They have ‘horns’ which project into the frontal, occipital and temporal lobes. The ventricles are structures that produce cerebrospinal fluid, and transport it around the cranial cavity. They are lined by ependymal cells, which form a structure called the choroid plexus. The medulla oblongata controls breathing, blood pressure, heart rhythms and swallowing. Messages from the cortex to the spinal cord and nerves that branch from the spinal cord are sent through the pons and the brainstem.

The choroid plexus is part of the blood-brain barrier that protects the central nervous system from harmful chemicals, and is the primary source of the various components of cerebrospinal fluid. The choroid plexus or plica choroidea borders the membrane of the pia mater and the ventricles of the brain. It is an area of specialized cells that surrounds a direct blood source . The choroid plexus also plays neuroendocrine, neuro-immune, and excretory roles. The left and right lateral ventricles are located within their respective hemispheres of the cerebrum. They have ‘horns’ which project into the frontal, occipital and temporal lobes.

The floor and the lateral wall are formed by the head of the caudate nucleus, the corpus callosum constitutes the roof and anterior border, and the septum pellucidum delineates the medial wall. The posterior or occipital horn is located within the occipital lobe. The fibers of the corpus callosum and the splenium form the roof. The forceps major is located on the medial side and forms the bulb of the occipital horn. The ventricles of the brain The soft tissue of the brain is surrounded by three membranes called the meninges.

The cerebrospinal fluid within the skull and spine provides further protection and also buoyancy, and is found in the subarachnoid space between the pia mater and the arachnoid mater. The wall between the lateral ventricles is called the falx cerebri. Figure 1.17E is a butt lifting bikini section taken at the level of the junction of the midbrain with the diencephalon. Notice that the plane of section differs from those of the previous sections. At this level, a landmark structure of the diencephalon is the thalamus, which surrounds the third ventricle.

The gap between the cerebrum and the cerebellum at the transverse fissure can reveal some internal parts of the brain. In this image, a student is bending the cerebellum down to show the superior and inferior colliculi. Just behind the colliculi, the pineal gland is just barely visible. Non-communicating Hydrocephalus – Abnormal collection of CSF, with flow obstructed within the ventricular system.