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11.1: Introduction
• The central nervous system (CNS) consists of the brain and spinal cord.
• The brainstem connects the brain to the spinal cord.
• Communication to the peripheral nervous system (PNS) is by way of the spinal cord.
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11.2: Meninges• The meninges
• Membranes of CNS• Protect the CNS• Three (3) layers:
• Dura mater• “Tough mother”• Venous sinuses
• Arachnoid mater• “Spider mother”• Space contains cerebrospinal fluid (CSF)
• Pia mater• “Little mother”• Encapsulates blood vessels
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Scalp
Cranium
Cerebrum
Cerebellum
Spinal cord
Meninges
Meninges
Cerebrum
(b)(a)
Gray matterWhite matter
Subarachnoid space
Falx cerebri
Pia mater
Dura mater
Bone of skull
Subcutaneous tissue
Skin
Tentoriumcerebelli
Vertebra
Dural sinus (superiorsagittal sinus)
Arachnoidgranulation
Arachnoidmater
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Meninges of the Spinal CordCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Spinal cord
Spinal cord
Pia mater
Arachnoid mater
Dura mater
Dorsal root
Dorsal root
Spinal nerve
Epidural space
(a) (b)
Ventral root
Dorsal rootganglion
Thoracicvertebra
Spinalnerve
Dorsal rootganglion
Subarachnoidspace
Dorsal branch(dorsal ramus)
Ventral branch(ventral ramus)
Ventral root
Epiduralspace
Body ofvertebra
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11.3: Ventricles and Cerebrospinal Fluid
• There are four (4) ventricles• The ventricles are interconnected cavities within cerebral hemispheres and brain stem• The ventricles are continuous with the central canal of the spinal cord• They are filled with cerebrospinal fluid (CSF)
• The four (4) ventricles are:• Lateral ventricles (2)
• Known as the first and second ventricles
• Third ventricle• Fourth ventricle
• Interventricular foramen• Cerebral aqueduct
Lateral ventricle
Third ventricle
Fourth ventricle
(a)
Interventricularforamen
Cerebralaqueduct
To central canalof spinal cord
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Third ventricle
(b)
Cerebralaqueduct
To central canalof spinal cord
Fourthventricle
Lateralventricle
Interventricularforamen
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Cerebrospinal Fluid
• Secreted by the choroid plexus• Circulates in ventricles, central canal of spinal cord, and the subarachnoid space• Completely surrounds the brain and spinal cord•Clear fluid similar to blood plasma• Volume is only about 120 ml.• Nutritive and protective• Helps maintain stable ion concentrations in the CNS
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Third ventricle
Fourth ventricle
Cerebral aqueductSubarachnoid space
Arachnoid mater
Dura mater
Pia mater
Pia materCentral canal of spinal cord
Subarachnoid space
Filum terminaleArachnoid mater
Dura mater
Arachnoidgranulations
Choroid plexusesof third ventricle
Blood-filleddural sinus
Choroid plexus offourth ventricle
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11.4: Spinal Cord
• Slender column of nervous tissue continuous with brain and brainstem• Extends downward through vertebral canal• Begins at foramen magnum and ends at L1/L2 interspace• Conduit for nerve impulses to and from brain and brainstem• Center for spinal reflexes
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Brainstem
Spinal cord
(a) (b)
Foramenmagnum
Cervicalenlargement
Vertebralcanal
LumbarenlargementConusmedullarisCaudaequina
Filumterminale
Conusmedullaris
Lumbarenlargement
Cervicalenlargement
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Structure of the Spinal Cord Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
White matter
Gray matter
Lateral funiculus
Posterior funiculus
Gray commissure
Central canal
(a)
Posterior horn
Dorsal rootof spinal nerve
Dorsal rootganglion
Ventral rootof spinal nerve
Anteriorhorn
Anteriormedianfissure
Portion ofspinal nerve
Anteriorfuniculus
Posterior mediansulcus
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Reflex Arcs
• Reflexes are automatic, subconscious responses to stimuli within or outside the body
• Simple reflex arc (sensory – motor)• Most common reflex arc (sensory – association – motor)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Receptor
(a)
Sensory orafferent neuron
Motor orefferent neuronCentral
NervousSystem
Effector(muscle or gland)
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Reflex Arcs
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General Components of a Spinal Reflex
Receptor
Sensory neuron
