Download The Brain and Cranial Nerves

14
The Brain
and Cranial Nerves
PowerPoint® Lecture Presentations prepared by
Jason LaPres
Lone Star College—North Harris
© 2012 Pearson Education, Inc.
An Introduction to the Brain and Cranial Nerves
• Learning Outcomes
• 14-1 Name the major brain regions, vesicles, and
ventricles, and describe the locations and
functions of each.
• 14-2 Explain how the brain is protected and
supported, and discuss the formation,
circulation, and function of cerebrospinal fluid.
• 14-3 Describe the anatomical differences between
the medulla oblongata and the spinal cord, and
identify the main components and functions of
the medulla oblongata.
© 2012 Pearson Education, Inc.
An Introduction to the Brain and Cranial Nerves
• Learning Outcomes
• 14-4 List the main components of the pons, and
specify the functions of each.
• 14-5 List the main components of the cerebellum,
and specify the functions of each.
• 14-6 List the main components of the midbrain, and
specify the functions of each.
• 14-7 List the main components of the diencephalon,
and specify the functions of each.
© 2012 Pearson Education, Inc.
An Introduction to the Brain and Cranial Nerves
• Learning Outcomes
• 14-8 Identify the main components of the limbic
system, and specify the locations and functions
of each.
• 14-9 Identify the major anatomical subdivisions and
functions of the cerebrum, and discuss the
origin and significance of the major types of
brain waves seen in an electroencephalogram.
• 14-10 Describe representative examples of cranial
reflexes that produce somatic responses or
visceral responses to specific stimuli.
© 2012 Pearson Education, Inc.
Synapse
Pre-synaptic
neuron
Synaptic cleft
Post-synaptic
neuron
Glutam
ate
AMP
AR
© 2012 Pearson Education, Inc.
NMD
AR
• In the pre-synaptic neuron, an
electrical signal comes in, opens up
to voltage-gated channels, and
signals the vesicles containing
neurotransmitters (chemical signal) to
be released into the synaptic cleft.
• Receptors on the post-synaptic
neuron bind to the neurotransmitter
signaling it to open its gate and let
ions flow through.
• The flow of ions will generate a
current that changes the resting
membrane potential. If the membrane
potential passes the threshold, then
an action potential is produced.
• The action potential is then
propagated to the next neuron, and
the communication continues from
neuron to neuron.
Picture adapted from MRC Centre for Synaptic Plasticity
An Introduction to the Brain and Cranial Nerves
• The Adult Human Brain
• Ranges from 750 cc to 2100 cc
• Contains almost 97% of the body’s neural tissue
• Average weight about 1.4 kg (3 lb)
© 2012 Pearson Education, Inc.
Brain Summary
• Important component of the CNS.
• Site for coordination and integration of sensations, emotions,
memory, and behavior.
• Divided into 6 regions (cerebrum, cerebellum, diencephalon,
mesencephalon, pons, and medulla oblongata)
• Protected by 3 connective tissue meninges: dura mater,
arachnoid, and the pia mater—just like the spinal cord.
• Large blood vessels called dural sinuses can be found
between 2 layers of dura mater.
• The subarachnoid space is filled with CSF
• Cranial nerves emerge from various parts of the brain
• The brain contains both gray matter and white matter
• Gray = interneurons and neuroglia
• White = fiber tracts
© 2012 Pearson Education, Inc.
