What is the Difference Between Perineum and Peritoneum

The main difference between perineum and peritoneum is that the perineum is the body region between the pubic arch and tailbone, whereas the peritoneum is the lining of the abdominal cavity. 

The perineum and peritoneum are two structures that occur in the animal body. They occur in the abdomen. 

Key Areas Covered

1. What is Perineum
– Definition, Structure, Function
2. What is Peritoneum
– Definition, Structure, Function
3. Similarities Between Perineum and Peritoneum
– Outline of Common Features
4. Difference Between Perineum and Peritoneum
– Comparison of Key Differences

Key Terms 

Perineum, Peritoneum

What is Perineum

Perineum is a thin layer of skin between the genitals and anus. Also, it contains the tissue that makes up the bottom of the pelvic cavity. Internally, it occurs below the pelvic floor’s primary muscle, the levator ani. It begins at the pubic symphysis, the joint in front of the pelvis connecting the left and right pelvic bones. It reaches the tailbone from the back. Also, it extends from sides to the sitz bones from the left and right sides of the pelvis. Structure-wise, the perineum is diamond-shaped. It extends from one sitz bone to the pelvis. It has two triangle regions: the urogenital triangle and the anal triangle. The urogenital triangle contains the urethra, genitals, and other associated muscles. In comparison, the anal triangle includes the anal sphincter and the opening of the anus.

Figure 1: Perineum

Furthermore, the length of the perineum is around 1.5 inches. It is made up of fatty tissue, multiple layers of connective tissue, muscles, and membranes. The pudendal nerve runs through it, and the nerve branches into many regions, such as the pelvic region, anus, and pelvic floor muscles. The pudendal nerve makes sexual sensations and helps to poop. 

What is Peritoneum

The peritoneum is the serous membrane that covers the peritoneal cavity. Therefore, it serves as a continuous membrane, covering the abdominal viscera and providing support and pathways for blood and lymphatic vessels to pass in and out from the viscera. However, the peritoneum is a double-layered structure consisting of a mesothelial layer of simple squamous epithelium and a thin connective tissue layer. Usually, the two types of peritonea are the parietal peritoneum and the visceral peritoneum. 

Parietal Peritoneum 

The parietal peritoneum is the part of the peritoneum lining the internal surface of the abdominopelvic wall. Since it develops from the somatic mesoderm, the parietal peritoneum receives the same somatic nerve supply. The parietal peritoneum is sensitive to pressure, laceration, pain, and temperature. Meanwhile, its pain is a well-localized signal.

Figure 2: Peritoneum

Visceral Peritoneum 

The visceral peritoneum is the second part of the peritoneum, covering the outer layer of most of the abdominal viscera. However, it develops from the splanchnic mesoderm and has the same autonomic nerve supply. It is sensitive to stretch and chemical irritation while producing poorly localized pain.  

Similarities Between Perineum and Peritoneum

• The perineum and peritoneum are two regions of the abdomen of the animal body. 

Difference Between Perineum and Peritoneum

Definition

Perineum refers to the tiny patch of sensitive skin between your genitals (vaginal opening or scrotum) and anus, and it’s also the bottom region of your pelvic cavity, while peritoneum refers to the serous membrane lining the cavity of the abdomen and covering the abdominal organs.

Type

The perineum is sensitive skin, while the peritoneum is a serous membrane.

Function

Perineum strengthens the pelvic floor, while the peritoneum supports the organs of the abdomen and acts as a conduit for the passage of nerves, blood vessels, and lymphatics. 

Conclusion

In brief, the perineum and peritoneum are two anatomical structures that occur in the abdomen of animals. The perineum is sensitive skin that strengthens the pelvic floor. In comparison, the peritoneum is a serous membrane that supports the organs of the abdomen. It acts as a conduit for the passage of nerves, blood vessels, and lymphatics. Therefore, the main difference between the perineum and peritoneum is their structure and function.  

References:

1. Perineum: Location, anatomy, Function & Conditions. Cleveland Clinic. https://my.clevelandclinic.org/health/body/24381-perineum
2. Kalra A, Wehrle CJ, Tuma F. Anatomy, Abdomen and Pelvis, Peritoneum. [Updated 2022 Jul 25]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-.

Image Courtesy:

1. “Diagram showing the anatomy of the vulva CRUK 285.” By Cancer Research UK – Own work (CC-BY SA 4.0) via Commons Wikimedia
2. “2403 The PeritoneumN” By OpenStax College – Own Work (CC-BY 3.0) via Commons Wikimedia