Coronal Plane

The coronal plane is one of the three principal anatomical planes used to examine the brain and nervous system. It is a vertical plane that passes from side to side and divides the brain into anterior and posterior portions.

Coronal images are particularly valuable in neuroanatomy because they display the right and left cerebral hemispheres simultaneously while preserving superior-inferior relationships. They provide excellent views of the ventricular system, basal ganglia, internal capsules, thalami, temporal lobes, hippocampi, corpus callosum, brainstem, and cerebellum.

Modern CT and MRI datasets can be reconstructed in the coronal plane, while many MRI examinations also acquire dedicated coronal sequences when the anatomy of structures such as the hippocampus, pituitary region, temporal lobes, or cranial nerves requires detailed evaluation.

Definition of the Coronal Plane

A coronal plane, also called a frontal plane, is oriented vertically and extends from one side of the body to the other. It separates structures located anteriorly from those located posteriorly.

Within the brain, consecutive coronal sections can be imagined as a series of vertical slices progressing from the frontal poles anteriorly toward the occipital poles posteriorly.

Major Neuroimaging Planes

Plane	Division	General View
Axial	Superior and inferior	Horizontal cross-section
Coronal	Anterior and posterior	Front-facing cross-section
Sagittal	Right and left	Side-facing section

Coronal versus Frontal Plane

The terms coronal plane and frontal plane refer to the same general anatomical orientation. In neuroimaging, coronal is the more commonly used term.

The name reflects a plane oriented approximately parallel to the coronal suture of the skull.

Coronal Image Orientation

Coronal images are conventionally viewed as though the observer is facing the patient. The superior aspect of the brain appears at the top of the image, and inferior structures appear toward the bottom.

Under standard radiological display convention, the patient's right side appears on the viewer's left and the patient's left side appears on the viewer's right.

Coronal Orientation Guide

Image Position	Anatomical Direction
Top of image	Superior
Bottom of image	Inferior
Left side of displayed image	Patient's right
Right side of displayed image	Patient's left

Anterior and Posterior Progression

A single coronal image represents only one position along the anterior-posterior axis. Moving through sequential sections changes the structures that are visible.

Anterior sections predominantly demonstrate the frontal lobes. More posterior sections progressively reveal the frontal horns of the lateral ventricles, basal ganglia, temporal lobes, thalami, ventricular atria, posterior cerebral regions, and eventually the occipital lobes.

Reading a Coronal Series

Coronal images should be reviewed as a sequence rather than as isolated sections. Following a structure from one slice to the next reveals its three-dimensional shape and its relationship to neighboring structures.

A useful learning approach is to move systematically from anterior to posterior while identifying several stable anatomical landmarks at each level.

Structures Visible on Coronal Brain Imaging

Depending on the anterior-posterior level, coronal images may demonstrate:

• Cerebral cortex and white matter
• Frontal, parietal, temporal, and occipital lobes
• Corpus callosum
• Septum pellucidum
• Lateral ventricles
• Third ventricle
• Caudate nuclei
• Putamen and globus pallidus
• Internal capsules
• Thalami
• Insular cortex
• Hippocampi
• Amygdalae
• Brainstem
• Cerebellum

Representative Coronal Levels

Approximate Level	Important Structures
Anterior frontal	Frontal cortex, frontal white matter, interhemispheric fissure
Frontal horns	Lateral ventricles, caudate heads, corpus callosum
Basal ganglia	Caudate, putamen, globus pallidus, internal capsule
Thalamic level	Thalami, third ventricle, internal capsules
Temporal-medial level	Hippocampi, temporal horns, medial temporal structures
Posterior cerebral level	Atria and occipital horns, posterior white matter, occipital cortex

Anterior Frontal Sections

At the most anterior levels, coronal sections primarily demonstrate the frontal lobes. The cerebral hemispheres are separated by the interhemispheric fissure, and cortical gray matter surrounds the deeper frontal white matter.

As the plane moves posteriorly, the frontal horns of the lateral ventricles become visible and provide important landmarks for identifying deeper structures.

Interhemispheric Fissure

The interhemispheric fissure separates the right and left cerebral hemispheres. On coronal images it extends vertically along the midline between the hemispheres.

