The Nervous System: the Brain and Cranial Nerves

16 The Nervous System: The Brain and Cranial Nerves

PowerPoint® Lecture Presentations prepared by Steven Bassett Southeast Community College Lincoln, Nebraska

• The brain is a complex three-dimensional structure that performs a bewildering array of functions • Think of the brain as an organic computer • However, the brain is far more versatile than a computer • The brain is far more complex than the spinal cord • The brain consists of roughly 20 billion neurons

• Embryology of the brain • The CNS begins as a neural tube • The lumen of the tube (neurocoel) is filled with fluid • In the fourth week of development, the cephalic area of the neural tube enlarges to form: • Prosencephalon • Mesencephalon • Rhombencephalon

• Embryology of the brain (continued) • Prosencephalon eventually develops to form: • Telencephalon: forms the cerebrum • Diencephalon: forms the epithalamus, thalamus, and hypothalamus

• Mesencephalon • Does not subdivide • Becomes the midbrain • Rhombencephalon • Eventually develops to form: • Metencephalon: forms the pons and cerebellum • Myelencephalon: forms the medulla oblongata

CEREBRUM Sulci

• Conscious thought processes, intellectual functions Fissures • Memory storage and processing • Conscious and subconscious regulation of skeletal muscle contractions

DIENCEPHALON

THALAMUS • Relay and processing centers for sensory information

HYPOTHALAMUS • Centers controlling emotions, autonomic CEREBELLUM functions, and hormone production • Coordinates complex Spinal somatic motor cord patterns MESENCEPHALON • Adjusts output of Brain other somatic motor • Processing of visual stem centers in brain and and auditory data spinal cord • Generation of reflexive somatic motor responses • Maintenance of consciousness

PONS • Relays sensory MEDULLA OBLONGATA information to cerebellum and • Relays sensory information to thalamus and thalamus to other portions of the brain stem • Subconscious • Autonomic centers for regulation of visceral somatic and visceral function (cardiovascular, respiratory, and motor centers digestive system activities) © 2012 Pearson Education, Inc. An Introduction to the Organization of the Brain

• Major Regions and Landmarks of the Brain • Medulla oblongata • Pons • Cerebellum • Mesencephalon (midbrain) • Diencephalon • Cerebrum (telencephalon)

© 2012 Pearson Education, Inc. Figure 16.13a Sectional Views of the Brain Precentral gyrus Central sulcus Postcentral gyrus Cingulate gyrus Fornix Corpus callosum Thalamus Membranous portion Septum of epithalamus pellucidum Hypothalamus Pineal gland Interventricular foramen Parieto-occipital sulcus Frontal lobe Superior colliculus Anterior Corpora commissure Inferior quadrigemina colliculus Optic chiasm Aqueduct of midbrain Mamillary body Fourth ventricle Temporal lobe Cerebellum Mesencephalon Pons Medulla oblongata

A sagittal section through the brain

• Medulla oblongata • Relays information to the thalamus and brain stem • Regulates visceral function • Pons • Relays information to the thalamus and cerebellum • Regulates subconscious somatic and visceral motor centers

• Cerebellum • Coordinates somatic motor function • Adjusts output of somatic motor centers resulting in smooth operation • Mesencephalon (midbrain) • Processes visual and auditory data • Maintains consciousness and alertness

• Diencephalon • Epithalamus • Contains the pineal gland • Thalamus • Relays information to the cerebrum • Processes sensory information • Hypothalamus • Involved in emotions, thirst, some habitual activity

• Telencephalon (cerebrum) • Conscious thought processes • Memory storage • Conscious regulation of skeletal muscle contractions

CEREBRUM Sulci

• Conscious thought processes, intellectual functions Fissures • Memory storage and processing • Conscious and subconscious regulation of skeletal muscle contractions

DIENCEPHALON

THALAMUS • Relay and processing centers for sensory information

• Gray Matter and White Matter Organization • The cerebrum consists of: • Inner region of gray matter • Surrounded by tracts of white matter • Gray matter consists of cell bodies

• The Ventricles of the Brain • Ventricles are fluid-filled cavities • Filled with cerebrospinal fluid (CSF) • Fluid transports nutrients to the CNS and transports waste away from the CNS • CSF also provides protection • There are four ventricles • Ventricles 1 and 2 (called lateral ventricles) are in the cerebral hemispheres (separated by a partition called the septum pellucidum) • Ventricle 3 is in the diencephalon • Ventricle 4 lies between the pons and the cerebellum

