Anatomy & Physiology I · Introduction to the Human Body
Body Planes and Sections
On this page 7 sections
In 30 seconds
A Plane an imaginary flat surface passing through the body used as a reference for a cut. is an imaginary flat surface passing through the body, and a Section the actual cut or the surface exposed by cutting along a plane. is the cut made along that plane. This section covers the three standard planes — sagittal, frontal (coronal), and transverse — plus oblique sections, and explains how these ideas let us view and describe the body's interior, especially in medical imaging.
Why this matters
You cannot understand internal anatomy, or read a CT or MRI, without knowing which "slice" of the body you are looking at. The same organ looks completely different depending on the plane of the cut. When a radiology report says "axial view" or "coronal image," it is telling you the plane. Nurses interpret these descriptions when reviewing imaging, positioning patients for scans, and understanding surgical or ultrasound reports.
The college version
Imagine slicing through the body with a large pane of glass. The orientation of that glass defines the plane, and the exposed surface is the section. There are three standard orientations, each dividing the body a different way. All are described with the body in anatomical position.
Sagittal plane a vertical plane dividing the body into left and right parts. — divides left from right. A sagittal plane runs vertically from front to back. If it passes exactly down the midline, splitting the body into equal right and left halves, it is the midsagittal (or median) plane. If it runs parallel to the midline but off to one side, producing unequal portions, it is a parasagittal plane. A side-view ("profile") image of the head is a sagittal view.
Frontal (coronal) plane a vertical plane dividing the body into anterior (front) and posterior (back) parts. — divides front from back. A frontal plane also runs vertically, but at a right angle to the sagittal plane. It separates the body into an anterior portion and a posterior portion — imagine a sheet of glass entering through the top of the head and coming out at the shoulders, so you are looking at the person face-on but seeing their interior. "Coronal" is the term you will most often see in imaging.
Transverse (horizontal / axial) plane a horizontal plane dividing the body into superior (upper) and inferior (lower) parts. — divides top from bottom. A transverse plane runs horizontally, parallel to the ground, dividing the body into superior and inferior portions. Because CT scanners produce a stack of these horizontal slices, this view is very commonly called an axial image. Each slice looks as if you were viewing the body from above or below, seeing a cross-section of everything at that level.
Oblique sections — angled cuts. An oblique section is made along a plane that lies at an angle, not aligned with any of the three standard planes. Oblique sections can be hard to interpret because structures appear distorted or foreshortened, so they are avoided when a clean standard view will do, but they sometimes occur unavoidably (for example, when a structure runs diagonally through the body).
Why the plane changes the picture
The same object looks different depending on where you slice it — a hard-boiled egg cut lengthwise (sagittal) shows the yolk as an oval, while cut across (transverse) shows the yolk as a circle. Organs behave the same way: a transverse section of the kidney and a frontal section of the same kidney reveal different internal relationships. This is why every imaging study specifies its plane, and why anatomists learn to mentally rotate structures between views.
How it works
Modern imaging is built directly on these planes:
- CT (computed tomography) typically acquires a series of transverse (axial) slices, which software can then reconstruct into coronal or sagittal views.
- MRI (magnetic resonance imaging) can be set to image in sagittal, coronal, or transverse planes directly, chosen to best show the target tissue.
- Ultrasound produces sectional images along whatever plane the probe is angled, so the sonographer names the plane as they scan.
In each case, knowing the plane tells you what "up, down, left, and right" mean on the image — essential for locating anything correctly.
Comparisons
| Plane | Orientation | Divides body into | Common imaging name |
|---|---|---|---|
| Sagittal | Vertical, front-to-back | Left and right | Sagittal |
| Midsagittal | On the midline | Equal left and right | Median |
| Frontal | Vertical, side-to-side | Anterior and posterior | Coronal |
| Transverse | Horizontal | Superior and inferior | Axial / horizontal |
| Oblique | Angled | Angled portions | (specified case-by-case) |
The two vertical planes (sagittal and frontal) are perpendicular to each other; the transverse plane is perpendicular to both.
Common confusions
- Frontal vs transverse. Both can look "horizontal-ish" in casual drawings, but frontal is a vertical plane (front/back split) while transverse is a horizontal plane (top/bottom split).
