What is the control center of the parasympathetic nervous system? What is the center of control Which specific nerve receptors do Beta blockers block in the involuntary nervous system? How is a nerve impulse propagated along the neuron and across a synapse? Why are detergents required to extract integral membrane proteins, but not peripheral membrane proteins? What is the highest dextrose concentration solution that may be administered through a Hydrocephalus develops when this balance is altered and is characterized by an abnormal accumulation of CSF within the ventricles.
This accumulation of CSF increases the pressure in the brain causing the ventricles to enlarge and the brain to be pressed against the skull. CSF is primarily produced within the lateral the third ventricles by delicate tufts of specialized tissue called the choroid plexus.
In some cases, hydrocephalus can develop when the choroid plexus produces too much CSF. This can happen when there is a tumor on the choroid plexus, for example. CSF flows from the lateral ventricles through two narrow passageways into the third ventricle. From the third ventricle, it flows down another long passageway known as the aqueduct of Sylvius into the fourth ventricle.
From the fourth ventricle, it passes through three small openings called foramina and into the subarachnoid space surrounding the brain and the spinal cord. If the flow of CSF at any of these points is blocked, hydrocephalus can develop. This is often referred to as non-communicating hydrocephalus. It has traditionally been thought that CSF is absorbed through tiny, specialized cell clusters called arachnoid villi near the top and midline of the brain.
Each cerebral hemisphere is divided into five lobes, four of which have the same name as the bone over them: the fontal lobe , the parietal lobe , the occipital lobe , and the temporal lobe. A fifth lobe, the insula or Island of Reil, lies deep within the lateral sulcus.
The diencephalons is centrally located and is nearly surrounded by the cerebral hemispheres. It includes the thalamus , hypothalamus , and epithalamus. The thalamus, about 80 percent of the diencephalons, consists of two oval masses of gray matter that serve as relay stations for sensory impulses, except for the sense of smell , going to the cerebral cortex. The hypothalamus is a small region below the thalamus, which plays a key role in maintaining homeostasis because it regulates many visceral activities.
The epithalamus is the most dorsal portion of the diencephalons. This small gland is involved with the onset of puberty and rhythmic cycles in the body. It is like a biological clock. The brain stem is the region between the diencephalons and the spinal cord. It consists of three parts: midbrain , pons , and medulla oblongata. The midbrain is the most superior portion of the brain stem. The pons is the bulging middle portion of the brain stem. This region primarily consists of nerve fibers that form conduction tracts between the higher brain centers and spinal cord.
The medulla oblongata, or simply medulla , extends inferiorly from the pons.
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