• Lateral ventricles (ventricles 1 and 2) • Main portion of the ventricle lies in the parietal lobes • Each has an anterior horn extending into the frontal lobe • Each has a posterior horn extending into the occipital lobe • Each has an inferior horn extending into the temporal lobe • Each communicates with the third ventricle • Through the interventricular foramen

Lateral ventricles Interventricular foramen

Third ventricle Anterior Posterior horns of horns lateral ventricles of lateral ventricles Inferior horns of lateral ventricles Aqueduct of Pons midbrain Medulla oblongata Fourth ventricle Central canal Cerebellum Spinal cord

Orientation and extent of the ventricles as seen in a lateral view of a transparent brain

• Third ventricle • Communicates with the fourth ventricle • Through the aqueduct of the midbrain • Fourth ventricle • Communicates with the central canal of the spinal cord

Lateral ventricles Interventricular foramen

Orientation and extent of the ventricles as seen in a lateral view of a transparent brain

Interventricular foramen Posterior Third ventricle horn of lateral Aqueduct of midbrain ventricle Fourth ventricle

Interventricular Third foramen ventricle Inferior horns of Aqueduct of lateral ventricles midbrain Pons Fourth ventricle

Cerebellum Medulla oblongata

Central canal

Lateral ventricles

Interventricular foramen

Third ventricle

Inferior horn of lateral ventricle

Aqueduct of Septum midbrain pellucidum

• Protection involves: • Bones of the skull • Parietal, frontal, occipital, and temporal bones • Cranial meninges • Dura mater, arachnoid mater, and pia mater • Cerebrospinal fluid • Blood–brain barrier

• Cranial Meninges: The Dura Mater • Consists of two layers • Endosteal layer • This is the layer felt within the anterior fontanel of a baby • Meningeal layer • Space between the two layers is called the dural sinus • The meningeal layer forms folds called: • falx cerebri • tentorium cerebelli • falx cerebelli • diaphragma sellae

• Folds of the Dura Mater • Falx cerebri • Meningeal layer that extends into the longitudinal fissure • Inferior/anterior portion attaches to the crista galli • Inferior/posterior portion attaches to the internal occipital crest and the tentorium cerebelli • Tentorium cerebelli • Separates the cerebellar hemispheres from the cerebral hemispheres • Extends across the cranium at right angles to the falx cerebri

• Folds of the Dura Mater (continued) • Falx cerebelli • Extends from the tentorium cerebelli to separate the cerebellar hemispheres • Diaphragma sellae • Lines the sella turcica of the sphenoid bone • It anchors the dura mater to the sphenoid bone • It encases the pituitary gland

Cranium Dura mater (endosteal layer)

Dural sinus Dura mater (meningeal layer) Subdural space

Cerebral Arachnoid cortex mater Cerebral Pia Subarachnoid cortex mater space

Cerebellum

Medulla oblongata

Spinal cord Lateral view of the brain showing its position in the cranium and the organization of the meningeal coverings

Superior sagittal sinus

Cranium Inferior sagittal sinus Falx cerebri Diaphragma sellae Dura mater

Tentorium cerebelli

Pituitary gland Transverse sinus

Falx cerebelli Sella turcica of sphenoid

A corresponding view of the cranial cavity with the brain removed showing the orientation and extent of the falx cerebri and tentorium cerebelli

Coronal section

Superior sagittal sinus Dura mater

Subdural Arachnoid space mater Arachnoid Arachnoid granulation trabeculae Pia mater Falx cerebri

Subarachnoid space Cerebral cortex

• Cranial Meninges: The Arachnoid Mater • Consists of projections called arachnoid granulations • CSF flows through these to enter into blood circulation • Consists of weblike material underlining the arachnoid layer • These collagenous fibers help anchor cerebral blood vessels

Coronal section

Arachnoid mater

Arachnoid trabecula

Cerebral vein Pia mater Cerebral cortex

Perivascular space

A detailed view of the arachnoid membrane, the subarachnoid space, and the pia mater. Note the relationship between the cerebral vein and the subarachnoid space. © 2012 Pearson Education, Inc. Protection and Support of the Brain

• Cranial Meninges: The Pia Mater • Attached to the surface of the brain • Follows the sulci and gyri of the brain • Helps to anchor the larger blood vessels of the cerebrum

