Final answer:
Superficial thickness refers to the measurement of the epidermis, the outermost layer of the skin, which varies in thickness depending on the body part. The skin is superficial to other body structures like bones and comes in two varieties, thick and thin, which can be distinctly observed under a microscope.
Step-by-step explanation:
The term 'Superficial Thickness' generally refers to the measurement of the uppermost layer of the skin, known as the epidermis. This layer varies greatly in thickness across different parts of the body. For instance, the epidermis is thinnest on the eyelids, measuring approximately 0.05 mm, and thickest on the palms of the hands and soles of the feet, where it can be up to 1.50 mm thick. The epidermis is an important barrier that covers almost the entire body surface. It is structurally distinct from the mucous membranes and is continuous with them at several body sites.
There is also a distinction between thick and thin skin which refers to the differences in the epidermal layer. 'Thin skin' covers most of the body and has a thinner epidermis while 'thick skin' covers areas such as the palms and soles and has a much thicker epidermis. When comparing cross-sections of thin and thick skin under a microscope, as shown in Figure 5.3, one can observe a significant difference in the thickness of the epithelial layer of the thick skin. Superficial also describes anatomical position, indicating that a structure is closer to the surface of the body, such as the skin being superficial to the bones.