14 The Brain and Cranial Nerves C h a p t e r

14 The Brain and Cranial Nerves C h a p t e r
PowerPoint® Lecture Slides prepared by Jason LaPres Lone Star College - North Harris Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

An Introduction to the Brain and Cranial Nerves
The Adult Human Brain Ranges from 750 cc to 2100 cc Contains almost 97% of the body’s neural tissue Average weight about 1.4 kg (3 lb) Male brains are typically larger but there is no correlation between brain size and intelligence. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Brain Six Regions of the Brain Cerebrum Cerebellum Diencephalon
Mesencephalon Pons Medulla oblongata 3D Peel-Away of the Brain Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Brain Cerebrum Largest part of brain
Controls higher mental functions conscious thoughts, sensations, intellect, memory, and skeletal muscle contractions all occur in the cerebrum Divided into left and right cerebral hemispheres Surface layer of gray matter (neural cortex) Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Brain Cerebrum Neural cortex Also called cerebral cortex
Folded surface increases surface area Elevated ridges (gyri) Shallow depressions (sulci) Deep grooves (fissures) Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Brain Cerebellum Second largest part of brain
Coordinates repetitive body movements Two hemispheres Covered with cerebellar cortex Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Brain Diencephalon Located under cerebrum and cerebellum
Links cerebrum with brain stem Composed of: L & R thalamus Relays and processes sensory information Hypothalamus Contains centers involved with emotions, autonomic function, and hormone control. Connected to the pituitary gland by infundibulum (stalk) Epithalamus Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Brain The Brain Stem Processes information between Includes
Spinal cord and cerebrum or cerebellum Includes Mesencephalon Pons Medulla oblongata Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Brain The Brain Stem Mesencephalon Pons Also called midbrain
Processes sight, sound, and associated reflexes Closing your eyes at loud noises Maintains consciousness Pons Connects cerebellum to brain stem Is involved in somatic and visceral motor control Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Brain The Brain Stem Medulla oblongata
Connects brain to spinal cord Relays sensory information Regulates autonomic functions: heart rate, blood pressure, and digestion Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Brain Embryological Development
Determines organization of brain structures Neural tube Origin of brain Hollow cylinder filled with neurocoel Enlarges into three primary brain vesicles Prosencephalon - forebrain Mesencephalon - midbrain Rhombencephalon - hindbrain Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Brain Origins of Brain Structures
The prosencephalon and rhombencephalon are further subdivided forming the secondary brain vesicles. Prosencephalon forms the: Telencephalon – forms the cerebrum Diencephalon – composed of L & R thalamus, and hypothalamus Rhombencephalon forms the: Metencephalon It will ultimately form the cerebellum and pons Myelencephalon It will ultimately form the medulla oblongata. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Brain Ventricles of the Brain Origins of ventricles
Neural tube encloses neurocoel Neurocoel expands to form chambers (ventricles) lined with ependymal cells Each cerebral hemisphere contains one large lateral ventricle Separated by a thin medial partition (septum pellucidum) Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Brain Ventricles of the Brain Third ventricle
Ventricle of the diencephalon Lateral ventricles communicate with third ventricle: via interventricular foramen (foramen of Monro) Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Brain Ventricles of the Brain Fourth ventricle
Extends into medulla oblongata Becomes continuous with central canal of the spinal cord Connects with third ventricle: via narrow canal in mesencephalon aqueduct of midbrain Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Brain Figure 14–2 Ventricles of the Brain.
Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Brain Cerebrospinal Fluid (CSF)
All of the ventricles are filled with CSF which continuously circulates from the ventricles and central canal into the subarachnoid space of the surrounding meninges. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Brain Protection and Support
Physical protection in the brain is done by: Bones of the cranium Cranial meninges Cerebrospinal fluid Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Cranial Meninges Made of three layers: Dura mater Arachnoid mater Pia mater All are continuous with spinal meninges Protect the brain from cranial trauma Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Cranial Meninges Dura mater Inner fibrous layer (meningeal layer) Outer fibrous layer (endosteal layer) fused to periosteum Venous sinuses between two layers Arachnoid mater Covers brain Contacts epithelial layer of dura mater Subarachnoid space: between arachnoid mater and pia mater Pia mater Attached to brain surface by astrocytes Extends into every fold Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Dural Folds Folded inner layer of dura mater Extend into cranial cavity Stabilize and support brain Contain collecting veins (dural sinuses) Three largest dural folds are: falx cerebri tentorium cerebelli falx cerebelli Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Dural Folds Falx cerebri Projects between the cerebral hemispheres Contains superior sagittal sinus and inferior sagittal sinus Tentorium cerebelli Separates cerebellum and cerebrum Contains transverse sinus Falx cerebelli Divides cerebellar hemispheres below the tentorium cerebelli Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Cerebrospinal Fluid (CSF) Surrounds all exposed surfaces of CNS Interchanges with interstitial fluid of brain Functions of CSF Cushions delicate neural structures Supports brain Transports nutrients, chemical messengers, and waste products Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Cerebrospinal Fluid (CSF) Produced in the choroid plexus Consists of a combination of specialized ependymal cells and permeable capillaries. About 500 ml of CSF is made per day It circulates from the choroids plexus through the ventricles, central canal of the spinal cord, subarachnoid space, brain, spinal cord, and cauda equina. It is then absorbed into the venous circulation at the arachnoid granulations (formed from arachnoid villi). Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Medulla Oblongata The Medulla Oblongata
Connects the brain to the spinal cord All communication between the brain and spinal cord involve tracts that ascend or descend through here Center for coordination of relatively complex autonomic reflexes and the control visceral functions Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Medulla Oblongata The Medulla Oblongata
Includes three groups of nuclei Autonomic nuclei Sensory and motor nuclei of cranial nerves Relay stations along sensory and motor pathways Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Medulla Oblongata Autonomic Nuclei of the Medulla Oblongata
Reticular formation Gray matter with embedded nuclei Regulates autonomic functions Reflex centers Control peripheral systems: cardiovascular centers: cardiac center control blood flow through peripheral tissues respiratory rhythmicity centers sets pace for respiratory movements Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Medulla Oblongata Sensory and Motor Nuclei of the Medulla Oblongata Associated with 5 of 12 cranial nerves (VIII, IX, X, XI, XII) Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Medulla Oblongata Relay Stations of the Medulla Oblongata
Nucleus gracilis and nucleus cuneatus Pass somatic sensory information to thalamus Solitary nucleus Receives visceral sensory information Olivary nuclei (olives) Relay information about somatic motor commands Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Medulla Oblongata Figure 14–6a The Medulla Oblongata and Pons.

