An Introduction to the Brain and Cranial Nerves

An Introduction to the Brain and Cranial Nerves
The Adult Human Brain Volume ranges from 750 mL to 2100 mL Contains almost 97 percent of the body’s neural tissue Average weight about 1.4 kg (3 lb)

14-1 The Brain Six Regions of the Brain Cerebrum Cerebellum
Diencephalon Midbrain Pons Medulla oblongata

14-1 The Brain Cerebrum Largest part of brain
Controls higher mental functions Divided into left and right cerebral hemispheres Surface layer of gray matter (neural cortex)

14-1 The Brain Cerebrum Neural cortex Also called cerebral cortex
Folded surface increases surface area Elevated ridges (gyri) Shallow depressions (sulci) Deep grooves (fissures)

14-1 The Brain Cerebellum Second largest part of brain
Coordinates repetitive body movements Two hemispheres Covered with cerebellar cortex

Cerebellum Cerebrum Left cerebral hemisphere Gyri Sulci
Figure 14-1 An Introduction to Brain Structures and Functions (Part 1 of 2). Left cerebral hemisphere Gyri Cerebrum Sulci • Conscious thought processes, intellectual functions • Memory storage and processing • Conscious and subconscious regulation of skeletal muscle contractions Fissures Cerebellum • Coordinates complex somatic motor patterns • Adjusts output of other somatic motor centers in brain and spinal cord Spinal cord

14-1 The Brain Diencephalon Located under cerebrum and cerebellum
Links cerebrum with brain stem Three divisions of the diencephalon Left thalamus Right thalamus Hypothalamus

14-1 The Brain Diencephalon Thalamus Hypothalamus
Relays and processes sensory information Hypothalamus Hormone production Emotion Autonomic function

14-1 The Brain Diencephalon Pituitary gland Major endocrine gland
Connected to hypothalamus Via infundibulum (stalk) Interfaces nervous and endocrine systems

14-1 The Brain The Brain Stem Processes information between: Includes:
Spinal cord and cerebrum or cerebellum Includes: Midbrain Pons Medulla oblongata

14-1 The Brain Midbrain Pons Also called mesencephalon
Processes sight, sound, and associated reflexes Maintains consciousness Pons Connects cerebellum to brain stem Is involved in somatic and visceral motor control

14-1 The Brain Medulla Oblongata Connects brain to spinal cord
Relays information Regulates autonomic functions Heart rate, blood pressure, and digestion

Diencephalon Midbrain Pons Medulla oblongata Thalamus
Figure 14-1 An Introduction to Brain Structures and Functions (Part 2 of 2). Diencephalon Thalamus • Relay and processing centers for sensory information Hypothalamus • Centers controlling emotions, autonomic functions, and hormone production Midbrain Brain stem • Processing of visual and auditory date • Generation of reflexive somatic motor responses • Maintenance of consciousness Pons • Relays sensory information to cerebellum and thalamus • Subconscious somatic and visceral motor centers Medulla oblongata • Relays sensory information to thalamus and to other portions of the brain stem • Autonomic centers for regulation of visceral function (cardiovascular, respiratory, and digestive system activities)

14-1 The Brain Embryonic Development
Determines organization of brain structures Neural tube Origin of brain Enlarges into three primary brain vesicles Prosencephalon Mesencephalon Rhombencephalon

14-1 The Brain Five Secondary Brain Vesicles Telencephalon
Diencephalon Mesencephalon Metencephalon Myelencephalon

14-1 The Brain Origins of Brain Structures
Diencephalon and mesencephalon persist Telencephalon Becomes cerebrum Metencephalon Forms cerebellum and pons Myelencephalon Becomes medulla oblongata

Table 14-1 Development of the Brain.

14-1 The Brain Ventricles of the Brain Origins of ventricles
Neural tube encloses neurocoel Neurocoel expands to form chambers (ventricles) lined with ependyma Each cerebral hemisphere contains one large lateral ventricle Separated by a thin medial partition (septum pellucidum)

14-1 The Brain Ventricles of the Brain Third ventricle
Ventricle of the diencephalon Lateral ventricles communicate with third ventricle Via interventricular foramen (foramen of Monro)

14-1 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 midbrain called the cerebral aqueduct

Figure 14-2a Ventricles of the Brain.
Cerebral hemispheres Lateral ventricles Interventricular foramen Third ventricle Cerebral aqueduct Fourth ventricle Pons Medulla oblongata Spinal cord Central canal Ventricles, lateral view a

Figure 14-2b Ventricles of the Brain.
Cerebral hemispheres Ventricles of the Brain Lateral ventricles Interventricular foramen Third ventricle Cerebral aqueduct Fourth ventricle Central canal Cerebellum Ventricles, anterior view b

14-1 The Brain The Brain The brain is a large, delicate mass of neural tissue Containing internal passageways and chambers filled with cerebrospinal fluid Each of the six major brain regions has specific functions Ascending from the medulla oblongata to the cerebrum, brain functions become more complex and variable Conscious thought and intelligence Are produced in the neural cortex of the cerebral hemispheres

14-2 Brain Protection and Support
Physical Protection of the Brain Bones of the cranium Cranial meninges Cerebrospinal fluid Biochemical Isolation Blood–brain barrier

The Cranial Meninges Have three layers Dura mater Arachnoid mater Pia mater Are continuous with spinal meninges Protect the brain from cranial trauma

The Cranial Meninges Dura mater Inner fibrous layer (meningeal layer) Outer fibrous layer (periosteal layer) fused to periosteum Venous sinuses between two layers

The Cranial Meninges 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

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 Falx cerebri Tentorium cerebelli Falx cerebelli

