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8 The Nervous System
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The Meninges (8-5) The neural tissue in the CNS is protected by three layers of specialized membranes Dura mater Arachnoid Pia mater © 2013 Pearson Education, Inc.
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The Dura Mater (8-5) Is the outer, very tough covering
The dura mater has two layers, with the outer layer fused to the periosteum of the skull Dural folds contain large veins, the dural sinuses In the spinal cord the dura mater is separated from the bone by the epidural space © 2013 Pearson Education, Inc.
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The Arachnoid Is separated from the dura mater by the subdural space
That contains a little lymphatic fluid Below the epithelial layer is arachnoid space Created by a web of collagen fibers Contains cerebrospinal fluid © 2013 Pearson Education, Inc.
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The Pia Mater Is the innermost layer
Firmly bound to the neural tissue underneath Highly vascularized Providing needed oxygen and nutrients © 2013 Pearson Education, Inc.
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Spinal Cord Structure (8-6)
The major neural pathway between the brain and the PNS Can also act as an integrator in the spinal reflexes Involving the 31 pairs of spinal nerves Consistent in diameter except for the cervical enlargement and lumbar enlargement Where numerous nerves supply upper and lower limbs © 2013 Pearson Education, Inc.
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Spinal Cord Structure (8-6)
Central canal A narrow passage containing cerebrospinal fluid Surface of the spinal cord is indented by the: Posterior median sulcus Deeper anterior median fissure © 2013 Pearson Education, Inc.
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31 Spinal Segments (8-6) Identified by a letter and number relating to the nearby vertebrae Each has a pair of dorsal root ganglia Containing the cell bodies of sensory neurons with axons in dorsal root Ventral roots contain motor neuron axons Roots are contained in one spinal nerve © 2013 Pearson Education, Inc.
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Figure 8-14a Gross Anatomy of the Spinal Cord.
Cervical spinal nerves C3 C4 C5 C6 Cervical enlargement C7 C8 T1 T2 T3 T4 T5 T6 T7 Thoracic spinal nerves T8 Posterior median sulcus T9 T10 T11 Lumbar enlargement T12 L1 Inferior tip of spinal cord L2 Lumbar spinal nerves L3 Cauda equina L4 L5 S1 Sacral spinal nerves S2 S3 S4 S5 Coccygeal nerve (Co1) In this superficial view of the adult spinal cord, the designations to the left identify the spiral nerves. © 2013 Pearson Education, Inc.
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Figure 8-14b Gross Anatomy of the Spinal Cord.
Posterior median sulcus Dorsal root Dorsal root ganglion Central canal Gray matter White matter Spinal nerve Ventral root Anterior median fissure C3 This cross section through the cervical region of the spinal cord shows some prominent features and the arrangement of gray matter and white matter. © 2013 Pearson Education, Inc.
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Sectional Anatomy of the Spinal Cord (8-6)
The central gray matter is made up of glial cells and nerve cell bodies Projections of gray matter are called horns Which extend out into the white matter White matter is myelinated and unmyelinated axons The location of cell bodies in specific nuclei of the gray matter relate to their function © 2013 Pearson Education, Inc.
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Sectional Anatomy of the Spinal Cord (8-6)
Posterior gray horns are somatic and visceral sensory nuclei Lateral gray horns are visceral (ANS) motor nuclei The anterior gray horns are somatic motor nuclei White matter can be organized into three columns Which contain either ascending tracts to the brain, or descending tracts from the brain to the PNS © 2013 Pearson Education, Inc.
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Figure 8-15 Sectional Anatomy of the Spinal Cord.
Posterior white column Posterior median sulcus Functional Organization of Gray Matter Posterior gray commissure The cell bodies of neurons in the gray matter of the spinal cord are organized into functional groups called nuclei. Posterior gray horn Somatic Lateral white column Lateral gray horn Visceral Sensory nuclei Dorsal root ganglion Visceral Anterior gray horn Motor nuclei Somatic Ventral root Anterior gray commissure Anterior white column Anterior white commissure Anterior median fissure The left half of this sectional view shows important anatomical landmarks, including the three columns of white matter. The right half indicates the functional organization of the nuclei in the anterior, lateral, and posterior gray horns. POSTERIOR Structural Organization of Gray Matter Posterior median sulcus The projections of gray matter toward the outer surface of the spinal cord are called horns. Posterior gray commissure Dura mater Posterior gray horn Arachnoid mater (broken) Lateral gray horn Dorsal root Central canal Anterior gray commissure Anterior gray horn Anterior median fissure Dorsal root ganglion ANTERIOR Pia mater Ventral root A micrograph of a section through the spinal cord, showing major landmarks in and surrounding the cord. © 2013 Pearson Education, Inc.
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Figure 8-15a Sectional Anatomy of the Spinal Cord.
Posterior white column Posterior median sulcus Functional Organization of Gray Matter Posterior gray commissure The cell bodies of neurons in the gray matter of the spinal cord are organized into functional groups called nuclei. Posterior gray horn Somatic Sensory nuclei Lateral white column Lateral gray horn Visceral Dorsal root ganglion Visceral Motor nuclei Anterior gray horn Somatic Ventral root Anterior gray commissure Anterior white column Anterior white commissure Anterior median fissure The left half of this sectional view shows important anatomical landmarks, including the three columns of white matter. The right half indicates the functional organization of the nuclei in the anterior, lateral, and posterior gray horns. © 2013 Pearson Education, Inc.
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Figure 8-15b Sectional Anatomy of the Spinal Cord.
