Nervous System Lecture Presentation PDF

NERVOUS SYSTEM Lester S. Manzanares, PTRP, RN, MAN  Structural Classification ▪ Central nervous system (CNS) ▪ Organs ▪ Brain ▪ Spinal cord ▪ Function ▪ Integration; command center ▪ Inter...

NERVOUS SYSTEM Lester S. Manzanares, PTRP, RN, MAN  Structural Classification ▪ Central nervous system (CNS) ▪ Organs ▪ Brain ▪ Spinal cord ▪ Function ▪ Integration; command center ▪ Interprets incoming sensory information ▪ Issues outgoing instructions © 2018 Pearson Education, Ltd.  Structural Classification ▪ Peripheral nervous system (PNS) ▪ Nerves extending from the brain and spinal cord ▪ Spinal nerves—carry impulses to and from the spinal cord ▪ Cranial nerves—carry impulses to and from the brain ▪ Functions ▪ Serve as communication lines among sensory organs, the brain and spinal cord, and glands or muscles © 2018 Pearson Education, Ltd.  Functional Classification ▪ Sensory (afferent) division ▪ Nerve fibers that carry information to the central nervous system ▪ Somatic sensory (afferent) fibers carry information from the skin, skeletal muscles, and joints ▪ Visceral sensory (afferent) fibers carry information from visceral organs ▪ Motor (efferent) division ▪ Nerve fibers that carry impulses away from the central nervous system organs to effector organs (muscles and glands) © 2018 Pearson Education, Ltd.  Functional Classification ▪ Motor (efferent) division (continued) ▪ Two subdivisions ▪ Somatic nervous system = voluntary ▪ Consciously (voluntarily) controls skeletal muscles ▪ Autonomic nervous system = involuntary ▪ Automatically controls smooth and cardiac muscles and glands ▪ Further divided into the sympathetic and parasympathetic nervous systems © 2018 Pearson Education, Ltd.  Nervous Tissue: Neurons ▪ Functional properties of neurons ▪ Irritability ▪ Ability to respond to a stimulus and convert it to a nerve impulse ▪ Conductivity ▪ Ability to transmit the impulse to other neurons, muscles, or glands © 2018 Pearson Education, Ltd.  Nervous Tissue: Neurons ▪ Somatic reflexes ▪ Reflexes that stimulate the skeletal muscles ▪ Involuntary, although skeletal muscle is normally under voluntary control ▪ Example: pulling your hand away from a hot object ▪ Autonomic reflexes ▪ Regulate the activity of smooth muscles, the heart, and glands ▪ Example: regulation of smooth muscles, heart and blood pressure, glands, digestive system © 2018 Pearson Education, Ltd.  Central Nervous System (CNS) ▪ Functional anatomy of the brain ▪ Brain regions ▪ Cerebral hemispheres ▪ Diencephalon ▪ Brain stem ▪ Cerebellum © 2018 Pearson Education, Ltd.  Functional Anatomy of the Brain ▪ Cerebral hemispheres are paired (left and right) superior parts of the brain ▪ Include more than half of the brain mass ▪ The surface is made of ridges (gyri) and grooves (sulci) ▪ Fissures are deeper grooves ▪ Lobes are named for the cranial bones that lie over them © 2018 Pearson Education, Ltd.  Functional Anatomy of the Brain ▪ Three main regions of cerebral hemisphere 1. Cortex is superficial gray matter 2. White matter 3. Basal nuclei are deep pockets of gray matter © 2018 Pearson Education, Ltd. Figure 7.12b Development and regions of the human brain. Cerebral hemisphere Diencephalon Cerebellum Brain stem (b) Adult brain © 2018 Pearson Education, Ltd. Figure 7.13ab Left lateral view of the brain. Precentral gyrus Central sulcus Parietal lobe Postcentral gyrus Frontal lobe Parietal lobe Left cerebral Parieto-occipital hemisphere sulcus (deep) Lateral sulcus Frontal Occipital lobe lobe Occipital Temporal lobe Temporal lobe Cerebellum lobe Pons Superior Cerebral cortex Medulla Brain Cerebellum Inferior (gray matter) oblongata stem Gyrus Spinal (b cord ) Sulcus Cerebral Fissure white (a deep sulcus) matter (a ) © 2018 Pearson Education, Ltd.  