Loose connective Cranium tissue and periosteum Dura mater of cranium Subarachnoid Epicranial space aponeurosis Arachnoid mater

Scalp

Cerebral cortex covered by pia mater

• Cerebrospinal Fluid (CSF) • Provides protection of the brain and spinal cord • Provides support • Transports nutrients to the CNS tissue • Transports waste away from the CNS

• Formation of CSF • Produced by the ependymal cells of the choroid plexus • They actively transport nutrients, vitamins, and ions into the CSF • They actively remove waste from the CSF

INTERSTITIAL FLUID IN THALAMUS

Nutrients (especially glucose) Ependymal Oxygen cells Capillary

Capillary Endothelial cell Blood–brain CO2 Waste products barrier

Tight junction Astrocyte Neuron

The location of the choroid plexus in Choroid each of the four ventricles of the brain plexus cells Waste products Ions Amino acids (when necessary)

Ions     2 2 (Na , K , Cl , HCO3 , Ca , Mg ) Vitamins Organic nutrients The structure and function of the Oxygen choroid plexus. The ependymal cells are a selective barrier, actively Tight junction transporting nutrients, vitamins, and ions into the CSF. When necessary, these cells also actively CHOROID PLEXUS remove ions or compounds from the CSF to stabilize its composition. CEREBROSPINAL FLUID IN THIRD VENTRICLE

• Circulation of CSF • CSF from the choroid plexus of the lateral ventricles • Flows through the interventricular foramen • Flows into the third ventricle • Flows into the aqueduct of the midbrain • Flows into the fourth ventricle • Through the lateral aperture and median aperture and central canal of the spinal cord • Flows into the subarachnoid space • Flows around the brain and spinal cord eventually enters circulation via the arachnoid granulations

Extension of choroid Fluid plexus into movement lateral ventricle Arachnoid trabecula

Cerebral Dura mater cortex (meningeal layer)

Pia Subarachnoid Subdural Superior mater space space sagittal Arachnoid sinus mater

Choroid plexus of third ventricle

Aqueduct of midbrain Lateral aperture

Choroid plexus of fourth ventricle Median aperture Central canal Arachnoid mater

Subarachnoid space

Dura mater Spinal cord

Filum terminale

• Blood–Brain Barrier • The lining of the blood vessels consists of endothelial cells that are highly interconnected by tight junctions • Due to this tight connection, only lipid-soluble material can pass from the blood to the cells of the brain and spinal cord • Water-soluble material can only pass via the action of transport mechanisms • The transport mechanisms are very specific

• Medulla oblongata • Continuous with the spinal cord to the brain stem • All communication between the brain and spinal cord passes through the medulla oblongata • Nuclei in the medulla oblongata are: • Relay stations for sensory or motor pathways • Associated with cranial nerves connected to the medulla oblongata • Associated with the autonomic control of visceral organs

• Relay stations • Nucleus gracilis and nucleus cuneatus • Pass sensory information to the thalamus • Olivary nuclei • Pass information to the cerebrum, diencephalon, and brain stem

• Nuclei of cranial nerves • Contains sensory and motor nuclei of cranial nerves: • VIII, IX, X, XI, and XII • Autonomic nuclei • Major centers include: • Cardiovascular centers (cardiac and vasomotor) • Respiratory centers (rhythmic breathing)

Olivary nucleus

Cardiovascular centers

Pons Medulla oblongata Solitary nucleus

Nucleus cuneatus

Olive Nucleus gracilis Pyramids

Reticular formation

Spinal cord Lateral white column

Anterior view

Olivary nucleus Attachment to Cardiovascular membranous centers roof of fourth ventricle Respiratory Pons rhythmicity center

Solitary nucleus

Nucleus cuneatus

Olive Nucleus gracilis Pyramids Posterior median sulcus Reticular formation

Lateral white column Posterior Spinal cord white columns

Posterolateral view

• The pons is a prominent bulge superior to the medulla oblongata and consists of: • Sensory and motor nuclei for cranial nerves: • V, VI, VII, and VIII • Nuclei involved with involuntary control of breathing: • Consist of apneustic center and pneumotaxic center • Nuclei that relay cerebellar commands: • Consist of cerebellar peduncles • Ascending, descending, and transverse tracts

Descending tracts

Pneumotaxic Ascending center tracts Apneustic center Transverse fibers Cerebellum

