Anatomical Terminology: Positions and Sectional Anatomy

1. Anatomical Position

before you start

Anatomists and healthcare 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 the back-side? By using precise anatomical terminology, you eliminate ambiguity. Anatomical terms derive from ancient Greek and Latin words.

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.

think about it

Let’s say you have pain in your right arm between your elbow and wrist. It feels okay if you hold it over your head, but it bothers you enough that you’ve decided to go to the doctor to have it checked out. When the doctor comes in, you are holding your arm over your head (your wrist above your elbow). The doctor examines your arm in that position and sends you to get an X-ray. The doctor informs the X-ray technician to take images “of the right arm above the elbow”, namely between the elbow and wrist as you are holding your arm up to help with the pain.

When you arrive to get your X-ray, the X-ray technician asks you to stand straight, with your arms at your sides, and to hold still. Your elbow is now above the wrist. The X-ray technician takes images as instructed, the “right arm above the elbow”.

When you go back to the doctor’s office, the doctor is perplexed because the X-ray images are of the wrong part of the body. But they’re positive the instructions were clear, “above the elbow.” When they call the X-ray technician, the X-ray technician is also perplexed because they did exactly as they were told, they took images above the elbow.

What Happened?
In this scenario, the doctor wanted images taken of the area between the elbow and wrist which when you were in the office was being held in a position where the wrist was above the elbow. However, when you arrived to get your X-ray, that same position was now positioned below the elbow. The description of “above” the elbow was only accurate in the first position which led to confusion between the two individuals. How could this scenario have been avoided?

Living organisms are dynamic—they move. When talking about regions of the body relative to one another, the description has to accommodate all possible body positions. Because of this, anatomists have developed their own way of talking about the body to avoid confusion.

Anatomists, people who study the structure of the body, standardize the way in which they view the body. Just as maps are normally oriented with the north at the top, the standard body “map,” or anatomical position has a specific orientation.

• Body standing upright
• Head facing forward
• Arms hanging at the side, palms facing forward
• Feet at shoulder width, parallel, toes pointed forward

Using this standard position as a reference reduces confusion. It does not matter how the body being described is oriented - lying down, hands overhead, headstand, or superman position, - the chosen terms are used as if it is in an anatomical position (see the image below).

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.

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.

Additionally, the right and left sides of any observed body or body structure is based on that of the observed and not the observer. For example, when observing a person’s left arm, it is referred to as the left arm, even though it is on the right side of the observer.

1a. Regional Terms

The human body’s numerous regions have specific terms to help increase precision as seen in this lesson’s first image (“Regions of the Human Body”).

learn more

These terms are provided in that image and in this attached PDF A&P I - Regions of the Human Body.pdf as a table for your reference. You will not be tested on these terms now, but learning them will make future lessons simpler.

Take note that the common terms "arm" and "leg" refer to only portions of their respective appendages. In anatomy, "arm" refers to the upper arm or brachium while the lower arm is known as the forearm or antebrachium. The term "leg" in anatomy refers to the lower leg or crus while the upper leg is known as the femur or thigh. You will be able to describe the body’s regions using these terms from the image/provided PDF.

terms to know

Anatomical Position

A standard body map or orientation with the body standing upright, face forward, arms at the side, palms facing forward, feet shoulder width apart, feet pointed forward that all descriptions are created in reference to.

Prone

A face-down orientation.

Supine

A face up orientation.

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2. Directional Terms

think about it

When meeting new people, a common question is to ask where you live. If you live in an area they are unfamiliar with, it is uncommon that they have heard of your neighborhood, town, or even city. In that instance, it is common to reference other more recognizable cities or locations that might be more recognizable.

I live north of Miami.
I live just east of Denver.
I live a little south of the famous bagel shop.
I live west of the river.

These types of directional terms are based on cardinal directions, north, east, south, and west, that do not change no matter the orientation. The direction of north is still north even when facing east, south, or west.

Anatomists talk about regions of the body in reference to one another using a system of directional terms that are similar to cardinal directions on a map. These terms are essential for describing the relative locations of different body structures. For instance, an anatomist might describe a patient’s injury as “lateral to” another or a physician might describe a tumor as “superficial to” a deeper body structure. These terms provide precise positional information. Commit these terms to memory to avoid confusion when you are studying or describing the locations of particular body parts.

