Directional Terms: Body Sides - Online Tutor, Practice Problems & Exam Prep

Understanding body orientation involves recognizing bilateral symmetry, where the right and left sides are mirror images. Key terms include medial (toward the midline) and lateral (away from the midline), with examples like the hip being lateral to the navel. Additionally, ipsilateral refers to structures on the same side, while contralateral indicates opposite sides. For instance, the left knee is ipsilateral to the left hand and contralateral to the right hand. These concepts are essential for accurately describing anatomical relationships in the body.

Medial and Lateral

We're talking about directional turns for the sides of the body. The first thing that you always want to remember is that bodies have bilateral symmetry. Right? We've talked about this before. You have a right side of the body, you have the left side of the body, and those two sides are largely mirror images of each other.

So for that reason, I'm going to start by just drawing a midline down this body. Alright. So there we go. That's separating this anatomical module's right and left side. The next thing we always want to remember is that it's the body's right and left, not your right and left. And when you're looking at the body, this is her right, this is her left. That right and left are probably going to be opposite to your right and left depending on your perspective. Okay.

When talking about this axis, we're going to have different words that indicate how close you are towards that midline, and those two words are going to be "medial" and "lateral." "Medial" is just going to mean "towards or closer to the midline," and "lateral" is going to mean "away from or farther from the midline." So, we can give some quick examples: The hip here is going to be lateral to the navel or the belly button. The navel or belly button is going to be medial to the hip. We can say that the ear is lateral to the eye, and the eye is medial to the ear. Remember, all things are relative. It's always a comparison between two things.

So while the eye was medial to the ear, the eye is lateral to the nose, and the nose is medial to the eye. Okay. On this left and right spectrum, we can also talk about things being between two things, and that being between two things is going to be described as "intermediate," which is between medial and lateral.

Now, sometimes you may be tempted to say it's "intermediate" on, like, the inferior-superior axis. You can't do that. "Intermediate" only refers to the medial-lateral axis. Alright. So an example: the eye is intermediate between the ear and the nose. Your collarbone right here is intermediate between your shoulder and your sternum. Okay.

Now, once we've divided a body in half by a midline, we now have two sides of the body, and we may want to say something is on the same side of the body, or we may want to say something is on the opposite side of the body. We have words for that too. Our words for the same or different sides of the body are going to be "ipsilateral" and "contralateral."

"Ipsilateral" just means on the same side, while "contralateral" means on the opposite side. Now those roots, "ipsa" and "contra" - "ipsa" means the same, "contra" means opposite. I don't have any way to remember "ipsa." "Ipsa" is a root that's really only used in medical terminology, so I don't really know any other words that use it. Contra, however, right? You can contradict something. Something can be contrary. "Contra" means opposite or against, and so I always remember that one. So when trying to keep these straight, I can always remember "contralateral," and then I use that to remind myself what "ipsilateral" means. So we can do an example here.

If we're looking at this knee, this is the left knee. The left knee is ipsilateral to the left hand. The left hand and the left knee are ipsilateral. This left knee is contralateral to the right hand. The right hand and the left knee are contralateral.

Okay. With that, you have enough information to go ahead and try our example below and the practice problems to follow. I'll see you there.

Directional Terms: Body Sides Example 1

This example again asks us to mark up this body using some of the directional terms that we just learned, so let's go ahead and give it a try. First off, it asks for an asterisk lateral to the left of the navel. So go ahead and think about that. Alright. The first thing I want to do is put a left and right on the body, but I'm also going to remind myself this body's facing me by putting a little smiley face on it.

Alright. We have the left. We have the right. Okay. Lateral to the left of the navel.

Well, lateral just means to the side. I mean, it's to the left, and the navel is in the middle. So, that one's pretty straightforward. So just a little bit to the left of the navel, I'm going to put an asterisk.

Second, we have an "o," intermediate to the nose and the right ear. Alright. Intermediate, think about that for a second. Intermediate means between on the left-to-right axis, so between the right ear and the nose is going to be right here. Alright.

Next, we have a plus sign on the hip, contralateral to the right knee. Think about that for a moment. Alright. We have "contralateral." Remember, lateral means side, and "contra" means against or opposite of something.

So, this is going to be the opposite side. So, we have the right knee here. The hip on the contralateral side is going to be the other side. It's going to be right here. So, I'm going to put a plus sign actually right close to where I put the asterisk.

And then finally, it says an "x" on the medial side of the left wrist. Alright, think about that for a second. Alright. This one might be a little tricky because when you hear medial, you might think the middle of the wrist. But remember, medial always means towards the midline of the body.

So, we're talking about the left wrist. The medial side of the left wrist is just going to be the side that's closest to the body, and we're going to put a big old "x" right there. Alright? So that's where my marks go. There you go.

Imagine you are a surgeon about to perform a procedure on the liver, which is located on the right side of body just below the ribs. Relative to the navel (belly button) where would you prepare the incision?

• A. Medial and ipsilateral to the right.
• B. Inferior and medial to the left.
• C. Contralateral and superior to the left.
• D. Superior and lateral to the right.

According to anatomical position, what is the most lateral part of the body?

• A. Anywhere on the midline
• B. The hips or shoulders
• C. The thumbs
• D. The feet

The left knee and the left ankle are _______________.

• A. Ipsilateral
• B. Intermediate
• C. Contralateral
• D. Medial

The right hemisphere of the brain processes signals from sensory nerves on the left side of the body. Another way to say this is that sensory neurons are located ________________ to the hemisphere of the brain that processes them.

• A. Ipsilateral
• B. Medial
• C. Contralateral
• D. Lateral

Here’s what students ask on this topic:

What is the difference between medial and lateral in anatomical terms?

In anatomical terms, 'medial' refers to a position closer to the midline of the body, while 'lateral' refers to a position farther from the midline. For example, the navel (belly button) is medial to the hip because it is closer to the midline, whereas the hip is lateral to the navel because it is farther from the midline. These terms help describe the relative positions of structures within the body.

How do ipsilateral and contralateral differ in describing body sides?

'Ipsilateral' means that structures are on the same side of the body, while 'contralateral' means that structures are on opposite sides. For instance, the left hand is ipsilateral to the left knee because they are on the same side. Conversely, the left hand is contralateral to the right knee because they are on opposite sides. These terms are crucial for accurately describing anatomical relationships and movements.

Can you provide examples of structures that are intermediate in the body?

In anatomical terms, 'intermediate' refers to a structure that is between two other structures on the medial-lateral axis. For example, the eye is intermediate to the ear and the nose. Another example is the collarbone (clavicle), which is intermediate to the shoulder and the sternum. This term helps specify the relative position of structures more precisely.

Why is it important to understand bilateral symmetry in anatomy?

Understanding bilateral symmetry is crucial in anatomy because it helps in accurately describing the positions and relationships of body structures. Bilateral symmetry means that the right and left sides of the body are mirror images of each other. This concept is foundational for using directional terms like medial, lateral, ipsilateral, and contralateral, which are essential for clear and precise communication in medical and anatomical contexts.

How do you determine the right and left sides of the body in anatomical terms?

In anatomical terms, the right and left sides of the body are determined from the perspective of the body being described, not the observer. This means that the right side of the body is the body's own right side, and the left side is the body's own left side. This distinction is important to avoid confusion, especially when describing anatomical positions and relationships.