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

Figure 14-3a The Relationship among the Brain, Cranium, and Cranial Meninges.
Dura mater (periosteal layer) Cranium Dural sinus Dura mater (meningeal layer) Subarachnoid space Pia mater Subdural space Arachnoid mater Cerebral cortex Cerebrum Cerebellum Medulla oblongata Spinal cord a A lateral view of the brain, showing its position in the cranium and the organization of the meninges

Superior sagittal sinus Inferior sagittal sinus
Figure 14-3b The Relationship among the Brain, Cranium, and Cranial Meninges. Dura mater Superior sagittal sinus Cranium Inferior sagittal sinus Dural folds Falx cerebri Tentorium cerebelli Falx cerebelli Transverse sinus b A diagrammatic view, showing the orientation of the three largest dural folds: the falx cerebri, tentorium cerebelli, and falx cerebelli

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

Cerebrospinal Fluid (CSF) Choroid plexus Specialized ependymal cells and capillaries Secrete CSF into ventricles Remove waste products from CSF Adjust composition of CSF Produces about 500 mL of CSF/day

Cerebrospinal Fluid (CSF) CSF circulates: From choroid plexus Through ventricles To central canal of spinal cord Into subarachnoid space via two lateral apertures and one median aperture around the brain, spinal cord, and cauda equina

Cerebrospinal Fluid (CSF) CSF in subarachnoid space Arachnoid villi Extensions of subarachnoid space Extend through dura mater to superior sagittal sinus Arachnoid granulations Large clusters of villi Absorb CSF into venous circulation

Figure 14-4 Formation and Circulation of Cerebrospinal Fluid (Part 2 of 3).
Choroid plexus of third ventricle Choroid plexus of fourth ventricle 2 The CSF circulates from the choroid plexuses through the ventricles and fills the central canal of the spinal cord. As it circulates, materials diffuse between the CSF and the interstitial fluid of the CNS across the ependymal cells. 3 The CSF reaches the subarachnoid space through two lateral apertures and a single median aperture in the roof of the fourth ventricle. Spinal cord Central canal 4 Cerebrospinal fluid then flows through the subarachnoid space surrounding the brain, spinal cord, and cauda equina. Dura mater Cauda equina Arachnoid mater Filum terminale

Interstitial Fluid in thalamus Cerebrospinal Fluid in third ventricle
Figure 14-4 Formation and Circulation of Cerebrospinal Fluid (Part 1 of 3). Nutrients, O2 Interstitial Fluid in thalamus Capillaries Waste products, CO2 Neuron Astrocyte 1 The choroid plexus produces and maintains CSF. Two extensive folds of the choroid plexus originate in the roof of the third ventricle and extend through the interventricular foramina. These folds cover the floors of the lateral ventricles. In the inferior brain stem, a region of the choroid plexus in the roof of the fourth ventricle projects between the cerebellum and the pons. Choroid plexus ependymal cells Ependymal cells Removal of waste Production of CSF Cerebrospinal Fluid in third ventricle Tight junction Choroid plexus

Superior sagittal sinus
Figure 14-4 Formation and Circulation of Cerebrospinal Fluid (Part 3 of 3). Dura mater (periosteal layer) Arachnoid granulation Arachnoid trabecula Cranium CSF fluid movement Superior sagittal sinus Dura mater (meningeal layer) Subdural space Arachnoid mater Cerebral cortex Subarachnoid space Pia mater 5 Fingerlike extensions of the arachnoid membrane, called the arachnoid villi, penetrate the meningeal layer of the dura mater and extend into the superior sagittal sinus. In adults, these extensions form large arachnoid granulations. CSF is absorbed into the venous circulation at the arachnoid granulations.

Blood Supply to the Brain Supplies nutrients and oxygen to brain Delivered by internal carotid arteries and vertebral arteries Removed from dural sinuses by internal jugular veins

Cerebrovascular Disease Disorders interfere with blood circulation to brain Stroke or cerebrovascular accident (CVA) Shuts off blood to portion of brain Neurons die

Blood–Brain Barrier (BBB) Isolates CNS neural tissue from general circulation Formed by network of tight junctions Between endothelial cells of CNS capillaries Lipid-soluble compounds (O2, CO2), steroids, and prostaglandins Diffuse into interstitial fluid of brain and spinal cord Astrocytes control blood–brain barrier by: Releasing chemicals that control permeability of endothelium

Blood–CSF Barrier Formed by special ependymal cells Surrounds capillaries of choroid plexus Limits movement of compounds transferred Allows chemical composition of blood and CSF to differ

Four Breaks in the BBB Portions of hypothalamus Secrete hypothalamic hormones Posterior lobe of pituitary gland Secretes hormones ADH and oxytocin Pineal gland Pineal secretions Choroid plexus Where special ependymal cells maintain blood– CSF barrier

14-3 The Medulla Oblongata
Allows brain and spinal cord to communicate Coordinates complex autonomic reflexes Controls visceral functions Nuclei in the medulla Autonomic nuclei control visceral activities Sensory and motor nuclei of cranial nerves Relay stations along sensory and motor pathways

Figure 14-5a The Diencephalon and Brain Stem.
Cerebral peduncle Thalamus Lateral geniculate nucleus Optic tract Medial geniculate nucleus Cranial nerves Midbrain N II Superior colliculus Inferior colliculus N III N IV Cerebellar peduncles Superior cerebellar peduncle N V Pons Middle cerebellar peduncle N VI N VII Inferior cerebellar peduncle N VIII N IX N X Medulla oblongata N XI N XII Spinal nerve C1 Spinal nerve C2 Spinal cord a Lateral view

Figure 14-5b The Diencephalon and Brain Stem.
Optic chiasm Infundibulum Cranial nerves Thalamus N II Optic tract N III Cerebral peduncle N IV Mammillary body N V Pons N VI N VII N VIII N IX N X N XI N XII Medulla oblongata Ventral roots of spinal nerves C1 and C2 Spinal cord Anterior view b