The falx cerebri occupies part of this fissure and provides a useful midline reference.

Corpus Callosum

The corpus callosum is the largest commissural fiber bundle connecting the cerebral hemispheres. Coronal sections demonstrate its relationship to the lateral ventricles and cerebral white matter.

At appropriate levels, callosal fibers form the superior relationship of the lateral ventricular cavities.

Frontal Horns of the Lateral Ventricles

The paired frontal horns appear as CSF-containing cavities within the frontal portions of the cerebral hemispheres. They are separated medially by the septum pellucidum.

The heads of the caudate nuclei form prominent lateral relationships of the frontal horns.

Septum Pellucidum

The septum pellucidum is a thin midline membrane separating portions of the lateral ventricles. On coronal imaging it can be visualized between the paired frontal horns and ventricular bodies.

Its position can also provide information about the cerebral midline and displacement caused by mass effect.

Caudate Nucleus

The caudate nucleus is closely related to the lateral ventricular system. On anterior coronal sections, the large head of the caudate lies lateral to the frontal horn.

As sections progress posteriorly, the caudate becomes smaller and its body remains related to the lateral ventricle.

Basal Ganglia on Coronal Imaging

Coronal imaging provides an excellent view of the relative positions of the caudate nucleus, putamen, globus pallidus, and internal capsule.

These structures should be identified according to their relationships rather than by shape alone because their appearance changes considerably across successive sections.

Putamen

The putamen forms the lateral portion of the lentiform nucleus. On coronal images it lies lateral to the globus pallidus and internal capsule.

The external capsule, claustrum, extreme capsule, and insular cortex are located progressively lateral to the putamen.

Globus Pallidus

The globus pallidus forms the medial portion of the lentiform nucleus. It lies between the putamen laterally and internal capsule medially.

Its internal and external segments may be distinguishable on some MRI sequences but are not always clearly separable on routine structural imaging.

Lentiform Nucleus

The putamen and globus pallidus together form the lentiform nucleus. On coronal sections this deep gray matter complex lies lateral to the internal capsule.

Recognition of the lentiform nucleus is useful for orienting both the basal ganglia and adjacent white matter structures.

Internal Capsule

The internal capsule contains densely packed projection fibers connecting the cerebral cortex with the thalamus, brainstem, and spinal cord.

On coronal imaging, portions of the internal capsule can be identified as white matter separating the lentiform nucleus laterally from the caudate and thalamic regions medially.

Deep Lateral Anatomy

Coronal MRI can demonstrate a characteristic sequence of structures extending laterally from the deep cerebral nuclei toward the insular cortex.

1. Internal capsule
2. Lentiform nucleus
3. External capsule
4. Claustrum
5. Extreme capsule
6. Insular cortex

External Capsule

The external capsule is a thin layer of white matter located immediately lateral to the putamen. It separates the putamen from the claustrum.

Its thin configuration is usually more readily appreciated on MRI than on routine CT.

Claustrum

The claustrum is a thin sheet of gray matter located between the external and extreme capsules.

Because it is narrow, careful attention to the layered lateral anatomy is necessary for reliable identification.

Insular Cortex

The insula lies deep within the lateral sulcus and is located lateral to the extreme capsule. It is covered by portions of the frontal, parietal, and temporal lobes known collectively as the opercula.

Coronal sections clearly demonstrate the depth of the insula relative to the lateral surface of the cerebral hemisphere.

Thalamic Level

More posterior coronal sections reveal the paired thalami on either side of the third ventricle. At these levels, the relationship between the thalamus, internal capsule, basal ganglia, and ventricular system becomes particularly important.

The thalami occupy a relatively central position within the diencephalon.

Third Ventricle

The third ventricle is a narrow midline cavity located between the paired thalami and related hypothalamic structures.

On coronal images, it provides a useful central landmark for identifying the diencephalon and evaluating cerebral symmetry.

Thalamus

The thalamus forms a substantial portion of the lateral wall of the third ventricular region. The internal capsule lies lateral to the thalamus.

Coronal imaging helps demonstrate the superior-inferior extent of the thalamus more clearly than a single axial section.

Hypothalamic Region

The hypothalamus lies inferior to the thalamus and forms important portions of the walls and floor of the third ventricle.