Fourth ventricle

Pons

Medulla oblongata Reticular formation

Olivary nucleus

• Mesencephalon (also called the midbrain) • Consists of two pairs of nuclei collectively called corpora quadrigemina • Responsible for processing auditory and visual stimuli • Auditory processing occurs in the inferior colliculus • Visual processing occurs in the superior colliculus • Consists of nuclei of the reticular formation • Involved in maintaining alertness

• Mesencephalon (continued) • Consists of: • Red nucleus: integrates information between the cerebrum and cerebellum • Substantia nigra: regulates motor output of the basal nuclei • Cerebral peduncles: have ascending fibers that synapse in the thalamus and descending fibers of the corticospinal pathway

Thalamus

Superior Pineal colliculi Corpora gland Substantia quadrigemina Inferior Superior nigra colliculi colliculus Red nucleus Cerebral Trochlear peduncle Inferior nerve (N IV) colliculus Cerebral peduncle Reticular Superior formation cerebellar peduncle Diagrammatic and posterior views of the diencephalon Reticular formation Fourth ventricle in floor of and brain stem. The diagrammatic view is drawn, as if fourth ventricle transparent, to show the positions of important nuclei.

• The diencephalon consists of: • Epithalamus • Thalamus • Hypothalamus

Parietal lobe

Corpus callosum

Septum Choroid plexus pellucidum in epithalamus Thalamus (surrounds Fornix third ventricle)

Anterior Pineal gland cerebral artery

Frontal lobe Hypothalamus Aqueduct of Anterior midbrain commissure Cerebellum

Optic chiasm Fourth ventricle Optic Infundibulum Tuberal Mamillary nerve (cut) area body Midsagittal section through the brain. This view shows the major features of the diencephalon and adjacent portions of the brain stem.

• The epithalamus • Forms the roof of the third ventricle • Contains the pineal gland • Produces the hormone melatonin • Regulates our day/night cycles

• The thalamus • Forms the walls of the third ventricle • There is a right and a left thalamus • Thalamic nuclei are egg-shaped • Each thalamic nucleus is divided into: • Anterior group: part of the limbic system • Medial group: relays information to the frontal lobe • Ventral group: relays information to the parietal lobes • Posterior group: relays information to the occipital lobe • Lateral group: adjusts activity in the cingulate gyrus

Frontal Parietal lobe lobe

Occipital lobe

Lateral view of the brain showing the positions of the major thalamic structures. Functional areas of cerebral cortex are also indicated, with colors corresponding to those of the associated thalamic nuclei. © 2012 Pearson Education, Inc. Figure 16.11b The Thalamus Limbic Frontal Parietal lobe and Association areas system lobes cingulate gyrus of cerebral cortex

Anterior Medial group group Lateral group Posterior Pulvinar group V e n t r a l g r o u p Auditory input

Medial geniculate Basal nucleus nuclei General Lateral sensory Visual geniculate Cerebellum input input nucleus

Enlarged view of the thalamic nuclei of the left side. The color of each nucleus or group of nuclei matches the color of the associated cortical region. The boxes either provide examples of the types of sensory input relayed to the basal nuclei and cerebral cortex or indicate the existence of important feedback loops involved with emotional states, learning, and memory. © 2012 Pearson Education, Inc. Table 16.5 The Thalamus

• The hypothalamus • Forms the floor of the third ventricle • Consists of numerous nuclei • Consists of an infundibulum, which connects to the pituitary gland • Consists of the mamillary body on the posterior wall of the hypothalamus

• The hypothalamus (continued) • Consists of nuclei to control: • Subconscious control of skeletal muscles • Heart rate, blood pressure, respiration, and digestive functions • Secretion of antidiuretic hormone and oxytocin • Emotional and behavioral drives and thirst drives • Coordination between voluntary and autonomic functions • Body temperature • Circadian rhythm

Parietal lobe

Corpus callosum

Septum Choroid plexus pellucidum in epithalamus Thalamus (surrounds Fornix third ventricle)

Anterior Pineal gland cerebral artery

Frontal lobe Hypothalamus Aqueduct of Anterior midbrain commissure Cerebellum

Preoptic area

Autonomic centers Hypothalamus (parasympathetic) Suprachiasmatic nucleus Supraoptic nucleus

Tuberal nuclei Tuberal Optic chiasm area Infundibulum Mamillary body Anterior lobe of Pars distalis Posterior lobe of Pons pituitary Pars intermedia gland pituitary gland (pars nervosa)