- "Coronal" vs "coronial." The imaging term is coronal (from corona, crown), the same plane as frontal.
- Midsagittal vs parasagittal. Only the midline cut is midsagittal (equal halves); any parallel off-center cut is parasagittal (unequal).
- Plane vs section. The plane is the imaginary flat orientation; the section is the actual cut surface produced along it.
Memory aids
- Sagittal = "Split into Sides" (both start with S; left/right).
- Coronal = "Crown" — a plane entering like a crown across the head, separating front from back.
- Transverse = "Traverse across" — a horizontal cut, like the horizon.
(Shortcuts for recall — the divisions themselves are the substance.)
Quick review
- A plane is an imaginary flat surface; a section is the cut along it.
- Sagittal = left/right (midsagittal = equal halves; parasagittal = off-center); frontal (coronal) = front/back; transverse (axial) = top/bottom.
- Oblique sections are angled and harder to interpret.
- Imaging (CT is typically axial; MRI can use any plane) always specifies the plane so you can orient the image correctly.
Eli explains
The same idea, in plain words
Explain it like I’m 10
Simple idea
To look inside the body, we imagine slicing it with a big flat sheet of glass. Which way we hold the glass decides what kind of "slice picture" we get.
Analogy
Think about slicing a loaf of bread. If you cut straight down the middle lengthwise, you get two long side-by-side halves — that's the sagittal slice (left and right). If you cut down the middle the other way, separating the front of the loaf from the back, that's the frontal (coronal) slice. If you cut straight across to make sandwich slices, that's the transverse (axial) slice (top and bottom). Cut at a slant and you get a lopsided piece — an oblique slice.
What is actually happening
These "slices" are how CT and MRI machines show doctors the inside of a body without surgery. A CT scan is basically a stack of transverse (axial) bread-slice pictures. Because the same organ looks totally different depending on the direction of the cut, every scan is labeled with its plane so everyone knows which way they're looking.
Where the analogy stops
Bread actually gets cut apart; the body's "planes" are imaginary — the scanner sees the slices without harming the person. Also, a real body has left, right, front, and back that must line up correctly, so the picture's orientation follows medical rules a bread slice doesn't have.
Key takeaway
When you review a patient's imaging, the plane label tells you how to orient yourself. On an axial (transverse) CT, structures on the image's left are usually on the patient's right — a convention that matters when localizing findings. Understanding coronal versus sagittal views helps you follow surgical notes, ultrasound reports, and radiology impressions, and it makes anatomy lab dissections far less disorienting because you know which section you are looking at.
Study tools & related lessonsYou’ll learn to · Key vocabulary · Related
You’ll learn to
- Define the sagittal, frontal (coronal), and transverse planes.
- Distinguish midsagittal from parasagittal sections.
- Describe an oblique section and when it occurs.
- Relate each plane to how medical imaging and dissection display the body.
Key vocabulary
- Plane
- an imaginary flat surface passing through the body used as a reference for a cut.
- Section
- the actual cut or the surface exposed by cutting along a plane.
- Sagittal plane
- a vertical plane dividing the body into left and right parts.
- Midsagittal (median) plane
- a sagittal plane exactly on the midline, giving equal left and right halves.
- Parasagittal plane
- a sagittal plane off the midline, giving unequal left and right parts.
- Frontal (coronal) plane
- a vertical plane dividing the body into anterior (front) and posterior (back) parts.
- Transverse (horizontal / axial) plane
- a horizontal plane dividing the body into superior (upper) and inferior (lower) parts.
- Oblique plane
- a plane cutting at an angle, not parallel to any of the three standard planes.
Sources & references
- OpenStax, *Anatomy and Physiology 2e*, Chapter 1.6: Anatomical Terminology (planes and sections). https://openstax.org/books/anatomy-and-physiology-2e/pages/1-6-anatomical-terminology
- U.S. National Library of Medicine, MedlinePlus — CT Scan. https://medlineplus.gov/ctscans.html
This lesson was adapted from the open educational references above; their licenses and attributions are preserved. See Copyright & Licensing.
Educational content only. It is not medical, legal or professional advice. Found an error? Tell us.