Functional Anatomy of the Brain ▪ Cerebral cortex ▪ Primary somatic sensory area ▪ Located in parietal lobe posterior to central sulcus ▪ Receives impulses from the body’s sensory receptors ▪ Pain, temperature, light touch (except for special senses) © 2018 Pearson Education, Ltd. Figure 7.13c Left lateral view of the brain. Central sulcus Primary motor area Primary somatic sensory Premotor area area Anterior Gustatory area (taste) association area Working memory Speech/language and judgment (outlined by dashes) Problem Posterior association solving area Language comprehension Visual area Broca’s area (motor speech) Olfactory Auditory area area (c ) © 2018 Pearson Education, Ltd. Figure 7.14 Sensory and motor areas of the cerebral cortex. Posterior Moto Sensor Motor map in r Anterior y Sensory map in Shoul precentral postcentral Head Ha earm Trunk gyrus Neck gyrus Trunk Arm ow Hip Leg der Knee Elb t Arm Wri Hip Ha s r nd Elb er Fi Fo nd ow s ng ng e Fi Knee rs Th b u um m Foot b Th Nec e Ey Bro k se w o N Eye Toes ce Fa s Face Genitals Lip Lips Teeths Gum Jaw Jaw Tongue Tongue Primary motor Primary Pharynx cortex somatic Intra- Swallowing (precentral gyrus) sensory cortex abdominal (postcentral gyrus) © 2018 Pearson Education, Ltd.  Functional Anatomy of the Brain ▪ Cerebral areas involved in special senses ▪ Visual area (occipital lobe) ▪ Auditory area (temporal lobe) ▪ Olfactory area (temporal lobe) © 2018 Pearson Education, Ltd.  Functional Anatomy of the Brain ▪ Cerebral cortex ▪ Primary motor area ▪ Located anterior to the central sulcus in the frontal lobe ▪ Allows us to consciously move skeletal muscles ▪ Motor homunculus is a spatial map © 2018 Pearson Education, Ltd. Figure 7.13a Left lateral view of the brain. Precentral gyrus Central sulcus Postcentral gyrus Frontal lobe Parietal lobe Parieto-occipital sulcus (deep) Lateral sulcus Occipital lobe Temporal lobe Cerebellum Pons Cerebral cortex Medulla (gray matter) oblongata Gyrus Spinal cord Sulcus Cerebral Fissure white (a deep sulcus) matter (a © 2018 Pearson Education, Ltd. Figure 7.14 Sensory and motor areas of the cerebral cortex. Posterior Moto Sensor Motor map in r Anterior y Sensory map in Shoul precentral postcentral Head Ha earm Trunk gyrus Neck gyrus Trunk Arm ow Hip Leg der Knee Elb t Arm Wri Hip Ha s r nd Elb er Fi Fo nd ow s ng ng e Fi Knee rs Th b u um m Foot b Th Nec e Ey Bro k se w o N Eye Toes ce Fa s Face Genitals Lip Lips Teeths Gum Jaw Jaw Tongue Tongue Primary motor Primary Pharynx cortex somatic Intra- Swallowing (precentral gyrus) sensory cortex abdominal (postcentral gyrus) © 2018 Pearson Education, Ltd.  