Motor neuron
White matter
Gray matter
Spinal cord
DorsalInterneuron
4
5
3
2
1
(b)
Cell bodyof sensoryneuron
Effector(muscleor gland)
Centralcanal
Ventral
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
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Reflex Behavior
• Example is the knee-jerk reflex• Simple monosynaptic reflex• Helps maintain an upright posture
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Spinal cord
Patella
Patellar ligamentDirection of impulse
Axon of sensoryneuron
Cell body ofsensory neuron Cell body of
motor neuron
Axon of motorneuron
Effector (quadriceps femorismuscle group)
Receptor associated withdendrites of sensory neuron
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Reflex Behavior• Example is a withdrawal reflex• Prevents or limits tissue damage
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Interneuron
Spinal cord
Axon of sensory neuron
Cell body of sensory neuron
Dendrite ofsensoryneuron
Painreceptorin skin
Directionof impulse
Cell body ofmotor neuron
Axon ofmotor neuron
Effector (flexormuscle contractsand withdraws partbeing stimulated)
Tack
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11.5: Brain
• Functions of the brain:• Interprets sensations• Determines perception• Stores memory• Reasoning• Makes decisions• Coordinates muscular movements• Regulates visceral activities• Determines personality
• Major parts of the brain:• Cerebrum
• Frontal lobes• Parietal lobes• Occipital lobes• Temporal lobes• Insula
• Diencephalon• Cerebellum • Brainstem
• Midbrain• Pons• Medulla oblongata
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The BrainCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Cerebrum
Diencephalon
Midbrain
Pons
Medulla oblongata
Spinal cord
Cerebellum
Fornix
(b)
Skull
Meninges
Cerebrum
Diencephalon
Brainstem
(a)
Sulcus
Gyrus
Fornix
Cerebellum
Spinal cord
Midbrain
Pons
Medullaoblongata
Corpuscallosum
Corpuscallosum
Transverse fissure
b: © Martin M. Rotker/Photo Researchers, Inc.
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Structure of the Cerebrum• Corpus callosum
• Connects cerebral hemispheres (a commissure)
• Gyri • Bumps or convolutions
• Sulci• Grooves in gray matter
• Central sulcus of Rolando
• Fissures• Longitudinal: separates the cerebral hemispheres• Transverse: separates cerebrum from cerebellum• Lateral fissure of Sylvius
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Central sulcus
Gyrus
Sulcus
Frontal lobe
Lateral sulcus
Parietal lobe
Occipital lobe
Central sulcus
Parietal lobe
Occipital lobe
(a)
(b) (c)
Parietal lobe
Central sulcus
Occipital lobeFrontal lobeInsula
Temporal lobe
Longitudinalfissure
TransversefissureCerebellarhemisphere
Retractedtemporal lobe
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Lobes of the Cerebrum
• Five (5) lobes bilaterally:• Frontal lobe• Parietal lobe• Temporal lobe• Occipital lobe• Insula aka ‘Island of Reil’ (functions in interoceptive awareness & judging intensity of pain, among other things)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
(c)
Parietal lobe
Central sulcus
Occipital lobe
Frontal lobe
Insula
Retractedtemporal lobe
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Functions of the Cerebrum
• Interpreting impulses• Initiating voluntary movements• Storing information as memory• Retrieving stored information • Reasoning• Seat of intelligence and personality
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Functional Regions of theCerebral Cortex
• Cerebral cortex• Thin layer of gray matter that constitutes the outermost portion of cerebrum• Contains 75% of all neurons in the nervous system
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Frontal eye field
Central sulcus
Parietal lobe
Occipital lobe
Cerebellum
Brainstem
Interpretation of auditory patterns
Lateral sulcus
Auditory area
Sensory areas involved withcutaneous and other senses
Sensory speech area( Wernicke’s area)
Combiningvisual images,visual recognitionof objects
Visual area
Temporal lobe
Motor speech area(Broca’s area)
Motor areas involved with the controlof voluntary muscles
Concentration, planning,problem solving
Front lobe
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Functions of the Cerebral Lobes
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Sensory Areas(post-central sulcus)
• Cutaneous sensory area• Parietal lobe• Interprets sensations on skin
• Visual area• Occipital lobe• Interprets vision
• Auditory area• Temporal lobe• Interprets hearing
• Sensory area for taste• Near base of the central sulcus
