The document describes the four ventricles in the brain: the lateral ventricles located in the cerebral hemispheres, the third ventricle between the diencephalon, the cerebral aqueduct connecting the third ventricle to the fourth ventricle, and the fourth ventricle located between the pons and cerebellum. Each ventricle has distinct features such as shape, walls, and structures surrounding them. Blockage of openings between the ventricles can cause hydrocephalus, an abnormal increase in cerebrospinal fluid leading to increased intracranial pressure and potential mental retardation.

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Ventricles of Brain
Introduction: Cavities in the brain containing cerebrospinal fluid is known as Ventricles.
Cavities of Brain:
Cavities of Cerebrum: Lateral Ventricles (Right and Left Lateral ventricle in right and left cerebral
hemispheres.
Cavity of Diencepahlon: Third Ventricle.
Cavity of Midbrain: Cerebral aqueduct connecting third ventricle with fourth ventricle.
Cavity of Hindbrain (Pons-Medulla oblongata and Cerebellum): Fourth ventricle.
Lateral Ventricle (Cavity of cerebrum)
(*****Most Important Short Note)

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FEATURES SEEN IN LATERAL VENTRICLE
 Cavity of Telencephalon-cerebrum
 Shape: “C” shaped
 Parts with features seen in each part:
 Anterior Horn: Located in frontal lobe.
 Features and boundaries:
 Floor contains head of caudate nucleus.
 Anterior wall, floor and roof formed by corpus callosum.
 Medial wall by septum pellucidum.
 Lateral wall and floor is sloping and formed by head of caudate nucleus.
 Central Part: Located in parietal lobe.
 Features and boundaries:
 Floor contain: Body of caudate nucleus and thalamus.
 Roof by trunk of corpus callosum.

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 Medial wall by septum pellucidum.
 Lateral wall and floor is sloping and formed by head of caudate nucleus.
 Posterior horn: Located in occipital lobe. Small and inconstant.
 Features: If this horn is present it shows following features:
 Bulb of posterior horn raised by forceps major.
 Calcar avis raised by calcarine sulcus is seen into it.
 Inferior horn: Located in temporal lobe.
 Features seen:
 Features in the floor: Hippocampus and pes hippocampi seen its floor covered
by alveus and fimbria.
 Roof formed by tail of caudate nucleus and amygdaloid body.
 Communication with third ventricle by interventricular foramen of Monroe
 Function: Contain choroid plexus responsible for secretion of cerebrospinal fluid.
 Applied Anatomy: Blockage of interventricular foramen leads to dilatation of lateral ventricle.
This condition is known as Hydrocephalus. It leads to mental retardation.
Third Ventricle (Cavity of Diencephalon)
(***Important Short Note)
 Cavity of diencephalon located between diencephalon i.e. between two thalami.
 Shape: Slit like
 Anterior wall: Lamina terminalis, anterior commissure and anterior column of fornix.
 Posterior wall: Pineal gland with pineal recess and habenular and posterior commissure.
 Lateral wall: Thalamus and Hypothalamus separated by hypothalamic sulcus
 Superior wall (Roof): Ependyma, tela choroidea of third ventricle, internal cerebral veins,
fornix and corpus callosum.
 Inferior wall (Floor): Optic chiasma, tuber cinerium, infundibulum with its recess, mammilary
bodies, tegmentum of cerebral peduncles of midbrain.

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 Recesses:
 Pineal recess
 Supraoptic recess
 Infundibular recess
 Communications:
 Anterosuperiorly with lateral ventricle by interventricular foramen of Monroe.
 Posteroinferiorly with fourth ventricle by cerebral aqueduct.
 Function: Contain choroid plexus responsible for secretion of cerebrospinal fluid.
 Applied Anatomy: Blockage of cerebral aqueduct leads to dilatation of third ventricle and both
lateral ventricle. This condition is known as Hydrocephalus. It leads to mental retardation.

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Fourth Ventricle (Cavity of Hindbrain)
(*****Most Important Short Note)
 Cavity of hindbrain located between pons and medulla anteriorly and cerebellum posteriorly.
 Shape: “Tent: shape in sagittal section.
 Lateral Boundaries: Caudal part by inferior cerebellar peduncle and cranial part by superior
cerebellar peduncle.
 Posterior wall (Roof): tent shaped projects into cerebellum. Related to superior and nferior
medullary velum. Contains Median aperture (Foramen of Megendie) anf Lateral openings
(Foramen of Luschka).
 Rhomboid Fossa (Floor of fourth ventricle): Diamond shaped. Formed by posterior surface of
pons and medulla oblongata.
 Boundaries: Superolaterlly by superior cerebellar peduncle and inferolaterally by
Inferior cerebellar peduncle.
 Features seen:

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 Hypoglossal and vagal triangles
 facial colliculus
 Vestibular area
 Median sulcus
 Medial eminence
 Sulcus limitans
 Recesses:
 Dorsal median recess
 Two lateral recesses with lateral aperture.
 Communications:
 Superiorly with third ventricle by cerebral
 Inferiorly with central canal of spinal cord, and subarachnoid space by Median
aperture of Megendie.

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 Laterally with subarachnoid space by lateral aperture of Lushka.
 Function: Contain choroid plexus responsible for secretion of cerebrospinal fluid.
 Applied Anatomy: Blockage of openings leads to dilatation of all ventricles. This condition is
known as Hydrocephalus. It leads to mental retardation.
Applied Anatomy of Ventricles:
 HYDROCEPHALUS: Abnormal increase in the volume of cerebrospinal fluid within skull.
 Types:
 Non-communicating hydrocephalus: raised pressure is due to blockage between
choroid plexus and exit foramina.
 Communicating hydrocephalus: No obstruction. Causes can be excessive formation
or diminished absorption.
 INTRACRANIAL HYPERTENSION AND PAPILLEDEMA: congestion of retinal veins,
bulging forward of optic disc and edema of the disc.
Hydrocephalus
(Photo for understanding dilatation of ventricles and thinning of brain tissue)
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