14-1 The Brain
• Six Regions of the Brain
1. Cerebrum
2. Cerebellum
3. Diencephalon
4. Mesencephalon (midbrain)
5. Pons
6. Medulla oblongata
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Brain Stem
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)
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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)
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14-1 The Brain
• Cerebellum
• Second largest part of brain
• Coordinates repetitive body movements
• Two hemispheres
• Covered with cerebellar cortex
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Figure 14-1 An Introduction to Brain Structures and Functions
Left cerebral
hemisphere
Gyri
Sulci
CEREBRUM
• Conscious thought processes,
intellectual functions
• Memory storage and processing
• Conscious and subconscious regulation
of skeletal muscle contractions
Fissures
CEREBELLUM
Spinal
cord
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• Coordinates complex
somatic motor
patterns
• Adjusts output of
other somatic motor
centers in brain and
spinal cord
14-1 The Brain
•
Diencephalon
•
Located under cerebrum and cerebellum
•
Links cerebrum with brain stem
•
Three divisions of the diencephalon
1. Epithalamus
2. thalamus
3. Hypothalamus
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14-1 The Brain
• Diencephalon
• Thalamus
• Relays and processes sensory information
• Hypothalamus
• Hormone production
• Emotion
• Autonomic function
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14-1 The Brain
• Diencephalon
• Pituitary gland
• Major endocrine gland
• Connected to hypothalamus
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14-1 The Brain
• The Brain Stem
• Processes information between:
• Spinal cord and cerebrum or cerebellum
• Includes:
• Midbrain
• Pons
• Medulla oblongata
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14-1 The Brain
• Midbrain
• 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
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14-1 The Brain
• Medulla Oblongata
• Connects brain to spinal cord
• Relays information
• Regulates autonomic functions
• Heart rate, blood pressure, and digestion
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Figure 14-1 An Introduction to Brain Structures and Functions
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 data
• Generation of reflexive
somatic motor
responses
• Maintenance of
consciousness
PONS
• Relays sensory
information to
cerebellum and
thalamus
• Subconscious
somatic and visceral
motor centers
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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
• Ventricles of the Brain
• Within the brain are 4 spaces called ventricles
• 2 lateral ventricles
• Third ventricle
• Fourth ventricle
• Connects with third ventricle via narrow canal in
midbrain called the cerebral aqueduct
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Figure 14-2a Ventricles of the Brain
Cerebral
hemispheres
Ventricles of
the Brain
Lateral ventricles
Third ventricle
Cerebral aqueduct
Fourth ventricle
Pons
Medulla oblongata
Spinal cord
Ventricular system,
lateral view
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Central canal
Figure 14-2b Ventricles of the Brain
Ventricles of
the Brain
Cerebral hemispheres
Lateral ventricles
Third ventricle
Fourth ventricle
Central canal
Cerebellum
Ventricular system,
anterior view
© 2012 Pearson Education, Inc.
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
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14-2 Brain Protection and Support
• Physical Protection of the Brain
• Bones of the cranium
• Cranial meninges
• Cerebrospinal fluid
• Biochemical Isolation
• Blood–brain barrier
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14-2 Brain Protection and Support
• The Cranial Meninges
•
Have three layers
1. Dura mater
2. Arachnoid mater
3. Pia mater
•
Are continuous with spinal meninges
•
Protect the brain from cranial trauma
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14-2 Brain Protection and Support
• The Cranial Meninges
• Dura mater
• Inner fibrous layer
• 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
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14-2 Brain Protection and Support
• Dural Folds
•
Folded inner layer of dura mater
•
Extend into cranial cavity
•
Stabilize and support brain
•
Contain collecting veins (dural sinuses)
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Figure 14-3a The Relationship among the Brain, Cranium, and Meninges
Dura mater (endosteal layer)
Dural sinus
Dura mater (meningeal layer)
Subdural space
Arachnoid mater
Subarachnoid space
Arachnoid trabeculae
Pia mater
Cerebral cortex
Cerebral
cortex
Cerebellum
Medulla
oblongata
Spinal cord
A lateral view of the brain, showing its
position in the cranium and the organization
of the meninges
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Cranium
(skull)
14-2 Brain Protection and Support
• Cerebrospinal Fluid (CSF) – subarachnoid
space is filled with 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