POSTERIOR Structural Organization of Gray Matter Posterior median sulcus The projections of gray matter toward the outer surface of the spinal cord are called horns. Posterior gray commissure Dura mater Posterior gray horn Arachnoid mater (broken) Lateral gray horn Dorsal root Central canal Anterior gray horn Anterior gray commissure Anterior median fissure Dorsal root ganglion ANTERIOR Pia mater Ventral root A micrograph of a section through the spinal cord, showing major landmarks in and surrounding the cord. © 2013 Pearson Education, Inc.
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Six Major Regions of the Brain (8-7)
The cerebrum The diencephalon The midbrain The pons The medulla oblongata The cerebellum © 2013 Pearson Education, Inc.
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Major Structures of the Brain (8-7)
The cerebrum Is divided into paired cerebral hemispheres Deep to the cerebrum is the diencephalon Which is divided into the thalamus, the hypothalamus, and the epithalamus The brain stem Contains the midbrain, pons, and medulla oblongata The cerebellum Is the most inferior/posterior part © 2013 Pearson Education, Inc.
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Right cerebral hemisphere Longitudinal fissure CEREBRUM
Figure 8-16a The Brain. Right cerebral hemisphere Longitudinal fissure CEREBRUM Left cerebral hemisphere A N T E R I O P O S T E R I CEREBELLUM Cerebral veins and arteries below arachnoid mater Superior view © 2013 Pearson Education, Inc.
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Central sulcus Precentral gyrus Postcentral gyrus Parietal
Figure 8-16b The Brain. Central sulcus Precentral gyrus Postcentral gyrus Parietal lobe Frontal lobe of left cerebral hemisphere Lateral sulcus Occipital lobe Temporal lobe CEREBELLUM PONS Lateral view MEDULLA OBLONGATA © 2013 Pearson Education, Inc.
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Corpus callosum Precentral gyrus Postcentral gyrus
Figure 8-16c The Brain. Corpus callosum Precentral gyrus Central sulcus Postcentral gyrus Fornix Thalamus Hypothalamus Frontal lobe DIENCEPHALON Pineal gland (part of epithalamus) Parieto-occipital sulcus Optic chiasm CEREBELLUM Mamillary body Temporal lobe MIDBRAIN Brain stem PONS MEDULLA OBLONGATA Sagittal section © 2013 Pearson Education, Inc.
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The Ventricles of the Brain (8-7)
Filled with cerebrospinal fluid and lined with ependymal cells The two lateral ventricles within each cerebral hemisphere drain through the: Interventricular foramen into the: Third ventricle in the diencephalon, which drains through the cerebral aqueduct into the: Fourth ventricle, which drains into the central canal © 2013 Pearson Education, Inc.
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Figure 8-17 The Ventricles of the Brain.
Cerebral hemispheres Cerebral hemispheres Ventricles of the Brain Lateral ventricles Interventricular foramen Third ventricle Cerebral aqueduct Fourth ventricle Pons Medulla oblongata Central canal Spinal cord Cerebellum Central canal A lateral view of the ventricles An anterior view of the ventricles © 2013 Pearson Education, Inc.
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Cerebrospinal Fluid (8-7)
CSF Surrounds and bathes the exposed surfaces of the CNS Floats the brain Transports nutrients, chemicals, and wastes Is produced by the choroid plexus Continually secreted and replaced three times per day Circulation from the fourth ventricle into the subarachnoid space into the dural sinuses © 2013 Pearson Education, Inc.
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Figure 8-18a The Formation and Circulation of Cerebrospinal Fluid.
Arachnoid granulations Extension of choroid plexus into lateral ventricle Choroid plexus of third ventricle Cerebral aqueduct Superior sagittal sinus Lateral aperture Choroid plexus of fourth ventricle Median aperture Arachnoid mater Central canal Subarachnoid space Spinal cord Dura mater A sagittal section of the CNS. Cerebrospinal fluid, formed in the choroid plexus, circulates along the routes indicated by the red arrows. © 2013 Pearson Education, Inc.
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Figure 8-18b The Formation and Circulation of Cerebrospinal Fluid.
Superior sagittal sinus Cranium Dura mater (outer layer) Arachnoid granulation Fluid movement Dura mater (inner layer) Cerebral cortex The relation-ship of the arachnoid granulations and dura mater. Subdural space Arachnoid mater Subarachnoid space Pia mater © 2013 Pearson Education, Inc.
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The Cerebrum (8-7) Contains an outer gray matter called the cerebral cortex Deep gray matter in the cerebral nuclei and white matter of myelinated axons beneath the cortex and around the nuclei The surface of the cerebrum Folds into gyri Separated by depressions called sulci or deeper grooves called fissures © 2013 Pearson Education, Inc.
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The Cerebral Hemispheres (8-7)
Are separated by the longitudinal fissure The central sulcus Extends laterally from the longitudinal fissure The frontal lobe Is anterior to the central sulcus Is bordered inferiorly by the lateral sulcus © 2013 Pearson Education, Inc.
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The Cerebral Hemispheres (8-7)
The temporal lobe Inferior to the lateral sulcus Overlaps the insula The parietal lobe Extends between the central sulcus and the parieto-occipital sulcus © 2013 Pearson Education, Inc.
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The Cerebral Hemispheres (8-7)
The occipital lobe Located most posteriorly The lobes are named for the cranial bone above it Each lobe has sensory regions and motor regions Each hemisphere sends and receives information from the opposite side of the body © 2013 Pearson Education, Inc.
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