• The cerebellum consists of: • Two hemispheres • Folia (folds similar to gyri of the cerebrum) • Anterior and posterior lobes • Vermis (separates the hemispheres) • Flocculonodular lobes • Arbor vitae • Cerebellar peduncles

Dendrites projecting into the gray matter of the cerebellum

Cell body of Purkinje cell Axons of Purkinje cells projecting into the white Superior colliculus matter of the cerebellum Purkinje cells LM  120 Aqueduct of midbrain Mesencephalon

Mamillary Inferior colliculus body Anterior lobe Anterior lobe Arbor vitae Arbor Pons vitae Cerebellar cortex Pons Cerebellar Cerebellar nucleus nucleus Cerebellar cortex Fourth Posterior Superior Posterior lobe ventricle lobe Cerebellar Middle peduncles Inferior Choroid plexus of Medulla Flocculonodular lobe the fourth ventricle oblongata Medulla oblongata Flocculonodular lobe

Sagittal view of the cerebellum showing the arrangement of gray matter and white matter. Purkinje cells are seen in the photomicrograph; these large neurons are found in the cerebellar cortex.

Cerebellum

Vermis Vermis

Anterior lobe Primary fissure

Posterior lobe Folia Folia

Right hemisphere Left hemisphere of cerebellum of cerebellum

Superior surface of the cerebellum. This view shows major anatomical landmarks and regions.

• The cerebellum • Cerebellar cortex: subconscious coordination of movements • Arbor vitae: connects cerebellar cortex with cerebellar peduncles • Cerebellar peduncles • Superior: connect cerebellum with mesencephalon, diencephalon, and cerebrum • Middle: communicate between cerebellum and pons • Inferior: connect cerebellum with the medulla oblongata

Dendrites projecting into the gray matter of the cerebellum

Cell body of Purkinje cell Axons of Purkinje cells projecting into the white Superior colliculus matter of the cerebellum Purkinje cells LM  120 Aqueduct of midbrain Mesencephalon

Sagittal view of the cerebellum showing the arrangement of gray matter and white matter. Purkinje cells are seen in the photomicrograph; these large neurons are found in the cerebellar cortex.

• The cerebrum consists of: • Two hemispheres • Several lobes • Frontal, parietal, occipital, and temporal • Gyri and sulci • Longitudinal fissure • Corpus callosum • Basal nuclei • Limbic system

• The Cerebral Hemispheres • The hemispheres consist of: • Gyri and sulci • Central sulcus • Longitudinal fissure • Cerebral lobes

Longitudinal fissure Left cerebral Right cerebral hemisphere hemisphere

Cerebral veins and arteries covered by arachnoid mater

Central sulcus

Parieto-occipital sulcus

Cerebellum

POSTERIOR

• The Cerebral Hemispheres • The Cerebral Lobes • Frontal lobe: conscious control of skeletal muscles • Occipital lobe: perception of visual stimuli • Parietal lobe: conscious perception of touch, pressure, vibration, pain, temperature, and taste • Temporal lobe: conscious perception of auditory and olfactory stimuli

Precentral gyrus Postcentral gyrus

PARIETAL LOBE Central sulcus

FRONTAL LOBE of left cerebral hemisphere OCCIPITAL LOBE Lateral sulcus

Branches of middle cerebral artery emerging from lateral sulcus Cerebellum

TEMPORAL LOBE Pons

Lateral view of intact brain after removal of the Medulla oblongata dura mater and arachnoid mater showing superficial surface anatomy of the left hemisphere

• Motor and Sensory Areas of the Cerebral Cortex • Precentral gyrus • Anterior to the central gyrus • Neurons direct voluntary movements by controlling somatic motor neurons in the brain stem and spinal cord • Postcentral gyrus • Posterior to the central gyrus • Neurons receive somatic sensory information for touch, pressure, pain, taste, and temperature from the dorsal columns and spinothalamic tracts

A sagittal section through the brain

• Hemispheric Specialization • Left hemisphere • Speech center, writing, language, mathematics • Right hemisphere • Analysis by touch, spatial visualization

LEFT HAND RIGHT HAND

Prefrontal Prefrontal cortex cortex

Speech center Anterior C commissure O R P U Writing S Analysis by touch C Auditory cortex A Auditory cortex (right ear) L L (left ear) O S U General interpretive M Spatial center (language visualization and mathematical and analysis calculation)