Figure 14-5c The Diencephalon and Brain Stem.
Choroid plexus in third and fourth ventricles Thalamus Third ventricle Pineal gland Corpora quadrigemina Superior colliculi Inferior colliculi N IV Cerebral peduncle Cerebellar peduncles Superior Middle Choroid plexus in roof of fourth ventricle Inferior Dorsal roots of spinal nerves C1 and C2 c Posterior view

Figure 14-5d The Diencephalon and Brain Stem.
Thalamus Third ventricle Pineal gland Corpora quadrigemina Superior colliculi Inferior colliculi Cerebral peduncle Trochlear nerve (N IV) Cerebellar peduncles Superior Middle Inferior Fourth ventricle Posterior view, cadaver dissection d

Includes three groups of nuclei Autonomic nuclei Sensory and motor nuclei of cranial nerves Relay stations along sensory and motor pathways

Autonomic Nuclei of the Medulla Oblongata Reticular formation Gray matter with embedded nuclei Regulates autonomic functions

Autonomic Nuclei of the Medulla Oblongata Reflex centers Control peripheral systems Cardiovascular centers Cardiac center Control blood flow through peripheral tissues Respiratory rhythmicity centers Set pace for respiratory movements

Sensory and Motor Nuclei of the Medulla Oblongata Associated with 5 of 12 cranial nerves (VIII, IX, X, XI, XII)

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

Figure 14-6a The Medulla Oblongata.
Autonomic centers Reticular formation Medulla oblongata Cardiovascular centers Solitary nucleus Pons Relay stations Olivary nucleus Nucleus cuneatus Olive Spinal cord Nucleus gracilis Pyramids Decussation of pyramids Lateral white columns a Anterior view

Figure 14-6b The Medulla Oblongata.
Region/Nucleus Function GRAY MATTER Olivary nucleus Relay information from the red nuclei, other midbrain centers, and the cerebral cortex to the cerebellum Attachment to membranous roof of fourth ventricle Reflex centers Regulate heart rate and force of contraction Set the basic pace of respiratory movements Cardiovascular center Respiratory rhythmicity center Nucleus gracilis Relay somatic information to the thalamus Nucleus cuneatus Other nuclei/centers Sensory and motor nuclei of five cranial nerves; nuclei relay ascending information from the spinal cord to higher centers Cranial nerves VIII (in part), IX, X, XI (in part), and XII Posterior median sulcus Reticular formation Contains nuclei and centers that regulate vital autonomic functions; extends into the pons and midbrain Lateral white column Posterior white columns WHITE MATTER Ascending and descending tracts within columns Link the brain with the spinal cord b Posterolateral view

14-4 The Pons The Pons Sensory and motor nuclei of cranial nerves (V, VI, VII, VIII) Nuclei involved with respiration Apneustic center and pneumotaxic center Modify respiratory rhythmicity center activity Nuclei that process and relay information to and from cerebellum Ascending, descending, and transverse tracts Transverse fibers (axons) Link nuclei of pons with opposite cerebellar hemisphere

The Pons Figure 14-7 The Pons. WHITE MATTER Descending tracts
Region/Nucleus Function WHITE MATTER Descending tracts Carry motor commands from higher centers to nuclei of cranial or spinal nerves Ascending tracts Carry sensory information from brain stem nuclei to the thalamus Transverse fibers Interconnect cerebellar hemispheres Pons Cerebellum GRAY MATTER Apneustic and pneumotaxic centers Adjust activities of the respiratory rhythmicity centers in the medulla oblongata Fourth ventricle Reticular formation Medulla oblongata Automatic processing of incoming sensations and outgoing motor commands Spinal cord Olivary nucleus Cranial nerve nuclei N V, VI, VII, and VIII (in part) Relay sensory information and issue somatic motor commands Other nuclei/relay centers Relay sensory and motor Information to the cerebellum

14-5 The Cerebellum Functions of the Cerebellum
Adjusts postural muscles Fine-tunes conscious and subconscious movements

14-5 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

14-5 The Cerebellum Structures of the Cerebellum Vermis
Narrow band of cortex Flocculonodular lobe Below fourth ventricle

14-5 The Cerebellum Structures of the Cerebellum Purkinje cells
Large, branched cells Found in cerebellar cortex Receive input from up to 200,000 synapses Arbor vitae (“tree of life”) Highly branched, internal white matter of cerebellum Cerebellar nuclei embedded in arbor vitae Relay information to Purkinje cells

14-5 The Cerebellum Structures of the Cerebellum The peduncles
Tracts link cerebellum with brain stem, cerebrum, and spinal cord Superior cerebellar peduncles Middle cerebellar peduncles Inferior cerebellar peduncles

14-5 The Cerebellum Disorders of the Cerebellum Ataxia
Damage from trauma or stroke Intoxication (temporary impairment) Disturbs muscle coordination

Figure 14-8a The Cerebellum (Part 1 of 2).
Vermis Anterior lobe Primary fissure Folia Posterior lobe Left Hemisphere of Cerebellum Right Hemisphere of Cerebellum a The posterior, superior surface of the cerebellum, showing major anatomical landmarks and regions

Figure 14-8a The Cerebellum (Part 2 of 2).
Vermis Anterior lobe Primary fissure Folia Posterior lobe Left Hemisphere of Cerebellum Right Hemisphere of Cerebellum a The posterior, superior surface of the cerebellum, showing major anatomical landmarks and regions