The Pons The Pons Links cerebellum with mesencephalon, diencephalon, cerebrum, and spinal cord Contains four groups of components: sensory and motor nuclei of cranial nerves V, VI, VII, and VIII They innervate the jaw muscles, the anterior surface of the face, one of the extraocular muscles, and the sense organs of the inner ear. Nuclei involved with the control of respiration nuclei and tracts that process and relay information heading to or from the cerebellum Ascending, Descending, and Transverse Tracts Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Cerebellum Autonomic processing center Functions of the Cerebellum
adjusting the postural muscles of the body coordinates rapid, automatic adjustments that maintain balance and equilibrium programming and fine-tuning movements controlled at the conscious and subconscious levels Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

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 © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Cerebellum Structures of the Cerebellum Purkinje cells Arbor vitae
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 © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Mesencephalon Tectum Tegmentum
roof of the mesencehalon and area posterior to mesencephalic aqueduct It contains two pairs of sensory nuclei collectively known as the corpora quadrigemina process visual and auditory sensations. Tegmentum area anterior to the mesencephalic aqueduct On each side, the tegmentum contains: Red nucleus- gives red color because of numerous blood vessels. It issues subconscious motor commands that affect upper limb position and background muscle tone. Substantia nigra – the gray matter in this region give it a black color Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Mesencephalon Structures of the Mesencephalon Cerebral peduncles
Nerve fiber bundles on ventrolateral surfaces Contain: descending fibers to cerebellum motor command fibers Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Mesencephalon Figure 14–8a The Mesencephalon.

The Mesencephalon Figure 14–8b The Mesencephalon.

The Diencephalon Integrates sensory information and motor commands
Includes epithalamus thalamus hypothalamus Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Diencephalon Epithalamus
Is the roof of the diencephalon superior to the third ventricle The anterior portion contains an extensive area of choroids plexus The posterior portion contains the pineal gland endocrine structure that secretes melatonin important in the regulation of day-night cycles and also in the regulation of reproductive functions. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Diencephalon The Thalamus
Filters ascending sensory information for primary sensory cortex Called “sensory relay center” Final relay point for ascending sensory information 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 © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Diencephalon The Thalamus Thalamic nuclei
Are rounded masses that form thalamus Relay sensory information to basal nuclei and cerebral cortex Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

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 © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

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 © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Diencephalon Figure 14–9 The Thalamus.

The Diencephalon Hypothalamus
Extends from the area superior to the optic chiasm (crossover of optic tracts from the eyes) to the posterior margins of the mamillary bodies Mamillary bodies Process olfactory and other sensory information Control reflex eating movements chewing, licking, swallowing Infundibulum A narrow stalk Connects hypothalamus to pituitary gland Tuberal area Located between the infundibulum and mamillary bodies Helps control pituitary gland function Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Diencephalon Figure 14–10a The Hypothalamus in Sagittal Section.

