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Chapter 7 : The Nervous System Central Nervous System, Anatomy
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Regions of the Brain Figure 7.12 Central Nervous System: Anatomy
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Protection of the Central Nervous System: Scalp and skin Skull and vertebral column Meninges Cerebrospinal fluid Blood brain barrier Figure 7.16a Central Nervous System: Anatomy
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Meninges Dura mater Double-layered external covering Periosteum – attached to surface of the skull Meningeal layer – outer covering of the brain Folds inward in several areas Central Nervous System: Anatomy
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Meninges Arachnoid layer Middle layer Web-like Pia mater Internal layer Clings to the surface of the brain Central Nervous System: Anatomy
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Cerebral Anatomy The surface is made of ridges (gyri) and grooves (sulci) Deep sulci are called fissures Figure 7.13a Central Nervous System: Anatomy
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Gray matter Outer layer Composed mostly of neuron cell bodies Basal nuclei – internal islands of gray matter Figure 7.13a Central Nervous System: Anatomy Cerebral Anatomy
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White matter Fiber tracts inside the gray matter Example: corpus callosum connects hemispheres Central Nervous System: Anatomy Cerebral Anatomy
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Cerebral Hemispheres (Cerebrum) Paired (left and right) superior parts of the brain Include more than half of the brain mass Central Nervous System: Cerebral Anatomy
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Lobes of the Cerebrum Fissures (deep grooves) divide the cerebrum into lobes Surface lobes of the cerebrum Frontal lobe Parietal lobe Occipital lobe Temporal lobe Central Nervous System: Cerebral Anatomy
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Cerebellum Two hemispheres with convoluted surfaces Provides involuntary coordination of body movements Central Nervous System: Cerebellar Anatomy
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Diencephalon Sits on top of the brain stem Enclosed by the cerebral hemispheres Made of three parts Thalamus Hypothalamus Epithalamus Central Nervous System: Anatomy
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Thalamus - Surrounds the third ventricle Hypothalamus - Under the thalamus The pituitary gland is attached to the hypothalamus Epithalamus – Upon the thalamus Forms the roof of the third ventricle Houses the pineal body (an endocrine gland) Includes the choroid plexus – forms cerebrospinal fluid Central Nervous System: Diencephalon
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Brain Stem Attaches to the spinal cord Parts of the brain stem Midbrain Pons Medulla oblongata Central Nervous System: Anatomy
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Midbrain Mostly composed of tracts of nerve fibers Has two bulging fiber tracts – cerebral peduncles Has four rounded protrusions – corpora quadrigemina Central Nervous System: Brain Stem Pons The bulging center part of the brain stem Mostly composed of fiber tracts Includes nuclei involved in the control of breathing Medulla Oblongata The lowest part of the brain stem Merges into the spinal cord Includes important fiber tracts
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Figure 7.15a Central Nervous System: Anatomy
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Ventricles and Location of the Cerebrospinal Fluid Central Nervous System: Anatomy
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Figure 7.17b Central Nervous System: Ventricles and Cerebrospinal Fluid
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Cerebrospinal Fluid Similar to blood plasma composition Formed by the choroid plexus Forms a watery cushion to protect the brain Circulated in arachnoid space, ventricles, and central canal of the spinal cord Central Nervous System: Ventricles and Cerebrospinal Fluid
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Nervous Tissue: Supporting Cells (Neuroglia, or simply Glia) Astrocytes Abundant, star-shaped cells Anchor neurons Form barrier between capillaries and neurons Control the chemical environment of the brain Figure 7.3a Central Nervous System: Neuroglia
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Microglia Spider-like phagocytes Dispose of debris Ependymal cells Line cavities of the brain and spinal cord Circulate cerebrospinal fluid with beating cilia Figure 7.3b, c Central Nervous System: Neuroglia
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Oligodendrocytes Produce myelin sheath around nerve fibers in the CNS Figure 7.3d Central Nervous System: Neuroglia Function like Schwann cells in the PNS
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Spinal Cord Extends from the medulla oblongata to the region of T12 Below T12 is the cauda equina (a collection of spinal nerves) Enlargements occur in the cervical and lumbar regions Figure 7.18 Central Nervous System: Spinal Cord
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Spinal Cord Anatomy Meninges cover the spinal cord Nerves leave at the level of each vertebrae Dorsal root Associated with the dorsal root ganglia – collections of cell bodies outside the central nervous system Ventral root Central Nervous System: Spinal Cord
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Exterior white mater – conduction tracts Figure 7.19 Central Nervous System: Spinal Cord Central canal filled with cerebrospinal fluid
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Internal gray matter - mostly cell bodies Dorsal (posterior) horns Anterior (ventral) horns Figure 7.19 Central Nervous System: Spinal Cord
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Michelangelo’s “The Creation of Adam” from his fresco in the Sistine Chapel. Does the red cloth look familiar?
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