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The Pons • The Pons – Nuclei involved with respiration • Apneustic center and pneumotaxic center: – modify respiratory rhythmicity center activity – Nuclei and tracts • Process and relay information to and from cerebellum • Ascending, descending, and transverse tracts: – transverse fibers (axons): » link nuclei of pons with opposite cerebellar hemisphere Copyright © 2010 Pearson Education, Inc. The Pons Figure 13–6b The Medulla Oblongata and Pons. Copyright © 2010 Pearson Education, Inc. The Pons Figure 13–6c The Medulla Oblongata and Pons. Copyright © 2010 Pearson Education, Inc. The Pons Copyright © 2010 Pearson Education, Inc. The Pons Copyright © 2010 Pearson Education, Inc. The Cerebellum • Functions of the Cerebellum – Adjusts postural muscles – Fine-tunes conscious and subconscious movements Copyright © 2010 Pearson Education, Inc. The Cerebellum • Structures of the Cerebellum – Folia • Surface of cerebellum • Highly folded neural cortex – Anterior and posterior lobes • Separated by primary fissure – Cerebellar hemispheres: • Separated at midline by vermis – Vermis • Narrow band of cortex – Flocculonodular lobe • Below fourth ventricle Copyright © 2010 Pearson Education, Inc. The Cerebellum • Structures of the Cerebellum – Purkinje cells • Large, branched cells • Found in cerebellar cortex • Receive input from up to 200,000 synapses – Arbor vitae • Highly branched, internal white matter of cerebellum • Cerebellar nuclei: embedded in arbor vitae: – relay information to Purkinje cells Copyright © 2010 Pearson Education, Inc. The Cerebellum • Structures of the Cerebellum – The peduncles • Tracts link cerebellum with brain stem, cerebrum, and spinal cord: – superior cerebellar peduncles – middle cerebellar peduncles – inferior cerebellar peduncles Copyright © 2010 Pearson Education, Inc. The Cerebellum • Disorders of the Cerebellum – Ataxia • Damage from trauma or stroke • Intoxication (temporary impairment) • Disturbs muscle coordination Copyright © 2010 Pearson Education, Inc. The Cerebellum Figure 13–7a The Cerebellum. Copyright © 2010 Pearson Education, Inc. The Cerebellum Figure 13–7b The Cerebellum. Copyright © 2010 Pearson Education, Inc. The Cerebellum Copyright © 2010 Pearson Education, Inc. The Mesencephalon • Structures of the Mesencephalon – Tectum • Two pairs of sensory nuclei (corpora quadrigemina): – superior colliculus (visual) – inferior colliculus (auditory) – Tegmentum • Red nucleus (many blood vessels) • Substantia nigra (pigmented gray matter) Copyright © 2010 Pearson Education, Inc. The Mesencephalon • Structures of the Mesencephalon – Cerebral peduncles • Nerve fiber bundles on ventrolateral surfaces • Contain: – descending fibers to cerebellum – motor command fibers Copyright © 2010 Pearson Education, Inc. The Mesencephalon Figure 13–8a The Mesencephalon. Copyright © 2010 Pearson Education, Inc. The Mesencephalon Figure 13–8b The Mesencephalon. Copyright © 2010 Pearson Education, Inc. The Mesencephalon Copyright © 2010 Pearson Education, Inc. The Diencephalon • Integrates sensory information and motor commands • Thalamus, epithalamus, and hypothalamus – The pineal gland • Found in posterior epithalamus • Secretes hormone melatonin Copyright © 2010 Pearson Education, Inc. The Diencephalon • The Thalamus – Filters ascending sensory information for primary sensory cortex – Relays information between basal nuclei and cerebral cortex – The third ventricle • Separates left thalamus and right thalamus • Interthalamic adhesion (or intermediate mass): – projection of gray matter – extends into ventricle from each side Copyright © 2010 Pearson Education, Inc. The Diencephalon • The Thalamus – Thalamic nuclei • Are rounded masses that form thalamus • Relay sensory information to basal nuclei and cerebral cortex Copyright © 2010 Pearson Education, Inc. The Diencephalon • Five Groups of Thalamic Nuclei – Anterior group • Anterior nuclei • Part of limbic system (emotions) – Medial group • Provides awareness of emotional states – Ventral group • Relays sensory information Copyright © 2010 Pearson Education, Inc. The Diencephalon • Five Groups of Thalamic Nuclei – Posterior group • Pulvinar nucleus (sensory) • Lateral geniculate nucleus (visual) • Medial geniculate nucleus (auditory) – Lateral group • Affects emotional states • Integrates sensory information Copyright © 2010 Pearson Education, Inc. The Diencephalon Figure 13–9 The Thalamus. Copyright © 2010 Pearson Education, Inc. The Diencephalon Figure 13–9a The Thalamus. Copyright © 2010 Pearson Education, Inc. The Diencephalon Figure 13–9b The Thalamus. Copyright © 2010 Pearson Education, Inc. The Diencephalon Copyright © 2010 Pearson Education, Inc. The Diencephalon • The Hypothalamus – Mamillary bodies • Process olfactory and other sensory information • Control reflex eating movements – Infundibulum • A narrow stalk • Connects hypothalamus to pituitary gland – Tuberal area • Located between the infundibulum and mamillary bodies • Helps control pituitary gland function Copyright © 2010 Pearson Education, Inc. The Diencephalon Figure 13–10a The Hypothalamus in Sagittal Section. Copyright © 2010 Pearson Education, Inc. The Diencephalon Figure 13–10b The Hypothalamus in Sagittal Section. Copyright © 2010 Pearson Education, Inc. The Diencephalon • Eight Functions of the Hypothalamus – Provides subconscious control of skeletal muscle – Controls autonomic function – Coordinates activities of nervous and endocrine systems – Secretes hormones • Antidiuretic hormone (ADH) by supraoptic nucleus • Oxytocin (OT; OXT) by paraventricular nucleus Copyright © 2010 Pearson Education, Inc. The Diencephalon • Eight Functions of the Hypothalamus – Produces emotions and behavioral drives • The feeding center (hunger) • The thirst center (thirst) – Coordinates voluntary and autonomic functions – Regulates body temperature • Preoptic area of hypothalamus – Controls circadian rhythms (day–night cycles) • Suprachiasmatic nucleus Copyright © 2010 Pearson Education, Inc. The Diencephalon Copyright © 2010 Pearson Education, Inc. The Limbic System • The Limbic System – Is a functional grouping that • Establishes emotional states • Links conscious functions of cerebral cortex with autonomic functions of brain stem • Facilitates memory storage and retrieval Copyright © 2010 Pearson Education, Inc. The Limbic System • Components of the Limbic System – Amygdaloid body • Acts as interface between the limbic system, the cerebrum, and various sensory systems – Limbic lobe of cerebral hemisphere • Cingulate gyrus • Dentate gyrus • Parahippocampal gyrus • Hippocampus Copyright © 2010 Pearson Education, Inc. The Limbic System • Components of the Limbic System – Fornix • Tract of white matter • Connects hippocampus with hypothalamus – Anterior nucleus of the thalamus • Relays information from mamillary body to cingulate gyrus – Reticular formation • Stimulation or inhibition affects emotions (rage, fear, pain, sexual arousal, pleasure) Copyright © 2010 Pearson Education, Inc. The Limbic System Figure 13–11a The Limbic System. Copyright © 2010 Pearson Education, Inc. The Limbic System Figure 13–11b The Limbic System. Copyright © 2010 Pearson Education, Inc. The Limbic System Copyright © 2010 Pearson Education, Inc. The Cerebrum • The Cerebrum – Is the largest part of the brain – Controls all conscious