The Diencephalon Figure 14–10b The Hypothalamus in Sagittal Section.

The Diencephalon Eight Functions of the Hypothalamus
1. The subconscious control of skeletal muscle contractions such as those associated with rage, pleasure, pain, and sexual arousal. 2. The control of autonomic function such as heart rate, blood pressure, and respiration The coordination of activities of the nervous and endocrine systems 4. The secretion of two hormones antidiuretic hormone (ADH) which restricts water loss in the kidneys oxytocin (OT) which stimulates smooth muscle contractions in the uterus and mammary glands of females and the prostate of males. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Diencephalon Eight Functions of the Hypothalamus
The production of emotions and behavioral drives such as the sensation of hunger and thirst. Coordination between voluntary and autonomic functions Regulation of body temperature 8. The control of circadian rhythms which tells you when to sleep. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Limbic System The Limbic System
Is a functional grouping (not anatomical) that Establishes emotional states Links conscious functions of cerebral cortex with autonomic functions of brain stem Facilitates memory storage and retrieval Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Limbic System Components of the Limbic System Amygdaloid body
Acts as interface between the limbic system, the cerebrum, and various sensory systems Regulation of heart rate, “fight or flight response”, and linking emotions with specific memories Limbic lobe of cerebral hemisphere * Consists of the superficial folds (gyri) and underlying structures adjacent to the diencephalon. * There are three gyri in the limbic lobe: -cingulated gyrus -dentate gyrus -parahippocampal gyrus Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Limbic System Components of the Limbic System Hippocampus Fornix
important in learning and the storage and retrieval of long-term memories 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 © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

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 © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Cerebrum Cerebral cortex
The cortical surface contains gyri (elevated ridges) separated by sulci (shallow depressions) or fissures (deeper grooves). The two cerebral hemispheres are almost completely separated by a deep longitudinal fissure. Each hemisphere can be divided into lobes (regions) Central sulcus (a deep grove) divides the frontal lobe from the parietal lobe Lateral suclus separates the frontal lobe from the temporal lobe Parieto-occipital sulcus separates the parietal lobe from the occipital lobe Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Cerebrum Figure 14–12b The Brain in Lateral View.

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 © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Cerebrum The interior of the cerebrum consists primarily of white matter The axons can be classified as: Association fibers interconnect areas of neural cortex within a single cerebral hemisphere Commissural fibers interconnect and permit communication between the cerebral hemispheres. Includes the corpus callosum and anterior commissure Projection fibers link the cerebral cortex to the diencephalons, brain stem, cerebellum, and spinal cord Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Cerebrum The Basal Nuclei Also called cerebral nuclei
Are masses of gray matter Are embedded in white matter of cerebrum Involved with The subconscious control of skeletal muscle tone The coordination of learned movement patterns (walking, lifting) Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Cerebrum Structures of Basal Nuclei Caudate nucleus
Curving, slender tail Lentiform nucleus Globus pallidus Putamen Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Cerebrum Figure 14–14c The Basal Nuclei.

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 © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

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 © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Cerebrum Special Sensory Cortexes Visual cortex Auditory cortex
Information from sight receptors Auditory cortex Information from sound receptors Olfactory cortex Information from odor receptors Gustatory cortex Information from taste receptors Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

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 © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

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 Allows you to understand that c + a + t = cat Auditory association area Monitors auditory cortex Word recognition Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Cerebrum General Interpretive Area Also called Wernicke area
Present in only one hemisphere (usually left) Receives information from all sensory association areas Coordinates access to complex visual and auditory memories Plays an essential role in your personality Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Cerebrum Other Integrative Areas Speech center
Also called Broca’s area Is associated with general interpretive area Coordinates all vocalization functions (breathing and vocalization needed for speech) Prefrontal cortex of frontal lobe Integrates information from sensory association areas Performs abstract intellectual activities (e.g., predicting consequences of actions) Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

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 © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Cerebrum The Left Hemisphere The Right 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 © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Cerebrum Figure 14–16 Hemispheric Lateralization.

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 © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Cerebrum Four Categories of Brain Waves Alpha waves Beta 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 © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Cerebrum Figure 14–17a-d Brain Waves.

The Cerebrum Synchronization Seizure 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 © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

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 © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

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 © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Cranial Nerves Figure 14–18 Origins of the Cranial Nerves.

