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Chapter 14
The Brain and Cranial Nerves
Lecture Outline
Principles of Human Anatomy and Physiology, 11e
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INTRODUCTION
• The brain is the center for registering sensations, correlating
them with one another and with stored information, making
decisions, and taking action.
• It is also the center for intellect, emotions, behavior, and
memory.
• It also directs our behavior towards others.
• In this chapter we will consider the principal parts of the
brain, how the brain is protected and nourished, and how it
is related to the spinal cord and to the 12 pairs of cranial
nerves.
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Chapter 14
The Brain and Cranial
Nerves
• Largest organ in the body at almost 3 lb.
• Brain functions in sensations, memory, emotions, decision making,
behavior
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OVERVIEW OF BRAIN ORGANIZATION AND
BLOOD SUPPLY
• The major parts of the brain are the brain stem,
diencephalon, cerebrum, and cerebellum (Figure 14.1).
• The CNS develops from an ectodermal neural tube
– Three primary vesicles: prosencephalon,
mesencephalon, and rhombencephalon develop from the
neural tube. (Figure 14.29)
• The embryologic development of the CNS is summarized in
table 14.1
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Principal Parts of
the Brain
• Cerebrum
• Diencephalon
– thalamus & hypothalamus
• Cerebellum
• Brainstem
– medulla, pons & midbrain
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Blood Supply to Brain
• Arterial blood supply is branches from circle of Willis on base of brain
• Vessels on surface of brain----penetrate tissue
• Uses 20% of our bodies oxygen & glucose needs
– blood flow to an area increases with activity in that area
– deprivation of O2 for 4 min does permanent injury
• at that time, lysosome release enzymes
• Blood-brain barrier (BBB)
– protects cells from some toxins and pathogens
• proteins & antibiotics can not pass but alcohol & anesthetics do
– tight junctions seal together epithelial cells, continuous basement
membrane, astrocyte processes covering capillaries
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Blood Flow and the Blood-Brain Barrier
• An interruption of blood flow for 1 or 2 minutes impairs
neuronal function.
– A total deprivation of oxygen for 4 minutes causes
permanent injury.
• Because carbohydrate storage in the brain is limited, the
supply of glucose to the brain must be continuous.
– Glucose deficiency may produce mental confusion,
dizziness, convulsions, and unconsciousness.
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BBB
• A blood-brain barrier (BBB) protects brain cells from harmful
substances and pathogens by serving as a selective barrier
to prevent passage of many substances from the blood to
the brain.
• An injury to the brain due to trauma, inflammation, or toxins
causes a breakdown of the BBB, permitting the passage of
normally restricted substances into brain tissue.
• The BBB may also prevent entry of drugs that could be
used as therapy for brain cancer or other CNS disorders, so
research is exploring ways to transport drugs past the BBB.
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Protective Covering of the Brain
• The brain is protected by the cranial bones (Figure 7.4) and
the cranial meninges (Figure 14.2).
– The cranial meninges are continuous with the spinal
meninges and are named dura mater, arachnoid, and pia
mater.
– Three extensions of the dura mater separate parts of the
brain: the falx cerebri, falx cerebelli, and the tentorium
cerebelli.
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Protective Coverings of the Brain
• Bone, meninges & fluid
• Meninges same as around the
spinal cord
– dura mater
– arachnoid mater
– pia mater
• Dura mater extensions
– falx cerebri
– tentorium cerebelli
– falx cerebelli
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CEREBROSPINAL FLUID
• Cerebrospinal fluid (CSF) is a clear, colorless liquid that
protects the brain and spinal cord against chemical and
physical injuries.
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Cerebrospinal Fluid (CSF)
• 80-150 ml (3-5oz)
• Clear liquid containing glucose, proteins, & ions
• Functions
– mechanical protection
• floats brain & softens impact with bony walls
– chemical protection
• optimal ionic concentrations for action
potentials
– circulation
• nutrients and waste products to and from
bloodstream
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Ventricles
• There are four CSF filled cavities within the brain called
ventricles (Figure 14.3).
– A lateral ventricle is located in each hemisphere of the
cerebrum. The lateral ventricles are separated by the
septum pellucidum.
– The third ventricle is a narrow cavity along the midline
superior to the hypothalamus and between the right and
left halves of the thalamus.
– The fourth ventricle is between the brain stem and the
cerebellum.
