11 1 Introduction The central nervous system CNS

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. 1

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 Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Skin Scalp Subcutaneous tissue Cranium Bone of skull Cerebrum Dural sinus (superior sagittal sinus) Tentorium cerebelli Arachnoid granulation Dura mater Cerebellum Vertebra Arachnoid mater Pia mater Spinal cord Subarachnoid space Falx cerebri Meninges (a) Meninges Gray matter White matter (b) 2 Cerebrum

Meninges of the Spinal Cord Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Spinal cord Ventral root Dorsal root Spinal nerve Dorsal root ganglion Subarachnoid space Pia mater Arachnoid mater Epidural space Dura mater Dorsal root Dorsal branch (dorsal ramus) Spinal nerve Ventral branch (ventral ramus) Dorsal root ganglion Spinal cord Ventral root Epidural space Thoracic vertebra (a) (b) Body of vertebra 3

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 Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Lateral ventricle Interventricular foramen Third ventricle Cerebral aqueduct Fourth ventricle To central canal of spinal cord (a) Interventricular foramen Lateral ventricle Third ventricle Cerebral aqueduct Fourth ventricle 4 (b) To central canal of spinal cord

Cerebrospinal Fluid • Secreted by the choroid plexus (Can you recall the specific cells? ) • Circulates in ventricles, central canal of spinal cord, and the subarachnoid space • Completely surrounds the brain and spinal cord • Excess or wasted CSF is absorbed by the arachnoid villi (And where are these located? ) • 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 Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Arachnoid granulations Blood-filled dural sinus Choroid plexuses of third ventricle Pia mater Third ventricle Cerebral aqueduct Fourth ventricle Subarachnoid space Arachnoid mater Dura mater Choroid plexus of fourth ventricle Central canal of spinal cord Pia mater Subarachnoid space Filum terminale Arachnoid mater Dura mater 5

11. 4: Spinal Cord Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. • Slender column of nervous tissue continuous with brain and brainstem • Extends downward through vertebral canal • Begins at foramen magnum and ends at L 1/L 2 interspace • Conduit for nerve impulses to and from brain and brainstem • Center for spinal reflexes Brainstem Foramen magnum Cervical enlargement Spinal cord Vertebral canal Lumbar enlargement Conus medullaris Cauda equina Conus medullaris Filum terminale 6 (a) (b)

Structure of the Spinal Cord Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Posterior horn Posterior funiculus Posterior median sulcus White matter Gray commissure Lateral funiculus Dorsal root of spinal nerve Central canal Anterior funiculus Dorsal root ganglion (a) Ventral root Anterior of spinal nerve horn Anterior median fissure Portion of spinal nerve 7

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 Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Sensory or afferent neuron Receptor (a) Central Nervous System Motor or efferent neuron Effector (muscle or gland) 12 8

Reflex Arcs 9

General Components of a Spinal Reflex Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Spinal cord Interneuron Dorsal 1 Receptor 3 2 Sensory neuron Cell body of sensory neuron White matter Gray matter 4 Ventral Motor neuron Central canal 5 Effector (muscle or gland) (b) 10

Reflex Behavior • Example is the knee-jerk reflex • Simple monosynaptic reflex • Helps maintain an upright posture Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Axon of sensory neuron Cell body of sensory neuron Spinal cord Cell body of motor neuron Axon of motor neuron Direction of impulse Effector (quadriceps femoris muscle group) Receptor associated with dendrites of sensory neuron Patellar ligament 11

Reflex Behavior • Example is a withdrawal reflex • Prevents or limits tissue damage Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Cell body of sensory neuron Axon of sensory neuron Direction of impulse Dendrite of sensory neuron Pain receptor in skin Tack Effector (flexor muscle contracts and withdraws part being stimulated) Interneuron Axon of motor neuron Spinal cord Cell body of motor neuron 12

Reflex Arc • Example crossed extensor reflex • Crossing of sensory impulses within the reflex center to produce an opposite effect Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Interneuron + = Stimulation – = Inhibition – + – Sensory neuron Extensor relaxes + Extensor contracts Flexor relaxes Motor neurons Flexor contracts 13 17