Cranial Nerves Olfactory Nerves (I)
The olfactory nerve is composed of axons from the olfactory receptors in the nasal sensory epithelium. It carries olfactory information (sense of smell) to the olfactory bulb of the brain. This is a pure sensory nerve fiber. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Cranial Nerves Olfactory Nerve Structures Olfactory bulbs
Located on either side of crista galli Olfactory tracts Axons of postsynaptic neurons Leading to cerebrum Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Cranial Nerves Optic Nerves (II)
The optic nerve is composed of axons of the ganglion cells in the eye. It carries visual information to the brain. This is a pure sensory nerve fiber. This nerve travels posteromedially from the eye, exiting the orbit at the optic canal in the lesser wing of the sphenoid bone. The optic nerves join each other in the middle cranial fossa to form the optic chiasm. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Cranial Nerves Optic Nerve Structures Optic chiasm Optic tracts
Where sensory fibers converge And cross to opposite side of brain Optic tracts Reorganized axons Leading to lateral geniculate nuclei Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Cranial Nerves Oculomotor Nerves (III) This is a pure motor nerve.
It provides somatic motor innervation to four of the extrinsic eye muscles: the superior rectus inferior rectus medial rectus inferior oblique muscles. It also innervates the muscles of the upper eyelid and the intrinsic eye muscles (the pupillary eye muscle.) Together, CN III, CN IV and CN VI control the six muscles of the eye. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Cranial Nerves The Trochlear Nerves (IV)
The trochlear nerve provides somatic motor innervation to the superior oblique eye muscle. This cranial nerve originates at the trochlear nucleus located in the tegmentum of the midbrain at the inferior colliculus level and exits the posterior side of the brainstem. A pure motor nerve fiber. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Cranial Nerves The Trigeminal Nerves (V) the largest cranial nerve .
It provides sensory information from the face, forehead, nasal cavity, tongue, gums and teeth (touch, and temperature) and provides somatic motor innervation to the muscles of mastication or “chewing”. It is composed of both sensory and motor axons. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Cranial Nerves Figure 14–22 The Trigeminal Nerve.

Cranial Nerves The Abducens Nerves (VI)
The abducens nerve carries somatic motor innervation to one of the extrinsic eye muscles, the lateral rectus muscle. It is another pure motor nerve fiber and originates from the abducens nucleus located in the caudal pons at the facial colliculus level. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Cranial Nerves The Facial Nerves (VII)
The facial nerve carries somatic motor innervation to the many muscles for facial expression. It carries sensory information form the face (deep pressure sensation) and taste information from the anterior two thirds of the tongue. It is composed of both sensory and motor axons. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Cranial Nerves Figure 14–23a The Facial Nerve.

Cranial Nerves Figure 14–23b The Facial Nerve.

Cranial Nerves The Vestibulocochlear Nerves (VIII)
The vestibulocochlear nerve innervates the hair cell receptors of the inner ear. balance hearing It is pure sensory nerve fiber. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Cranial Nerves Figure 14–24 The Vestibulocochlear Nerve.

Cranial Nerves The Glossopharyngeal Nerves (IX)
The glossopharyngeal nerve innervates the pharynx (upper part of the throat), the soft palate and the posterior one-third of the tongue. sensory information (touch, temperature, and pressure) from the pharynx and soft palate taste sensation from the taste buds swallowing salivary glands supplies the carotid sinus and reflex control to the heart It is composed of both sensory and motor axons and originates from the nucleus ambiguous in the reticular formation of the medulla. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Cranial Nerves Figure 14–25 The Glossopharyngeal Nerve.

Cranial Nerves The Vagus Nerves (X)
Consists of many rootlets that come off of the brainstem just behind the glossopharyngeal nerve. Longest cranial nerve Innervates many structures in the throat, including the muscles of the vocal cords, thorax and abdominal cavity. Sensory information (touch, temperature and pressure) from the external auditory meatus (ear canal) and a portion of the external ear. Taste sensation from taste buds in the pharynx. Sensory information from the esophagus, respiratory tract, and abdominal viscera (stomach, intestines, liver, etc.). It provides visceral motor innervation to the heart, stomach, intestines, and gallbladder. It is composed of both sensory and motor axons. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Cranial Nerves Figure 14–26 The Vagus Nerve.

Cranial Nerves The Accessory Nerves (XI)
The spinal accessory nerve has two branches. Cranial branch provides somatic motor innervation to some of the muscles in the throat involved in swallowing. The spinal branch provides somatic motor innervation to the trapezius muscles, providing muscle movement for the upper shoulders head and neck. It is pure motor nerve fiber. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Cranial Nerves The Hypoglossal Nerves (XII)
The hypoglossal nerve provides somatic motor innervation to the muscles of the tongue. This pure motor nerve originates from the hypoglossal nucleus located in the tegmentum of the medulla. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Cranial Nerves Figure 14–27 The Accessory and Hypoglossal Nerves.

14 The Brain and Cranial Nerves C h a p t e r

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