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Origin of CSF
• Choroid plexus = capillaries covered by ependymal cells
– 2 lateral ventricles, one within each cerebral hemisphere
– roof of 3rd ventricle
– fourth ventricle
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Drainage of CSF from Ventricles
• One median aperture & two lateral apertures allow CSF to exit from the
interior of the brain
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Flow of Cerebrospinal Fluid
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Reabsorption of CSF
•
•
Reabsorbed through arachnoid villi
– grapelike clusters of arachnoid penetrate dural venous sinus
20 ml/hour reabsorption rate = same as production rate
• Reabsorption of CSF
– Reabsorbed through arachnoid villi
» grapelike clusters of arachnoid penetrate dural venous sinus
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Hydrocephalus
• Blockage of drainage of CSF (tumor, inflammation,
developmental malformation, meningitis, hemorrhage
or injury)
– Continued production cause an increase in
pressure --- hydrocephalus
– In newborn or fetus, the fontanels allow this
internal pressure to cause expansion of the skull
and damage to the brain tissue
• Neurosurgeon implants a drain shunting the CSF to
the veins of the neck or the abdomen
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THE BRAIN STEM
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Medulla Oblongata
•
•
•
•
•
Continuation of spinal cord
Ascending sensory tracts
Descending motor tracts
Nuclei of 5 cranial nerves
Cardiovascular center
– force & rate of heart beat
– diameter of blood vessels
• Respiratory center
– medullary rhythmicity area sets
basic rhythm of breathing
• Information in & out of cerebellum
• Reflex centers for coughing,
sneezing, swallowing etc.
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Ventral Surface of Medulla Oblongata
• Ventral surface bulge
– pyramids
– large motor tract
– decussation of most fibers
• left cortex controls right
muscles
• Olive = olivary nucleus
– neurons send input to cerebellum
– proprioceptive signals
– gives precision to movements
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Dorsal Surface of Medulla
Oblongata
• Nucleus gracilis & nucleus cuneatus = sensory neurons
– relay information to thalamus on opposite side of brain
• 5 cranial nerves arise from medulla -- 8 thru 12
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XII = Hypoglossal Nerve
• Controls muscles of tongue
during speech and
swallowing
• Injury deviates tongue to
injured side when protruded
• Mixed, primarily motor
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XI = Spinal Accessory Nerve
• Cranial portion
– arises medulla
– skeletal mm of throat & soft
palate
• Spinal portion
– arises cervical spinal cord
– sternocleidomastoid and
trapezius mm.
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X = Vagus Nerve
• Receives sensations from
viscera
• Controls cardiac muscle and
smooth muscle of the viscera
• Controls secretion of digestive
fluids
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IX = Glossopharyngeal Nerve
• Stylopharyngeus m. (lifts
throat during swallowing)
• Secretions of parotid gland
• Somatic sensations & taste
on posterior 1/3 of tongue
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VIII = Vestibulocochlear Nerve
• Cochlear branch begins in medulla
– receptors in cochlea
– hearing
– if damaged deafness or tinnitus
(ringing) is produced
• Vestibular branch begins in pons
– receptors in vestibular
apparatus
– sense of balance
– vertigo (feeling of rotation)
– ataxia (lack of coordination)
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Injury to the Medulla
• Hard blow to the back of the head may be fatal
• Cranial nerve malfunctions on same side as injury;
loss of sensation or paralysis of throat or tongue;
irregularities in breathing and heart rhythm
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Pons
• The pons is located superior to the medulla. It connects the
spinal cord with the brain and links parts of the brain with
one another by way of tracts (Figures 14.1, 14.5).
– relays nerve impulses related to voluntary skeletal
movements from the cerebral cortex to the cerebellum.
– contains the pneumotaxic and apneustic areas, which
help control respiration along with the respiratory center
in the medulla (Figure 23.24).
– contains nuclei for cranial nerves V trigeminal, VI
abducens, VII facial, and VIII vestibulocochlear
(vestibular branch only).(Figure 14.5).
