Anatomical Terminology Basics

To increase precision, medical professionals use a standard map of the body that details the anatomical position. Using a standard position clarifies the area the doctor is describing, eliminating any confusion between practitioners. In the anatomical position, the body is standing upright. The feet are shoulder-width apart and parallel to one another, with the toes facing forward. The arms are extended to the side, palms facing forward. Anatomical terminology refers to body parts assuming the body is in this position. In other words, even if a person is sitting or lying down, practitioners apply descriptors as if they were standing in the anatomical position.

In anatomical terminology, specific terms describe structures relative to other structures of the body. Anterior or ventral refers to the front of the body, while posterior or dorsal refers to the back. When something is located higher or above another part of the body, it is said to be superior; the knee is superior to the foot. When something is lower than another part of the body, it is inferior. The stomach is inferior to the heart.

Other terms used in anatomical terminology describe direction. Lateral refers to something that is toward the side of the body. The thumb is lateral to the fingers (because in anatomical position, the palm faces forward). Medial describes something toward the middle of the body: the nose is medial to the ears. Proximal and distal refer to how close something is to the trunk of the body — the elbow is proximal to the hand, and the foot is distal to the hip. Finally, specific terms describe depth. Superficial refers to something close to the surface (like a hair follicle), while something "deep" is farther from the surface (like bone marrow).

In anatomical terminology, a plane is an imaginary two-dimensional surface passing through the body. Anatomy commonly refers to three planes. The sagittal plane divides the body from left to right, running head-to-toe. A frontal or coronal plane divides the body from front to back and would be at a 90-degree angle from the sagittal plane. Finally, a transverse plane separates the body horizontally into an upper and lower portion, creating cross-sections. Planes do not have to divide the body evenly.

The abdomen is typically divided into four quadrants. This is useful in describing the location of organs and for pinpointing the exact location of pain or a mass. A horizontal and a vertical line crossing through the belly button designate these quadrants. These sections are the left and right upper and lower quadrants.

There are also anatomical terms for types of bones. Flat bones, like those in the skull, rib cage, and pelvis, protect internal organs. Long bones support weight and movement in the arms and legs. The femur is a long bone. Short bones are long and wide and primarily offer support but help with movement, too, like the short bones in the wrists and ankles. Sesamoid bones like the knee cap are embedded in tendons and protect them from wear and tear. Finally, irregular bones are those that do not fit into any other category. They are complex in shape and protect organs. The vertebrae are an example of irregular bones.

Motion is another important part of anatomical terminology, particularly when it comes to explaining muscle movement. Flexion is bending that decreases the angle, for example, bending the elbow. Extension is the opposite, it increases the angle as in when the elbow is unbent. Abduction is moving away from midline like when the fingers are splayed apart while adduction pulls toward the midline as in making a fist.

Some anatomical terminology of motion applies only to certain parts of the body. When looking at the foot, dorsiflexion describes when the toes are brought closer to the top of the foot or shin, as when walking on the heels. Plantar flexion is the opposite, bringing the sole of the foot closer to the back of the leg, like when walking on tiptoe. The terminology is similar for the hand. Dorsiflexion brings the back of the hand closer to the arm, while palmar flexion brings the palm closer to the inner forearm.

Part of understanding how muscles move bones is knowing where muscles attach. The "origin" of a muscle is the bone that stabilizes it when it contracts, while the "insertion" is where it attaches and causes movement. The insertion is usually a connection between the muscle, a tendon, and bone. In most cases, the origin is a larger bone with more mass than the insertion so it can support the muscle contraction and intended movement.

Anatomical terminology is also important when it comes to internal membranes. The walls and organs in the abdominal and thoracic cavities are covered by serous membranes that prevent friction. The location of this membrane determines its name. The serous membrane surrounding the lungs is the pleura. The pericardium surrounds the heart, and the peritoneum surrounds the abdominal and pelvic organs.