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14-2 Brain Protection and Support
• Cerebrospinal Fluid (CSF)
• Choroid plexus—site of CSF production
• 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
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14-2 Brain Protection and Support
• 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
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14-2 Brain Protection and Support
• 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
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Figure 21–24a Arteries of the Brain
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Figure 21–29a Major Veins of the Head, Neck, and Brain
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14-2 Brain Protection and Support
• 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) and steroids
• Diffuse into interstitial fluid of brain and spinal cord
• Astrocytes control blood–brain barrier by:
• Releasing chemicals that control permeability of endothelium
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14-2 Brain Protection and Support
• 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
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14-2 Brain Protection and Support
• Protection and Support
• Meninges stabilize brain in cranial cavity
• Cerebrospinal fluid protects against sudden
movement
• CSF provides nutrients and removes wastes
• Blood–brain barrier and blood–CSF barrier
• Selectively isolate brain from chemicals in blood that
might disrupt neural function
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14-3 The Medulla Oblongata
• The Medulla Oblongata
• Allows brain and spinal cord to communicate
• Coordinates complex autonomic reflexes
• Controls visceral functions
• Sensory and Motor Nuclei of the Medulla
Oblongata
• Associated with 5 of 12 cranial nerves (VIII, IX, X,
XI, XII)
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Figure 14-5a The Diencephalon and Brain Stem
Diencephalon
Cerebral peduncle
Lateral geniculate nucleus
Thalamus
Optic tract
Medial geniculate nucleus
Cranial
nerves
Midbrain
Superior colliculus
N II
Inferior colliculus
N III
N IV
Cerebellar peduncles
Superior cerebellar peduncle
NV
Pons
N VI
N VII
N VIII
N IX
NX
N XI
Middle cerebellar peduncle
Inferior cerebellar peduncle
Medulla
oblongata
N XII
Spinal
nerve C1
Spinal
nerve C2
Spinal
cord
Lateral view
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Medulla Oblongata Summary
• The pathway from spinal cord to brain
through which all ascending (sensory) and
descending (motor) fibers pass. Many of the
nuclei involved in basic survival processes
such as coughing, sneezing, sweating, and
chewing are found here as well as nuclei that
control the heart rate, respiratory rate, and
blood pressure.
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14-4 The Pons
• The Pons
• Sensory and motor nuclei of cranial nerves (V, VI, VII, VIII)
• “the bridge” contains fiber tracts that connect the medulla and
midbrain as well as transverse tracks between left and right
cerebellar hemispheres.
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Figure 14-6c The Medulla Oblongata and Pons
Tracts
Ascending tracts
Respiratory Centers
Descending tracts
Pneumotaxic center
Apneustic center
Transverse fibers
Cerebellum
Midbrain
Fourth
ventricle
Pons
Medulla oblongata
Medulla
oblongata
Reticular formation
Olivary nucleus
Spinal cord
Lateral view
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14-5 The Cerebellum
• Summary
• Located in the posterior part of the brain, it plays an important role in
motor control, interpreting textures of objects, some spatial perception,
understanding some aspects of speech, and time keeping.
• It is the second largest part of the brain and externally exhibits gyri and
folia
• Functions of the Cerebellum
1. Adjusts postural muscles
2. Fine-tunes conscious and subconscious movements
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Figure 14-7a The Cerebellum
Vermis
Anterior
lobe
Posterior
lobe
Left Hemisphere
of Cerebellum
Primary
fissure
Folia
Right Hemisphere
of Cerebellum
The posterior, superior surface of the cerebellum, showing
major anatomical landmarks and regions
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Figure 14-7b The Cerebellum
Midbrain
Anterior lobe
Cerebellar
Peduncles
Pons
Arbor
vitae
Superior cerebellar
peduncle
Cerebellar
nucleus
Middle cerebellar
peduncle
Cerebellar
cortex
Posterior
lobe
Inferior cerebellar
peduncle
Choroid plexus of
the fourth ventricle
Medulla oblongata
Flocculonodular lobe
A sectional view of the cerebellum, showing the arrangement of gray
matter and white matter
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14-6 The Midbrain
• Structures of the Midbrain
• Two pairs of sensory nuclei (corpora quadrigemina)
• Superior colliculus (visual)
• Inferior colliculus (auditory)
• Summary
• The corpora quadrigemina control reflexes of the eye
and ear. Fiber tracts extend between the pons and
cerebrum and between the midbrain and the
cerebellum. Contains nuclei of cranial nerves III and
IV.
