Frontal Lobe Anterior Corpora Commissure Quadrigemina Superior Colliculus Optic Chiasm Inferior Colliculus

Chapter 16

The Nervous System The Brain and Cranial Nerves

Lecture Presentation by Steven Bassett Southeast Community College

• 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

© 2015 Pearson Education, Inc. An Introduction to the Organization of the Brain • Embryology of the Brain • The CNS begins as a neural tube • The lumen of the tube (neurocoel) is filled with fluid • The lumen of the tube will expand thus forming the various ventricles of the brain • In the fourth week of development, the cephalic area of the neural tube enlarges to form: • Prosencephalon • Mesencephalon • Rhombencephalon

© 2015 Pearson Education, Inc. An Introduction to the Organization of the Brain • Embryology of the Brain (continued) • Prosencephalon eventually develops to form: • Telencephalon forms: • Cerebrum • Diencephalon forms: • Epithalamus, thalamus, and hypothalamus.

© 2015 Pearson Education, Inc. An Introduction to the Organization of the Brain • Embryology of the Brain (continued) • Rhombencephalon • Eventually develops to form: • Metencephalon: forms the pons and cerebellum • Myelencephalon: forms the medulla oblongata

Sulci CEREBRUM • 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 functions, and hormone CEREBELLUM production • Coordinates complex Spinal somatic motor cord patterns • Adjusts output of MESENCEPHALON 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)

© 2015 Pearson Education, Inc. An Introduction to the Organization of the Brain • Major Regions and Landmarks • Medulla oblongata • Pons • Mesencephalon (midbrain) • Diencephalon • Cerebellum • Cerebrum (telencephalon)

Corpus callosum Thalamus Membranous portion Septum of epithalamus pellucidum Hypothalamus Interventricular foramen Parieto-occipital sulcus Pineal gland Frontal lobe Anterior Corpora commissure Quadrigemina Superior colliculus Optic chiasm Inferior colliculus

Mamillary body Aqueduct of midbrain

Temporal lobe Cerebellum

Mesencephalon Fourth ventricle Pons Medulla oblongata

a A sagittal section through the brain

© 2015 Pearson Education, Inc. An Introduction to the Organization of the Brain • Major Regions and Landmarks • Medulla oblongata • Relays information to the thalamus and brain stem • Regulates heart rate, blood pressure, and digestion • Pons • Relays information to the cerebellum and the thalamus • Regulates somatic and visceral motor centers

Sulci CEREBRUM • 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

© 2015 Pearson Education, Inc. An Introduction to the Organization of the Brain • Major Regions and Landmarks • Mesencephalon (midbrain) • Processes visual and auditory data • Maintains consciousness and alertness • Involved with reflexive somatic motor responses to stimuli

Sulci CEREBRUM • 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

© 2015 Pearson Education, Inc. An Introduction to the Organization of the Brain • Major Regions and Landmarks • Diencephalon • Epithalamus • Contains the pineal gland • Thalamus • Relays information to the cerebrum • Processes sensory information • Hypothalamus • Involved in emotions, thirst, some habitual activity

Sulci CEREBRUM • 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

© 2015 Pearson Education, Inc. An Introduction to the Organization of the Brain • Major Regions and Landmarks • Cerebellum • Coordinates somatic motor function • Adjusts output of somatic motor centers resulting in smooth operation • Cerebrum (telencephalon) • Conscious thought processes • Intellectual functions • Memory storage • Conscious regulation of skeletal muscle contractions

Sulci CEREBRUM • 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

© 2015 Pearson Education, Inc. An Introduction to the Organization of the Brain • 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

Ventricular System of the Brain Lateral ventricles in cerebral hemispheres Septum Interventricular pellucidum foramen Third ventricle

Aqueduct of midbrain Inferior horn of lateral Fourth ventricle ventricles

Cerebellum

Central canal

d Diagrammatic coronal section showing the interconnections between the ventricles

© 2015 Pearson Education, Inc. An Introduction to the Organization of the Brain • The Ventricular System 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 cushion for the CNS

© 2015 Pearson Education, Inc. An Introduction to the Organization of the Brain • The Ventricular System of the Brain • There are four ventricles • Ventricles 1 and 2 (called lateral ventricles) • Located 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