Tracts of the Spinal Cord • Ascending tracts (dorsal) conduct sensory impulses to the brain • Descending tracts (ventral) conduct motor impulses from the brain to motor neurons reaching muscles and glands Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Dorsal column Fasciculus gracilis Fasciculus cuneatus Posterior spinocerebellar tract Lateral corticospinal tract Lateral reticulospinal tract Rubrospinal tract Anterior spinocerebellar tract Anterolateral system Lateral spinothalamic tract Anterior reticulospinal tract Medial reticulospinal tract Anterior corticospinal tract 14

Nerve Tracts of the Spinal Cord 15

11. 5: Brain • Functions of the brain: • Major parts of the brain: • Interprets sensations • Cerebrum • Determines perception • Frontal lobes • Stores memory • Parietal lobes • Reasoning • Occipital lobes • Makes decisions • Temporal lobes • Coordinates muscular movements • Insula • Regulates visceral activities • Diencephalon • Determines personality • Cerebellum • Brainstem • Midbrain • Pons 16 • Medulla oblongata

The Brain Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Gyrus Skull Sulcus Meninges Cerebrum Corpus callosum Diencephalon Fornix Midbrain Brainstem Pons Cerebellum Medulla oblongata Spinal cord (a) Fornix Cerebrum Midbrain Pons Corpus callosum Transverse fissure Diencephalon Cerebellum Medulla oblongata Spinal cord 17 (b) b: © Martin M. Rotker/Photo Researchers, Inc.

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 Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Central sulcus Parietal lobe Gyrus Sulcus Frontal lobe Lateral sulcus Occipital lobe Transverse fissure Cerebellar hemisphere Temporal lobe (a) Central sulcus Parietal lobe Central sulcus Longitudinal fissure Parietal lobe Occipital lobe (b) Occipital lobe Frontal lobe Insula Retracted temporal lobe (c) 18

Split Brain Research The following videos give some idea as to what occurs on each side of the brain and what happens when the corpus callosum is severed (video 1) or missing altogether (video 2). http: //www. youtube. com/watch? v=lf. Gws. Ad. S 9 Dc&feature=related http: //www. youtube. com/watch? v=VHg. Cl. WAPb. BY&feature=related 19

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 Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Central sulcus Parietal lobe Occipital lobe Frontal lobe Insula Retracted temporal lobe (c) 20

Functions of the Cerebrum • Interpreting impulses • Initiating voluntary movements • Storing information as memory • Retrieving stored information • Reasoning • Seat of intelligence and personality 21

Functional Regions of the Cerebral 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 Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Central sulcus Motor areas involved with the control of voluntary muscles Sensory areas involved with cutaneous and other senses Concentration, planning, problem solving Frontal eye field Parietal lobe Auditory area Sensory speech area ( Wernicke’s area) Front lobe Occipital lobe Motor speech area (Broca’s area) Combining visual images, visual recognition of objects Lateral sulcus Visual area Interpretation of auditory patterns Cerebellum Temporal lobe Brainstem 22

Functions of the Cerebral Lobes 23

Sensory Areas (post-central sulcus) • Cutaneous sensory area • Sensory area for taste • Near base of the central sulcus • Sensory area for smell • Parietal lobe • Interprets sensations on skin • Visual area • Occipital lobe • Interprets vision • Arises from centers deep within the cerebrum Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Central sulcus Motor areas involved with the control of voluntary muscles Sensory areas involved with cutaneous and other senses Concentration, planning, problem solving Frontal eye field Parietal lobe Auditory area • Auditory area • Temporal lobe • Interprets hearing Sensory speech area ( Wernicke’s area) Front lobe Occipital lobe Motor speech area (Broca’s area) Combining visual images, visual recognition of objects Lateral sulcus Visual area Interpretation of auditory patterns Cerebellum Temporal lobe Brainstem 24

Motor & Sensory Areas Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Arm Forearm Trunk Pelvis Neck Forearm Arm Thigh Thumb, fingers, and hand Leg Foot and toes Facial expression Hand, fingers, and thumb Upper face Leg Foot and toes Genitals Lips Salivation Vocalization Mastication Teeth and gums Swallowing Tongue and pharynx Longitudinal fissure (a) Motor area Longitudinal fissure (b) Sensory area Frontal lobe Motor area Sensory area Central sulcus Parietal lobe 25