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Figure 14-8a The Midbrain
Thalamus
Pineal
gland
Red nucleus
Substantia
nigra
Corpora
quadrigemina
Cerebral
peduncle
Superior
colliculus
Inferior
colliculus
Reticular
formation
A posterior view. The underlying
nuclei are colored only on the right.
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14-7 The Diencephalon
• The Diencephalon
• Integrates sensory information and motor commands
• Thalamus, epithalamus, and hypothalamus
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14-7 The Diencephalon
• Thalamus: site of some aspects of emotion and memory; relay and filter to
the cerebrum for the special senses and motor activity
• Hypothalamus: Inferior to the thalamus. The major controller of the
autonomic nervous system and the link between the nervous system and
much of the endocrine system via its connection with the pituitary gland. It is
also involved in memory, thermoregulation, satiety, thirst, sleep, and
emotion.
• Epithalamus: contains the pineal gland (endocrine in function) and a relay
from the limbic system to the midbrain.
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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
© 2012 Pearson Education, Inc.
14-9 The Cerebrum
• The Cerebrum Summary
• Forms the bulk of the brain, is folded superficially to form
ridges (gyri) and grooves (sulci).
• A longitudinal fissure divides the cerebrum into 2 cerebral
hemispheres. Each hemisphere is further subdivided into
5 lobes: frontal, parietal, temporal, insula, and occipital.
© 2012 Pearson Education, Inc.
Figure 14-12a The Brain in Lateral View
Central sulcus
FRONTAL
LOBE
PARIETAL LOBE
OCCIPITAL
LOBE
Lateral sulcus
TEMPORAL LOBE
Pons
Medulla oblongata
Lateral view, cadaver brain
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Cerebellum
Figure 14-12b The Brain in Lateral View
Precentral
gyrus
Central
sulcus
Postcentral
gyrus
PARIETAL LOBE
FRONTAL
LOBE
OCCIPITAL
LOBE
TEMPORAL
LOBE
Lateral sulcus
Cerebellum
Pons
Medulla oblongata
Lateral view
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Figure 14-12c The Brain in Lateral View
Insula
Retractors along the lateral
sulcus showing the insula
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Figure 14-12d The Brain in Lateral View
Precentral gyrus
Central sulcus
Postcentral gyrus
Cingulate
gyrus
PARIETAL LOBE
FRONTAL
LOBE
Parietooccipital sulcus
OCCIPITAL
LOBE
TEMPORAL LOBE
Medulla oblongata
Midsagittal section
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Pons
Cerebellum
14-9 The Cerebrum
• The Cerebrum Summary
• The cerebrum receives sensory information from both internal and
external stimuli. Within the cerebral gray matter, this information is
evaluated in conjunction with memory and is used to coordinate motor
output .
• The fiber tracts (white matter) of the brain serve to receive or send
information to the rest of the body (projection tracts), cross from one
cerebral hemisphere to the other (commissural tracts such as the corpus
collosum), or connect different regions within one hemisphere
(association tracts).
• Deep pockets of gray matter called the basal nuclei are involved in motor
control.
© 2012 Pearson Education, Inc.
14-9 The Cerebrum
• Three Functional Principles of the Cerebrum
1. Each cerebral hemisphere receives sensory
information from, and sends motor commands to,
the opposite side of the body
2. The two hemispheres have different functions,
although their structures are alike
3. Correspondence between a specific function and a
specific region of cerebral cortex is not precise
© 2012 Pearson Education, Inc.