Interventricular foramen

Third ventricle

Posterior horns of lateral ventricles

Inferior horns of lateral ventricles

Aqueduct of Pons midbrain

Medulla oblongata Fourth ventricle Central canal Cerebellum Spinal cord

a Orientation and extent of the ventricles as seen in a lateral view of a transparent brain © 2015 Pearson Education, Inc. An Introduction to the Organization of the Brain • The Ventricular System of the Brain • 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

© 2015 Pearson Education, Inc. An Introduction to the Organization of the Brain • The Ventricular System of the 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

Third ventricle

Posterior horns of lateral ventricles

Inferior horns of lateral ventricles

Aqueduct of Pons midbrain

Medulla oblongata Fourth ventricle Central canal Cerebellum Spinal cord

a Orientation and extent of the ventricles as seen in a lateral view of a transparent brain © 2015 Pearson Education, Inc. Figure 16.2c Ventricles of the Brain Longitudinal fissure Ventricular System of the Brain Lateral ventricles in cerebral hemispheres

Interventricular foramen

Third ventricle

Inferior horn Aqueduct of of lateral midbrain ventricle

Pons Fourth ventricle

Cerebellum

Medulla oblongata

Central canal

c Anterior view of the ventricles as if seen through a transparent brain

• 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

• The Cranial Meninges • The cranial meninges surround the brain and the spinal cord • There are three layers of the meninges • Dura mater • Most superficial layer (outermost layer) • Arachnoid mater • Middle layer • Pia mater • Deepest (innermost layer)

Dura mater (endosteal layer) Cranium Dural sinus Dura mater (meningeal layer) Cerebral cortex Subdural space Arachnoid mater Cerebral Pia Subarachnoid cortex mater space

Cerebellum

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

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

Scalp

Cerebral cortex covered by pia mater

• The Cranial Meninges • The Dura Mater • Consists of two layers • Endosteal layer • Outermost layer of the dura mater • This is the layer felt within the anterior fontanel of a baby • Fused to the periosteum lining of the cranial bones • Meningeal layer • Innermost layer of the dura mater • Space between the two layers contains the dural sinus

Dura mater (endosteal layer) Cranium Dural sinus Dura mater (meningeal layer) Cerebral cortex Subdural space Arachnoid mater Cerebral Pia Subarachnoid cortex mater space

Cerebellum

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

• The Cranial Meninges • Folds of the dura mater • The meningeal layer forms folds called: • Falx cerebri • Tentorium cerebelli • Talx 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

Superior sagittal Cranial sinus Meninges Dura mater Subdural Arachnoid mater space Arachnoid trabeculae Arachnoid granulation Pia mater

Falx cerebri Cerebral vein Subarachnoid space Cerebral cortex

a Organization and relationship of the cranial meninges to the brain.

Superior sagittal sinus

Inferior sagittal sinus

Cranium

Diaphragma Dura Mater sellae Falx cerebri Tentorium cerebelli

Pituitary gland Diaphragma sellae

Sella turcica Falx cerebelli of sphenoid

Transverse sinus

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

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

Dura mater (endosteal layer) Cranium Dural sinus Dura mater (meningeal layer) Cerebral cortex Subdural space Arachnoid mater Cerebral Pia Subarachnoid cortex mater space

Cerebellum

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

• The 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

Superior sagittal Cranial sinus Meninges Dura mater Subdural Arachnoid mater space Arachnoid trabeculae Arachnoid granulation Pia mater

Falx cerebri Cerebral vein Subarachnoid space Cerebral cortex

a Organization and relationship of the cranial meninges to the brain.

Arachnoid trabeculae Pia mater

Cerebral vein Cerebral Perivascular space cortex

b A detailed view of the arachnoid mater, the subarachnoid space, and the pia mater. Note the relationship between the cerebral vein and the subarachnoid space.