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 Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Central sulcus Motor areas involved with the control of voluntary muscles Sensory areas involved with cutaneous and other senses Concentration, planning, problem solving Frontal eye field Parietal lobe Auditory area Sensory speech area ( Wernicke’s area) Front lobe Occipital lobe Motor speech area (Broca’s area) Combining visual images, visual recognition of objects Lateral sulcus Visual area Interpretation of auditory patterns Cerebellum Temporal lobe Brainstem 26

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 27

Motor Areas (pre-central sulcus) • Primary motor areas • Frontal lobes • Control voluntary muscles • Broca’s area Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Central sulcus Motor areas involved with the control of voluntary muscles Sensory areas involved with cutaneous and other senses Concentration, planning, problem solving Frontal eye field Parietal lobe Auditory area • Anterior to primary motor cortex • Usually in left hemisphere • Controls muscles needed for speech Sensory speech area ( Wernicke’s area) Front lobe Occipital lobe Motor speech area (Broca’s area) Combining visual images, visual recognition of objects Lateral sulcus Visual area Interpretation of auditory patterns Cerebellum Temporal lobe Brainstem • Frontal eye field • Above Broca’s area • Controls voluntary movements of eyes and eyelids 28

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 29

Memory • Short term memory • Long term memory • Working memory • Changes structure or • Closed neuronal circuit function of neurons • Circuit is stimulated over and • Enhances synaptic over transmission • When impulse flow ceases, memory does also unless it enters long-term memory via memory consolidation • Limited to 7 bits of information 30

Basal Nuclei • Masses of gray matter • Deep within cerebral hemispheres • Produce dopamine • Control certain muscular activities • Primarily by inhibiting motor functions Basal nuclei Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Longitudinal fissure Right cerebral hemisphere Caudate nucleus Putamen Globus pallidus Thalamus Cerebellum Hypothalamus Brainstem Spinal cord 31

Diencephalon • Between cerebral hemispheres and above the brainstem • Surrounds the third ventricle Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. • Thalamus • Epithalamus • Hypothalamus • Optic tracts • Optic chiasm • Infundibulum • Posterior pituitary • Mammillary bodies • Pineal gland Superior colliculus Corpora quadrigemina Optic nerve Inferior colliculus Optic chiasma Pituitary gland Thalamus Mammillary body Third ventricle Optic tract Pons Cerebral peduncles Pineal gland Fourth ventricle Pyramidal tract Olive Cerebellar peduncles Medulla oblongata Spinal cord (a) (b) 32

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) 33

Diencephalon The Limbic System • 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 34

Brainstem Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Hypothalamus Three parts: 1. Midbrain 2. Pons 3. Medulla Oblongata Diencephalon Thalamus Corpus callosum Corpora quadrigemina Midbrain Pons Cerebral aqueduct Reticular formation Medulla oblongata Spinal cord 35

Midbrain Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Superior colliculus Corpora quadrigemina Optic nerve Inferior colliculus Optic chiasma Pituitary gland Thalamus Mammillary body Third ventricle Optic tract • 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) Pons Cerebral peduncles Pineal gland Fourth ventricle Pyramidal tract Olive Cerebellar peduncles Medulla oblongata Spinal cord (a) (b) 36

Pons • 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) Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Superior colliculus Corpora quadrigemina Optic nerve Inferior colliculus Optic chiasma Pituitary gland Thalamus Mammillary body Third ventricle Optic tract Pons Cerebral peduncles Pineal gland Fourth ventricle Pyramidal tract Olive Cerebellar peduncles Medulla oblongata Spinal cord (a) (b) 37

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 Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Superior colliculus Corpora quadrigemina Optic nerve Inferior colliculus Optic chiasma Pituitary gland Thalamus Mammillary body Third ventricle Optic tract Pons Cerebral peduncles Pineal gland Fourth ventricle Pyramidal tract Olive Cerebellar peduncles Medulla oblongata Spinal cord (a) (b) 38

Reticular Formation Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. • Complex network of nerve fibers scattered throughout the brain stem • Extends into the diencephalon • Connects to centers of hypothalamus, basal nuclei, cerebellum, and cerebrum • Filters incoming sensory information • Arouses cerebral cortex into state of wakefulness Hypothalamus Diencephalon Thalamus Corpus callosum Corpora quadrigemina Midbrain Pons Cerebral aqueduct Reticular formation Medulla oblongata Spinal cord 39