• The Central White Matter • Consists of bundles called: • Association fibers: tracts that interconnect areas of neural cortex within a hemisphere (arcuate fibers and longitudinal fasciculi) • Commissural fibers: tracts that connect the two hemispheres (anterior commissure and corpus callosum) • Projection fibers: tracts that link the cerebrum with other regions of the brain and spinal cord

Longitudinal fasciculi

Projection fibers of internal capsule

Anterior commissure

• The Basal Nuclei • These are masses of gray matter embedded in the white matter inferior to the lateral ventricles • Consist of: • Caudate nucleus • Amygdaloid body • Claustrum • Putamen • Globus pallidus

• The Basal Nuclei • Caudate nucleus, putamen, and globus pallidus • Control the cycles of arm and leg movements when walking • Claustrum • Plays a role in subconscious processing of visual information • Amygdaloid body • Component of the limbic system

Lateral ventricle

Corpus callosum Head of caudate nucleus Septum pellucidum Internal capsule Claustrum Lateral sulcus Insula

Anterior commissure Putamen Lentiform Globus nucleus Tip of inferior horn of pallidus lateral ventricle Amygdaloid body Frontal section

• The Limbic System • Located between the cerebrum and the diencephalon just superior to the corpus callosum • Functions: • Establishes emotional states • Links the conscious functions with the unconscious autonomic functions • Facilitates memory storage and retrieval

Interthalamic Central Cingulate gyrus adhesion sulcus (limbic lobe) Fornix Pineal gland Corpus callosum

Thalamus Hypothalamus Temporal lobe Parahippocampal gyrus (limbic lobe) Hippocampus Mamillary (within dentate gyrus) body

Sagittal section through the cerebrum showing the cortical areas associated with the limbic system. The parahippocampal and dentate gyri are shown as if transparent so that deeper limbic components can be seen. © 2012 Pearson Education, Inc. The Cerebrum

• The limbic system consists of: • Cingulate gyrus • Dentate gyrus • Parahippocampal gyrus • Hippocampus

Anterior nucleus of thalamus

Hypothalamic nuclei

Olfactory tract

Amygdaloid body

Mamillary Hippocampus Parahippocampal body (within dentate gyrus) gyrus

Interthalamic Central Cingulate gyrus adhesion sulcus (limbic lobe) Fornix Pineal gland Corpus callosum

Thalamus Hypothalamus Temporal lobe Parahippocampal gyrus (limbic lobe) Hippocampus Mamillary (within dentate gyrus) body

• The Limbic System • The fornix • Tract of white matter connecting the hippocampus with the hypothalamus • Many fornix fibers extend to the mamillary bodies • Mamillary bodies control reflex movements associated with eating

• There are 12 pairs of cranial nerves • These nerves innervate the periphery emerging from the brain (not the spinal cord) • These nerves are on the ventrolateral surface of the brain • They are numbered beginning at the anterior aspect of the brain • They are numbered CN I to CN XII

Optic chiasm Optic nerve (N II) Infundibulum

Oculomotor nerve (N III)

Trochlear nerve (N IV)

Trigeminal nerve (N V)

Abducens nerve (N VI)

Facial nerve (N VII)

Vestibulocochlear nerve (N VIII) Glossopharyngeal nerve (N IX) Vagus nerve (N X)

Hypoglossal nerve (N XII)

Accessory nerve (N XI)

Diagrammatic inferior view of the human brain. Compare view with part (a). © 2012 Pearson Education, Inc. Figure 16.22a Origins of the Cranial Nerves Olfactory bulb, termination of olfactory nerve (N I) Olfactory tract Mamillary Optic chiasm body Basilar Optic nerve (N II) artery Infundibulum Pons Oculomotor nerve (N III)

Trochlear nerve (N IV)

Trigeminal nerve (N V)

Abducens nerve (N VI)

Facial nerve (N VII)

Vestibulocochlear nerve (N VIII) Glossopharyngeal Vertebral nerve (N IX) artery Vagus nerve (N X) Cerebellum

Medulla oblongata Hypoglossal nerve (N XII)

Spinal cord Accessory nerve (N XI)

• CN I: The Olfactory Nerve • Function: sensory (smell) • Origin: olfactory epithelium • Foramen: olfactory foramina • Destination: olfactory bulbs

Left olfactory bulb (termination of olfactory nerve) Olfactory tract (to olfactory cortex of cerebrum) Olfactory OLFACTORY nerve fibers NERVE (N I) Cribriform plate of ethmoid Olfactory epithelium

