1.3: Anatomical Terminology

Master this section and you'll be able to:

• Demonstrate the anatomical position
• Describe the human body using directional and regional terms

Anatomists and health care providers use terminology that can be bewildering to the uninitiated. However, the purpose of this language is not to confuse, but rather to increase precision and reduce medical errors. For example, is a scar “above the wrist” located on the forearm two or three inches away from the hand? Or is it at the base of the hand? Is it on the palm-side or back-side? By using precise anatomical terminology, we eliminate ambiguity. Anatomical terms derive from ancient Greek and Latin words. Because these languages are no longer used in everyday conversation, the meaning of their words does not change.

Anatomical terms are made up of roots, prefixes, and suffixes. The root of a term often refers to an organ, tissue, or condition, whereas the prefix or suffix often describes the root. For example, in the disorder hypertension, the prefix “hyper-” means “high” or “over,” and the root word “tension” refers to pressure, so the word “hypertension” refers to abnormally high blood pressure.

Anatomical Position

To begin, anatomists use a standard reference position so that everyone describes the body in the same way. Just as maps are typically drawn with north at the top, the body is described using a standard “map” called the anatomical position. In this position, the person is standing upright, feet about shoulder-width apart and parallel, toes pointing forward. The arms are at the sides of the body, and the palms face forward, as shown in the figure below.

Using this standard position reduces confusion. It does not matter how the body being described is oriented, the terms are used as if it is in anatomical position. For example, a scar in the “anterior (front) carpal (wrist) region” would be present on the palm side of the wrist. The term “anterior” would be used even if the hand were palm down on a table.

 Figure \(\PageIndex{1}\):Axial and Appendicular Skeleton in Anatomical Position.
This human skeleton is shown in anatomical position, with the body standing upright, feet flat and slightly apart, arms at the sides, and palms facing forward.

The image also highlights the two major regions into which the human body is divided:

Axial region
This is the central core of the body. It includes the head, neck, and trunk. The trunk consists of the chest, abdomen, and pelvis.
In Figure 1.3.1, the axial skeleton (shown in blue) includes the skull, vertebral column, ribs, and sternum, which together form the central axis of the body.

Appendicular region
This region includes the limbs that attach to the axial region. In other words, it refers to the arms and legs.
In Figure 1.3.1, the appendicular skeleton (shown in light brown) includes the shoulder girdle, upper limbs, pelvic girdle, and lower limbs. These structures attach to the axial skeleton and are primarily responsible for movement.

A body that is lying down is described as either prone or supine. Prone describes a face-down orientation, and supine describes a face up orientation. These terms are sometimes used in describing the position of the body during specific physical examinations or surgical procedures.

---

In the paragraphs above, we introduced the two broad regional categories of the body: axial and appendicular. To describe specific locations more precisely, anatomists and medical professionals use many smaller regional terms within each of these categories (see figure below).

Regional Terms

 

Figure \(\PageIndex{2}\): Regions of the Human Body. The human body is shown in anatomical position in an (a) anterior view and a (b) posterior view.  Note that some regions are on both the anterior (a) aspect and the posterior (b) aspect, while others are on one side or the other only. (Image credit: "Regions of the Body" by Sofia Elizondo is licensed under CC BY-NC-SA 4.0.)

For example:

• The brachial region refers specifically to the upper arm and is part of the appendicular region.

• The abdominal region refers to the abdomen and is part of the axial region.

Pay close attention to correct terminology.

• Brachial means upper arm.

• Antebrachial only means forearm, not “lower arm.”

• Femoral means thigh.

• Crural refers only to the area between the knee and the ankle, not the entire lower limb.

Using these specific terms allows you to describe body locations clearly and accurately.

---

Directional Terms

Directional terms are words used to describe the location of an anatomical structure by comparing its position to other structures within the body or within the orientation of the body itself. Certain directional anatomical terms appear throughout this and any other anatomy textbook. These terms are essential for describing the relative locations of different body structures. For instance, an anatomist might describe one band of tissue as “inferior to” another or a physician might describe a tumor as “superficial to” a deeper body structure. Commit these terms to memory to avoid confusion when you are studying or describing the locations of particular body parts.

Standard anatomical terms for direction include:

• Superior and inferior (cranial and caudal) are used when referring to parts of the body (trunk) and the head. Superior structures are toward the head (cranial). Inferior (or caudal = tail) describes a position below or lower than another part of the body proper; near or toward the tail (in humans, the coccyx, or lowest part of the spinal column). Examples include:
  • The pelvic region is inferior to the abdominal region. 
  • The superior and inferior vena cava carry deoxygenated blood away from the head (superior) and from the lower body (inferior) to the heart. 
  • The frontal region is superior to the nasal region.
     
• Anterior (or ventral) is used to describe the front or direction toward the front of the body, while posterior (or dorsal) describes the back or direction toward the back of the body. Examples include:
  • The popliteal region is posterior to the patellar region.
  • The pituitary gland has an anterior and posterior part, each of which secretes different types of hormones.  
  • The toes are anterior to the tarsal region.
     
• Lateral is used to describe anything closer to the sides of the body (toward the arms, in the standard anatomical position), while medial is used to describe anything toward the middle of the body. In general, many structures of the human body are bilateral and symmetrical with the middle of the body, such as the lungs or the arms. Examples include:
  • The thumb (pollex) is lateral to the digits. Remember you have to think of the body in anatomical position!
  • The hallux is the medial toe.
     

• Deep refers to structures closer to the interior center or farther from the surface of the body. Superficial describes a position closer to the exterior surface of the body. Examples include:
  • The skin is superficial to the muscles. 
  • The brain is deep to the skull.
     
• Proximal describes a position in a limb that is nearer to the point of attachment or the trunk of the body, while distal describes a position in a limb that is farther from the point of attachment or the trunk of the body. When describing appendages (arms and legs) always use proximal and distal (instead of superior and inferior). The proximal end of an appendage connects the appendage to the body, while the distal end is away from the body.  Examples include:
  • The brachial region is proximal to the antebrachial region.
  • The patellar region is distal to the femoral region.

   
Figure \(\PageIndex{3}\): Paired Directional Terms. Comparison of a four-legged animal and a human body.