The document summarizes the normal radiological anatomy of the brain and pituitary gland as seen on computed tomography (CT) and magnetic resonance imaging (MRI). It describes the overall structure of the brain, including the cerebrum, cerebellum, brainstem, and four ventricles. It details the anatomy of the lateral, third, and fourth ventricles. It then outlines the major lobes and gyri of the cerebral hemispheres, including important motor and sensory areas. The document concludes by reviewing sectional anatomy as seen on axial CT and MRI scans.

1. Radiological anatomy of the
brain and pituitary gland.
Dr/ ABD ALLAH NAZEER. MD.

13. Normal Brain Anatomy.
The advent of high-resolution computed tomography (CT) and
magnetic resonance imaging (MRI) scanners has allowed the
fine anatomic structure to be seen in detail.
The brain is semisolid and conforms to the shape of the skull.
Its hemispheric surface is convoluted and has gyri and sulci. The
brain consists of the cerebrum, cerebellum, and brain stem.
There are four ventricles within the brain. They are lined
with ependyma and contain the CSF, produced by the choroid
plexus. Lateral ventricles are formed by the two ependyma-lined
cavities of the cerebral hemisphere and communicate with the
third ventricle via the midline foramen of Monro. They can be
divided into five parts: the anterior (frontal) horn, the
ventricular body, the collateral (atrium) trigone, the inferior
(temporal) horn, and the posterior (occipital) horn.

14. The third ventricle is a slit like ventricle midline cavity of
the diencephalons. It communicates with the lateral ventricles
via the interventricular foramina of Monro and with the fourth
ventricle via the cerebral aqueduct. It contains choroid plexus
in its roof.
The fourth ventricle is a rhomboid-shaped cavity overlying
the pons and medulla, extending from the central canal of the
upper cervical spinal cord to the cerebral aqueduct of the
midbrain. There is a small lateral recess on each side of the
fourth ventricle, which contains choroid plexus that protrudes
through the foramina of Luschka into the subarachnoid space.
A small median aperture in the caudal part of the ventricle is
known as the foramen of Magendie. Via the two lateral
foramina of Luschka and the single medial foramen of
Magendie, CSF flows into the ventricular system into the
subarachnoid spaces.

15. The two cerebral hemispheres are separated by
interhemispheric fissures and falx cerebri. On the lateral surface of the
brain, the sylvian fissure (lateral fissure) and the rolandic fissure (central
fissure) separate the cerebral hemisphere into the frontal lobe, temporal
lobe, parietal lobe, and a line drawn from the parieto-occipital sulcus
onto the preoccipital notch, delineating the boundaries of the parietal
and temporal lobes from that of the occipital lobe.
The frontal lobe, the largest of all the brain, has four principal
gyri: the precentral gyrus and the superior frontal, middle frontal, and
inferior frontal gyri. The precentral gyrus, parallel to the central sulcus,
together with the anterior bank of the central sulcus, comprises the
primary motor area, which is one of the most important cortical areas
for movement. Rostral to the precentral sulcus is the premotor area,
another important area for movement. The middle frontal gyrus contains
Brodmann’s area 8, known as the frontal eye field, which is important for
conjugate eye movements. Another important motor area for speech
called Broca’s area, is located at the triangular and the opercular parts of
the inferior frontal gyrus in the dominant hemisphere.

16. In the parietal lobe, there are a postcentral gyrus, a superior
parietal lobule, and an inferior parietal lobule. The postcentral gyrus
is a primary somesthetic area involved in general body sensation.
In the temporal lobe, the superior, middle, and inferior temporal
gyri are separated by the two transverse sulci. The posterior fossa
contains the cerebellum and brain stem.
The posterior fossa is outlined by the clivus and petrous bones
anteroinferiorly, the tentorium cerebelli superiorly, and the occipital
bone posteroinferiorly. The cerebellum is located posteriorly in the
two thirds of the posterior fossa, separated from the brain stem by
the fourth ventricle. The brain stem occupies the anterior third of
the posterior fossa, including the midbrain, pons, and medulla
oblongata.
The brain derives its vascular supply via two carotid and two
vertebral arteries. The internal carotid artery bifurcates terminally into
the anterior and middle cerebral arteries. The two vertebral arteries
unite at the caudal border of the pons to form the basilar artery.

17. Sectional Anatomy:
Normal Axial CT and MRI Anatomy.
On CT and MR scans, the brain has been briefly viewed in
infratentorial and supratentorial sections, as described below.
CT scans are performed with a 15- to 20-degree angulation to
the canthomeatal line at 8-mm increments. MRI scans are
generally obtained parallel to the AC-PC line in the axial plane
with 6-mm slice thickness. Using the sagittal view, the coronal
sections are acquired parallel to the brain stem, and the
sagittal sections are obtained perpendicular to the axial
section.
On MRI studies, cranial nerves IX and X can be demonstrated
at this level because they emerge from the postolivary sulcus.
The posterior aspect of the cerebellar hemispheres is outlined
by the inferior portion of the cisterna magna.

18. Axial CT Anatomy.

34. The Corpus Callosum.

49. The Foramina of Magendie and Luschka.
4th
FM
4th

98. Pituitary Fossa.

99. Suprasellar Cistern
And Optic Apparatus.

116. Thank You.