• 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 • These transport mechanisms are very specific

• Blood–Brain Barrier • The blood-brain barrier is intact throughout the CNS except in three areas • Portions of the hypothalamus • Pineal gland • The roof portions of the third and fourth ventricles

• Cerebrospinal Fluid (CSF) • Prevents contact of neural tissue with the surrounding bones • 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

a 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 b 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 • Most flows into the subarachnoid space and a small amount enters the central canal of the spinal cord • Flows around the brain and spinal cord eventually enters circulation via the arachnoid granulations

© 2015 Pearson Education, Inc. Figure 16.7 Circulation of Cerebrospinal Fluid Extension of choroid plexus Arachnoid Superior Dura mater Cranium into lateral ventricle granulations sagittal sinus (endosteal layer) Arachnoid granulation

Fluid movement

Arachnoid trabecula

Cerebral Dura mater cortex (meningeal Superior layer) sagittal Pia Subdural sinus mater space Subarachnoid Arachnoid Choroid plexus space of third ventricle mater

Aqueduct of midbrain

Lateral aperture

Choroid plexus of fourth ventricle

Median aperture Central canal Arachnoid mater

Subarachnoid space

Dura mater Spinal cord

Filum terminale

• The medulla oblongata is 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 somatic sensory information to the thalamus • Olivary nuclei • Pass information from the cerebrum, spinal cord, diencephalon, and brain stem to the cerebellum

Olivary nucleus Cardiovascular centers

Medulla Pons oblongata Solitary nucleus

Nucleus cuneatus

Olive Nucleus gracilis Pyramids Reticular formation Spinal cord Lateral white column

a Anterior view

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

Olivary nuclei Attachment to membranous roof of fourth ventricle Cardiovascular centers

Respiratory rhythmicity centers

Nucleus gracilis Nucleus cuneatus

Other nuclei/centers Lateral white column Reticular formation Posterior white columns Posterior median sulcus Spinal cord

b 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

Parietal lobe Corpus callosum Choroid plexus in Septum epithalamus pellucidum Thalamus (surrounds third ventricle) Fornix

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

a Midsagittal section through the brain. This view shows the major features of the diencephalon and adjacent portions of the brain stem.

Descending tracts Ascending tracts Transverse fibers Pons Cerebellum Fourth ventricle

Pneumotaxic center

Medulla oblongata Apneustic center 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

Mamillary body Aqueduct of midbrain

Temporal lobe Cerebellum

Mesencephalon Fourth ventricle Pons Medulla oblongata

a A sagittal section through the brain

• 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

Pineal gland

Thalamus Superior colliculi

Inferior colliculi

Substantia nigra

Red nuclei

Reticular formation

Cerebral peduncles b Diagrammatic view of the diencephalon and brain stem. This view is drawn as if transparent, to show the positions of important nuclei.

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

Mamillary body Aqueduct of midbrain

Temporal lobe Cerebellum

Mesencephalon Fourth ventricle Pons Medulla oblongata

a A sagittal section through the brain

• The Epithalamus • Forms the roof of the third ventricle • Posterior portion 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 nuclei: part of the limbic system • Medial nuclei: relay information to the frontal lobe • Ventral nuclei: relay information to the parietal lobes • Posterior nuclei: relay information to the occipital lobe • Lateral nuclei: adjust activity in the cingulate gyrus

Frontal Parietal lobe lobe

Occipital lobe

a 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.

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

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

b 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. © 2015 Pearson Education, Inc. The Diencephalon

• 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

Mamillary body Aqueduct of midbrain

Temporal lobe Cerebellum

Mesencephalon Fourth ventricle Pons Medulla oblongata

a A sagittal section through the brain

• 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

b Enlarged view of the hypothalamus showing Thalamus the locations of major Paraventricular nucleus nuclei and centers.

Preoptic area Tuberal area Hypothalamus

Sympathetic Optic chiasm Parasympathetic Tuberal nuclei Infundibulum

Posterior lobe of Mamillary bodies pituitary gland Suprachiasmatic nucleus Pars distalis Anterior lobe of Pons Pars intermedia Supraoptic nucleus pituitary gland

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

Mamillary body Aqueduct of midbrain

Temporal lobe Cerebellum

Mesencephalon Fourth ventricle Pons Medulla oblongata

a A sagittal section through the brain

Cerebellum

Vermis

Anterior lobe

Primary fissure

Posterior lobe

Folia

Left Hemisphere of Cerebellum Right Hemisphere of Cerebellum Left Hemisphere of Cerebellum Right Hemisphere of Cerebellum

