Final answer:
Muscles are classified as either superficial or deep with respect to their location beneath the skin. Superficial muscles are closer to the surface, making them more visible, whereas deep muscles are situated further in and are integral to the function of internal organs.
Step-by-step explanation:
Muscles are categorized based on their location in the body as either superficial or deep. Superficial muscles are those closer to the surface of the body, while deep muscles are located underneath the superficial muscles. For instance, in the legs, superficial muscles can be seen in the anterior view, as they are closer to the surface, whereas both superficial and deep muscles are noted in the posterior view.
The skin is the outermost layer of the body, and beneath it lies the hypodermis or superficial fascia, which connects the skin to the underlying muscles and bones. The muscles that are most apparent and that we typically work out at the gym, such as the biceps and triceps, are examples of superficial muscles. However, beyond these visible muscles, there are many deep muscles that are vital for the function of internal organs and are not under our voluntary control, such as those in the heart and digestive system.
The hypodermis is a layer directly below the dermis, containing connective tissue and adipose tissue, which not only connects the skin to the muscles but also stores fat and provides insulation and cushioning.