Figure 14-8b The Cerebellum (Part 1 of 2).
Region/Nuclei Function GRAY MATTER Anterior lobe Cerebellar cortex Involuntary coordination and control of ongoing body movements Midbrain Cerebellar nuclei Involuntary coordination and control of ongoing body movements Choroid plexus of the fourth ventricle Pons WHITE MATTER Arbor vitae Connects cerebellar cortex and nuclei with cerebellar peduncles Flocculonodular lobe Cerebellar peduncles Superior Link cerebellum with midbrain, diencephalon, and cerebrum Medulla oblongata Posterior lobe Middle Carry communications between the cerebellum and pons Inferior Link the cerebellum with the medulla oblongata and spinal cord Transverse fibers Interconnect pontine nuclei with the opposite cerebellar hemisphere b A sectional view of the cerebellum, showing the arrangement of gray matter and white matter

Figure 14-8b The Cerebellum (Part 2 of 2).
Dendrites Cell body of Purkinje cell Axons Purkinje cells LM × 320 b A sectional view of the cerebellum, showing the arrangement of gray matter and white matter

14-6 The Midbrain Structures of the Midbrain Tectum Tegmentum
Two pairs of sensory nuclei (corpora quadrigemina) Superior colliculus (visual) Inferior colliculus (auditory) Tegmentum Red nucleus (many blood vessels) Substantia nigra (pigmented gray matter)

14-6 The Midbrain Structures of the Midbrain Cerebral peduncles
Nerve fiber bundles on ventrolateral surfaces Contain: Descending fibers to cerebellum Motor command fibers

Figure 14-9a The Midbrain. The Midbrain Region/Nuclei Function GRAY MATTER Pineal gland Tectum (roof) Superior colliculus Integrate visual information with other sensory input; initiate reflex responses to visual stimuli Thalamus Inferior colliculus Relay auditory information to medial geniculate nuclei; initiate reflex responses to auditory stimuli Walls and floor Substantia nigra Regulates activity in the basal nuclei Red nucleus Subconscious control of upper limb position and background muscle tone Reticular formation Automatic processing of incoming sensations and outgoing motor commands; can initiate involuntary motor responses to stimuli; helps maintain consciousness Other nuclei/centers: Nuclei associated with cranial nerves III and IV A posterior view. The underlying nuclei are colored only on the right. WHITE MATTER a Cerebral peduncles Connect primary motor cortex with motor neurons in brain and spinal cord; carry ascending sensory information to thalamus

Figure 14-9b The Midbrain. Thalamus Corpora quadrigemina Superior colliculi Inferior colliculi Cerebral peduncle Trochlear nerve (N IV) Superior cerebellar peduncle Fourth ventricle Posterior view of a cadaver dissection of the diencephalon and brain stem. b

A superior view of a transverse section at the level of the midbrain.
Figure 14-9c The Midbrain. ANTERIOR Cerebral peduncle Substantia nigra Red nucleus Tegmentum Cerebral aqueduct Superior colliculus Cerebellum Tectum (roof) POSTERIOR c A superior view of a transverse section at the level of the midbrain.

14-7 The Diencephalon The Diencephalon
Integrates sensory information and motor commands Thalamus, epithalamus, and hypothalamus The pineal gland Found in posterior epithalamus Secretes hormone melatonin

14-7 The Diencephalon The Thalamus
Filters ascending sensory information for primary sensory cortex Relays information between basal nuclei and cerebral cortex

14-7 The Diencephalon The Thalamus The third ventricle
Separates left thalamus and right thalamus Interthalamic adhesion Projection of gray matter Extends into ventricle from each side

14-7 The Diencephalon The Thalamus Thalamic nuclei
Are rounded masses that form thalamus Relay sensory information to basal nuclei and cerebral cortex

14-7 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

14-7 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

Parietal lobe and cingulate gyrus Association areas of cerebral cortex
Figure The Thalamus. Frontal lobe Parietal lobe Occipital lobe a A lateral view of the brain, color coded to indicate the regions that receive input from the thalamic nuclei shown in part (b) Limbic system Frontal lobes Parietal lobe and cingulate gyrus Association areas of cerebral cortex Anterior group Medial group Lateral group Posterior group Pulvinar nucleus Ventral group Auditory input Medial geniculate nucleus Basal nuclei General Sensory input Lateral geniculate nucleus Visual input Cerebellum b An enlarged view of the thalamic nuclei of the left side

Figure 14-10a The Thalamus. Frontal lobe Parietal lobe Occipital lobe a A lateral view of the brain, color coded to indicate the regions that receive input from the thalamic nuclei shown in part (b)

Parietal lobe and cingulate gyrus Association areas of cerebral cortex
Figure 14-10b The Thalamus. Limbic system Frontal lobes Parietal lobe and cingulate gyrus Association areas of cerebral cortex Medial group Anterior group Lateral group Posterior group Pulvinar nucleus Ventral Auditory input group Medial geniculate nucleus Basal nuclei General sensory input Lateral geniculate nucleus Visual input Cerebellum b An enlarged view of the thalamic nuclei of the left side

Table 14-2 The Thalamus.

14-7 The Diencephalon The Hypothalamus Mammillary bodies Infundibulum
Process olfactory and other sensory information Control reflex eating movements Infundibulum A narrow stalk Connects hypothalamus to pituitary gland Tuberal area Located between the infundibulum and mammillary bodies Helps control pituitary gland function

Figure 14-11a The Hypothalamus in Sagittal Section.
Parietal lobe Corpus callosum Septum pellucidum Choroid plexus Thalamus (surrounds third ventricle) Fornix Anterior cerebral artery Pineal gland Hypothalamus Frontal lobe Cerebral aqueduct Anterior commissure Cerebellum Optic chiasm Fourth ventricle Optic nerve a The hypothalamus and adjacent portions of the brain Infundibulum (cut) Tuberal area Mammillary body

