How long is the human rectum?

Many people don't know much about medical care and anatomy, so they don't know enough about how long the human rectum is. In order to have a specific understanding of these aspects, they want to know how long the human rectum is and what its structure is. In order for you to have a comprehensive understanding, take a look at the introduction below. I hope you can have a comprehensive understanding of how long the human rectum is and its structure.

The upper end of the rectum is at the level of the third sacral vertebra, connected to the sigmoid colon, and connected to the anal canal at the dentate line. About 12 to 15 cm long. The upper end of the rectum is similar in size to the colon, and its lower end expands into the rectal ampulla, which is a temporary storage site for feces before it is discharged. The lowest end becomes thinner and connects to the anal canal. The position of the rectum in the pelvic cavity is closely related to the ventral surface of the sacrum and has the same curvature as the sacrum. The rectum has curves that bulge to the left and right in the frontal plane. When performing a sigmoidoscopy, these curves must be paid attention to to avoid damaging the intestinal wall. The upper 1/3 of the rectum is covered with peritoneum on the front and both sides; the middle 1/3 is covered with peritoneum in front and folds forward to form the rectovesical pouch or rectouterine pouch; the lower 1/3 is entirely located outside the peritoneum, so the rectum is an intestine that is half inside and half outside the abdominal cavity. The rectum has no true mesentery, but the peritoneum above and behind it often surrounds the superior rectal blood vessels and cellulite, so some people call it the rectal mesentery. There are lateral ligaments on both sides that secure the rectum to the side walls of the pelvis. The mucosa of the rectal ampulla has three folds: upper, middle and lower, which contain circular muscle fibers and are called rectal valves. The middle valve is often opposite to the peritoneal reflection plane. However, the number of rectal valves can vary and can be up to 5. When the rectum expands, the rectal valve disappears, which has the function of preventing the discharge of feces.

The structure of the rectum

The mucosa on the inner surface of the rectal ampulla forms 2 to 3 semilunar transverse rectal folds, one of which is located on the anterior right wall. It is large and constant, about 7 cm away from the anus, which is equivalent to the level of the peritoneal fold. This transverse fold is often used as a landmark when determining the position of the rectal tumor and the peritoneal cavity through sigmoidoscopy. These folds serve to support stool.

The mucosa of the upper part of the rectum and anal canal forms 6 to 10 longitudinal mucosal folds, called anal columns. The lower ends of each column are connected by small semi-lunar folds, called anal valves. There is a small depression between the anal valve and the lower ends of the two adjacent columns, called the anal sinus. The anal valves and the lower end of the anal columns are connected to form a serrated circular line, called the dentate line, which is the dividing line where the skin and mucous membrane transition together. The smooth and slightly shiny annular area below the dentate line is called the anal pecten or hemorrhoidal ring. There are abundant venous plexuses on the deep surface of the hemorrhoidal ring and anal column. If this plexus expands due to congestion, hemorrhoids are easily formed. Those above the dentate line are called internal hemorrhoids, and those below the dentate line are called external hemorrhoids.

The rectum is surrounded by internal and external sphincters. The internal anal sphincter is composed of thickened circular smooth muscle of the rectal wall, which can assist defecation when contracted. The external anal sphincter is a circular muscle bundle located around the internal anal sphincter. It is a skeletal muscle that can sphincter the anus at will.

How long is the human rectum? What is its structure? The above content provides detailed answers for many friends, so if you want to know more details, you can fully understand the above introduction. I believe that through understanding, you can have a comprehensive understanding of the rectum and what is the structure of the rectum? So if you want to fully understand, you can read the above introduction as soon as possible.