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

Dendrites projecting into the gray matter of the cerebellum

Cell body of Purkinje cell

Axons of Purkinje cells projecting into the white matter of the cerebellum Purkinje cells LM  120

b 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 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

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

Longitudinal Right cerebral fissure hemisphere

Left cerebral Cerebral veins and hemisphere arteries covered by arachnoid mater

Central sulcus

Parieto-occipital Cerebellum sulcus

POSTERIOR

Corpus callosum

Lateral ventricle Caudate nucleus Septum pellucidum Putamen Insula

Lateral sulcus Globus pallidus

Internal Claustrum capsule

Anterior commissure Amygdaloid body

Tip of inferior horn of lateral c Frontal section ventricle

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

• 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

Lateral sulcus Occipital lobe

Branches of middle cerebral artery emerging from lateral sulcus Cerebellum Temporal lobe

Pons

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

• The Insula • Lies deep to the lateral sulcus • Consists of olfactory cortex and gustatory cortex

Central sulcus Frontal Lobe (retracted Parietal Lobe to show insula) Primary sensory cortex Primary motor cortex (postcentral gyrus) (precentral gyrus) Somatic motor association area Somatic sensory association area (premotor cortex) Retractor

Occipital Lobe Visual association area Prefrontal cortex

Visual cortex

Gustatory cortex

Insula Temporal Lobe (retracted Lateral sulcus to show olfactory cortex) Auditory association area Auditory cortex a Major anatomical landmarks on the surface of the left cerebral hemisphere. To expose the Olfactory cortex insula, the lateral sulcus has been pulled open.

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

Precentral gyrus Postcentral gyrus

Parietal Lobe

Central sulcus

Frontal lobe of left cerebral hemisphere

Lateral sulcus Occipital lobe

Branches of middle cerebral artery emerging from lateral sulcus Cerebellum Temporal lobe

Pons

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

• Higher-Order Functions • Characteristics of higher-order functions • They are performed by the cerebral cortex • They involve communication between cerebral cortex areas and other areas of the brain • They involve conscious and unconscious information processing • The functions are subject to modifications and adjustments

• Integrative Regions of the Cerebral Cortex • The centers of the various regions of the cerebral cortex do the following: • Integrate complex sensory stimuli • Integrate complex motor responses • The various centers are: • General interpretive area • The speech center • The prefrontal cortex • Brodmann’s areas

Speech center Frontal eye field (Broca’s area) General interpretive area (gnostic area) Prefrontal association cortex

a Higher-order integrative regions of the cerebral cortex

4 6 1

40 39

44 41 42 18 17

b Selected Brodmann’s areas of the cerebral cortex

• Integrative Regions of the Cerebral Cortex • The general interpretive area • Found only in one hemisphere, usually the left • Analytical center • The speech center • Also called Broca’s area • A motor center that regulates patterns of breathing and vocalization for speech

• Integrative Regions of the Cerebral Cortex • The prefrontal cortex • Performs complicated learning and reasoning functions • Brodmann’s areas and cortical function • Assigned numbers to various brain regions by analyzing each area's cellular structure • Perhaps the various cellular structures can correlate with specific functions

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

Visual cortex Visual cortex (right visual field) (left visual field)

• 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

Arcuate fibers

Longitudinal fasciculi a Lateral aspect of the brain showing arcuate fibers and longitudinal fasciculi

Corpus callosum Longitudinal fissure Anterior commissure

Projection fibers

Internal capsule

b Anterior view of the brain showing orientation of the commissural and projection fibers

• The Basal Nuclei • These are masses of gray matter embedded in the white matter inferior to the lateral ventricles • General function: • Involved with subconscious control and integration of skeletal muscle tone • Involved with the coordination of learned movement patterns • Involved in the processing, integration, and relay of information from the cerebral cortex

• The Basal Nuclei • Consist of: • Caudate nucleus • Amygdaloid body • Claustrum • Putamen • Globus pallidus

Corpus callosum

Lateral ventricle Caudate nucleus Septum pellucidum Putamen Insula

Lateral sulcus Globus pallidus

Internal Claustrum capsule

Anterior commissure Amygdaloid body

Tip of inferior horn of lateral c Frontal section ventricle

• 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

• 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 Hippocampus Mamillary gyrus (limbic lobe) (within dentate gyrus) body

a 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.