thoughts and intellectual functions – Processes somatic sensory and motor information Copyright © 2010 Pearson Education, Inc. The Cerebrum • Gray matter – In cerebral cortex and basal nuclei • White matter – Deep to basal cortex – Around basal nuclei Copyright © 2010 Pearson Education, Inc. The Cerebrum • Structures of the Cerebrum – Gyri of neural cortex • Increase surface area (number of cortical neurons) – Insula (island) of cortex • Lies medial to lateral sulcus – Longitudinal fissure • Separates cerebral hemispheres – Lobes • Divisions of hemispheres Copyright © 2010 Pearson Education, Inc. The Cerebrum • Structures of the Cerebrum – Central sulcus divides • Anterior frontal lobe from posterior parietal lobe – Lateral sulcus divides • Frontal lobe from temporal lobe – Parieto-occipital sulcus divides • Parietal lobe from occipital lobe Copyright © 2010 Pearson Education, Inc. The Cerebrum Figure 13–12a The Brain in Lateral View. Copyright © 2010 Pearson Education, Inc. The Cerebrum Figure 13–12b The Brain in Lateral View. Copyright © 2010 Pearson Education, Inc. The Cerebrum Figure 13–12c The Brain in Lateral View. Copyright © 2010 Pearson Education, Inc. The Cerebrum • Three Functional Principles of the Cerebrum – Each cerebral hemisphere receives sensory information from, and sends motor commands to, the opposite side of the body – The two hemispheres have different functions, although their structures are alike – Correspondence between a specific function and a specific region of cerebral cortex is not precise Copyright © 2010 Pearson Education, Inc. The Cerebrum • White Matter of the Cerebrum – Association fibers – Commissural fibers – Projection fibers Copyright © 2010 Pearson Education, Inc. The Cerebrum • White Matter of the Cerebrum – Association fibers • Connections within one hemisphere: – arcuate fibers: » are short fibers » connect one gyrus to another – longitudinal fasciculi: » are longer bundles » connect frontal lobe to other lobes in same hemisphere Copyright © 2010 Pearson Education, Inc. The Cerebrum • White Matter of the Cerebrum – Commissural fibers • Bands of fibers connecting two hemispheres: – corpus callosum – anterior commissure Copyright © 2010 Pearson Education, Inc. The Cerebrum • White Matter of the Cerebrum – Projection fibers • Pass through diencephalon • Link cerebral cortex with: – diencephalon, brain stem, cerebellum, and spinal cord • Internal capsule: – all ascending and descending projection fibers Copyright © 2010 Pearson Education, Inc. The Cerebrum Figure 13–13a Fibers of the White Matter of the Cerebrum. Copyright © 2010 Pearson Education, Inc. The Cerebrum Figure 13–13b Fibers of the White Matter of the Cerebrum. Copyright © 2010 Pearson Education, Inc. The Cerebrum • The Basal Nuclei – Also called cerebral nuclei – Are masses of gray matter – Are embedded in white matter of cerebrum – Direct subconscious activities Copyright © 2010 Pearson Education, Inc. The Cerebrum • Structures of Basal Nuclei – Caudate nucleus • Curving, slender tail – Lentiform nucleus • Globus pallidus • Putamen Copyright © 2010 Pearson Education, Inc. The Cerebrum Figure 13–14a The Basal Nuclei. Copyright © 2010 Pearson Education, Inc. The Cerebrum Figure 13–14b The Basal Nuclei. Copyright © 2010 Pearson Education, Inc. The Cerebrum Figure 13–14c The Basal Nuclei. Copyright © 2010 Pearson Education, Inc. The Cerebrum • Functions of Basal Nuclei – Involved with • The subconscious control of skeletal muscle tone • The coordination of learned movement patterns (walking, lifting) Copyright © 2010 Pearson Education, Inc. The Cerebrum • Motor and Sensory Areas of the Cortex – Central sulcus separates motor and sensory areas – Motor