Figure 14-11b The Hypothalamus in Sagittal Section.
Interthalamic adhesion The Hypothalamus Thalamus Region/Nuclei Function Paraventricular nucleus Secretes oxytocin, stimulating smooth muscle contractions in uterus and mammary glands Preoptic area Regulates body temperature by control of autonomic centers in the medulla oblongata Hypothalamus Tuberal area Autonomic centers Control heart rate and blood pressure by regulation of autonomic centers in the medulla oblongata Sympathetic Optic chiasm Parasympathetic Tuberal nucleus Produces inhibitory and releasing hormones that control endocrine cells of the anterior lobe of the pituitary gland (adenohypophysis) Mid- brain Infundibulum Mammillary body Control feeding reflexes (licking, swallowing, etc.) Suprachiasmatic nucleus Regulates daily (circadian) rhythms Pituitary gland Pons Supraoptic nucleus Secretes antidiuretic hormone, restricting water loss by the kidneys b A diagrammatic view of the hypothalamus, showing the locations and functions of major nuclei and centers

14-7 The Diencephalon Eight Functions of the Hypothalamus
Provides subconscious control of skeletal muscle Controls autonomic function Coordinates activities of nervous and endocrine systems Secretes hormones Antidiuretic hormone (ADH) by supraoptic nucleus Oxytocin (OT; OXT) by paraventricular nucleus

14-7 The Diencephalon Eight Functions of the Hypothalamus
Produces emotions and behavioral drives The feeding center (hunger) The thirst center (thirst) Coordinates voluntary and autonomic functions Regulates body temperature Preoptic area of hypothalamus Controls circadian rhythms (day–night cycles) Suprachiasmatic nucleus

14-8 The Limbic System The Limbic System
Is a functional grouping that: Establishes emotional states Links conscious functions of cerebral cortex with autonomic functions of brain stem Facilitates memory storage and retrieval

14-8 The Limbic System Components of the Limbic System Amygdaloid body
Acts as interface between the limbic system, the cerebrum, and various sensory systems Limbic lobe of cerebral hemisphere Cingulate gyrus Dentate gyrus Parahippocampal gyrus Hippocampus

14-8 The Limbic System Components of the Limbic System Fornix
Tract of white matter Connects hippocampus with hypothalamus Anterior nucleus of the thalamus Relays information from mammillary body to cingulate gyrus Reticular formation Stimulation or inhibition affects emotions (rage, fear, pain, sexual arousal, pleasure)

Figure 14-12a The Limbic System.
Corpus callosum Pineal gland Fornix Cingulate gyrus (superior portion of limbic lobe) Anterior group of thalamic nuclei Parahippocampal gyrus (inferior portion of limbic lobe) Hypothalamus Mammillary body Hippocampus (within dentate gyrus) Temporal lobe of cerebrum a A diagrammatic sagittal section through the cerebrum, showing the cortical areas associated with the limbic system. The parahippocampal gyrus is shown as though transparent to make deeper limbic components visible.

Figure 14-12b The Limbic System.
Cerebral Components Limbic lobe cortical areas Diencephalic Components Corpus callosum Cingulate gyrus (superior portion of limbic lobe) Thalamus Anterior nuclei group Parahippocampal gyrus (inferior portion of limbic lobe) Hypothalamus Dentate gyrus Hypothalamic nuclei Tracts Mammillary body Fornix Other Components Nuclei Reticular formation Amygdaloid body (not shown) Olfactory tract Hippocampus (within dentate gyrus) b A three-dimensional reconstruction of the limbic system, showing the relationships among the major components.

14-9 The Cerebrum The Cerebrum Is the largest part of the brain
Controls all conscious thoughts and intellectual functions Processes somatic sensory and motor information

14-9 The Cerebrum Gray Matter White Matter
In cerebral cortex and basal nuclei White Matter Deep to basal cortex Around basal nuclei

14-9 The Cerebrum Structures of the Cerebrum Gyri of neural cortex
Increase surface area (number of cortical neurons) Insula (“island” of cortex) Lies medial to lateral sulcus Longitudinal fissure Separates cerebral hemispheres Lobes Divisions of hemispheres

14-9 The Cerebrum Structures of the Cerebrum Central sulcus divides:
Anterior frontal lobe from posterior parietal lobe Lateral sulcus divides: Frontal lobe from temporal lobe Parieto-occipital sulcus divides: Parietal lobe from occipital lobe

Figure 14-13a The Brain in Lateral View.
Central sulcus Frontal lobe Parietal lobe Occipital lobe Lateral sulcus Temporal lobe Cerebellum Pons Medulla oblongata a Lateral view, cadaver brain

Figure 14-13b The Brain in Lateral View.
Precentral gyrus Central sulcus Postcentral gyrus Frontal lobe Parietal lobe Occipital lobe Temporal lobe Lateral sulcus Cerebellum Pons Medulla oblongata b Lateral view

Figure 14-13c The Brain in Lateral View.
Insula c Retractors along the lateral sulcus showing the insula

Figure 14-13d The Brain in Lateral View.
Precentral gyrus Central sulcus Postcentral gyrus Cingulate gyrus Parietal lobe Frontal lobe Parieto- occipital sulcus Occipital lobe Pons Temporal lobe Cerebellum Medulla oblongata d Midsagittal section

14-9 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

14-9 The Cerebrum White Matter of the Cerebrum Association fibers
Connections within one hemisphere Commissural fibers Bands of fibers connecting two hemispheres Projection fibers Connect cerebrum with lower areas

14-9 The Cerebrum Commissural Fibers Corpus callosum
Anterior commissure

14-9 The Cerebrum Projection Fibers Pass through diencephalon
Link cerebral cortex with: Diencephalon, brain stem, cerebellum, and spinal cord Internal capsule All ascending and descending projection fibers

