Central Nervous System/Ana Salgado P.7 (CNS (The central canal of the…
Central Nervous System/Ana Salgado P.7
Protection of the Central Nervous System
The three connective tissue membrane covering and protecting the CNS structures are meninges.
The outermost layer, the leathery Dura mater, meaning "tough or hard mother," is a double-layered membrane where it surrounds the brain.
The middle meningeal layer is the web like arachnoid mater. Means spider Pia mater its threadlike extensions span the subarachnoid space to attach it to the innermost membrane, the pia mater.
Arachnoid Villi, protrude through the Dura mater.
The central canal of the neural tube, which is continuous between the brain and the spinal cord, becomes enlarged in four regions of the brain to form chambers called ventricles.
The NUERAL TUBE: which extends down the dorsal median plane of the developing embryos body
The paired Cerebral hemispheres are the most superior part of the brain and together are a good deal larger than the other three brain regions combined.
The entire surface of the cerebral hemispheres exhibits elevated ridges of tissue called gyri, separated by shallow grooves called SULCI.
Less numerous are the deeper grooves called the FISSURES, which separate large regions of the brain.
The cerebral hemisphere are separated by a single deep fissure, the longitudinal fissure.
Other fissures or sulci divide each cerebral hemispheres into a number of LOBES, named for the cranial bones that lie over them.
The somatic sensory area is located in the parietal lobe posterior to the central sulcus.
The visual area is located in the posterior part of the occipital lobe, the auditory is in the temporal lobe bordering the lateral sulcus, and the olfactory area is found deep inside the temporal lobe.
The primary motor area that allows us to consciously move our skeletal muscles is anterior to the central sulcus in the frontal lobe.
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The diencephalon, or interbraib, sits atop the brain stem and is enclosed by the cerebral hemispheres.
Three major structures of the diencephalon are the: thalamus, hypothalamus and epithalamus
The thalamus, which encloses the shallow third ventricle of the brain, relay station for sensory impulses passing upward to the sensory impulses passing upward to the sensory cortex.
The hypothalamus (literally, "under the thalamus") makes up the floor of the diencephalon.
The hypothalamus is also the center for many drives and emotions, and as such it is an important part of the so-called limbic system, or "emotional-visceral brain".
The pituary gland hangs from the anterior floor of the hypothalamus by a slender stalk.
The mammillary bodies, reflex centers involved in olfaction (the sense of smell), bulge from the floor of the hypothalamus posterior to the pituitary gland.
The epithalamus forms the roof of the third ventricle.
Important parts of the epithalamus are the pineal body (part of the endocrine system) and the choroid plexus of the third ventricle.
The brain stem is about the size of a thumb in diameter nd approximately 3 inches long.
Its structures are the midbrain, pons, and medulla oblongata.
The midbrain is a relatively small part of the brain stem.
The cerebral aqueduct is a tiny canal that travels through the midbrain and connects the third ventricle of the diencephalon to the fourth ventricle below.
Anteriorly the midbrain is composed primarily of two bulging fiber tracts, the cerebral peduncles (literally, "little feet of the cerebrum"), which convey ascending and descending impulses.
Dorsally located are four rounded protrusions called the corpora quadrigemina because they reminded some anatomist of two pairs of twins(Gemini).
Pons is the rounded structure that protrudes just below the midbrain.
The medulla oblongata is the most inferior part of the brain stem.
Reticular Formation : Extending the entire length of the brain stem is a diffuse mass of gray matter, the reticular formation.
A special group of reticular formation neurons, the reticular activating system (RAS), plays a role in consciousness and the awake/sleep cycles.
The large, cauliflowerlike cerebellum projects dorsally from the under the occipital lobe of the cerebrum.
Cerebrospinal Fluid (CSF) is a watery "broth" similar in its makeup to blood plasma, from which it forms.
The Blood-Brain Barrier consequently , neurons are kept separated from bloodborne substances by a so-called blood-brain barrier, composed of the least permeable capillaries in the whole body.