Functional Anatomy of the Brain ▪ Cerebral cortex (continued) ▪ Broca’s area (motor speech area) ▪ Involved in our ability to speak ▪ Usually in left hemisphere ▪ Other specialized areas ▪ Speech area (for sounding out words) © 2018 Pearson Education, Ltd. Figure 7.13c Left lateral view of the brain. Central sulcus Primary motor area Primary somatic sensory Premotor area area Anterior Gustatory area (taste) association area Working memory Speech/language and judgment (outlined by dashes) Problem Posterior association solving area Language comprehension Visual area Broca’s area (motor speech) Olfactory Auditory area area (c ) © 2018 Pearson Education, Ltd. Figure 7.13a Left lateral view of the brain. Precentral gyrus Central sulcus Postcentral gyrus Frontal lobe Parietal lobe Parieto-occipital sulcus (deep) Lateral sulcus Occipital lobe Temporal lobe Cerebellum Pons Cerebral cortex Medulla (gray matter) oblongata Gyrus Spinal cord Sulcus Cerebral Fissure white (a deep sulcus) matter (a © 2018 Pearson Education, Ltd.  Functional Anatomy of the Brain ▪ Diencephalon ▪ Sits on top of the brain stem ▪ Enclosed by the cerebral hemispheres ▪ Made of three structures 1. Thalamus 2. Hypothalamus 3. Epithalamus © 2018 Pearson Education, Ltd. Figure 7.12b Development and regions of the human brain. Cerebral hemisphere Diencephalon Cerebellum Brain stem (b) Adult brain © 2018 Pearson Education, Ltd. Figure 7.16a Diencephalon and brain stem structures. Cerebral hemisphere Corpus callosum Third ventricle Choroid plexus of third ventricle Occipital lobe of cerebral hemisphere Thalamus Anterior (encloses third ventricle) commissure Pineal gland (part of epithalamus) Hypothalamu Corpora s quadrigemina Optic chiasma Cerebral Midbrai aqueduct Pituitary gland n Cerebral peduncle Mammillary body Fourth ventricle Pon s Choroid plexus Medulla (part of epithalamus) oblongata Spinal cord Cerebellum (a) © 2018 Pearson Education, Ltd.  Functional Anatomy of the Brain ▪ Diencephalon: thalamus ▪ Encloses the third ventricle ▪ Relay station for sensory impulses © 2018 Pearson Education, Ltd.  Functional Anatomy of the Brain ▪ Diencephalon: hypothalamus ▪ Makes up the floor of the diencephalon ▪ Important autonomic nervous system center ▪ Regulates body temperature ▪ Regulates water balance ▪ Regulates metabolism ▪ Houses the limbic center for emotions ▪ Regulates the nearby pituitary gland ▪ Houses mammillary bodies for olfaction (smell) © 2018 Pearson Education, Ltd.  Functional Anatomy of the Brain ▪ Diencephalon: epithalamus ▪ Forms the roof of the third ventricle ▪ Houses the pineal body (an endocrine gland) ▪ Includes the choroid plexus—forms cerebrospinal fluid © 2018 Pearson Education, Ltd.  Functional Anatomy of the Brain ▪ Brain stem ▪ Attaches to the spinal cord ▪ Parts of the brain stem 1. Midbrain 2. Pons 3. Medulla oblongata © 2018 Pearson Education, Ltd. Figure 7.16a Diencephalon and brain stem structures. Cerebral hemisphere Corpus callosum Third ventricle Choroid plexus of third ventricle Occipital lobe of cerebral hemisphere Thalamus Anterior (encloses third ventricle) commissure Pineal gland (part of epithalamus) Hypothalamu Corpora s quadrigemina Optic chiasma Cerebral Midbrai aqueduct Pituitary gland n Cerebral peduncle Mammillary body Fourth ventricle Pon s Choroid plexus Medulla (part of epithalamus) oblongata Spinal cord Cerebellum (a) © 2018 Pearson Education, Ltd.  Functional Anatomy of the Brain ▪ Brain stem: midbrain ▪ auditory reflex centers © 2018 Pearson Education, Ltd.  Functional Anatomy of the Brain ▪ Brain stem: pons ▪ control of breathing © 2018 Pearson Education, Ltd.  Functional Anatomy of the Brain ▪ Brain stem: medulla oblongata ▪ Contains important centers that control: ▪ Heart rate ▪ Blood pressure ▪ Breathing ▪ Swallowing ▪ Vomiting © 2018 Pearson Education, Ltd.  