The main difference between visceral and parietal is that visceral is one of the two layers of the serous membrane, covering the organs, whereas parietal is the second layer of the serous membrane, lining the walls of the body cavity. Therefore, the term ‘visceral’ is used to describe the structures related to organs, while the term ‘parietal’ is used to describe the structures related to the wall of the body cavity.

Visceral and parietal are two anatomical terms that describe the structures of the serous membrane. Generally, the serous membrane or the serosa is a thin membrane that covers the walls of the organs of the thoracic and the abdominopelvic cavity. Moreover, the serous membranes associated with the three serous cavities in the human body are the pericardium, pleura, and the peritoneum. 

Key Areas Covered 

1. What is Visceral
     – Definition, Position, Importance
2. What is Parietal
     – Definition, Position, Importance
3. What are the Similarities Between Visceral and Parietal
     – Outline of Common Features
4. What is the Difference Between Visceral and Parietal
     – Comparison of Key Differences

Key Terms 

Parietal, Pericardium, Peritoneum, Pleura, Serous Membrane, Visceral

What is Visceral

Visceral is the serous membrane that covers the viscera or organs. It is the innermost layer of the serous membrane. Generally, the pericardium, pleura, and the peritoneum are the three serous cavities in the human body. The pericardium is the serous membrane that surrounds the heart while pleura is the serous membrane that surrounds the lungs. On the other hand, the peritoneum is the serous membrane that surrounds the organs in the abdominopelvic cavity. Each of the three serous membranes consists of two layers: visceral and parietal.

Figure 1: The Greater Omentum

Furthermore, the visceral peritoneum is a part of the epicardium. Moreover, it extends to the beginning of the great vessels and becomes one with the parietal layer of the serous pericardium. The visceral pleura extends into the interlobar fissures while covering the outer surface of the lungs. It is also continuous with the parietal pleura at the hilum of the lungs. Furthermore, visceral peritoneum wraps around the visceral organs in the intraperitoneal space, and it gives rise to omenta. 

What is Parietal

The parietal is the second serous membrane that lines the wall of the body cavity. Therefore, it is the outermost layer of the serous membrane. Generally, three types of parietal serous membranes occur in the three serous cavities; pericardium, pleura, and peritoneum. Typically, parietal pericardium is fused to and inseparable from the fibrous pericardium. Parietal pleura, on the other hand, is the outer membrane of the pleura and it attaches to the inner surface of the thoracic cavity. Furthermore, it separates the pleural cavity from the mediastinum. Intercostal nerves and the phrenic nerve innervate the parietal pleura.

Figure 2: Visceral and Parietal Pleura

Moreover, the parietal peritoneum is attached to the abdominal wall and the pelvic walls. Furthermore, it gives rise to the mesenteries, which attach organs to the wall of the abdomen. 

Similarities Between Visceral and Parietal

• Visceral and parietal are the two layers of the serous membrane, which covers the cavities of the body. 
• Both are associated with the pericardium, pleura, and the peritoneum. 
• Moreover, these two terms are used to describe other anatomical structures related to the serous membrane. 
• Also, both are mesothelial layers made up of a secretory epithelial layer and a connective tissue layer underneath.  
• They secrete the serous fluid.  
• Besides, a potential space occurs between the two layers of the serous membrane, which is mostly empty, except for a few millimetres of serous fluid. 
• Furthermore, their main function is to protect and lubricate internal organs, allowing their internal movements. 

Difference Between Visceral and Parietal 

Definition 

Visceral refers to the viscera, the internal organs of the body, specifically those within the chest or abdomen, while parietal refers to relating to or denoting the wall of the body cavity. Thus, this is the fundamental difference between visceral and parietal.

In the Serous Membrane 

Visceral is one of the two layers of the serous membrane, which covers the organs, whereas parietal is the second layer of the serous membrane, lining the walls of the body cavity.  

Anatomical Structures 

Therefore, the term ‘visceral’ is used to describe the structures related to organs, which occur more deeply, while the term ‘parietal’ is used to describe the structures related to the wall of the body cavity. 

Conclusion 

Visceral is the term that mainly describes the innermost layer of the serous membrane, covering the internal organs. Moreover, this term is used to other anatomical structures related to the visceral serous membrane or organs, which occur more deeply in the body cavities. On the other hand, parietal is the term that describes the outermost layer of the serous membrane, lining the wall of the abdominal cavity. Furthermore, it is used to describe other anatomical structures related to the parietal serous membrane or structures related to the wall of a hollow organ. Therefore, the main difference between visceral and parietal is their relative position. 

References:

1. “Serous Membrane.” Wikipedia, Wikimedia Foundation, 16 Apr. 2019, Available Here.

Image Courtesy:

1. “Sobo 1909 564” By Dr. Johannes Sobotta – Atlas and Text-book of Human Anatomy Volume III Vascular System, Lymphatic system, Nervous system and Sense Organs (Public Domain) via Commons Wikimedia   
2. “2313 The Lung Pleurea” By OpenStax College – Anatomy & Physiology, Connexions Web site.  (CC BY 3.0) via Commons Wikimedia   

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