• Sensory area for smell• Arises from centers deep within the cerebrum
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Frontal eye field
Central sulcus
Parietal lobe
Occipital lobe
Cerebellum
Brainstem
Interpretation of auditory patterns
Lateral sulcus
Auditory area
Sensory areas involved withcutaneous and other senses
Sensory speech area( Wernicke’s area)
Combiningvisual images,visual recognitionof objects
Visual area
Temporal lobe
Motor speech area(Broca’s area)
Motor areas involved with the controlof voluntary muscles
Concentration, planning,problem solving
Front lobe
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Motor & Sensory AreasCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Parietal lobe
Sensory area
Central sulcus
Motor area
Frontal lobe
Swallowing
ForearmArm
PelvisThigh
Leg
Lips
Forearm ArmNeck Pelvis
Thigh
Leg
Genitals
(a) Motor area (b) Sensory area
Longitudinalfissure
SalivationVocalizationMastication
Facialexpression
Thumb,fingers,and hand
Trunk
Foot andtoes
Tongue andpharynx
Teeth andgums
Upperface
Hand, fingers,and thumb
Trunk
Foot andtoes
Longitudinalfissure
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Association Areas• Regions that are not primary motor or primary sensory areas• Widespread throughout the cerebral cortex• Analyze and interpret sensory experiences• Provide memory, reasoning, verbalization, judgment, emotions
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Frontal eye field
Central sulcus
Parietal lobe
Occipital lobe
Cerebellum
Brainstem
Interpretation of auditory patterns
Lateral sulcus
Auditory area
Sensory areas involved withcutaneous and other senses
Sensory speech area( Wernicke’s area)
Combiningvisual images,visual recognitionof objects
Visual area
Temporal lobe
Motor speech area(Broca’s area)
Motor areas involved with the controlof voluntary muscles
Concentration, planning,problem solving
Front lobe
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Association Areas
• Frontal lobe association areas• Concentrating• Planning• Complex problem solving
• Parietal lobe association areas• Understanding speech• Choosing words to express thought
• Temporal lobe association areas• Interpret complex sensory experiences • Store memories of visual scenes, music, and complex patterns
• Occipital lobe association areas• Analyze and combine visual images with other sensory experiences
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Hemisphere Dominance
• The left hemisphere is dominant in most individuals
• Dominant hemisphere controls:• Speech• Writing• Reading• Verbal skills• Analytical skills• Computational skills
• Nondominant hemisphere controls:• Nonverbal tasks• Motor tasks• Understanding and interpreting musical and visual patterns• Provides emotional and intuitive thought processes
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Memory
• Short term memory• Working memory• Closed neuronal circuit• Circuit is stimulated over and over• When impulse flow ceases, memory does also unless it enters long-term memory via memory consolidation • Limited to 7 bits of information
• Long term memory• Changes structure or function of neurons• Enhances synaptic transmission
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Basal Nuclei
• Masses of gray matter• Deep within cerebral hemispheres• Produce dopamine• Control certain muscular activities
• Primarily by inhibiting motor functions
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Thalamus
Hypothalamus
Brainstem
Putamen
Cerebellum
Spinal cord
Longitudinalfissure
Right cerebralhemisphere
Caudatenucleus
Globuspallidus
Basalnuclei
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Diencephalon
• Between cerebral hemispheres and above the brainstem• Surrounds the third ventricle
• Thalamus• Epithalamus• Hypothalamus• Optic tracts• Optic chiasm• Infundibulum• Posterior pituitary• Mammillary bodies• Pineal gland
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Pyramidal tract
Pons
Optic nerveOptic chiasma
Thalamus
Spinal cord
Pituitary gland
Pineal gland
Optic tract
Mammillary body
(a) (b)
Olive
Corpora quadrigemina
Cerebralpeduncles
Superiorcolliculus
Inferiorcolliculus
Thirdventricle
Fourthventricle
Cerebellarpeduncles
Medullaoblongata
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Diencephalon
• Thalamus• Gateway for sensory impulses heading to cerebral cortex• Receives all sensory impulses (except smell)• Channels impulses to appropriate part of cerebral cortex for interpretation
• Epithalamus• Functions to connect the limbic system to other parts of the brain.