Figure 14-13b Fibers of the White Matter of the Cerebrum
Longitudinal
fissure
Corpus
callosum
Projection
fibers of
internal
capsule
Anterior
commissure
Anterior view
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• Motor and Sensory Areas of the Cortex
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Figure 14-15a Motor and Sensory Regions of the Cerebral Cortex
Primary motor cortex
(precentral gyrus)
Central sulcus
Primary sensory cortex
(postcentral gyrus)
Somatic motor association
area (premotor cortex)
PARIETAL LOBE
Somatic sensory
association area
FRONTAL LOBE
Visual association area
Prefrontal cortex
OCCIPITAL LOBE
Gustatory cortex
Visual cortex
Insula
Auditory association area
Lateral sulcus
Olfactory cortex
Auditory cortex
TEMPORAL
LOBE
Major anatomical landmarks on the surface of
the left cerebral hemisphere. The lateral sulcus
has been pulled apart to expose the insula.
© 2012 Pearson Education, Inc.
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
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14-9 The Cerebrum
• The Left Hemisphere
• In most people, left brain (dominant hemisphere) controls:
• Reading, writing, and math
• Decision making
• Speech and language
• The Right Hemisphere
• Right cerebral hemisphere relates to:
• Senses (touch, smell, sight, taste, feel)
• Recognition (faces, voice inflections)
© 2012 Pearson Education, Inc.
Figure 14-16 Hemispheric Lateralization
Left Cerebral Hemisphere
LEFT HAND
Prefrontal
cortex
Speech center
Writing
Auditory cortex
General interpretive center
(language and mathematical
calculation)
Visual cortex
(right visual field)
© 2012 Pearson Education, Inc.
C
O
R
P
U
S
C
A
L
L
O
S
U
M
Figure 14-16 Hemispheric Lateralization
Right Cerebral Hemisphere
RIGHT HAND
Prefrontal
cortex
Anterior commissure
C
O
R
P
U
S
C
A
L
L
O
S
U
M
Analysis by touch
Auditory cortex
Spatial visualization
and analysis
Visual cortex
(left visual field)
© 2012 Pearson Education, Inc.
14-10 Cranial Nerves
• Cranial Nerves
• 12 pairs connected to brain
• Four Classifications of Cranial Nerves
1. Sensory nerves carry somatic sensory information, including
touch, pressure, vibration, temperature, and pain
2. Special sensory nerves carry sensations such as smell, sight,
hearing, balance
3. Motor nerves: axons of somatic motor neurons
4. Mixed nerves: mixture of motor and sensory fibers
© 2012 Pearson Education, Inc.
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
© 2012 Pearson Education, Inc.
Cranial Nerve
I: Olfactory
II: Optic
III: Oculomotor
Nerve Type
sensory
sensory
primarily motor
IV: Trochlear
primarily motor
V: Trigeminal:
sensory
VI: Abducens
primarily motor
eyeball movement; proprioception (lateral rectus muscle)
VII: Facial
mixed
movement of facial muscles; tear and saliva secretion;
sense of taste and proprioception
VIII: Vestibulocochlear: cochlear branch
VIII: Vestibulocochle-ar: vestibular branch
sensory
sensory
hearing
sense of equilibrium
mixed
sensations of taste, touch, and pain from tongue and
pharynx; chemoreceptors (that monitor O2and CO2);
blood pressure receptors; movement of tongue and
swallowing; secretion of saliva
X: Vagus
mixed
parasympathetic sensation and motor control of smooth
muscles associated with heart, lungs, viscera; secretion
of digestive enzymes
XI: Accessory
primarily motor
head movement; swallowing; proprioception
XII: Hypoglossal
primarily motor
tongue movement, speech, and swallowing;
proprioception
IX: Glosso-phayrngeal
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Major Functions
smell
vision
eyeball and eyelid movement; lens shape
eyeball movement; proprioception (superior oblique
muscle)
sensations of touch and pain from facial skin, nose,
mouth, teeth, and tongue; proprioception motor control of
chewing
Figure 14-18 Origins of the Cranial Nerves
Olfactory bulb: termination
of olfactory nerve (I)
Olfactory tract
Optic nerve (II)
Infundibulum
Oculomotor nerve (III)
Pons
Basilar artery
Vertebral artery
Cerebellum
Medulla oblongata
Spinal cord
© 2012 Pearson Education, Inc.