Coronal MRI is useful for appreciating the relationship of the hypothalamic region to the third ventricle, optic pathways, pituitary stalk, and surrounding basal structures.

Temporal Lobes

The temporal lobes occupy the inferolateral portions of many coronal brain sections. Coronal imaging is particularly valuable for studying their medial structures because the plane crosses the temporal lobes approximately perpendicular to their long axes in commonly used acquisitions.

Important structures include the hippocampal formation, amygdala, temporal horn, parahippocampal gyrus, and surrounding temporal white matter.

Temporal Horns

The temporal horns of the lateral ventricles extend into the temporal lobes. On coronal images they appear as CSF-containing spaces closely related to the hippocampi.

The size and symmetry of the temporal horns can provide useful information about the surrounding medial temporal structures and ventricular system.

Hippocampus

The hippocampus is one of the most important structures studied in the coronal plane. It forms a prominent part of the floor and medial relationship of the temporal horn.

Coronal MRI is commonly used to compare hippocampal size, morphology, internal architecture, and signal between the two sides.

Hippocampal Formation

The hippocampal formation includes the hippocampus proper, dentate gyrus, and subicular complex. These structures curve through the medial temporal lobe and participate importantly in memory-related neural circuits.

Their detailed anatomy is particularly well appreciated using thin coronal MRI sections oriented appropriately relative to the hippocampal long axis.

Amygdala

The amygdala lies within the anteromedial temporal lobe, anterior and superior to much of the hippocampal formation.

Moving through sequential coronal images helps demonstrate the transition from the amygdalar region anteriorly to the hippocampal structures posteriorly.

Parahippocampal Gyrus

The parahippocampal gyrus lies along the medial inferior surface of the temporal lobe. It is closely related to the hippocampal formation and surrounding medial temporal cortex.

Coronal images provide useful cross-sectional views of these relationships.

Why Coronal MRI Is Useful for the Hippocampus

The hippocampus extends predominantly along an anterior-posterior axis. Coronal sections intersect it in cross-section and therefore allow comparison of its shape and size at successive levels.

This orientation is particularly useful in structural assessment of the medial temporal lobes.

Fornix

The fornix is a major white matter pathway associated with the hippocampal formation. Portions of the fornix can be identified near the ventricular system and midline on appropriate coronal sections.

Its relationship to the septal region, lateral ventricles, and third ventricle becomes clearer when coronal and sagittal images are reviewed together.

Corpus Callosum and Fornix

The corpus callosum lies superior to the ventricular system, while the fornix occupies a more inferior relationship near the midline.

Coronal sections demonstrate how these white matter structures frame portions of the ventricular cavities.

Brainstem on Coronal Imaging

Coronal sections through posterior portions of the brain can include the midbrain, pons, and medulla depending on the level and angulation of the image.

Although axial and sagittal planes are frequently more intuitive for detailed brainstem anatomy, coronal images provide useful information about superior-inferior relationships and lateral symmetry.

Midbrain

At appropriate coronal levels, the midbrain can be identified beneath the diencephalon. The cerebral peduncles, tegmental region, and surrounding structures may be visualized depending on image resolution and plane orientation.

Coronal imaging helps demonstrate the relationship between the midbrain and medial temporal structures.

Cerebellum

Posterior coronal sections demonstrate the cerebellar hemispheres and vermis. The cerebellum occupies the posterior fossa inferior to the occipital lobes and posterior to the brainstem.

Coronal imaging is useful for comparing the two cerebellar hemispheres and assessing superior-inferior lesion extent.

Fourth Ventricle

The fourth ventricle is located between the brainstem and cerebellum. Depending on the coronal level, portions of this cavity can be visualized within the posterior fossa.

Its relationship to the surrounding brainstem and cerebellar structures is usually best understood by correlating coronal images with axial and sagittal views.

Posterior Cerebral Sections

As coronal sections progress posteriorly, the basal ganglia become less prominent and the posterior ventricular system, parietal white matter, occipital lobes, and visual pathways become increasingly important.

The atria and occipital horns of the lateral ventricles may be visible at these levels.

Atrium of the Lateral Ventricle

The atrium is the region where the body of the lateral ventricle meets the occipital and temporal horns. Coronal sections through the posterior cerebral hemispheres can demonstrate this expanded ventricular region.

