Which layer lies between the mucosa and the muscularis externa?

Which layer lies between the mucosa and the muscularis externa?

• A. Serosa
• B. Submucosa
• C. Mucosa
• D. Muscularis externa

Answer: (B)

The wall of the gastrointestinal tract is organized in sequential layers: the mucosa lining the lumen, then the submucosa, followed by the muscularis externa, and finally the serosa (or adventitia in some regions) on the outer surface. The layer between the mucosa and the muscularis externa is the submucosa. It is a layer of dense connective tissue that supports the mucosa and contains blood vessels, lymphatics, and nerves, including the submucosal nerve plexus (Meissner) that helps regulate secretions and blood flow. External to the submucosa is the muscularis externa, which handles peristalsis and segmentation with its two muscle layers and the myenteric plexus.

The wall of the gastrointestinal tract is organized in sequential layers: the mucosa lining the lumen, then the submucosa, followed by the muscularis externa, and finally the serosa (or adventitia in some regions) on the outer surface. The layer between the mucosa and the muscularis externa is the submucosa. It is a layer of dense connective tissue that supports the mucosa and contains blood vessels, lymphatics, and nerves, including the submucosal nerve plexus (Meissner) that helps regulate secretions and blood flow. External to the submucosa is the muscularis externa, which handles peristalsis and segmentation with its two muscle layers and the myenteric plexus.