Types of Sleep • Slow wave • Rapid Eye Movement (REM) • Non-REM sleep • Paradoxical sleep • Person is tired • Some areas of brain active • Decreasing activity of • Heart and respiratory rates reticular system irregular • Restful • Dreaming occurs • Dreamless • Reduced blood pressure and respiratory rate • Ranges from light to heavy • Alternates with REM sleep 40

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 Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Longitudinal fissure Corpus callosum Thalamus Superior peduncle Pons Middle peduncle Inferior peduncle Cerebellum Medulla oblongata 41

Major Parts of the Brain 42

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 43

Nervous System Subdivisions 44

Structure of a Peripheral Nerve Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Fascicle Peripheral nerve Epineurium Motor neuron ending Axon Perineurium Endoneurium Node of Ranvier Schwann cell Sensory receptor Myelin sheath Neurilemma 45

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) 46

Nerve Fiber Classification • General somatic efferent (GSE) fibers • Carry motor impulses from CNS to skeletal muscles • General visceral efferent (GVE) fibers • Carry motor impulses away from CNS to smooth muscles and glands • General somatic afferent (GSA) fibers • Carry sensory impulses to CNS from skin and skeletal muscles • General visceral afferent (GVA) fibers • Carry sensory impulses to CNS from blood vessels and internal organs 47

Nerve Fiber Classification • Special somatic efferent (SSE) fibers • Carry motor impulses from brain to muscles used in chewing, swallowing, speaking and forming facial expressions • Special visceral afferent (SVA) fibers • Carry sensory impulses to brain from olfactory and taste receptors • Special somatic afferent (SSA) fibers • Carry sensory impulses to brain from receptors of sight, hearing and equilibrium 48

Cranial Nerves Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Olfactory bulb Olfactory (I) Olfactory tract Optic (II) Optic tract Oculomotor (III) Trochlear (IV) Trigeminal (V) Vestibulocochlear (VIII) Abducens (VI) Hypoglossal (XII) Facial (VII) Vagus (X) Glossopharyngeal (IX) Accessory (XI) 49

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 50

Cranial Nerves III and IV • Oculomotor nerve (CN III) • Primarily motor nerve • Motor impulses to muscles that: • Raise eyelids • Move the eyes • Focus lens • Adjust light entering eye • Trochlear nerve (CN IV) • Primarily motor nerve • Motor impulses to muscles that move the eyes • Some sensory • Proprioceptors 51

Cranial Nerve V Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. • Trigeminal nerve (CN V) • Mixed nerve • “Three (3) sisters” • (1) Ophthalmic division • Sensory from surface of eyes, tear glands, scalp, forehead, and upper eyelids Lacrimal nerve Ophthalmic division Eye Maxillary division • (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 Infraorbital nerve Mandibular division • (2) Maxillary division • Sensory from upper teeth, upper gum, upper lip, palate, and skin of face Lacrimal gland Maxilla Lingual nerve Inferior alveolar nerve Tongue Mental nerve 52 Mandible

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 Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Temporal nerve Zygomatic nerve Buccal nerve Facial nerve Posterior auricular nerve Parotid salivary gland Mandibular nerve Cervical nerve 53 68

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 54

Cranial Nerve X Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. • 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 Superior ganglion of vagus nerve Inferior ganglion of vagus nerve Nerve XI Superior laryngeal nerve Nerve XII Carotid body Recurrent laryngeal nerve Left vagus nerve Cardiac nerves Lung Heart Stomach Liver Spleen Pancreas Kidney Small intestine 55 Large intestine

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 56

Functions of Cranial Nerves 57

Spinal Nerves Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. • ALL are mixed nerves (except the first pair) • 31 pairs of spinal nerves: • 8 cervical nerves • (C 1 to C 8) • 12 thoracic nerves • (T 1 to T 12) • 5 lumbar nerves • (L 1 to L 5) • 5 sacral nerves • (S 1 to S 5) • 1 coccygeal nerve • (Co or Cc) C 1 C 2 C 3 C 4 C 5 C 6 C 7 C 8 T 1 T 2 Posterior view Cervical nerves T 3 T 4 T 5 T 6 T 7 Thoracic nerves T 8 T 9 T 10 T 11 T 12 L 1 Cauda equina L 2 L 3 L 4 Lumbar nerves L 5 S 1 S 2 S 3 S 4 S 5 Co Sacral nerves Coccygeal nerve 58

