Human anatomy is the scientific study of human body structures. In contrast to physiology, which is the study of why and how certain structures function, anatomy deals with human parts, including molecules, cells, tissues, organs, systems, and the way they interact. It also deals with outward characteristics, such as shape, structure, pattern, color, and composition. Together with physiology and biochemistry, human anatomy is considered a basic medical science.
The two subdivisions of human anatomy are gross anatomy and microscopic anatomy. Gross anatomy refers to the study of human organs that can be seen without magnification. Microscopic anatomy refers to the study of small anatomic parts that can only be seen with a microscope. Histology, the study of tissue organization, and cytology, the study of cellular organization, are both microscopic anatomy fields.
Different approaches may be used in teaching or learning about the human anatomy. For instance, anatomical structures may be studied as regional groups, such as the head and neck, upper limb, lower limb, thorax, abdomen, back, and pelvis and perineum. Each of these regions has boundaries. For instance, the head and neck is the region above the thoracic inlet, while the thorax is the region between the thoracic inlet and the thoracic diaphragm.
Another approach is to group the human body structures according to the major organ systems. These systems include the circulatory, digestive, endocrine, musculoskeletal, nervous, reproductive, respiratory, urinary, and immune systems. In this approach, body structures are grouped together according to their functions. For instance, the circulatory system functions in the delivery of blood and involves the heart, blood vessels, and blood. The musculoskeletal system functions in support and movement, and involves the bones, muscles, ligaments, tendons, and cartilage.
Anatomical position is the state when a person is standing erect, facing forward, with arms at the side, and with palms turned forward. When studying human anatomy, knowing superficial landmarks is important to be able to determine where a particular organ is located. Surface, or superficial, anatomy involves knowing anatomical landmarks that serve as reference points for deeper structures within the human body.
Human anatomy can only be fully understood when basic anatomy terms are known. Basic anatomy terms include superior, inferior, anterior or ventral to, posterior or dorsal to, medial, lateral, ipsilateral, contralateral, proximal, distal, superficial, deep, supine, and prone. An organ has different views based on where the observer is, thus body planes are also important in anatomy. The sagittal plane divides the body into right and left, while the frontal or coronal plane divides the body into anterior and posterior parts. Also called transverse or horizontal plane, the axial plane divides the body into upper and lower parts.
