Directional Terms

The most basic form of anatomy is understanding the communication and language of the body. The ability to understand and translate the positioning of specific structures is the foundation to learning more about anatomy.

Anatomical Position

The key aspects of anatomical position are that the person is standing upright, their legs and knees are together, their toes are pointed straight forward, their arms are by their sides, and their palms are facing forward. Image result for anatomic position model

The reason for this position is so that there is a universal guide to the use of the following directional terms. The memorization of this position is crucial in understanding the terminology for locating and identifying a variety of systems and structures throughout the body.

Terminology

Midline/Midsagittal Plane- The midline/midsagittal plane of the body is similar to the equator. The difference (other than the fact that the earth is not a human) is that instead of it cutting the body horizontally (reference transverse plane), it slices it vertically from the tip of the head to the bottom of the feet. The difference between the midline and the midsagittal plane is that  although they mean the same thing, midsagittal is directly related to the sagittal/parasagittal plane.

Sagittal/Parasagittal Planes- While having two names, these planes are the same. When trying to understand the sagittal/parasagittal plane, it helps to visualize the midsagittal plane as it sits in the center. In order to transform it into the sagittal plane, simply shift it to the left or the right. Once it is shifted even slightly, it is no longer the midsagittal plane. While sagittal by itself does not convey any universal location, it is important as it provides an understanding that it is in fact a vertical plane.

Frontal Plane- The frontal plane is directly perpendicular to the sagittal plane and has a much lesser range of opportunities. When it comes to the sagittal plane, it is able to shift from shoulder to shoulder, but the frontal plane can only shift from the tip of the nose to the back of the head. It makes more sense if you compare it to a headband, as it slices the scalp much like the plane does. If you envision the anatomical position from birds-eye view, it would pass through each of the ears and extend downward all the way to the bottom of the feet.

Transverse Plane- This plane is the exact opposite of the sagittal plane as instead of traveling vertically, it follows in pursuit of the horizon. If you imagine someone swimming and they get to the point where the water is low enough to stand with their head above it, the surface of the water acts just like the plane would. Another example would be that magicians act in which they slice the lady in half.

Posterior/Anterior- These words are used to simply define which side of the body you are looking at, posterior being the back and anterior being the front. I memorized them by paying attention to the “post” and the “ante.” When expressing something that happened afterwards/after an event, the common way to do it is to begin with “post” (AKA post-apocalyptic warfare or postpartum-depression). While “ante” is the Spanish word for “before.” This way, I would always remember which was which when in a rush.

Inferior/Superior- While these words sound like the evaluation of an enemy or job position, it is visually similar in it’s applications to anatomy. Inferior, commonly known as being lesser or lower, translates to being located in a lower position on the body. Superior, commonly known as being greater or higher, translates to being located in a higher position on the body. The gauge for these heights is in reference to the height of the person, aka it is from the tip of the head to the bottom of the feet. Examples of this would be to say that the mammary glands are inferior to the thyroid gland, and that the knees are superior to the ankles.

 Deep/Superficial- These are some of the more simple terms out of the bunch. They mean exactly what you would think they meant. Deep is to reference something that is closer to the center of the body, in reference to the midline and the frontal plane, and superficial is to reference something that is closer to the surface of the skin/outermost parts of the body. An example of these would be to say that the bladder is more deep than the skin/the rib cage is more superficial than the heart.

External/Internal- These two are similar to the previous, but instead of comparing one structure’s position to another, it primarily deals with only one subject. The purpose of these two terms are to determine whether something is “inside” or “outside” the body. Examples of this would be to describe a laceration as being an external wound, or to say that someone has an internal bleed.

Medial/Lateral- These terms are used in direct correlation to anatomical position. When looking at the front of a model in that position, compare the positioning of the arms to the abdomen. The abdomen is more medial than the arms because it is closer to the center of the body/is the center of the body. Opposite to that fact, the ears are more lateral to the eyes because they are on the outer edge of he head. The terms are used to describe the comparison between the distance of objects from the center of the body.

Proximal/Distal- These two terms refer to the points in which the limbs connect to the body. These points are the shoulders and the hips, which means, the terms are only used to describe something on the limbs and not the body. For example, if someone had a mole on their forearm, you would say that the mole is more proximal than the wrist, meaning that the mole is closer to the shoulder in comparison to the wrist. On the flip side you could say that the wrist is more distal than the mole.

 

Advertisements