Functional Anatomy of the Brain ▪ Brain stem: reticular formation ▪ Diffuse mass of gray matter along the brain stem ▪ Involved in motor control of visceral organs ▪ Reticular activating system (RAS) ▪ Plays a role in awake/sleep cycles and consciousness ▪ Filter for incoming sensory information © 2018 Pearson Education, Ltd.  Functional Anatomy of the Brain ▪ Cerebrum ▪ Controls balance ▪ Provides precise timing for skeletal muscle activity and coordination of body movements © 2018 Pearson Education, Ltd.  Protection of the Central Nervous System ▪ Meninges ▪ Cerebrospinal fluid (CSF) ▪ Blood-brain barrier © 2018 Pearson Education, Ltd.  Protection of the Central Nervous System ▪ Meninges (continued) ▪ Dura mater ▪ Outermost leathery layer © 2018 Pearson Education, Ltd.  Protection of the Central Nervous System ▪ Meninges (continued) ▪ Arachnoid layer ▪ Middle layer ▪ Pia mater ▪ Internal layer ▪ Clings to the surface of the brain and spinal cord © 2018 Pearson Education, Ltd. Figure 7.17a Meninges of the brain. Skin of scalp Periosteum Bone of skull Periosteal Dura Meningeal mater Superior sagittal sinus Arachnoid mater Subdural Pia mater space Arachnoid granulation Subarachnoid Blood space vessel Falx cerebri (in longitudinal (a fissure only) ) © 2018 Pearson Education, Ltd. Figure 7.17b Meninges of the brain. Skull Scalp Superior sagittal sinus Occipital lobe Dura mater Tentorium cerebelli Transverse Cerebellum sinus Temporal Arachnoid mater bone over medulla oblongata (b ) © 2018 Pearson Education, Ltd.  Protection of the Central Nervous System ▪ Cerebrospinal fluid ▪ Similar to blood plasma in composition ▪ Formed continually by the choroid plexuses ▪ Choroid plexuses—capillaries in the ventricles of the brain ▪ CSF forms a watery cushion to protect the brain and spinal cord ▪ Circulated in the arachnoid space, ventricles, and central canal of the spinal cord © 2018 Pearson Education, Ltd. Figure 7.18a Ventricles and location of the cerebrospinal fluid. Lateral ventricle Anterior horn Septum pellucidum Interventricular foramen Inferior horn Third ventricle Lateral Cerebral aperture aqueduct Fourth ventricle Central canal (a) Anterior view © 2018 Pearson Education, Ltd. Figure 7.18b Ventricles and location of the cerebrospinal fluid. Lateral ventricle Anterior horn Posterior Interventricular horn foramen Third Inferior horn ventricle Median Cerebral aqueduct aperture Fourth ventricle Lateral Central canal aperture (b) Left lateral view © 2018 Pearson Education, Ltd.  Brain Dysfunctions ▪ Traumatic brain injuries ▪ Concussion ▪ Slight brain injury ▪ Typically little permanent brain damage occurs ▪ Contusion ▪ Marked nervous tissue destruction occurs ▪ Coma may occur ▪ Death may occur after head blows due to: ▪ Intracranial hemorrhage ▪ Cerebral edema © 2018 Pearson Education, Ltd.  Brain Dysfunctions ▪ Cerebrovascular accident (CVA), or stroke ▪ Results when blood circulation to a brain area is blocked and brain tissue dies ▪ Loss of some functions or death may result ▪ Hemiplegia—one-sided paralysis ▪ Aphasia—damage to speech center in left hemisphere ▪ Transient ischemic attack (TIA) ▪ Temporary brain ischemia (restriction of blood flow) ▪ Numbness, temporary paralysis, impaired speech © 2018 Pearson Education, Ltd.  