CT Brain Anatomy

Instructions: Simply pause the mouse over the underlined words to see a transaxial CT demonstration of  the structure. If you wish to see a text-based description , click on the underlined word or image. To see the anatomy from base to top of brain, click  alphabetical order.

Ambient cisterns :

- cisterns located laterally on each side of midbrain

Amygdala :

- mass of gray matter in the anterior medial portion of the temporal lobe

Anterior clinoids :

- the lesser wings of the sphenoid bone form two sharp points called the anterrior clinoid processes

Anterior horn of lateral ventricle :

- the frontal portion of the lateral ventricles lying deep within the frontal lobe of the brain

Anterior limb of internal capsule :

- thin white matter portion of brain lying between the head of the caudate nucleus and the lentiform nucleus

Anterior medullary cistern :

- cistern lying anterior to the medulla

Basilar artery :

- on CT , appears as a small round structure running centrally and anterior to the medulla and pons

Body of caudate nucleus :

- appears superiorly in the brain as thin, gray matter, cresecent -shaped structure immediately

lateral to body of lateral ventricles

Body of lateral ventricles :

- superior most portion of lateral lateral ventricles

Calcified choroid plexus:

- choroid plexus on axial CT of the brain can most commonly be seen calcified within the occipital

horns of the lateral ventricles

Centrum semiovale :

- bilateral white matter portion of brain above the level of the lateral ventricles

Central sulcus :

- a deep furrow located on the upper lateral surface of the cerebral hemisphere

- separates the frontal and parietal lobes of the brain

Cerebellar hemisphere:

- the cerebellulum consists of two cerebellar hemispheres

Cerebellar tonsils:

- located on the inferior surface of the cerebellum, these two prominences (cerebellar tonsils)

can often be seen protruding through the foraman magnum

Cerebellar vermis :

- worm-like portion of cerebellum which lies posterior to midbrain

Cerebellopontine angle cisterns:

- located laterally on either side of the pons and communicating anteriorly with the prepontine cistern

Cerebral aqueduct:

- a narrow CSF pathway identifiable on CT as a tiny black dot posteriorly through midbrain

Cerebral peduncles:

- identifiable on CT as the two half-moon structures of the midbrain separated by the interpeduncular cistern

Cisterna magna:

- usually one of the largest cisterns

- identifiable on CT as bordered anteriorly by the medulla, laterally by the cerebellar hemispheres

and posteriorly by the occipital bone

Clivus:

- basilar portion of occipital bone which curves anterosuperiorly to articulate with the sphenoid bone

Confluence of sinuses:

- also known as the torcular Herophili

- identifiable on axial CT as the junction between the superior sagittal , transverse and straight sinuses

Corona radiata :

- bilateral white matter portion of brain usually referred to at the upper level of the lateral ventricles

Dorsum sellae:

- posterior portion of the sella turcica

- identifiable on axial CT as ridge of bone anterior to the pons and posterior to anterior clinoids

Ethmoid sinuses:

- black, air filled cavity lying anterior to the sphenoid sinus

External capsule:

- thin strip of white matter lying between the lentiform nucleus and the insula

Falx cerebri :

- vertical midline partition of dura mater which lies in the longitudinal fissure and separates the cerebral hemispheres

Foramen magnum :

- large oval opening on the inferior portion of the occipital bone

- on CT , structures such as the spinal cord and vertebral arteries can be identified within the foramen magnum

Fornix :

- commonly identified on CT lying posterior to the septum pellucidum between the anterior horns

of the lateral ventricles

Fourth ventricle :

- CSF pathway identifiable on CT as a cavity anterior to the cerebellum and posterior to the pons

Frontal sinus :

- large air-filled cavity within frontal bone

Genu of corpus callosum :

- identifiable on axial CT as white matter portion of brain connecting cerebral hemispherers located

anteromedial to anterior horns of lateral ventricles

Genu of internal capsule :