• 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

b Additional details concerning the three-dimensional structure of the limbic system.

• 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

Anterior nucleus of thalamus

Hypothalamic nuclei

Olfactory tract

Amygdaloid body

Mamillary Hippocampus Parahippocampal body (within dentate gyrus) gyrus

b Additional details concerning the three-dimensional structure of the limbic system.

• 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

Olfactory tract

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)

b Diagrammatic inferior view of the human brain. Compare view with part (a). © 2015 Pearson Education, Inc. Figure 16.23a Origins of the Cranial Nerves Olfactory bulb, termination of olfactory nerve (N I)

Olfactory tract Mamillary body Optic chiasm Optic nerve (N II) Basilar artery Infundibulum Oculomotor nerve (N III) Pons Trochlear nerve (N IV)

Trigeminal nerve (N V)

Abducens nerve (N VI) Facial nerve (N VII) Vestibulocochlear nerve (N VIII)

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

Medulla oblongata Hypoglossal nerve (N XII)

Spinal cord Accessory nerve (N XI) a The inferior surface of the brain as it appears on gross dissection. The roots of the cranial nerves are clearly visible. © 2015 Pearson Education, Inc. The Cranial Nerves

• 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 OLFACTORY (to olfactory cortex NERVE (N I) of cerebrum) Olfactory nerve fibers Cribriform plate of ethmoid

Olfactory epithelium

• CN II: The Optic Nerve • Function • Sensory (vision) • Origin • Retina • Foramen • Optic canal • Destinatio • Diencephalon, then to occipital lobe

Eye

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

Mesencephalon Lateral geniculate (cut) 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, medial rectus, inferior oblique • Levator palpebrae superioris • Origin • Mesencephalon • Foramen • Superior orbital fissure • Destination • Extra-ocular eye muscles

Superior OPTIC Optic OCULOMOTOR TROCHLEAR Superior rectus NERVE (N II) chiasm NERVE (N III) NERVE (N IV) oblique muscle 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 rectus ABDUCENS muscle muscle Lateral NERVE (N VI) Ciliary rectus ganglion muscle (cut)

• CN IV: The Trochlear Nerve • Function • Controls extra-ocular eye muscles • Motor function • Superior oblique • Origin • Mesencephalon • Foramen • Superior orbital fissure • Destination • Superior oblique muscle

Superior OPTIC Optic OCULOMOTOR TROCHLEAR Superior rectus NERVE (N II) chiasm NERVE (N III) NERVE (N IV) oblique muscle 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 rectus ABDUCENS muscle muscle Lateral NERVE (N VI) Ciliary rectus ganglion 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

Superior orbital Ophthalmic Semilunar fissure branch ganglion

Supraorbital nerves

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

Lingual nerve Otic ganglion

Mental nerve Mandibular branch Pterygopalatine Submandibular ganglion ganglion

• 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

• 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 OPTIC Optic OCULOMOTOR TROCHLEAR Superior rectus NERVE (N II) chiasm NERVE (N III) NERVE (N IV) oblique muscle 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 rectus ABDUCENS muscle muscle Lateral NERVE (N VI) Ciliary rectus ganglion 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

• CN VII: The Facial Nerve • Foramen • Internal acoustic meatus • Destination • Sensory: pons • Motor: muscles of the face

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

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

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: medulla oblongata • Visceral motor: parotid salivary gland • Somatic motor: pharyngeal muscles for swallowing

N V Pons N VIII N VII GLOSSOPHARYNGEAL Otic N VI NERVE (N IX) ganglion Medulla oblongata

Inferior Superior (jugular) ganglion (petrosal) ganglion Pharyngeal branches

Lingual Parotid salivary gland branch

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

VAGUS NERVE (N X) Pons Superior pharyngeal branch Medulla oblongata

Auricular branch to external ear Superior ganglion of vagus nerve Inferior ganglion of vagus nerve Pharyngeal branch

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

• CN XI: The Accessory Nerve • 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 of tongue Spinal 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 Ansa cervicalis Sternothyroid muscle (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 of tongue Spinal root of N XI Styloglossus muscle External Genioglossus muscle branch of N XI

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