Spinal Cord ▪ Extends from the foramen magnum of the skull to the first or second lumbar vertebra ▪ Cauda equina is a collection of spinal nerves at the inferior end ▪ Provides a two-way conduction pathway to and from the brain ▪ 31 pairs of spinal nerves arise from the spinal cord © 2018 Pearson Education, Ltd. Figure 7.19 Anatomy of the spinal cord, posterior view. Cervical Cervical spinal nerves enlargement C8 Dura and arachnoid Thoracic mater spinal nerves Lumbar enlargement T12 End of spinal cord Lumbar Cauda spinal nerves equina L5 End of S1 Sacral meningeal spinal nerves coverings S5 © 2018 Pearson Education, Ltd.  Peripheral Nervous System (PNS) ▪ PNS consists of nerves and ganglia outside the CNS © 2018 Pearson Education, Ltd.  Structure of a Nerve ▪ Nerves are bundles of neurons found outside the CNS ▪ Endoneurium is a connective tissue sheath that surrounds each fiber ▪ Perineurium wraps groups of fibers bound into a fascicle ▪ Epineurium binds groups of fascicles © 2018 Pearson Education, Ltd. Figure 7.22 Structure of a nerve. Axon Myelin sheath Endoneurium Perineurium Epineurium Fascicle Blood vessels © 2018 Pearson Education, Ltd.  Structure of a Nerve ▪ Mixed nerves ▪ Contain both sensory and motor fibers ▪ Sensory (afferent) nerves ▪ Carry impulses toward the CNS ▪ Motor (efferent) nerves ▪ Carry impulses away from the CNS © 2018 Pearson Education, Ltd.  Cranial Nerves ▪ 12 pairs of nerves serve mostly the head and neck ▪ Only the pair of vagus nerves extends to thoracic and abdominal cavities ▪ Most are mixed nerves, but three are sensory only 1. Optic 2. Olfactory 3. Vestibulocochlear © 2018 Pearson Education, Ltd.  Cranial Nerves Mnemonic Device ▪ Oh – Olfactory ▪ Oh – Optic ▪ Oh – Oculomotor ▪ To – Trochlear ▪ Touch – Trigeminal ▪ And – Abducens ▪ Feel – Facial ▪ Very – Vestibulocochlear ▪ Green – Glossopharyngeal ▪ Vegetables – Vagus ▪ A – Accessory ▪ H – Hypoglossal © 2018 Pearson Education, Ltd. Figure 7.23 Distribution of cranial nerves. III Oculomotor IV Trochlear VI Abducens I Olfactory II Optic V Trigeminal V Trigeminal VII Facial Vestibular branch Cochlear branch VIII Vestibulocochlear X Vagus IX Glossopharyngeal XII Hypoglossal XI Accessory © 2018 Pearson Education, Ltd. Table 7.2 The Cranial Nerves (1 of 6) © 2018 Pearson Education, Ltd. Table 7.2 The Cranial Nerves (2 of 6) © 2018 Pearson Education, Ltd. Table 7.2 The Cranial Nerves (3 of 6) © 2018 Pearson Education, Ltd. Table 7.2 The Cranial Nerves (4 of 6) © 2018 Pearson Education, Ltd. Table 7.2 The Cranial Nerves (5 of 6) © 2018 Pearson Education, Ltd. Table 7.2 The Cranial Nerves (6 of 6) © 2018 Pearson Education, Ltd.  Spinal Nerves ▪ Spinal nerves ▪ 31 pairs ▪ Formed by the combination of the ventral and dorsal roots of the spinal cord ▪ Named for the region of the spinal cord from which they arise © 2018 Pearson Education, Ltd. Figure 7.24a Spinal nerves. C1 2 3 Ventral rami form Cervical 4 nerves 5 cervical plexus 6 (C1 – C5) 7 Ventral rami form 8* T1 brachial plexus 2 (C5 – C8; T1) 3 4 Thoracic 5 nerves 6 7 8 No plexus 9 formed 10 (intercostal Lumbar 1 nerves) nerves 1 12 (T2 – T12) Sacral L1 nerves 2 3 Ventral rami form 4 lumbar plexus (L1 – L4) 5 S1 Ventral rami form 2 sacral plexus 3 (L4 – L5; S1 – S4) 4 (a )*Note that the cervical nerve C8 emerges inferior to the C7 vertebra, while the other seven cervical nerves emerge superior to the vertebrae for which they are named. © 2018 Pearson Education, Ltd.  Spinal Nerves ▪ 31 spinal nerves divide soon after leaving the spinal cord into a dorsal ramus and a ventral ramus © 2018 Pearson Education, Ltd.  