Anatomical Terms

Anatomy and Physiology

The branches of science called anatomy and physiology provide the foundation for understanding the body’s structure and function. Anatomy is the science that studies body structures and the relationships among them. Whereas physiology is the science that studies body functions or how the body parts work. To be able to describe the body’s structure, it is necessary to use special terms that everyone understands to communicate clearly and precisely. To prevent confusion, anatomists have developed a standard anatomical position and a special vocabulary for relation body parts to one another.

Body Positions

Descriptions of any region or part of the body assume that the body is in the anatomical position. In the anatomical position, the person stands erect, facing the observer, with the head level and the eyes facing forward. The feet are flat on the floor and directed forward, and the arms are hanging at the sides, with the palms facing forward. 

Regional Names

The human body can be divided into several major regions that can be identified externally, and they include the head, neck, trunk, upper limbs and lower limbs. The headcontains the skull, which encloses and protects the brain, and the face, which includes the eyes, nose, mouth, forehead, cheeks and chin. The neck supports the head and attaches it to the trunk. The trunk consists of the chest, abdomen, and pelvis. Each upper limb attaches to the trunk and consists of the shoulder, armpit, arm (the part of the limb from the shoulder to the elbow), forearm (the part of the limb from the elbow to the wrist), wrist, and hand. The lower limbs are each attached to the trunk, and consist of the buttock, thigh (the part of the limb from the buttock to the knee), leg (the part of the limb from the knee to the ankle), ankle, and foot. The groin is the area on the front surface of the body marked by a crease on each side where the trunk attaches to the thigh.

Directional Terms

Directional terms are words that describe the position of one body part relative to another, and they are used to locate various body structures. Most of the directional terms are grouped in pairs that have opposite meanings, for example anterior (front) and posterior (back). The chart below includes the most common directional terms used in anatomy, with their meaning and an example of its use.

Body Planes

Body planes are imaginary flat surfaces that are used to divide the body or organs to visualize interior structures. A sagittal plane is a vertical plane that divides the body or an organ into right and left sides. A midsagittal or median plane divides the body or organ into equal right and left sides, while a parasagittal plane divides them into unequal left and right sides. A frontal or coronal plane divides the body or organ into anterior and posterior parts.

A transverse plane divides the body or an organ into superior and inferior parts. The transverse plane can also be called a cross-sectional or horizontal plane. The sagittal, frontal, and transverse planes are all at right angles to each other. The oblique plane, by contrast, passes through the body or an organ at an angle between the transverse plane and either a sagittal or frontal plane.