•Hypothalamus• Maintains homeostasis by regulating visceral activities • Links nervous and endocrine systems (hence some say the neuroendocrine system)
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Diencephalon
• Consists of:• Portions of frontal lobe• Portions of temporal lobe• Hypothalamus• Thalamus• Basal nuclei• Other deep nuclei
• Functions:• Controls emotions• Produces feelings• Interprets sensory impulses
The Limbic System
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Brainstem
Three parts:1. Midbrain2. Pons3. Medulla Oblongata
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Spinal cord
Thalamus
HypothalamusDiencephalon
Pons
Midbrain
Corpuscallosum
Corporaquadrigemina
Cerebralaqueduct
Reticularformation
Medullaoblongata
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Midbrain
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Pyramidal tract
Pons
Optic nerveOptic chiasma
Thalamus
Spinal cord
Pituitary gland
Pineal gland
Optic tract
Mammillary body
(a) (b)
Olive
Corpora quadrigemina
Cerebralpeduncles
Superiorcolliculus
Inferiorcolliculus
Thirdventricle
Fourthventricle
Cerebellarpeduncles
Medullaoblongata
• Between diencephalon and pons• Contains bundles of fibers that join lower parts of brainstem and spinal cord with higher parts of the brain• Cerebral aqueduct• Cerebral peduncles (bundles of nerve fibers)• Corpora quadrigemina (centers for visual and auditory reflexes)
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Pons
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Pyramidal tract
Pons
Optic nerveOptic chiasma
Thalamus
Spinal cord
Pituitary gland
Pineal gland
Optic tract
Mammillary body
(a) (b)
Olive
Corpora quadrigemina
Cerebralpeduncles
Superiorcolliculus
Inferiorcolliculus
Thirdventricle
Fourthventricle
Cerebellarpeduncles
Medullaoblongata
• Rounded bulge on underside of brainstem• Between medulla oblongata and midbrain • Helps regulate rate and depth of breathing• Relays nerve impulses to and from medulla oblongata and cerebellum (bridge)
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Medulla Oblongata
• Enlarged continuation of spinal cord• Conducts ascending and descending impulses between brain and spinal cord• Contains cardiac, vasomotor, and respiratory control centers• Contains various nonvital reflex control centers (coughing, sneezing, swallowing, and vomiting)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Pyramidal tract
Pons
Optic nerveOptic chiasma
Thalamus
Spinal cord
Pituitary gland
Pineal gland
Optic tract
Mammillary body
(a) (b)
Olive
Corpora quadrigemina
Cerebralpeduncles
Superiorcolliculus
Inferiorcolliculus
Thirdventricle
Fourthventricle
Cerebellarpeduncles
Medullaoblongata
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Cerebellum
• Inferior to occipital lobes• Posterior to pons and medulla oblongata• Two hemispheres like cerebrum• Vermis connects hemispheres• Cerebellar cortex (gray matter)• Arbor vitae (white matter)• Cerebellar peduncles (nerve fiber tracts)• Dentate nucleus (largest nucleus in cerebellum)• Integrates sensory information concerning position of body parts• Coordinates skeletal muscle activity• Maintains posture
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Thalamus
Superior peduncle
Middle peduncleInferior peduncle
Pons
Medulla oblongata
Cerebellum
Corpus callosum
Longitudinalfissure
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Major Parts of the Brain
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11.6: Peripheral Nervous System
• Cranial nerves arising from the brain• Somatic fibers connecting to the skin and skeletal muscles• Autonomic fibers connecting to viscera
• Spinal nerves arising from the spinal cord• Somatic fibers connecting to the skin and skeletal muscles• Autonomic fibers connecting to viscera
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Nervous System Subdivisions
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Structure of a Peripheral NerveCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Peripheral nerve
Epineurium
Axon
Neurilemma
Myelin sheath
Schwann cell
Node of Ranvier
Endoneurium
Perineurium
Fascicle
Sensory receptor
Motor neuronending
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Nerve and Nerve Fiber Classification
• Sensory nerves• Conduct impulses into brain or spinal cord
• Motor nerves• Conduct impulses to muscles or glands
• Mixed (both sensory and motor) nerves• Contain both sensory nerve fibers and motor nerve fibers• Most nerves are mixed nerves• ALL spinal nerves are mixed nerves (except the first pair)