Figure 14-18 Origins of the Cranial Nerves
Optic chiasm
Optic tract
Mamillary body
Trochlear nerve (IV)
Trigeminal nerve (V)
Abducens nerve (VI)
Facial nerve (VII)
Vestibulocochlear
nerve (VIII)
Glossopharyngeal
nerve (IX)
Vagus nerve (X)
Hypoglossal nerve (XII)
Accessory nerve (XI)
© 2012 Pearson Education, Inc.
Figure 14-21 Cranial Nerves Controlling the Extra-Ocular Muscles
Superior
rectus
muscle
Superior
oblique
muscle
OPTIC
NERVE (N II)
Optic
chiasm
OCULOMOTOR
NERVE (N III)
TROCHLEAR
NERVE (N IV)
Trochlea
Levator
palpebrae
superioris
muscle
Trigeminal
nerve (N V), cut
Inferior
oblique
muscle
Vestibulocochlear
nerve (N VIII), cut
Inferior
rectus
muscle
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Ciliary
ganglion
Medial
rectus
muscle
Facial nerve
(N VII), cut
Lateral rectus
muscle (cut)
ABDUCENS
NERVE (N VI)
Figure 14-22 The Trigeminal Nerve
Superior orbital fissure
Supra-orbital
nerves
Ophthalmic
branch
Semilunar
ganglion
Ciliary ganglion
Pons
TRIGEMINAL
NERVE (N V)
Foramen
rotundum
Maxillary
branch
Infra-orbital
nerve
Foramen ovale
Lingual nerve
Otic ganglion
Submandibular
ganglion
Mandibular
branch
Pterygopalatine
ganglion
Mental nerve
© 2012 Pearson Education, Inc.
Figure 14-23a 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
The origin and branches of the facial nerve
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Submandibular
ganglion
Figure 14-24 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)
NV
Pons
N VI
N VII
N IX
N XII
NX
Medulla
oblongata
N XI
Tympanic membrane
© 2012 Pearson Education, Inc.
Auditory tube
Cochlea
Cochlear branch (N VIII)
Figure 14-25 The Glossopharyngeal Nerve
Pons
NV
N VII
N VIII
N VI
GLOSSOPHARYNGEAL
NERVE (N IX)
Otic ganglion
Medulla oblongata
Inferior
(petrosal)
ganglion
Superior (jugular)
ganglion
Parotid salivary gland
Lingual
branch
Pharyngeal branches
Carotid sinus branch
Carotid body
Carotid sinus
Common carotid artery
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Figure 14-26 The Vagus Nerve
Superior
pharyngeal
branch
VAGUS
NERVE (N X)
Pons
Medulla oblongata
Auricular branch
to external ear
Inferior
ganglion
of vagus
nerve
Internal branch
Superior
laryngeal nerve
External branch
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Superior ganglion
of vagus nerve
Pharyngeal branch
Superior laryngeal nerve
Figure 14-27 The Accessory and Hypoglossal Nerves
HYPOGLOSSAL NERVE (N XII)
ACCESSORY NERVE (N XI)
Internal branch: to palatal,
pharyngeal, and laryngeal
muscles with vagus nerve
Intrinsic muscles
of tongue
Trigeminal nerve (N V)
Medulla oblongata
Cranial root of N XI
Spinal
root of N XI
Styloglossus muscle
External
branch of N XI
Genioglossus muscle
Geniohyoid muscle
Spinal cord
Hyoglossus muscle
Hyoid bone
Thyrohyoid muscle
Trapezius muscle
Sternocleidomastoid
muscle
Sternohyoid muscle
Sternothyroid muscle
Ansa cervicalis
(cervical plexus)
Omohyoid muscle
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