areas • Precentral gyrus of frontal lobe: – directs voluntary movements • Primary motor cortex: – is the surface of precentral gyrus • Pyramidal cells: – are neurons of primary motor cortex Copyright © 2010 Pearson Education, Inc. The Cerebrum • Motor and Sensory Areas of the Cortex – Sensory areas • Postcentral gyrus of parietal lobe: – receives somatic sensory information (touch, pressure, pain, vibration, taste, and temperature) • Primary sensory cortex: – surface of postcentral gyrus Copyright © 2010 Pearson Education, Inc. The Cerebrum • Special Sensory Cortexes – Visual cortex • Information from sight receptors – Auditory cortex • Information from sound receptors – Olfactory cortex • Information from odor receptors – Gustatory cortex • Information from taste receptors Copyright © 2010 Pearson Education, Inc. The Cerebrum Figure 13–15a Motor and Sensory Regions of the Cerebral Cortex. Copyright © 2010 Pearson Education, Inc. The Cerebrum • Association Areas – Sensory association areas • Monitor and interpret arriving information at sensory areas of cortex – Somatic motor association area (premotor cortex) • Coordinates motor responses (learned movements) Copyright © 2010 Pearson Education, Inc. The Cerebrum • Sensory Association Areas – Somatic sensory association area • Interprets input to primary sensory cortex (e.g., recognizes and responds to touch) – Visual association area • Interprets activity in visual cortex – Auditory association area • Monitors auditory cortex Copyright © 2010 Pearson Education, Inc. The Cerebrum • Integrative Centers – Are located in lobes and cortical areas of both cerebral hemispheres – Receive information from association areas – Direct complex motor or analytical activities Copyright © 2010 Pearson Education, Inc. The Cerebrum • General Interpretive Area – Also called Wernicke area – Present in only one hemisphere – Receives information from all sensory association areas – Coordinates access to complex visual and auditory memories Copyright © 2010 Pearson Education, Inc. The Cerebrum • Other Integrative Areas – Speech center • Is associated with general interpretive area • Coordinates all vocalization functions – Prefrontal cortex of frontal lobe • Integrates information from sensory association areas • Performs abstract intellectual activities (e.g., predicting consequences of actions) Copyright © 2010 Pearson Education, Inc. The Cerebrum Figure 13–15b Motor and Sensory Regions of the Cerebral Cortex. Copyright © 2010 Pearson Education, Inc. The Cerebrum • Interpretive Areas of Cortex – Brodmann areas • Patterns of cellular organization in cerebral cortex Copyright © 2010 Pearson Education, Inc. The Cerebrum Figure 13–15c Motor and Sensory Regions of the Cerebral Cortex. Copyright © 2010 Pearson Education, Inc. The Cerebrum Copyright © 2010 Pearson Education, Inc. The Cerebrum • Hemispheric Lateralization – Functional differences between left and right hemispheres – Each cerebral hemisphere performs certain functions that are not ordinarily performed by the opposite hemisphere Copyright © 2010 Pearson Education, Inc. The Cerebrum • The Left Hemisphere – In most people, left brain (dominant hemisphere) controls • Reading, writing, and math • Decision making • Speech and language • The Right Hemisphere – Right cerebral hemisphere relates to • Senses (touch, smell, sight, taste, feel) • Recognition (faces, voice inflections) Copyright © 2010 Pearson Education, Inc. The Cerebrum Figure 13–16 Hemispheric Lateralization. Copyright © 2010 Pearson Education, Inc. The Cerebrum • Monitoring Brain Activity – Brain activity is assessed by an electroencephalogram (EEG) • Electrodes are placed on the skull • Patterns