Choroid plexus is commonly prominent within the atrial region.

Occipital Horns

The occipital horns extend posteriorly from the atria into the occipital lobes. Their size and degree of symmetry vary between individuals.

They become important landmarks on posterior coronal sections.

Occipital Lobes

The occipital lobes occupy the posterior cerebral hemispheres and contain the primary and association visual cortices.

Posterior coronal sections demonstrate the bilateral occipital cortices and intervening white matter around the posterior ventricular system.

Gray Matter and White Matter

Coronal CT and MRI demonstrate the relationship between the cortical gray matter, subcortical white matter, and deep gray nuclei.

The appearance of these tissues depends on the imaging modality and, for MRI, the sequence being used.

Gray-White Differentiation on CT

On normal noncontrast CT, cerebral gray matter is slightly more attenuating than white matter. This difference allows cortical and deep gray structures to be distinguished from surrounding white matter.

Loss of normal gray-white differentiation can occur in pathological processes such as acute ischemia and cerebral edema.

Coronal T1-Weighted MRI

On conventional T1-weighted MRI, white matter generally appears brighter than gray matter, while cerebrospinal fluid appears dark.

Coronal T1-weighted images provide detailed structural information and are useful for evaluating cerebral morphology, medial temporal anatomy, and ventricular relationships.

Coronal T2-Weighted MRI

On conventional T2-weighted MRI, cerebrospinal fluid appears bright and many pathological processes associated with increased tissue water also demonstrate increased signal.

The contrast between deep gray nuclei, white matter, ventricular CSF, and surrounding structures can assist anatomical identification.

Coronal FLAIR MRI

FLAIR suppresses normal CSF signal while retaining sensitivity to many T2-hyperintense abnormalities. Coronal FLAIR images can be particularly useful for evaluating abnormalities near the ventricular surfaces, cerebral cortex, and medial temporal lobes.

The dark ventricular CSF provides contrast against adjacent abnormal parenchymal signal.

Coronal Imaging of the Medial Temporal Lobes

Dedicated coronal imaging is particularly important when detailed assessment of the hippocampi and surrounding medial temporal structures is required.

Thin sections can demonstrate subtle differences in hippocampal volume, internal architecture, and signal that may be difficult to appreciate on thicker or differently oriented images.

Coronal Imaging of the Pituitary Region

The coronal plane is also valuable for evaluating the sellar and parasellar regions. It demonstrates the pituitary gland in relation to the cavernous sinuses, internal carotid arteries, optic pathways, and sphenoid sinus.

Coronal and sagittal images are commonly complementary when studying this region.

Optic Chiasm

The optic chiasm lies superior to the pituitary gland and anterior to the hypothalamic region. Coronal imaging can demonstrate the relationship of the chiasm to the pituitary stalk, suprasellar cistern, and adjacent vascular structures.

This relationship is clinically important when evaluating sellar and suprasellar masses.

Coronal Plane in Stroke Localization

Coronal images help determine the superior-inferior and medial-lateral extent of cerebral infarction. They can demonstrate involvement of the cortex, deep white matter, basal ganglia, internal capsule, thalamus, temporal lobes, brainstem, or cerebellum.

Coronal views are especially useful when an abnormality spans several axial levels and its vertical extent is difficult to appreciate from axial images alone.

Coronal Plane in Temporal Lobe Pathology

The coronal plane provides particularly useful visualization of the temporal lobes because it allows direct side-to-side comparison of medial temporal structures.

Abnormalities involving the hippocampus, amygdala, temporal horn, and parahippocampal region can therefore be assessed systematically.

Coronal Plane in Hydrocephalus

Coronal imaging demonstrates the width and symmetry of the lateral ventricles and third ventricle and their relationship to surrounding cerebral tissue.

It can help demonstrate ventricular enlargement, temporal horn dilatation, distortion of ventricular contours, and associated changes in surrounding structures.

Coronal Plane in Mass Lesions

Intracranial masses can be evaluated according to their superior-inferior extent and their effect on adjacent structures. Coronal imaging may clearly demonstrate displacement of the ventricles, basal ganglia, temporal lobes, or midline structures.