Figure 14-14a Fibers of the White Matter of the Cerebrum.
Fibers/Tracts Function Association fibers Interconnect cortical areas within the same hemisphere Arcuate fibers Interconnect gyri within a lobe Lateral view a Longitudinal fasciculi Interconnect the frontal lobe with other cerebral lobes

Figure 14-14b Fibers of the White Matter of the Cerebrum.
Fibers/Tracts Function Commissures Interconnect and permit communication between the cerebral hemispheres Corpus callosum Longitudinal fissure Anterior commissure Projection fibers Connect cerebral cortex to diencephalon, brain stem, cerebellum, and spinal cord Internal capsule Anterior view b

14-9 The Cerebrum The Basal Nuclei Are masses of gray matter
Are embedded in white matter of cerebrum Direct subconscious activities

14-9 The Cerebrum Anatomy of Basal Nuclei Caudate nucleus
Curving, slender tail Lentiform nucleus Globus pallidus Putamen

Figure 14-15a The Basal Nuclei.
Head of caudate nucleus Lentiform nucleus Tail of caudate nucleus Thalamus Amygdaloid body a The relative positions of the basal nuclei in the intact brain, lateral view

Figure 14-15c The Basal Nuclei.
Corpus callosum Nuclei Function Lateral ventricle Caudate nucleus Subconscious adjustment and modification of voluntary motor commands Septum pellucidum Internal capsule Lentiform nucleus Subconscious adjustment and modification of voluntary motor commands Putamen Lateral sulcus Globus pallidus Insula Anterior commissure Claustrum Plays a role in the subconscious processing of visual information Tip of inferior horn of lateral ventricle Amygdaloid body Component of limbic system c Frontal section

14-9 The Cerebrum Functions of Basal Nuclei Involved with:
The subconscious control of skeletal muscle tone The coordination of learned movement patterns (walking, lifting)

14-9 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

14-9 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

14-9 The Cerebrum Special Sensory Cortexes Visual cortex
Information from sight receptors Auditory cortex Information from sound receptors Olfactory cortex Information from odor receptors Gustatory cortex Information from taste receptors

Figure 14-16a Motor and Sensory Regions of the Cerebral Cortex.
Central sulcus Parietal Lobe Frontal Lobe Primary sensory cortex (postcentral gyrus) Primary motor cortex (precentral gyrus) Somatic motor association area (premotor cortex) Somatic sensory association area Retractor Occipital Lobe Visual association area Prefrontal cortex Visual cortex Gustatory cortex Insula Temporal Lobe Lateral sulcus Auditory association area Auditory cortex Olfactory cortex a Major anatomical landmarks on the surface of the left cerebral hemisphere. The lateral sulcus has been pulled apart to expose the insula.

14-9 The Cerebrum Association Areas Sensory association areas
Monitor and interpret arriving information at sensory areas of cortex Somatic sensory association area Interprets input to primary sensory cortex (e.g., recognizes and responds to touch)

14-9 The Cerebrum Sensory Association Areas Visual association area
Interprets activity in visual cortex Auditory association area Monitors auditory cortex Somatic motor association area (premotor cortex) Coordinates motor responses (learned movements)

14-9 The Cerebrum General Interpretive Area
Also called Wernicke’s area Present in only one hemisphere Receives information from all sensory association areas Coordinates access to complex visual and auditory memories

14-9 The Cerebrum Other Integrative Areas Speech center
Is associated with general interpretive area Coordinates all vocalization functions Prefrontal cortex of frontal lobe Integrates information from sensory association areas Performs abstract intellectual activities (e.g., predicting consequences of actions)

Figure 14-16b Motor and Sensory Regions of the Cerebral Cortex.
Frontal eye field Speech center Prefrontal cortex General interpretive area b The left hemisphere generally contains the general interpretive area and the speech center. The prefrontal cortex of each hemisphere is involved with conscious intellectual functions.

14-9 The Cerebrum Interpretive Areas of Cortex Brodmann areas
Patterns of cellular organization in cerebral cortex

Figure 14-16c Motor and Sensory Regions of the Cerebral Cortex.
40 39 44 41 42 18 17 c Regions of the cerebral cortex as determined by histological analysis. Several of the 50 Brodmann areas are shown for comparison with the results of functional mapping.

Table 14-3 The Cerebral Cortex.

14-9 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

14-9 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)

Figure 14-17 Hemispheric Lateralization (Part 1 of 2).
Left Cerebral Hemisphere LEFT HAND Prefrontal cortex Speech center C O R P U S Writing C A L L O S U M Auditory cortex (right ear) General interpretive center (language and mathematical calculation) Visual cortex (right visual field)

Figure 14-17 Hemispheric Lateralization (Part 2 of 2).
Right Cerebral Hemisphere RIGHT HAND Prefrontal cortex Anterior commissure C O R P U S Analysis by touch C A L L O S U M Auditory cortex (left ear) Spatial visualization and analysis Visual cortex (left visual field)

14-9 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

14-9 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

14-10 Cranial Nerves Cranial Nerves
12 pairs connected to brain Four Classifications of Cranial Nerves Sensory nerves: carriers of somatic sensory information, including touch, pressure, vibration, temperature, and pain Special sensory nerves: carriers of sensations such as smell, sight, hearing, and balance Motor nerves: axons of somatic motor neurons Mixed nerves: mixture of motor and sensory fibers

14-10 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

Figure 14-19 Origins of the Cranial Nerves (Part 1 of 2).
Olfactory bulb: termination of olfactory nerve (N I) Olfactory tract Optic nerve (N II) Infundibulum Oculomotor nerve (N III) Basilar artery Pons Vertebral artery Medulla oblongata Cerebellum Spinal cord

Figure 14-19 Origins of the Cranial Nerves (Part 2 of 2).
Optic chiasm Optic tract Mammillary body 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)