• CN II: The Optic Nerve • Function: sensory (vision) • Origin: retina • Foramen: optic canal • Destination: diencephalon, then to occipital lobe

Eye

Olfactory bulb Olfactory tract OPTIC NERVE (N II) Optic chiasm Pituitary Optic tract gland

Mesencephalon Lateral (cut) geniculate nucleus (in thalamus)

Optic projection fibers

Visual cortex (in occipital lobes)

• CN III: The Oculomotor Nerve • Function: controls extra-ocular eye muscles • Motor function • Superior, inferior, and medial rectus • Inferior oblique • Levator palpebrae superioris • Origin: mesencephalon • Foramen: superior orbital fissure • Destination: extra-ocular eye muscles

Superior rectus OPTIC Optic OCULOMOTOR TROCHLEAR Superior muscle NERVE (N II) chiasm NERVE (N III) NERVE (N IV) oblique muscle

Trochlea

Levator palpebrae superioris muscle

Trigeminal nerve (N V), cut

Inferior Vestibulocochlear oblique nerve (N VIII), cut muscle

Facial nerve Inferior Medial (N VII), cut rectus Ciliary rectus Lateral ABDUCENS muscle ganglion muscle rectus NERVE (N VI) muscle (cut)

• CN IV: The Trochlear Nerve • Function: controls extra-ocular eye muscles • Motor function • Superior oblique • Origin: mesencephalon • Foramen: superior orbital fissure • Destination: extra-ocular eye muscles

Superior rectus OPTIC Optic OCULOMOTOR TROCHLEAR Superior muscle NERVE (N II) chiasm NERVE (N III) NERVE (N IV) oblique muscle

Trochlea

Levator palpebrae superioris muscle

Trigeminal nerve (N V), cut

Inferior Vestibulocochlear oblique nerve (N VIII), cut muscle

Facial nerve Inferior Medial (N VII), cut rectus Ciliary rectus Lateral ABDUCENS muscle ganglion muscle rectus NERVE (N VI) muscle (cut)

• CN V: The Trigeminal Nerve • Function: • Mixed (sensory and motor) function • Ophthalmic: sensations from the forehead, eyelids, and nose • Maxillary: sensations from lower eyelid, upper lip, and cheek • Mandibular: controls mastication • Origin: ophthalmic, maxillary, and mandibular nerves

• CN V: The Trigeminal Nerve (continued) • Foramen: • Ophthalmic: superior orbital fissure • Maxillary: foramen rotundum • Mandibular: foramen ovale • Destination: • Ophthalmic and maxillary: Pons • Mandibular: mandibular muscles

Superior orbital Ophthalmic Semilunar fissure branch ganglion

Supraorbital nerves

Ciliary ganglion Pons TRIGEMINAL Foramen NERVE (N V) rotundum Infra-orbital Maxillary nerve branch

Foramen ovale Lingual nerve Otic ganglion Submandibular ganglion Mandibular branch

Mental nerve Pterygopalatine ganglion

• CN VI: The Abducens Nerve • Function: controls eye movements • Motor function • Origin: pons • Foramen: superior orbital fissure • Destination: innervates the lateral rectus eye muscle

Superior rectus OPTIC Optic OCULOMOTOR TROCHLEAR Superior muscle NERVE (N II) chiasm NERVE (N III) NERVE (N IV) oblique muscle

Trochlea

Levator palpebrae superioris muscle

Trigeminal nerve (N V), cut

Inferior Vestibulocochlear oblique nerve (N VIII), cut muscle

Facial nerve Inferior Medial (N VII), cut rectus Ciliary rectus Lateral ABDUCENS muscle ganglion muscle rectus NERVE (N VI) muscle (cut)

• CN VII: The Facial Nerve • Function: Mixed (sensory and motor) • Sensory: sensations from the face / taste • Motor: controls muscles of the face • Origin: • Sensory: taste buds • Motor: pons • Foramen: internal acoustic meatus • Destination: • Sensory: pons • Motor: muscles of the face

Greater Pterygopalatine petrosal Geniculate FACIAL ganglion nerve ganglion NERVE (N VII)

Temporal branch Pons

Zygomatic branches Posterior auricular branch

Stylomastoid Buccal foramen branch Chorda tympani nerve (with mandibular Mandibular branch of N V) branch Lingual branch Cervical (with lingual nerve branch of N V)