of electrical activity (brain waves) are printed out Copyright © 2010 Pearson Education, Inc. The Cerebrum • Four Categories of Brain Waves – Alpha waves • Found in healthy, awake adults at rest with eyes closed – Beta waves • Higher frequency • Found in adults concentrating or mentally stressed – Theta waves • Found in children • Found in intensely frustrated adults • May indicate brain disorder in adults – Delta waves • During sleep • Found in awake adults with brain damage Copyright © 2010 Pearson Education, Inc. The Cerebrum Figure 13–17a-d Brain Waves. Copyright © 2010 Pearson Education, Inc. The Cerebrum • Synchronization – A pacemaker mechanism • Synchronizes electrical activity between hemispheres – Brain damage can cause desynchronization • Seizure – Is a temporary cerebral disorder – Changes the electroencephalogram – Symptoms depend on regions affected Copyright © 2010 Pearson Education, Inc. Cranial Nerves • 12 pairs connected to brain • Four Classifications of Cranial Nerves – Sensory nerves: carry somatic sensory information, including touch, pressure, vibration, temperature, and pain – Special sensory nerves: carry sensations such as smell, sight, hearing, balance – Motor nerves: axons of somatic motor neurons – Mixed nerves: mixture of motor and sensory fibers Copyright © 2010 Pearson Education, Inc. Cranial Nerves • Cranial nerves are classified by primary functions • May also have important secondary functions – Distributing autonomic fibers to peripheral ganglia • The 12 cranial nerve groups are identified by – Primary function – Origin – Pathway – Destination Copyright © 2010 Pearson Education, Inc. Cranial Nerves Figure 13–18 Origins of the Cranial Nerves. Copyright © 2010 Pearson Education, Inc. Cranial Nerves • Olfactory Nerves (I) – Primary function • Special sensory (smell) – Origin • Receptors of olfactory epithelium – Pathway • Olfactory foramina in cribriform plate of ethmoid – Destination • Olfactory bulbs Copyright © 2010 Pearson Education, Inc. Cranial Nerves • Olfactory Nerve Structures – Olfactory bulbs • Located on either side of crista galli – Olfactory tracts • Axons of postsynaptic neurons • Leading to cerebrum Copyright © 2010 Pearson Education, Inc. Cranial Nerves Figure 13–19 The Olfactory Nerve. Copyright © 2010 Pearson Education, Inc. Cranial Nerves • Optic Nerves (II) – Primary function • Special sensory (vision) – Origin • Retina of eye – Pathway • Optic canals of sphenoid – Destination • Diencephalon via optic chiasm Copyright © 2010 Pearson Education, Inc. Cranial Nerves • Optic Nerve Structures – Optic chiasm • Where sensory fibers converge • And cross to opposite side of brain – Optic tracts • Reorganized axons • Leading to lateral geniculate nuclei Copyright © 2010 Pearson Education, Inc. Cranial Nerves Figure 13–20 The Optic Nerve. Copyright © 2010 Pearson Education, Inc. Cranial Nerves • Oculomotor Nerves (III) – Primary function • Motor (eye movements) – Origin • Mesencephalon – Pathway • Superior orbital fissures of sphenoid – Destination • Somatic motor: – superior, inferior, and medial rectus muscles – inferior oblique muscle – levator palpebrae superioris muscle • Visceral motor: – intrinsic eye muscles Copyright © 2010 Pearson Education, Inc. Cranial Nerves • Oculomotor Nerve Structures – Oculomotor nerve • Controls four of six eye-movement muscles • Delivers autonomic fibers to ciliary ganglion: – ciliary ganglion: controls intrinsic muscles of iris and lens Copyright © 2010 Pearson Education, Inc. Cranial Nerves • The Trochlear Nerves (IV) – Primary function • Motor (eye movements) – Origin • Mesencephalon – Pathway • Superior orbital fissure of sphenoid – Destination • Superior oblique