14-10 Cranial Nerves Olfactory Nerves (I) Primary function: Origin:
Special sensory (smell) Origin: Receptors of olfactory epithelium Pathway: Olfactory foramina in cribriform plate of ethmoid Destination: Olfactory bulbs

14-10 Cranial Nerves Olfactory Nerve Structures Olfactory bulbs
Located on either side of crista galli Olfactory tracts Axons of postsynaptic neurons Leading to cerebrum

Figure 14-20 The Olfactory Nerve.
Olfactory tract (to olfactory cortex of cerebrum) Left olfactory bulb (termination of olfactory nerve) Olfactory nerve (N I) Olfactory nerve fibers Cribriform plate of ethmoid bone Olfactory epithelium

14-10 Cranial Nerves Optic Nerves (II) Primary function: Origin:
Special sensory (vision) Origin: Retina of eye Pathway: Optic canals of sphenoid Destination: Diencephalon via optic chiasm

14-10 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

Figure 14-21 The Optic Nerve.
Eye Pituitary gland Olfactory bulb Olfactory tract Optic nerve (N II) Optic chiasm Optic tract Lateral geniculate nucleus (in thalamus) Midbrain (cut) Visual cortex (in occipital lobes) Optic projection fibers

14-10 Cranial Nerves Oculomotor Nerves (III) Primary function: Origin:
Motor (eye movements) Origin: Midbrain Pathway: Superior orbital fissures of sphenoid

14-10 Cranial Nerves Oculomotor Nerves (III) Destination:
Somatic motor Superior, inferior, and medial rectus muscles Inferior oblique muscle Levator palpebrae superioris muscle Visceral motor Intrinsic eye muscles

14-10 Cranial Nerves Oculomotor Nerve Structures Oculomotor nerve
Controls four of six eye-movement muscles Delivers autonomic fibers to ciliary ganglion Ciliary ganglion controls intrinsic muscles of iris and lens

14-10 Cranial Nerves The Trochlear Nerves (IV) Primary function:
Motor (eye movements) Origin: Midbrain Pathway: Superior orbital fissure of sphenoid Destination: Superior oblique muscle

14-10 Cranial Nerves The Abducens Nerves (VI) Primary function:
Motor (eye movements) Origin: Pons Pathway: Superior orbital fissures of sphenoid Destination: Lateral rectus muscle

Figure 14-22 Cranial Nerves Controlling the Extrinsic Eye Muscles.
Superior rectus muscle Optic nerve (N II) Optic chiasm Oculomotor nerve (N III) Trochlear nerve (N IV) Superior oblique muscle Trochlea Levator palpebrae superioris muscle Trigeminal nerve (N V), cut Inferior oblique muscle Vestibulocochlear nerve (N VIII), cut Facial nerve (N VII), cut Inferior rectus muscle Medial rectus muscle Ciliary ganglion Lateral rectus muscle (cut) Abducens nerve (N VI)

14-10 Cranial Nerves The Trigeminal Nerves (V) Primary function:
Mixed (sensory and motor) to face Origin: Ophthalmic branch (sensory) Orbital structures Nasal cavity Skin of forehead, upper eyelid, and eyebrow Part of nose

14-10 Cranial Nerves The Trigeminal Nerves (V) Origin:
Maxillary branch (sensory) Lower eyelid Upper lip, gums, and teeth Cheek and nose Palate and part of pharynx

14-10 Cranial Nerves The Trigeminal Nerves (V) Origin:
Mandibular branch (sensory) Lower gums, teeth, and lips Palate and part of tongue Mandibular branch (motor) Motor nuclei of pons

14-10 Cranial Nerves The Trigeminal Nerves (V) Pathway:
Ophthalmic branch Superior orbital fissure Maxillary branch Foramen rotundum Mandibular branch Foramen ovale

14-10 Cranial Nerves The Trigeminal Nerves (V) Destination:
Sensory nerves Sensory nuclei in pons Motor nerves of mandibular branch Muscles of mastication

14-10 Cranial Nerves Trigeminal Nerve Structures Trigeminal nerves
Largest cranial nerves With three major branches Semilunar ganglion Contains cell bodies of sensory neurons

Figure 14-23 The Trigeminal Nerve.
Superior orbital fissure Ophthalmic branch Supraorbital nerves Semilunar ganglion Ciliary ganglion Pons Trigeminal nerve (N V) Foramen rotundum Maxillary branch Infraorbital nerve Foramen ovale Otic ganglion Lingual nerve Submandibular ganglion Mandibular branch Mental nerve Pterygopalatine ganglion

14-10 Cranial Nerves The Facial Nerves (VII) Primary function: Origin:
Mixed (sensory and motor) to face Origin: Sensory Taste receptors on anterior 2/3 of tongue Motor Motor nuclei of pons Pathway: Internal acoustic meatus to facial canals (stylomastoid foramina)

14-10 Cranial Nerves The Facial Nerves (VII) Destination: Sensory
Sensory nuclei of pons Somatic motor Muscles of facial expression Visceral motor Tear and nasal mucous glands Submandibular and sublingual salivary glands

14-10 Cranial Nerves Facial Nerve Structures Facial nerve branches
Temporal Zygomatic Buccal Mandibular Cervical branches

Figure 14-24a The Facial Nerve.
Pterygopalatine ganglion Greater petrosal nerve Geniculate ganglion Facial nerve (N VII) Temporal branch Pons Zygomatic branches Posterior auricular branch Buccal branch Stylomastoid foramen Chorda tympani nerve (with mandibular branch of N V) Mandibular branch Lingual branch (with lingual nerve of N V) Cervical branch Submandibular ganglion a The origin and branches of the facial nerve

Figure 14-24b The Facial Nerve.
Temporal branch Zygomatic branch Buccal branch Mandibular branch Cervical branch b The superficial distribution of the five major branches of the facial nerve