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Cranial NervesCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Olfactory bulb
Hypoglossal (XII)
Optic tract
Olfactory tract
Olfactory (I)
Optic (II)
Oculomotor (III)
Abducens (VI)
Facial (VII)
Glossopharyngeal (IX)
Accessory (XI)
Trochlear (IV)
Trigeminal (V)
Vestibulocochlear (VIII)
Vagus (X)
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Cranial Nerves I and II
• Olfactory nerve (CN I)• Sensory nerve• Fibers transmit impulses associated with smell
• Optic nerve (CN II)• Sensory nerve• Fibers transmit impulses associated with vision
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Cranial Nerves III and IV
• Trochlear nerve (CN IV)• Primarily motor nerve• Motor impulses to muscles that move the eyes• Some sensory
• Proprioceptors
• Oculomotor nerve (CN III)• Primarily motor nerve• Motor impulses to muscles that:
• Raise eyelids• Move the eyes• Focus lens• Adjust light entering eye
• Some sensory• Proprioceptors
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Cranial Nerve V
• Trigeminal nerve (CN V)• Mixed nerve• “Three (3) sisters”• (1) Ophthalmic division
• Sensory from surface of eyes, tear glands, scalp, forehead, and upper eyelids
• (2) Maxillary division• Sensory from upper teeth, upper gum, upper lip, palate, and skin of face
• (3) Mandibular division• Sensory from scalp, skin of jaw, lower teeth, lower gum, and lower lip• Motor to muscles of mastication and muscles in floor of mouth
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Lacrimal nerve
Eye
Maxilla
Mandible
Lacrimalgland
Infraorbitalnerve
Tongue
Mentalnerve
Ophthalmicdivision
Maxillarydivision
Mandibulardivision
Lingualnerve
Inferioralveolarnerve
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Cranial Nerves VI and VII
• Abducens nerve (CN VI)• Primarily motor nerve• Motor impulses to muscles that move the eyes• Some sensory
•Proprioceptors
• Facial nerve (CN VII)• Mixed nerve• Sensory from taste receptors• Motor to muscles of facial expression, tear glands, and salivary glands
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Zygomatic nerve
Buccal nerve
Facial nerve
Mandibular nerve
Cervical nerve
Temporal nerve
Posterior auricularnerve
Parotid salivarygland
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Cranial Nerves VIII and IX
• Vestibulocochlear nerve (CN VIII)• Aka acoustic or auditory nerve• Sensory nerve• Two (2) branches:
• Vestibular branch• Sensory from equilibrium receptors of ear
• Cochlear branch • Sensory from hearing receptors
• Glossopharyngeal nerve (CN IX)• Mixed nerve• Sensory from pharynx, tonsils, tongue and carotid arteries• Motor to salivary glands and muscles of pharynx
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Cranial Nerve X
• Vagus nerve (CN X)• Mixed nerve• Somatic motor to muscles of speech and swallowing• Autonomic motor to viscera of thorax and abdomen• Sensory from pharynx, larynx, esophagus, and viscera of thorax and abdomen
Meningeal branch
Auricular branch
Pharyngeal branch
Palate
Cardiac nerves
Heart
Liver
Kidney
Nerve XI
Nerve XII
Carotid body
Large intestine
Lung
Stomach
Spleen
Pancreas
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Superior laryngealnerve
Recurrent laryngealnerve
Superior ganglionof vagus nerve
Inferior ganglionof vagus nerve
Left vagusnerve
Smallintestine
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Cranial Nerves XI and XII
• Accessory nerve (CN XI)• Primarily motor nerve• We called this “Spinal” Accessory because:
• Cranial branch• Motor to muscles of soft palate, pharynx and larynx
• Spinal branch • Motor to muscles of neck and back• Some sensory
• Proprioceptor
• Hypoglossal nerve (CN XII)• Primarily motor• Motor to muscles of the tongue• Some sensory
• Proprioceptor
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Functions of Cranial Nerves
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Spinal Nerves
• ALL are mixed nerves (except the first pair)• 31 pairs of spinal nerves:
• 8 cervical nerves• (C1 to C8)
• 12 thoracic nerves• (T1 to T12)
• 5 lumbar nerves• (L1 to L5)
• 5 sacral nerves• (S1 to S5)
• 1 coccygeal nerve• (Co or Cc)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Cauda equina
C1C2C3C4C5C6C7C8T1T2
T3
T4
T5
T6
T7
T8
T9
T10T11
T12
L1
L2
L3L4
L5
S2S3
S4
S1
S5Co
Posteriorview
Cervicalnerves
Thoracicnerves
Lumbarnerves
Sacralnerves
Coccygealnerve