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 Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Dorsal root ganglion Dorsal root Dorsal branch of spinal nerve Ventral root Paravertebral ganglion Posterior median sulcus Posterior horn Visceral branch of spinal nerve (b) Lateral horn Anterior horn Central canal Anterior median fissure (a) Ventral root Ventral branch of spinal nerve (ventral ramus) Dorsal branch of spinal nerve (dorsal ramus) Spinal nerve Paravertebral ganglion Visceral branch of spinal nerve 59

Dermatome • An area of skin that the sensory nerve fibers of a particular spinal nerve innervate Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. C 2 C 3 C 4 C 5 C 6 C 7 C 2 C 3 C 4 C 5 T 1 C 8 C 6 T 12 L 1 T 12 S 1 S 2 S 3 S 4 S 5 C 0 L 1 C 6 C 7 S 2 S 3 L 2 L 3 L 5 L 1 L 2 L 4 C 8 L 3 L 5 S 1 L 4 L 5 (a) (b) 60

Spinal Nerves • Ventral root (aka anterior root) • Motor root • Axons of motor neurons whose cell bodies are in the spinal cord Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Dorsal root ganglion Dorsal root Dorsal branch of spinal nerve Ventral root Paravertebral ganglion Posterior median sulcus Posterior horn • Spinal nerve • Union of ventral root and dorsal roots • Hence we now have a “mixed” nerve Visceral branch of spinal nerve (b) Lateral horn Anterior horn Central canal Anterior median fissure (a) Ventral root Ventral branch of spinal nerve (ventral ramus) Dorsal branch of spinal nerve (dorsal ramus) Spinal nerve Paravertebral ganglion Visceral branch of spinal nerve 61

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 62

Plexuses Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Posterior view Musculocutaneous nerve Axillary nerve Radial nerve Median nerve Ulnar nerve Phrenic nerve C 1 C 2 C 3 C 4 C 5 C 6 C 7 C 8 T 1 Cervical plexus (C 1–C 4) Brachial plexus (C 5–T 1) T 2 T 3 T 4 T 5 T 6 T 7 Intercostal nerves T 8 T 9 T 10 T 11 T 12 Cauda equina L 1 L 2 L 3 L 4 Femoral nerve L 5 S 1 S 2 S 3 S 4 S 5 Obturator nerve Sciatic nerve Lumbosacral plexus (T 12–S 5) Co 63

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 64

Sympathetic Division Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Lacrimal gland Eye Parotid gland, submandibular and sublingual glands Blood vessels Heart Celiac and pulmonary plexuses Trachea Lungs Skin Celiac ganglion Fibers to skin, blood vessels, and adipose tissue Liver Gallbladder Superior mesenteric ganglion Stomach Pancreas Small intestine Large intestine Spinal cord Inferior mesenteric ganglion Adrenal gland Kidney Sympathetic chain ganglia Urinary bladder Preganglionic Postganglionic neuron Ovary Penis Uterus Scrotum 65

Parasympathetic Division Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Sphenopalatine ganglion Lacrimal gland Ciliary ganglion Cranial nerve III Submandibular and sublingual glands Submandibular ganglion Cranial nerve VII Eye Parotid gland Otic ganglion Cranial nerve IX Heart Cranial nerve X (Vagus) Trachea Lung Cardiac and pulmonary plexuses Liver Gallbladder Stomach Celiac plexus Spleen Pancreas Superior hypogastric plexus Spinal cord Small intestine Large intestine Inferior hypogastric plexus Kidney Pelvic nerves Urinary bladder Preganglionic Postganglionic neuron Scrotum Uterus Penis Ovary 66

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 67

11. 8: Lifespan Changes • Brain cells begin to die before birth • Over average lifetime, brain shrinks 10% • Most cell death occurs in temporal lobes • By age 90, frontal cortex has lost half its neurons • Number of dendritic branches decreases • Decreased levels of neurotransmitters • Fading memory • Slowed responses and reflexes • Increased risk of falling • Changes in sleep patterns that result in fewer sleeping hours 68