Submandibular ganglion Origin and branches of the facial nerve

• CN VIII: The Vestibulocochlear Nerve • Function: • Sensory: balance and hearing • Origin: receptors of the vestibule and cochlea • Foramen: internal acoustic meatus • Destination: pons

Tympanic Vestibular Facial Internal cavity Semicircular branch nerve acoustic VESTIBULOCOCHLEAR (middle ear) canals (N VIII) (N VII), cut canal NERVE (N VIII)

N V

Pons

N VI N VII N IX N XII N X Medulla oblongata N XI

Tympanic Auditory Cochlea Cochlear membrane tube branch (N VIII)

• CN IX: The Glossopharyngeal Nerve • Function: Mixed (sensory and motor) • Sensory function: tongue pain • Motor function: swallowing • Origin: • Sensory: posterior 1/3 of the tongue • Motor: salivary gland

• CN IX: The Glossopharyngeal Nerve (continued) • Foramen: jugular foramen • Destination: • Sensory: pons • Visceral motor: parotid salivary gland • Somatic motor: pharyngeal muscles for swallowing

Pons N V N VII N VIII N VI GLOSSOPHARYNGEAL Otic ganglion NERVE (N IX) Medulla oblongata Inferior (petrosal) Superior (jugular) ganglion ganglion

Lingual branch Pharyngeal branches

Parotid salivary gland

Carotid sinus branch

Carotid body Carotid sinus

Common carotid artery

• CN X: The Vagus Nerve • Function: • Sensory: information from organs • Motor: sends information to the organs • Origin: • Sensory: from the organs • Motor: medulla oblongata

• CN X: The Vagus Nerve (continued) • Foramen: jugular foramen • Destination: • Sensory: autonomic centers of the medulla oblongata • Somatic motor: muscles of the palate and pharynx • Visceral motor: respiratory, cardiovascular, and digestive organs

Superior pharyngeal Medulla oblongata branch Auricular branch to external ear Superior ganglion of vagus nerve Inferior ganglion of Pharyngeal branch vagus nerve Superior laryngeal nerve Internal branch Superior laryngeal nerve External branch

Recurrent Cardiac branches laryngeal nerve Cardiac plexus

Right lung Left lung

Liver Anterior vagal trunk

Stomach Spleen Celiac Pancreas plexus

Colon Small intestine Hypogastric plexus

• CN XI: The Accessory Nerve • Function: • Motor: controls the sternocleidomastoid, trapezius, palate, pharynx, and larynx muscles • Origin: spinal cord and medulla oblongata • Foramen: jugular foramen • Destination: • Internal branch: muscles of the palate, pharynx, and larynx • External branch: sternocleidomastoid and trapezius muscles

HYPOGLOSSAL NERVE (N XII) Trigeminal nerve (N V) ACCESSORY NERVE (N XI) Medulla oblongata Internal branch: to palatal, pharyngeal, and laryngeal Cranial root of N XI muscles with vagus nerve

Intrinsic muscles Spinal of tongue root of N XI Styloglossus muscle External Genioglossus muscle branch of N XI

Geniohyoid muscle Spinal cord Hyoglossus muscle

Hyoid bone Trapezius muscle Thyrohyoid muscle Sternocleidomastoid muscle Sternohyoid muscle Sternothyroid muscle Ansa cervicalis (cervical plexus)

Omohyoid muscle

• CN XII: The Hypoglossal Nerve • Function: • Motor: controls tongue movement • Origin: medulla oblongata • Foramen: hypoglossal canal • Destination: tongue muscles

HYPOGLOSSAL NERVE (N XII) Trigeminal nerve (N V) ACCESSORY NERVE (N XI) Medulla oblongata Internal branch: to palatal, pharyngeal, and laryngeal Cranial root of N XI muscles with vagus nerve

Intrinsic muscles Spinal of tongue root of N XI Styloglossus muscle External Genioglossus muscle branch of N XI

Geniohyoid muscle Spinal cord Hyoglossus muscle

Hyoid bone Trapezius muscle Thyrohyoid muscle Sternocleidomastoid muscle Sternohyoid muscle Sternothyroid muscle Ansa cervicalis (cervical plexus)

Omohyoid muscle

• Summary of Cranial Nerve Branches and Functions • Mnemonic aid • Oh, Once One Takes The Anatomy Final, Very Good Vacations Are Heavenly