muscle Copyright © 2010 Pearson Education, Inc. Cranial Nerves • The Abducens Nerves (VI) – Primary function • Motor (eye movements) – Origin • Pons – Pathway • Superior orbital fissures of sphenoid – Destination • Lateral rectus muscle Copyright © 2010 Pearson Education, Inc. Cranial Nerves Figure 13–21 Cranial Nerves Controlling the Extra-Ocular Muscles. Copyright © 2010 Pearson Education, Inc. Cranial Nerves • The Trigeminal Nerves (V) – Primary function • Mixed (sensory and motor) to face – Origin • Ophthalmic branch (sensory): – orbital structures – nasal cavity – skin of forehead, upper eyelid, and eyebrow – part of nose Copyright © 2010 Pearson Education, Inc. Cranial Nerves • The Trigeminal Nerves (V) – Origin • Maxillary branch (sensory): – – – – lower eyelid upper lip, gums, and teeth cheek and nose palate and part of pharynx • Mandibular branch (sensory): – lower gums, teeth, and lips – palate and part of tongue • Mandibular branch (motor): – motor nuclei of pons Copyright © 2010 Pearson Education, Inc. Cranial Nerves • The Trigeminal Nerves (V) – Pathway • Ophthalmic branch: – superior orbital fissure • Maxillary branch: – foramen rotundum • Mandibular branch: – foramen ovale Copyright © 2010 Pearson Education, Inc. Cranial Nerves • The Trigeminal Nerves (V) – Destination • Sensory nerves: – sensory nuclei in pons • Motor nerves of mandibular branch: – muscles of mastication Copyright © 2010 Pearson Education, Inc. Cranial Nerves • Trigeminal Nerve Structures – Trigeminal nerves • Largest cranial nerves • With three major branches – Semilunar ganglion • Contains cell bodies of sensory neurons Copyright © 2010 Pearson Education, Inc. Cranial Nerves Figure 13–22 The Trigeminal Nerve. Copyright © 2010 Pearson Education, Inc. Cranial Nerves • The Facial Nerves (VII) – Primary function • Mixed (sensory and motor) to face – Origin • Sensory: – taste receptors on anterior 2/3 of tongue • Motor: – motor nuclei of pons – Pathway • Internal acoustic meatus to facial canals (stylomastoid foramina) Copyright © 2010 Pearson Education, Inc. Cranial Nerves • The Facial Nerves (VII) – Destination • Sensory: – sensory nuclei of pons • Somatic motor: – muscles of facial expression • Visceral motor: – tear and nasal mucous glands – submandibular and sublingual salivary glands Copyright © 2010 Pearson Education, Inc. Cranial Nerves • Facial Nerve Structures – Facial nerve branches • Temporal • Zygomatic • Buccal • Mandibular • Cervical branches Copyright © 2010 Pearson Education, Inc. Cranial Nerves • Facial Nerve Structures – Geniculate ganglia • Hold cell bodies of sensory neurons – Pterygopalatine ganglia • Postganglionic fibers innervate glands (lacrimal, nasal cavity, and pharynx) – Submandibular ganglia • Innervate salivary glands Copyright © 2010 Pearson Education, Inc. Cranial Nerves Figure 13–23a The Facial Nerve. Copyright © 2010 Pearson Education, Inc. Cranial Nerves Figure 13–23b The Facial Nerve. Copyright © 2010 Pearson Education, Inc. Cranial Nerves • The Vestibulocochlear Nerves (VIII) – Primary function: special sensory • Vestibular branch: – balance and equilibrium • Cochlear branch: – hearing – Origin • Receptors of inner ear – Pathway • Internal acoustic meatus of temporal bones – Destination • Vestibular and cochlear nuclei of pons and medulla oblongata Copyright © 2010 Pearson Education, Inc. Cranial Nerves • Vestibulocochlear Nerve Structures – Vestibular branch • Originates at receptors of vestibule (balance) • Connects to vestibular nuclei of pons and medulla oblongata – Cochlear branch • Originates at sensors of cochlea (hearing) • Connects with cochlear nuclei of pons and medulla oblongata Copyright © 2010 Pearson