Spinal Nerves ▪ Four plexuses 1. Cervical 2. Brachial 3. Lumbar 4. Sacral © 2018 Pearson Education, Ltd. Table 7.3 Spinal Nerve Plexuses (1 of 3) © 2018 Pearson Education, Ltd. Figure 7.25a Distribution of the major peripheral nerves of the upper and lower limbs. Axillary nerve Humerus Radia l nerve Musculo- cutaneou s Ulna nerve Radius Ulnar nerve Media n nerve (a) Brachial © 2018 Pearson Education, Ltd. plexus, Table 7.3 Spinal Nerve Plexuses (2 of 3) © 2018 Pearson Education, Ltd. Figure 7.25b Distribution of the major peripheral nerves of the upper and lower limbs. Femoral nerve Lateral femoral cutaneous nerve Obturator nerve Femur Anterior femoral cutaneous nerve Saphenous nerve (b) Lumbar © 2018 Pearson Education, Ltd. plexus, Table 7.3 Spinal Nerve Plexuses (3 of 3) © 2018 Pearson Education, Ltd. Figure 7.25c Distribution of the major peripheral nerves of the upper and lower limbs. Superior gluteal nerve Inferior gluteal nerve Sciatic nerve Posterior femoral cutaneous nerve Common fibular nerve Tibial nerve Sural (cut) nerve Deep fibular Superficial nerve fibular nerve Plantar branches (c) Sacral plexus, posterior © 2018 Pearson Education, Ltd. view Figure 7.27 Anatomy of the autonomic nervous system. Parasympatheti Sympatheti c Eye c Eye Brain stem Salivary Skin glands Cranial Sympathetic Salivary ganglia glands Heart Cervical Lungs Lungs T1 Heart Stomach Thoracic Stomach Pancreas Liver Pancreas and gall- L1 bladder Liver and Adrenal Lumbar gall- gland bladder Bladder Bladder Sacral Genitals nerves Genitals (S2–S4) © 2018 Pearson Education, Ltd.  Autonomic Functioning ▪ Sympathetic—“fight or flight” division ▪ Response to unusual stimulus when emotionally or physically stressed or threatened ▪ Takes over to increase activities ▪ Remember as the “E” division ▪ Exercise ▪ Excitement ▪ Emergency ▪ Embarrassment © 2018 Pearson Education, Ltd.  Autonomic Functioning ▪ Parasympathetic—“housekeeping” activites ▪ “Rest-and-digest” system ▪ Conserves energy ▪ Maintains daily necessary body functions ▪ Remember as the “D” division ▪ Digestion ▪ Defecation ▪ Diuresis © 2018 Pearson Education, Ltd. Table 7.4 Effects of the Sympathetic and Parasympathetic Divisions of the Autonomic Nervous System (1 of 2) © 2018 Pearson Education, Ltd. Table 7.4 Effects of the Sympathetic and Parasympathetic Divisions of the Autonomic Nervous System (2 of 2) © 2018 Pearson Education, Ltd.  Developmental Aspects of the Nervous System ▪ Severe congenital brain diseases include: ▪ Cerebral palsy ▪ Anencephaly ▪ Hydrocephalus ▪ Spina bifida © 2018 Pearson Education, Ltd.  Developmental Aspects of the Nervous System ▪ Premature babies have trouble regulating body temperature because the hypothalamus is one of the last brain areas to mature prenatally ▪ Development of motor control indicates the progressive myelination and maturation of a child’s nervous system © 2018 Pearson Education, Ltd.  Developmental Aspects of the Nervous System ▪ Brain growth ends in young adulthood. Neurons die throughout life and are not replaced; thus, brain mass declines with age ▪ Orthostatic hypotension is low blood pressure due to changes in body position ▪ Healthy aged people maintain nearly optimal intellectual function ▪ Disease—particularly cardiovascular disease—is the major cause of declining mental function with age ▪ Arteriosclerosis is decreased elasticity of blood vessels © 2018 Pearson Education, Ltd. © 2018 Pearson Education, Ltd.