It is especially helpful for understanding whether a lesion extends across anatomical compartments or displaces structures vertically.

Coronal Plane in Midline Shift

Coronal images can demonstrate displacement of the ventricular system, septum pellucidum, third ventricle, and cerebral hemispheres relative to the expected midline.

Axial imaging is commonly used for measurement of midline shift, while coronal views provide complementary information about the direction and extent of distortion.

Coronal Plane in Brain Herniation

Because coronal images clearly demonstrate superior-inferior relationships, they can be useful for evaluating displacement of cerebral structures associated with intracranial mass effect.

Changes involving the medial temporal lobe, diencephalon, ventricular system, and adjacent cisterns should be interpreted together with axial and sagittal images.

Coronal Plane in Cerebellar Lesions

Coronal sections allow direct comparison of the cerebellar hemispheres and demonstrate the vertical extent of posterior fossa lesions.

They can also show distortion of the fourth ventricle and relationships between cerebellar lesions, brainstem structures, and the tentorial region.

Coronal Plane in White Matter Disease

Coronal MRI can demonstrate the distribution of white matter abnormalities relative to the lateral ventricles, corpus callosum, deep white matter, and subcortical regions.

Reviewing the same abnormalities in multiple planes helps determine their true shape and anatomical distribution.

Symmetry on Coronal Images

Coronal images are especially useful for side-to-side comparison because corresponding structures in the right and left hemispheres are displayed at the same vertical level.

The hippocampi, amygdalae, basal ganglia, thalami, ventricles, cerebral cortex, and cerebellar hemispheres can all be compared for differences in size, position, signal, or morphology.

Normal Asymmetry

Perfect symmetry is not expected in the human brain. The ventricles, cortical sulci, temporal structures, and other anatomical features may demonstrate normal side-to-side variation.

An apparent asymmetry should therefore be assessed across multiple slices and correlated with other imaging planes before being considered abnormal.

Slice Angulation

Coronal images may be acquired in a strict anatomical coronal orientation or angled relative to specific structures. The chosen angle can substantially affect the apparent shape of structures on each section.

Dedicated neurological protocols may deliberately use oblique coronal imaging to optimize visualization of particular anatomical regions.

Oblique Coronal Imaging of the Hippocampus

For detailed medial temporal imaging, coronal sections may be oriented approximately perpendicular to the long axis of the hippocampus.

This produces reproducible cross-sectional views that improve assessment of hippocampal morphology and side-to-side comparison.

Partial Volume Effect

Because each image slice has finite thickness, a single voxel can contain more than one tissue type. This partial volume effect may blur boundaries or make small structures appear different from their true morphology.

Thin sections, adjacent images, and multiplanar correlation help reduce interpretive problems caused by partial volume averaging.

Multiplanar Reconstruction

Modern CT and MRI datasets can often be reconstructed into coronal images from volumetric acquisitions. This allows the same anatomy to be viewed from different orientations without requiring a separate acquisition for every plane.

High-resolution isotropic datasets are particularly suitable for multiplanar reconstruction.

Coronal and Axial Relationship

The axial plane emphasizes anterior-posterior and right-left relationships, while the coronal plane emphasizes superior-inferior and right-left relationships.

Using the two planes together is especially helpful for understanding the basal ganglia, ventricular system, cerebral lobes, and posterior fossa.

Coronal and Sagittal Relationship

The sagittal plane emphasizes anterior-posterior and superior-inferior relationships from the side. Coronal imaging provides the complementary front-facing perspective.

Structures such as the corpus callosum, hippocampus, ventricular system, pituitary region, and brainstem are easier to understand when both planes are correlated.

Coronal and Axial Appearance of the Basal Ganglia

Axial images are commonly used to learn the medial-lateral relationships of the caudate, internal capsule, and lentiform nucleus. Coronal images add information about their vertical extent and changing morphology from anterior to posterior.

Reviewing both planes helps transform these nuclei from isolated two-dimensional shapes into three-dimensional structures.

Coronal and Axial Appearance of the Ventricles

Axial sections demonstrate the curved course of the lateral ventricular system across different levels, while coronal sections emphasize the relative height and symmetry of the paired ventricular cavities.

Coronal views are particularly useful for appreciating the relationship of the temporal horns to the hippocampi.

