Visceral layerThe inner wall, which covers the organ itself.
Parietal layerThe outer wall, which lines the wall of the cavity.
Serous cavityThe space between the two layers, wet with serous fluid.
In the trunk 9
Parietal pleuraIt lines the chest wall and covers the diaphragm.
Visceral pleuraIt covers the lung's surface.
Pleural cavityThe potential space between the two layers of pleura.
Parietal pericardiumThe outer serous layer; it lines the fibrous pericardium.
Visceral pericardium (epicardium)It covers the heart and is also called the epicardium.
Pericardial cavityThe space between the two serous layers around the heart.
Parietal peritoneumIt lines the wall of the abdomen.
Visceral peritoneumIt is wrapped around the organs of the abdomen.
Peritoneal cavityThe potential space between parietal and visceral peritoneum.
How this list was compiled: Every name and detail line was read on 2026-10-03 and kept only where two independent sources give it. (1) Henry Gray, Anatomy of the Human Body (1918, public domain): The Pleurae, The Pericardium and The Abdomen (the peritoneum), https://www.theodora.com/anatomy/the_pleurae.html , https://www.theodora.com/anatomy/the_pericardium.html and https://www.theodora.com/anatomy/the_abdomen.html . (2) Wikipedia, text only: Pleura, Pericardium, Peritoneum and Serous fluid, https://en.wikipedia.org/wiki/Pleura . (3) US National Cancer Institute, SEER Training Modules, Membranes, https://training.seer.cancer.gov/anatomy/cells_tissues_membranes/membranes.html . (4) Textbook passages found by archive.org's full-text search: Human Anatomy (2012), https://archive.org/details/humananatomy0000mcki ; Laboratory Textbook of Anatomy and Physiology (1998), https://archive.org/details/laboratorytextbo0000wood ; Atlas and Text-book of Human Anatomy (1906, public domain), https://archive.org/details/atlasandtextboo01thomgoog ; Anatomy and Physiology the Easy Way (2004), https://archive.org/details/anatomyphysiolog0000alca_v8e1 ; Anatomical Terms and Their Derivation (2007), https://archive.org/details/anatomicaltermst0000liso . The drawing is our own. Licence: own work
The drawing: Drawn for this site on 2026-10-03 from plain geometry. Own original drawing; nothing traced or copied. Licence: own work
How it works
The first view is the model: a fist pushed into a balloon. The second shows the labeled serous membranes of the trunk, the pleura, the pericardium and the peritoneum, each drawn to the same pattern.
Read the full guide
The model
The fist is the organ and the balloon is the membrane. The wall wrapped around the fist is the visceral layer. The outer wall is the parietal layer. The two are one sheet, joined at the wrist, and the space between them is the serous cavity.
In the trunk
The pleura wraps each lung, the pericardium the heart and the peritoneum the organs of the abdomen. In each, the parietal layer lines the wall, the visceral layer covers the organ, and a film of serous fluid lies in the cavity. The layers and cavities are drawn far thicker than life.
Parietal comes from the Latin for wall; visceral from viscera, the organs.
Questions and answers
What are the three serous membranes?
The pleura around each lung, the pericardium around the heart and the peritoneum in the abdomen. Each is one thin sheet folded into two layers, with a slim cavity and a little fluid between them.
What is the difference between the parietal and visceral layers?
The parietal layer lines the wall of the cavity. The visceral layer covers the organ. The two are one continuous sheet, joined where the organ is attached.
What does serous fluid do?
It wets the facing surfaces of the two layers, so an organ can move against the wall of its cavity with very little friction.
Why is a fist in a balloon used to explain serous membranes?
The fist stands for the organ and the balloon for the membrane. The part of the balloon touching the fist is the visceral layer, the outer part is the parietal layer, and the space inside is the cavity.