A.2: Anatomical Terminology

Anatomical Planes

A body in anatomical position is situated as if the individual is standing upright; with head, eyes, and feet pointing forward; and with arms at the side and palms facing forward. In anatomical position, the bones of the forearm are not crossed (Figure A.7).

Figure A.7: A human body is shown in anatomical position in an (left) anterior view and a (right) posterior view. Credit: Regions of the Human Body (Anatomy & Physiology, Figure 1.12) by OpenStax has been modified (labels removed) and is under a CC BY 4.0 License.

In anatomical position, specific organs are situated within specific anatomical planes (Figure A.8). These imaginary planes divide the body into equal or subequal halves, depending on which plane is described. Coronal (frontal) planes divide the body vertically into anterior (front) and posterior (back) halves. Transverse planes divide the body horizontally into superior (upper) and inferior (lower) halves. Sagittal planes divide the body vertically into left and right halves. The plane that divides the body vertically into equal left and right halves is called the midsagittal plane. The midsagittal plane is also called the median plane because it is in the midline of the body. Every other sagittal plane divides the body into unequal right and left halves; these planes are called parasagittal planes.

Figure A.8: The three planes most commonly used in anatomical and medical imaging are the sagittal, coronal (or frontal), and transverse planes. A full text description of this image is available. Credit: Planes of the Body (Anatomy & Physiology, Figure 1.14) by OpenStax has been modified (some labels modified) and is under a CC BY 4.0 License. [Image Description]

Directional Terms

An anatomical feature that is anterior (or ventral) is located toward the front of the body, and a bone that is posterior (or dorsal) is located toward the back of the body (Figure A.9). For example, the sternum (breastbone) is anterior to the vertebral column (“backbone”). A feature that is medial is located closer to the midline (midsagittal plane) than a feature that is lateral, or located further from the midline. For example, the thumb is lateral to the index finger. A structure that is proximal is closer to the trunk of the body (usually referring to limb bones) than a distal structure, which is further from the trunk of the body. For example, the femur (thigh bone) is proximal to the tibia (leg bone). Finally, a structure that is superior (or cranial) is located closer to the head than a structure that is inferior (or caudal). For example, the rib cage is superior to the pelvis, and the foot is inferior to the knee.

Figure A.9: Paired directional terms are shown as applied to a human body. Credit: Directional Terms Applied to the Human Body (Anatomy & Physiology, Figure 1.13) by OpenStax is under a CC BY 4.0 License.