphincter and the internal anal sphincter. The external anal sphincter is a voluntary muscle and is a perineal muscle.

The internal anal sphincter is a thickened circular muscle in the intestine and is a smooth muscle. Its function is to completely remove the waste remaining in the anal canal when defecation is completed.

The rectum refers to the section of intestinal tube that starts from the sigmoid colon in front of the third sacral vertebra, goes down in front of the sacrum and coccyx, passes through the pelvic diaphragm and migrates to the anal canal. The rectum is the section of the digestive tube located in the lower part of the pelvic cavity. The rectum is not straight and forms two obvious curvatures in the sagittal plane, namely the rectosacral flexure and the rectoperineal flexure.

There are also three lateral bends on the coronal plane, but they are not constant. Generally, the larger one in the middle is convex to the left, and the upper and lower two are convex to the right. When performing clinical proctoscopy and sigmoidoscopy, attention should be paid to these curved parts to avoid damaging the intestinal wall.

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