14-10 Cranial Nerves The Vestibulocochlear Nerves (VIII)
Primary function: Special sensory Vestibular branch Balance and equilibrium Cochlear branch Hearing

14-10 Cranial Nerves The Vestibulocochlear Nerves (VIII) Origin:
Receptors of inner ear Pathway: Internal acoustic meatus of temporal bones Destination: Vestibular and cochlear nuclei of pons and medulla oblongata

14-10 Cranial Nerves Vestibulocochlear Nerve Structures
Vestibular branch Originates at receptors of vestibule (balance) Connects to vestibular nuclei of pons and medulla oblongata Cochlear branch Originates at sensors of cochlea (hearing) Connects with cochlear nuclei of pons and medulla oblongata

Figure 14-25 The Vestibulocochlear Nerve.
Tympanic cavity (middle ear) Semicircular canals Vestibular branch (N VIII) Facial nerve (N VII), cut Internal acoustic meatus Vestibulocochlear nerve (N VIII) N V Pons N VI N VII N IX N XII N X Medulla oblongata N XI Tympanic membrane Auditory tube Cochlea Cochlear branch (N VIII)

14-10 Cranial Nerves The Glossopharyngeal Nerves (IX)
Primary function: Mixed (sensory and motor) to head and neck

14-10 Cranial Nerves The Glossopharyngeal Nerves (IX) Origins: Sensory
Posterior 1/3 of tongue Part of pharynx and palate Carotid arteries Motor Motor nuclei of medulla oblongata

14-10 Cranial Nerves The Glossopharyngeal Nerves (IX) Pathway:
Jugular foramina between occipital and temporal bones Destination: Sensory Sensory nuclei of medulla oblongata Somatic motor Nerves involved in swallowing Visceral motor Parotid salivary gland

Figure 14-26 The Glossopharyngeal Nerve.
Pons N V N VII N VIII N VI Glossopharyngeal nerve (N IX) Otic ganglion Medulla oblongata Inferior (petrosal) ganglion Superior (jugular) ganglion Pharyngeal branches Lingual branch Parotid salivary gland Carotid sinus branch Carotid body Carotid sinus Common carotid artery

14-10 Cranial Nerves The Vagus Nerves (X) Primary function:
Mixed (sensory and motor) Widely distributed in thorax and abdomen

14-10 Cranial Nerves The Vagus Nerves (X) Origins: Sensory Motor
Part of pharynx Auricle and external acoustic meatus Diaphragm Visceral organs of thoracic and abdominopelvic cavities Motor Motor nuclei in medulla oblongata

14-10 Cranial Nerves The Vagus Nerves (X) Pathway: Jugular foramina
Between occipital and temporal bones

14-10 Cranial Nerves The Vagus Nerves (X) Destination: Sensory
Sensory nuclei and autonomic centers of medulla oblongata Visceral motor Muscles of the palate and pharynx Muscles of the digestive, respiratory, and cardiovascular systems in thoracic and abdominal cavities

Figure 14-27 The Vagus Nerve (Part 1 of 2).
Pharyngeal branch Vagus nerve (N X) Pons 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

Figure 14-27 The Vagus Nerve (Part 2 of 2).
Recurrent laryngeal nerve Cardiac branches Cardiac plexus Right lung Left lung Liver Anterior vagal trunk Spleen Stomach Celiac plexus Pancreas Colon Small intestine Hypogastric plexus

14-10 Cranial Nerves The Accessory Nerves (XI) Primary function:
Motor to muscles of neck and upper back Origin: Motor nuclei of spinal cord and medulla oblongata

14-10 Cranial Nerves The Accessory Nerves (XI) Pathway: Destination:
Jugular foramina between occipital and temporal bones Destination: Internal branch Voluntary muscles of palate, pharynx, and larynx External branch Sternocleidomastoid and trapezius muscles

14-10 Cranial Nerves Accessory Nerve Structures Spinal root
Motor fibers that originate in anterior gray horns of first five cervical segments of spinal cord Cranial root Motor fibers that originate in medulla oblongata

14-10 Cranial Nerves Accessory Nerve Structures Internal branch
Joins the vagus nerve External branch Controls muscles of neck and back

14-10 Cranial Nerves The Hypoglossal Nerves (XII) Primary function:
Motor (tongue movements) Origin: Motor nuclei of medulla oblongata Pathway: Hypoglossal canals of occipital bone Destination: Muscles of tongue

Figure 14-28 The Accessory and Hypoglossal Nerves.
Hypoglossal nerve (N XII) Trigeminal nerve (N V) Accessory nerve (N XI) Medulla oblongata Cranial root of N XI Internal branch: to palatal, pharyngeal, and laryngeal muscles with vagus nerve Spinal root of N XI Intrinsic muscles of tongue Styloglossus muscle External branch of N XI Genioglossus muscle Geniohyoid muscle Spinal cord Hyoglossus muscle Hyoid bone Trapezius muscle Thyrohyoid muscle Sternocleidomastoid muscle Sternohyoid muscle Ansa cervicalis (cervical plexus) Sternothyroid muscle Omohyoid muscle

Table 14-4 Cranial Nerve Branches and Functions (Part 1 of 2).

Table 14-4 Cranial Nerve Branches and Functions (Part 2 of 2).

Table 14-5 Cranial Reflexes.

An Introduction to the Brain and Cranial Nerves

Similar presentations

Presentation on theme: "An Introduction to the Brain and Cranial Nerves"— Presentation transcript:

Similar presentations

About project

Feedback

Log in

Auth with social network:

An Introduction to the Brain and Cranial Nerves

Similar presentations

Presentation on theme: "An Introduction to the Brain and Cranial Nerves"— Presentation transcript:

Similar presentations

About project

Feedback