Where is the rectum?

People often find that the various parts of the body are very magical because each part grows in a different location. Moreover, it is sometimes difficult for people to identify the specific locations of important parts, so it is necessary to understand some of the structures of the human body. The rectum is a body part that people are familiar with, but once a disease occurs, it is difficult to distinguish the location of the rectum. So where is the rectum?

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

Physiological structure

The rectum is located in the pelvis and is the last part of the large intestine. The total length is 12 to 15 cm. It descends along the front of the sacrum and coccyx, passes through the pelvic diaphragm, and ends at the anus. The part of the rectum above the pelvic diaphragm is called the pelvic part, and the part below is called the anal part and anal canal. The lower end of the pelvis sometimes becomes fusiform and enlarged, called the ampulla of the rectum. The rectum has two bends in the anterior-posterior direction. The upper curve is called the rectosacral flexure, which convexes toward the posterior side, and the lower curve convexes toward the anterior side, which is called the rectoperineal flexure. When performing a sigmoidoscopy, the tube must be inserted slowly, following these two bends, to avoid damaging the intestinal wall. The bladder, seminal vesicles and prostate are in front of the male rectum, and the uterus and vagina are in front of the female rectum, so these organs can be palpated through the rectum.

Anatomy

The rectum is the last section of the digestive tract, located in the pelvic cavity, about 15 to 20 cm long. Its course is not a straight line but has several bends. It has three transverse folds, two on the left and one on the right, with different heights. When 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 above the anal columns there is a venous plexus. The rectum ends at the anus. The anus has an external anal sphincter and an internal anal sphincter. The external anal sphincter is a voluntary muscle and belongs to the perineal muscles. The internal anal sphincter is formed by the thickening of the intestinal circular muscle and is a smooth muscle. Its function is to completely remove waste remaining in the anal canal at the end of defecation.

The rectum refers to the section of the intestine that starts from the sigmoid colon in front of the third lumbar vertebra, descends along the front of the sacrum and coccyx, passes through the pelvic diaphragm and transitions to the anal canal. The rectum is a section of the digestive tract located in the lower part of the pelvis, with a total length of 10 to 14 cm. The rectum is not straight, forming two obvious bends in the sagittal plane, namely the rectosacral flexure and the rectoperineal flexure. There are also three curves protruding to the side on the coronal plane, but they are not constant. Generally, the larger one in the middle bulges to the left, and the upper and lower two bulge to the right. When performing proctoscopy and sigmoidoscopy clinically, attention should be paid to these bends to avoid damaging the intestinal wall.