Ventricles of Brain | Neurology | Veterinary Anatomy

These Ventricles of Brain is present in the brain- Lateral ventricle, Third ventricle, and Fourth ventricle.

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They are right and left and each is an irregular cavity in the interior of each cerebral hemisphere communicating with each other and with the third ventricle by the foramen of Munro. Each ventricle has three parts, body and two cornua or horns.
The body extends backwards to the splenium and communicates with the third ventricle through the interventricular foramen of Munro situated below the fornix and between it and the thalamus. The anterior cornua is in front and it communicates with the cavity of the olfactory bulb. The posterior cornua curves downward and forward into piriform lobe. Each lateral ventricle has a roof, floor and a medial wall. The roof is formed by the corpus callosum and the medial wall is by the posterior part of the septum lucidum. The floor is formed by the two chief nuclei-caudate nucleus in front and the hippocampus behind and the body of the fornix medially and in front.
The caudate nucleus is a pear shaped body, the long axis of which is directed upward backward and outward. Hippocampus is white on its ventricular face, curves outward downward and then forward to join the piriform lobe. These two bodies are separated by an oblique groove that is occupied by the choroid plexus of the lateral ventricle. On drawing the chorioid plexus aside, along the margin of the caudate nucleus, a narrow band of the white mater called the stria terminalis (taenia semicircularis) is seen.

It is the narrow annular space around the fused medial faces of the two thalami.
It communicates in front with the lateral ventricles through the interventricular foramen of Munro and behind with the fourth ventricle through the cerebral aqueduct.
The floor of the ventricle is formed by the structures of the interpenduncular fossa.
The roof is formed by the telachorioidea and fornix.
The anterior wall is a thin layer of gray mater stretching from the superior face, of the optic chiasma to the rostrum of the corpus callosum.
The cavity of the third ventricle presents three recesses the optic recess into the optic chiasma, pineal recess into the stalk of pineal body, the infundibular recess in the infundibulum or stalk of the pituitary gland.

The fourth ventricle or rhomboid fossa is the cavity of the hindbrain. It communicates behind with the central canal of the spinal cord and in front with the third ventricle through the cerebral aqueduct.
The floor is formed by the medulla and the pons. The posterior part narrows to a point at its communication with the central canal and this part is termed the calamus scriptorius.
The lateral wall is formed by the restiform body and anterior cerebellar peduncles.
The roof is formed by the vermis and the anterior and posterior medullary vela.
The fourth ventricle communicates, with the cisterna magna by a central and two lateral microscopic foramina Megendie, Key and Retzius respectively in the posterior medullary velum.