American Academy of Professional Coders (AAPC) Practice Exam

Which type of membrane is specifically associated with the lining of cavities including the thoracic cavity?

1. Mucous Membrane

2. Serous Membrane

3. Synovial Membrane

4. Meninges

The correct answer is: Serous Membrane

The serous membrane is specifically associated with the lining of body cavities, including the thoracic cavity. This type of membrane produces serous fluid, which serves to reduce friction between the organs and the cavity walls, facilitating movement, especially in areas like the lungs and heart. The serous membrane is composed of a simple squamous epithelium (mesothelium) and underlying connective tissue, forming a double-layered structure where one layer lines the cavity (parietal layer) and the other covers the organs within it (visceral layer). In contrast, the mucous membrane primarily lines body cavities that open to the outside environment, such as the respiratory, digestive, and urogenital tracts, and is characterized by its secretion of mucus. Synovial membranes are found in joint cavities, producing synovial fluid to lubricate joints, while meninges are protective membranes covering the brain and spinal cord, which is unrelated to the cavities mentioned in the question. Each of these other types serve distinct functions and locations within the body, highlighting why the serous membrane is the correct choice for the lining related to the thoracic cavity.