- identifiable on axial CT as the boomerang-shaped junction between the anterior and posterior limbs

of the internal capsule

Great vein of Galen :

- identifiable on CT as posterior to the pineal gland

Gyri :

- convolutions of cerebral cortex (gray matter)

Habenular calcification :

- occasionally identifiable on axial CT as calcified anterior peduncle of pineal gland

Head of caudate nucleus :

- identifiable on axial CT as a kidney-shaped mass of gray matter, posterolaterally indenting the anterior horns of

the lateral ventricles

Hippocampus :

- mass of gray matter seen on CT posterior to temporal horn at level of midbrain

Hypothalamus :

- mass of gray matter located just below the thalamus on either side of the third venticle

Insula :

- ridge of gray matter bordering Sylvian fissure

Internal occipital protuberance :::

- triangular-shaped inward extension of occipital bone arising posteriorly and

lying midline between cerebellar hemispheres

Interpeduncular cistern :

- cistern located between the peduncles of the midbrain

Lateral medullary cistern :

- cisterns lying laterally on each side of medulla

Lentiform nucleus :

- biconvex gray matter structure lying between the internal and external capsule

Mastoid air cells ::

- hollow air spaces within the mastoid proceses of the temporal bone

Medulla :

- most inferior portion of the brain serving as transitional segment between the spinal cord and pons

- bound anteriorly by the basilar portion of occipital bone and posteriorly by the cerebellar hemispheres

Midbrain :

- part of brainstem just above pons at junction of middle and posterior cranial fossae

Pineal gland :

- most commonly seen calcified on CT

- attached to the posterior part of the roof of the third ventricle

Pituitary gland :

- lies within the sella turcica

- on axial CT it appears posterior to the anterior clinoids and anterior to the dorsum sellae

Pons :

- segment of brainstem between the medulla and midbrain

Postcentral sulcus :

- a furrow posterior to the central sulcus

- between the central and postcentral sulci lies the postcentral gyrus (important sensory area)

Posterior limb of internal capsule :

- strip of white matter between thalamus and lentiform nucleus

Precentral sulcus :

- a furrow anterior to the central sulcus

- between the precentral and central sulci lies the precentral gyrus (important motor area)

Prepontine cistern :

- cistern located anterior to the pons

Quadrigeminal cistern :

- cistern located posterior to midbrain

Septum pellucidum :

- visualized on axial CT as the narrow separation between the anterior horns of the

lateral ventricles

Sigmoid sinus :

- the transverse sinus curves down to become the sigmoid sinus at the junction

of the petrous and mastoid portion of the temporal bone

Sphenoid sinus :

- visualized on CT as lying posterior to the ethmoid sinuses

Spinal cord ::

- visualized on axial slices below the foramen magnum

Splenium of corpus callosum :

- visualized on CT as band of white matter lying posterior to occipital horns of

lateral ventricles

Sulci :

- spaces between gyri

Superior sagittal sinus :

- visualized on CT on superior slices mid-sagitally, both anteriorly and

posteriorly where the falx cerebri meets the inner skull table

Suprasellar cistern :

- large cistern situated above just above the level of the dorusm sellae

Sylvian fissure :

- fissure extending laterally between the frontal and temporal lobes

and posteriorly between the temporal and parietal lobes

Temporal horns of lateral ventricles :

- visualized bilaterally approximately at the level of the midbrain

Temporal lobe :

- visualized on CT as the lower lateral portion of the cerbral hemisphere

Tentorium :

- dural membrane separating the cerebellum from the cerebrum

Thalamus :

- oval-shaped structure lying one on either side of the third ventricle

Third ventricle :

- midline CSF containing structure flanked bilaterlly by the thalamus

Transverse sinus :

- lies between the sigmoid sinus and confluence of sinuses

Vertebral arteries :

- visualized at the level of the foramen magnum as two small

round structures lying anterior and lateral to the spinal cord or medulla

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© Ed Costanzo B. App. Sc.(Medical Imaging), MRT(R)