Which of the following are considered appendages of the skin?

Hair, nails, and sweat glands are classified as appendages of the skin because they originate from the dermis, which is the skin's inner layer. These structures are vital for a variety of functions: hair provides insulation and protection, nails protect the tips of fingers and toes, and sweat glands play a critical role in thermoregulation and excretion. Each of these appendages has a specific purpose that contributes to the overall health and functionality of the skin as an organ.

Blood vessels, while crucial for supplying nutrients and oxygen to the skin and removing waste products, are not considered appendages. Instead, they are part of the vascular system supporting the skin’s functions. Connective tissues provide structure and support but are not classified as skin appendages themselves. Muscles, particularly those associated with the skin (such as arrector pili, which cause hair to stand up), are also not considered appendages but rather part of the muscular and integumentary systems.