How can external dampness invade the body?

External dampness is understood in traditional Chinese medicine as an environmental factor that can invade the body, particularly affecting the body's channels and leading to various symptoms. When dampness penetrates through the channels, it notably manifests as conditions such as stiff joints, a sensation of heaviness in the limbs, and even a sluggish feeling throughout the body. This is largely due to dampness obstructing the normal flow of Qi and blood within the channels, which can create stagnation and discomfort.

While other factors like diet, the internal impact on the Stomach and Spleen, and implications for the Liver due to Qi stagnation are important, they pertain to different aspects of TCM pathology and do not specifically address the entry of external dampness into the body. The primary point revolves around the way that environmental dampness affects the musculoskeletal system and overall vitality through the channels, creating very tangible physical symptoms like stiffness and heaviness in the limbs.