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Spinal Nerves
• Dorsal root (aka posterior root)
• Sensory root• Axons of sensory neurons are in the dorsal root ganglion
• Dorsal root ganglion • Aka DRG• Cell bodies of sensory neurons whose axons conduct impulses inward from peripheral body parts
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Lateral horn
Ventral root(a)
(b)
Dorsal root
Dorsal root
Spinal nerve
Dorsal rootganglion
Posteriormedian sulcus
Posteriorhorn
Anteriorhorn
Centralcanal
Anteriormedianfissure
Dorsal branchof spinal nerveVentral branchof spinal nerve
Visceral branchof spinal nerve
Paravertebralganglion
Ventral branchof spinal nerve (ventral ramus)
Dorsal branchof spinal nerve (dorsal ramus)
Paravertebralganglion
Visceral branchof spinal nerve
Ventral root
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Spinal Nerves
• Ventral root (aka anterior root) • Motor root• Axons of motor neurons whose cell bodies are in the spinal cord
• Spinal nerve• Union of ventral root and dorsal roots• Hence we now have a “mixed” nerve
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Lateral horn
Ventral root(a)
(b)
Dorsal root
Dorsal root
Spinal nerve
Dorsal rootganglion
Posteriormedian sulcus
Posteriorhorn
Anteriorhorn
Centralcanal
Anteriormedianfissure
Dorsal branchof spinal nerveVentral branchof spinal nerve
Visceral branchof spinal nerve
Paravertebralganglion
Ventral branchof spinal nerve (ventral ramus)
Dorsal branchof spinal nerve (dorsal ramus)
Paravertebralganglion
Visceral branchof spinal nerve
Ventral root
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Nerve Plexuses
• Nerve plexus• Complex networks formed by anterior branches of spinal nerves• The fibers of various spinal nerves are sorted and recombined• There are three (3) nerve plexuses:
• (1) Cervical plexus – Lies deep within the neck• (2) Brachial plexus – Lies deep within shoulders• (3) Lumbosacral plexus – Extends from lumbar region into pelvic cavity
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Plexuses
C1C2C3C4C5C6C7C8T1
T2T3
T4
T5
T6
T8
T9
T10T11
T12
L1
L2
L3
L4
L5
S2S3S4S5
Co
Posterior view
Cervical plexus(C1–C4)
Lumbosacral plexus(T12–S5)
Sciatic nerve
Brachial plexus(C5–T1)
Obturator nerve
Phrenic nerve
Ulnar nerveMedian nerveRadial nerveAxillary nerve
T7
S1
Cauda equina
Musculocutaneousnerve
Femoralnerve
Intercostalnerves
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
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11.7: Autonomic Nervous System
• Functions without conscious effort• Controls visceral activities• Regulates smooth muscle, cardiac muscle, and glands• Efferent fibers typically lead to ganglia outside of the CNS
• Two autonomic divisions regulate:• Sympathetic division (speeds up)
• Prepares body for ‘fight or flight’ situations• Parasympathetic division (pauses or slows down)
• Prepares body for ‘resting and digesting’ activities
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Sympathetic DivisionCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Lacrimal gland
Skin
Eye
Blood vessels
Heart
Lungs
Adrenal gland
Kidney
UterusPenis
Liver
Stomach
Gallbladder
Pancreas
Ovary
Scrotum
Small intestine
Large intestine
Trachea
Parotid gland,submandibular andsublingual glands
UrinarybladderPreganglionic
neuronPostganglionicneuron
Sympatheticchain ganglia
Inferiormesentericganglion
Spinalcord
Superiormesentericganglion
Celiacganglion
Fibers toskin, blood vessels,and adipose tissue
Celiac andpulmonaryplexuses
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Parasympathetic DivisionCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Heart
Trachea
Lung
GallbladderLiver
Stomach
Spleen
Pancreas
Small intestine
Large intestine
Kidney
UterusScrotum
Otic ganglion
Ciliary ganglion Eye
Penis Ovary
Sphenopalatineganglion
Cranialnerve III
CranialnerveVII
Submandibularganglion
Cranialnerve IX
Cranial nerve X(Vagus)
Cardiac andpulmonaryplexuses
Celiacplexus
Superiorhypogastricplexus
Inferiorhypogastricplexus
Spinalcord
Pelvicnerves
Urinarybladder
Parotidgland
Submandibularand sublingualglands
Lacrimalgland
Preganglionicneuron
Postganglionicneuron
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Control of Autonomic Activity
• Controlled largely by CNS
• Medulla oblongata regulates cardiac, vasomotor and respiratory activities
• Hypothalamus regulates visceral functions, such as body temperature, hunger, thirst, and water and electrolyte balance
• Limbic system and cerebral cortex control emotional responses