Directional Terminology

The following terms are frequently used in medical terminology to describe anatomical directions. They can be used to describe the entire body or any of its parts. One should have a familiarity with them in order to fully understand the concepts, positions, and movements described throughout the book:

SUPERIOR--means in the direction of the top of the head or the top of the body. Saying "up" is often inaccurate because if a person is lying on their back, "up" is really anterior, so using the term "superior" is superior because it is always references towards the head's aspect of the anatomical part in question. The whole body or any part can be moved superiorly if it moves in the direction of the head.

INFERIOR--means in the direction of the soles of the feet and situated below or directed downward. It can also refer to that part of the body or body part closest to the feet (such as "the inferior aspect of the chin"). The whole body can be moved inferiorly if it moves in the direction of the feet.

LATERAL--refers to the sides of the body. There is a left and right lateral (side) aspect to just about every anatomical part as well as the body in general. When the term lateral aspect is used it refers to that component of anatomy away from the midline of the trunk. When something moves laterally, it moves away from the midline.

MEDIAL--refers to the center or midline of the body or body part. When an anatomical structure is said to be medial, it is more towards the midline of the torso. Often, the term, medial aspect, is used and that refers to that component of anatomy closest to the midline of the trunk. Something moves medially if it moves towards the midline.

ANTERIOR--means toward the front of the body. One can move a body part anteriorly by moving it towards the front of the body. A body part can have an anterior aspect, that being that component closest to the front of the body. From the word "ante" which refers to something "up front," before, or at the beginning, such as in antebellum (before the Civil War) or like what you do before you play a hand of "penny-"ante" poker. You put up a penny up front as a bet.

POSTERIOR--means toward the back surface or rear of the body, such as getting kicked in your "posterior." It can reference a part of the body in relation to another such as the vertebral bone parts that are closest to the back surface of the body are referred to as the posterior elements. One can also move a body part to the posterior by moving it towards the back surface of the body.

FLEXION--from "to bend" in Latin. Any time you decrease the angle made by two bones you "flex" at the joint which joins those two bones. In the case of the spine, bending forward produces the action of anterior flexion when viewed from the side. When viewed from the front, a person can bend to the side and the spine can be said to laterally flex or bend. Spinal Flexion in this book refers to any movement that bends the spine anteriorly whether the spine is in the neutral position or while in an extended posture flexes to return towards the neutral position.

EXTENSION--the opposite of flexion, from the Latin for "stretching out" and therefore is an increase in the angle formed by the axis of two bones. This can refer to the body being brought back to the neutral, resting, anatomical position from a flexed position, or going from the neutral anatomical position towards the posterior.

If a person bends backwards or posteriorly, the spine is said to perform EXTENSION, regardless of any other position the body may be assuming at the same time. The spine can be in flexion and extend to the neutral position or be in the neutral position and extend to the posterior. Also, the spine can be in EXTENSION and extend maximally beyond the usual range of motion into HYPEREXTENSION.

CIRCUMDUCTION--from the Latin "to draw around." This is actually a combination of the movements previously described. It consists of a smooth series of movements (Shown in Figure 3) starting with anterior flexion, leaning into lateral flexion, lateral extension, and posterior extension in that specific sequence. In this example, the circumduction takes the upper body in a clockwise direction. However, it could start at any point on the circle, go only part way around, or even go in the opposite direction; and it still would be considered circumduction. If this action is performed at any level of the spine, the portion of the body above the point of movement will be brought anteriorly and laterally, then posteriorly and then medially, resulting in the superior aspect of the anatomy to gyrate around in a circular pattern. Since the inferior aspect of the spine below the point of motion is fixed in this example, the upper section moves through its range of motion carving out the form of an inverted cone in space.

SUPINE--that position in which a person lies flat with the face, abdomen, and toes pointing up.

PRONE--that position in which a person lies flat with the face, abdomen, and toes all pointing down.

Further Reading:

Spinal Anatomy
Directional Terminology
Structural Anatomy
Functional Anatomy
Pathological Anatomy
Disc Hydraulics / Mechanics
Compression Forces
Correlation of Mechanical Anatomy with Disc Pain
Traction Forces

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