Education, Inc. Cranial Nerves Figure 13–24 The Vestibulocochlear Nerve. Copyright © 2010 Pearson Education, Inc. Cranial Nerves • The Glossopharyngeal Nerves (IX) – Primary function • Mixed (sensory and motor) to head and neck – Origins • Sensory: – posterior 1/3 of tongue – part of pharynx and palate – carotid arteries • Motor: – motor nuclei of medulla oblongata Copyright © 2010 Pearson Education, Inc. Cranial Nerves • The Glossopharyngeal Nerves (IX) – Pathway • Jugular foramina between occipital and temporal bones – Destination • Sensory: – sensory nuclei of medulla oblongata • Somatic motor: – nerves involved in swallowing • Visceral motor: – parotid salivary gland Copyright © 2010 Pearson Education, Inc. Cranial Nerves • Glossopharyngeal Nerve Structures – Superior and inferior ganglion • Sensory neurons of tongue and pharynx – Otic ganglion • Synapse visceral motor fibers Copyright © 2010 Pearson Education, Inc. Cranial Nerves Figure 13–25 The Glossopharyngeal Nerve. Copyright © 2010 Pearson Education, Inc. Cranial Nerves • The Vagus Nerves (X) – Primary function • Mixed (sensory and motor) • Widely distributed in thorax and abdomen – Origins • Sensory: – – – – part of pharynx auricle and external acoustic meatus diaphragm visceral organs of thoracic and abdominopelvic cavities • Motor: – motor nuclei in medulla oblongata Copyright © 2010 Pearson Education, Inc. Cranial Nerves • The Vagus Nerves (X) – Pathway • Jugular foramina • Between occipital and temporal bones – Destination • Sensory: – sensory nuclei and autonomic centers of medulla oblongata • Visceral motor: – muscles of the palate and pharynx – muscles of the digestive, respiratory, and cardiovascular systems in thoracic and abdominal cavities Copyright © 2010 Pearson Education, Inc. Cranial Nerves • Vagus Nerve Structures – Vagus nerves • Branch and radiate extensively – Superior (jugular) ganglion and inferior (nodose) ganglion • Hold sensory neurons Copyright © 2010 Pearson Education, Inc. Cranial Nerves Figure 13–26 The Vagus Nerve. Copyright © 2010 Pearson Education, Inc. Cranial Nerves Figure 13–26 The Vagus Nerve. Copyright © 2010 Pearson Education, Inc. Cranial Nerves • The Accessory Nerves (XI) – Primary function • Motor to muscles of neck and upper back – Origin • Motor nuclei of spinal cord and medulla oblongata – Pathway • Jugular foramina between occipital and temporal bones – Destination • Internal branch: – voluntary muscles of palate, pharynx, and larynx • External branch: – sternocleidomastoid and trapezius muscles Copyright © 2010 Pearson Education, Inc. Cranial Nerves • Accessory Nerve Structures – Spinal root • Motor fibers that originate in anterior gray horns of first five cervical segments of spinal cord – Cranial root • Motor fibers that originate in medulla oblongata – Internal branch • Joins the vagus nerve – External branch • Controls muscles of neck and back Copyright © 2010 Pearson Education, Inc. Cranial Nerves • The Hypoglossal Nerves (XII) – Primary function • Motor (tongue movements) – Origin • Motor nuclei of medulla oblongata – Pathway • Hypoglossal canals of occipital bone – Destination • Muscles of tongue Copyright © 2010 Pearson Education, Inc. Cranial Nerves Figure 13–27 The Accessory and Hypoglossal Nerves. Copyright © 2010 Pearson Education, Inc. Cranial Nerves Copyright © 2010 Pearson Education, Inc. Cranial Nerves Copyright © 2010 Pearson Education, Inc. Cranial Reflexes • Cranial Reflexes – Monosynaptic and polysynaptic reflex arcs – Involve sensory and motor fibers of cranial nerves – Clinically useful to check cranial nerve or brain damage Copyright © 2010 Pearson Education, Inc. Cranial Reflexes Copyright © 2010 Pearson Education, Inc.