Directional Term	Definition	Example
Anterior (Ventral)	Towards the front	The toes are anterior to the foot.
Posterior (Dorsal)	Towards the back	The tongue is posterior to the lips
Superior (Cranial)	Towards the head	The eyes are superior to the mouth
Inferior (Caudal)	Towards the tail (lowest part of the spinal column)	The pelvis is inferior to the abdomen
Medial	Towards the midline (middle of body)	The belly button is medial to the hand
Lateral	Away from the midline (middle of body)	The ears are lateral to the nose
Proximal	Towards the trunk (limbs only)	The elbow is proximal to the wrist
Distal	Away from the trunk (limbs only)	The foot is distal to the thigh
Superficial	Towards the surface	The skin is superficial to the bones
Deep	Away from the surface	The brain is deep to the skull

try it

Using the examples in the table above, identify the references on the image below.

terms to know

Anterior (Ventral)

A directional term meaning towards the front.

Posterior (Dorsal)

A directional term meaning towards the back.

Superior (Cranial)

A directional term meaning towards the head.

Inferior (Caudal)

A directional term meaning towards the tail (lowest part of the spinal column).

Medial

A directional term meaning towards the midline (middle of body).

Lateral

A directional term meaning away from the midline (middle of body).

Proximal

A directional term meaning towards the trunk. This term is only used when describing regions of the limbs.

Distal

A directional term meaning away from the trunk. This term is only used when describing regions of the limbs.

Superficial

A directional term meaning towards the surface.

Deep

A directional term meaning away from the surface.

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3. Body Planes

Anatomical directions and position apply to both the outside and the inside of the body. When looking at medical imaging such as X-rays, MRIs, and cat scans, or when performing dissections, it is important to know how the body or organ was “cut” or “sectioned” in order to maintain your orientation (anterior, posterior, right, left). Anatomists call these body sections or planes.

A section is a two-dimensional surface of a three-dimensional structure that has been cut. Modern medical imaging devices enable clinicians to obtain “virtual sections” of living bodies, called scans. Body sections and scans can be correctly interpreted, however, only if the viewer understands the plane along which the section was made. A plane is an imaginary two-dimensional surface that passes through the body. There are three planes commonly referred to in anatomy and medicine.

• The sagittal plane is the plane that divides the body or an organ vertically into right and left sides. If this vertical plane runs directly down the middle of the body and creates equal right and left halves, it is called the midsagittal or median plane. If it divides the body into unequal right and left sides, it is called a parasagittal plane. This is less commonly referred to as a longitudinal section.
• The frontal plane is the plane that divides the body or an organ into an anterior (front) portion and a posterior (rear) portion. The frontal plane is often referred to as a coronal plane. (“Corona” is Latin for “crown.”)
• The transverse plane is the plane that divides the body or organ horizontally into superior (upper) and inferior (lower) portions. The transverse plane is also referred to as a horizontal plane. Transverse planes produce images referred to as cross-sections.

There is a fourth body plane that is not as common as the three planes above called the oblique plane'. The oblique plane is the plane that divides the body unevenly along any angle not at 90 degrees from the other three.

Below you can see a visual representation on the three common planes and the oblique plane.

terms to know

Section

A two-dimensional surface of a three-dimensional structure that has been cut.

Plane

An imaginary two-dimensional surface that passes through the body.

Sagittal Plane

The plane that divides the body or an organ vertically into right and left sides.

Midsagittal Plane

The plane that divides the body or an organ vertically into equal right and left sides along the midline.

Parasagittal Plane

The plane that divides the body or an organ vertically into unequal right and left sides lateral to the midline.

Frontal (Coronal) Plane

The plane that divides the body or an organ into an anterior (front) and a posterior (rear) portion.

Transverse (Horizontal) Plane

The plane that divides the body or organ horizontally into superior (upper) and inferior (lower) portions.

Oblique Plane

The plane that divides the body unevenly along any angle not at 90 degrees from the other three.

summary

In this lesson, you learned how to position the body in the anatomical position and why it is used as a reference position. You were also introduced to regional terms, the body’s numerous regions that all have specific terms to help increase precision when identifying. You also learned the directional terms to reference relative position throughout the body that never change. Finally, you learned about the three common body planes used when imaging or sectioning the body.