Common Orientation Errors

Error	Correct Approach
Confusing displayed right and left	Check orientation markers and remember radiological convention
Confusing superior and inferior	Top of the conventional coronal image is superior
Ignoring anterior-posterior level	Use ventricles, basal ganglia, thalami, and temporal structures as landmarks
Identifying structures by shape alone	Use relationships with neighboring structures
Reviewing only one coronal slice	Follow structures through adjacent sections
Ignoring slice angulation	Recognize that image orientation affects apparent morphology

Determining the Coronal Level

Before identifying individual structures, determine approximately where the section lies along the anterior-posterior axis.

The presence of frontal horns, caudate heads, basal ganglia, thalami, temporal horns, hippocampi, ventricular atria, or occipital horns provides useful information about the level of the image.

Practical Coronal Reading Sequence

1. Confirm the right-left orientation.
2. Identify the superior and inferior directions.
3. Determine the approximate anterior-posterior level.
4. Locate the interhemispheric fissure and midline.
5. Identify the ventricular system.
6. Examine the cerebral cortex and white matter.
7. Identify the basal ganglia and internal capsules when present.
8. Locate the thalami and third ventricle at appropriate levels.
9. Examine the temporal lobes, hippocampi, and temporal horns.
10. Assess the brainstem and cerebellum on posterior sections.
11. Compare corresponding structures on the right and left sides.
12. Correlate findings with axial and sagittal images.

Key Coronal Landmarks

Landmark	What It Helps Identify
Interhemispheric fissure	Cerebral midline
Frontal horns	Caudate heads and anterior ventricular anatomy
Internal capsule	Relationship between deep gray nuclei
Third ventricle	Thalami and diencephalon
Temporal horn	Hippocampus and medial temporal lobe
Corpus callosum	Superior ventricular and interhemispheric relationships
Insula	Deep lateral cerebral anatomy
Fourth ventricle	Brainstem-cerebellar relationship

Advantages of the Coronal Plane

• Provides direct comparison of right and left cerebral structures
• Clearly demonstrates superior-inferior relationships
• Excellent for medial temporal and hippocampal anatomy
• Useful for basal ganglia and ventricular relationships
• Helpful for evaluating sellar and parasellar anatomy
• Demonstrates the vertical extent of lesions
• Complements axial and sagittal imaging

Limitations of the Coronal Plane

No single imaging plane provides complete anatomical information. Some structures that are easily identified axially or sagittally may be less intuitive in coronal sections.

The apparent morphology of a structure also depends on the exact anterior-posterior position and angulation of the section. For this reason, coronal images should be interpreted as part of a multiplanar dataset whenever possible.

Clinical Importance

The coronal plane is fundamental to neuroimaging because it provides a front-facing cross-sectional view of the brain and displays right-left symmetry together with superior-inferior anatomy. It is particularly valuable for evaluating the medial temporal lobes, ventricular system, deep gray nuclei, pituitary region, cerebral hemispheres, and posterior fossa.

Coronal imaging also provides an important complementary view when determining the extent of stroke, tumors, edema, hydrocephalus, temporal lobe abnormalities, white matter lesions, and other neurological pathology.

Functional Importance

Understanding coronal anatomy helps convert two-dimensional neuroimaging into a three-dimensional representation of the brain. Anterior sections begin within the frontal lobes, intermediate sections reveal the ventricular system and basal ganglia, more posterior sections demonstrate the thalami and medial temporal structures, and posterior sections progressively reveal the ventricular atria and occipital regions.

The coronal plane is particularly useful for learning anatomical relationships that are difficult to appreciate from axial images alone. The caudate nuclei can be related to the lateral ventricles, the lentiform nuclei to the internal capsules, the thalami to the third ventricle, and the hippocampi to the temporal horns.

Rather than memorizing the appearance of structures on individual sections, coronal neuroanatomy is best learned by following structures through consecutive slices and using stable neighboring landmarks to determine their identity.

Mastery of the coronal plane provides a foundation for understanding brain MRI, brain CT, hippocampal anatomy, medial temporal anatomy, basal ganglia anatomy, ventricular anatomy, pituitary imaging, stroke localization, intracranial masses, and cross-sectional neuroanatomy.