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Pons
• One inch long
• White fiber tracts
ascend and descend
• Pneumotaxic &
apneustic areas help
control breathing
• Middle cerebellar
peduncles carry
sensory info to the
cerebellum
• Cranial nerves 5
through 7
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VII = Facial Nerve
• Motor portion
– facial muscles
– salivary & nasal and oral
mucous glands & tears
• Sensory portion
– taste buds on anterior
2/3’s of tongue
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VI = Abducens Nerve
• Lateral rectus eye muscle
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V = Trigeminal Nerve
• Motor portion
– muscles of mastication
• Sensory portion
– touch, pain, &
temperature receptors
of the face
• ophthalmic branch
• maxillary branch
• mandibular branch
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Midbrain
• One inch in length
• Extends from pons
to diencephalon
• Cerebral aqueduct
connects 3rd
ventricle above to
4th ventricle below
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Midbrain in Section
• Cerebral peduncles---clusters of motor & sensory fibers
• Substantia nigra---helps controls subconscious muscle activity
• Red nucleus-- rich blood supply & iron-containing pigment
– cortex & cerebellum coordinate muscular movements by sending
information here from the cortex and cerebellum
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Dorsal Surface of Midbrain
• Corpora quadrigemina = superior & inferior colliculi
– coordinate eye movements with visual stimuli
– coordinate head movements with auditory stimuli
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IV = Trochlear Nerve
• Superior oblique eye muscle
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III = Oculomotor Nerve
• Levator palpebrae raises
eyelid (ptosis)
• 4 extrinsic eye muscles
• 2 intrinsic eye muscles
– accomodation for near
vision (changing shape of
lens during reading)
– constriction of pupil
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Reticular Formation
• Scattered nuclei in medulla, pons & midbrain
• Reticular activating system
– alerts cerebral cortex to sensory signals (sound of
alarm, flash light, smoke or intruder) to awaken from
sleep
– maintains consciousness & helps keep you awake
with stimuli from ears, eyes, skin and muscles
• Motor function is involvement with maintaining muscle
tone
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Cerebellum
• 2 cerebellar hemispheres and vermis (central area)
• Function
– correct voluntary muscle contraction and posture based on sensory
data from body about actual movements
– sense of equilibrium
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Cerebellum
• Transverse fissure between cerebellum & cerebrum
• Cerebellar cortex (folia) & central nuclei are grey matter
• Arbor vitae = tree of life = white matter
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Cerebellar Peduncles
• Superior, middle & inferior peduncles attach to brainstem
– inferior carries sensory information from spinal cord
– middle carries sensory fibers from cerebral cortex & basal
ganglia
– superior carries motor fibers that extend to motor control
areas
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THE DIENCEPHALON
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Diencephalon Surrounds 3rd Ventricle
• Surrounds 3rd ventricle
• Superior part of walls is thalamus
• Inferior part of walls & floor is hypothalamus
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Thalamus
• The thalamus is located superior to the midbrain and
contains nuclei that serve as relay stations for all sensory
impulses, except smell, to the cerebral cortex (Figure 14.9).
– seven major groups of thalamic nuclei on each side
(Figure 14.9 c and d).
– They are the Anterior nucleus, medial nuclei, lateral
group, ventral group, intralaminar nuclei, midline nucleus,
and the reticular nucleus.
• It also registers conscious recognition of pain and
temperature and some awareness of light touch and
pressure.
• It plays an essential role in awareness and the acquisition of
knowledge (cognition.)
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Thalamus
• 1 inch long mass of gray mater in each half of brain
(connected across the 3rd ventricle by intermediate mass)
• Relay station for sensory information on way to cortex
• Crude perception of some sensations
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Thalamic Nuclei
• Nuclei have different roles
– relays auditory and visual impulses, taste and
somatic sensations
– receives impulses from cerebellum or basal
ganglia
– anterior nucleus concerned with emotions,
memory and acquisition of knowledge (cognition)
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Hypothalamus
• The hypothalamus
– inferior to the thalamus, has four major regions
(mammillary, tuberal, supraoptic, and preoptic)
– controls many body activities, and is one of the major
regulators of homeostasis (Figure 14.10).
• The hypothalamus has a great number of functions.
–
–
–
–
It controls the ANS.
It produces hormones.
It functions in regulation of emotional and behavioral patterns.
It regulates eating and drinking through the feeding center, satiety
center, and thirst center.
– It aids in controlling body temperature.
– It regulates circadian rhythms and states of consciousness.
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Hypothalamus
• Dozen or so nuclei in 4 major regions
– mammillary bodies are relay station for olfactory reflexes;
infundibulum suspends the pituitary gland
• Major regulator of homeostasis
– receives somatic and visceral input, taste, smell & hearing information;
monitors osmotic pressure, temperature of blood
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Epithalamus
• The epithalamus lies superior and posterior to the thalamus
and contains the pineal gland and the habenular nuclei
(Figure 14.7).
– The pineal gland secretes melatonin to influence diurnal
cycles in conjunction with the hypothalamus.
– The habenular nuclei (Figure 14.7a) are involved in
olfaction, especially emotional responses to odors.
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Epithalamus
• Pineal gland
– endocrine gland
the size of small
pea
– secretes melatonin
during darkness
– promotes
sleepiness & sets
biological clock
• Habenular nuclei
– emotional
responses to odors
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Subthalamus
• The subthalamus lies immediately inferior to the thalamus
and includes tracts and the paired subthalamic nuclei, which
connect to motor areas of the cerebrum.
– The subthalamic nuclei and red nucleus and substantia
nigra of the midbrain work together with the basal
ganglia, cerebellum, and cerebrum in control of body
movements.
• Table 14.2 summarizes the functions of the parts of the
diencephalon.
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Circumventricular Organs
• Parts of the diencephalon, called circumventricular organs
(CVOs), can monitor chemical changes in the blood
because they lack a blood-brain barrier.
• CVOs include
– part of the hypothalamus,
– the pineal gland,
– the pituitary gland, and a few other nearby structures.
• They function to coordinate homeostatic activities of the
endocrine and nervous systems.
• They are also thought to be the site of entry into the brain of
HIV.
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THE CEREBRUM
• The cerebrum is the largest part of the brain .
– The surface layer, the cerebral cortex, is 2-4 mm thick
and is composed of gray matter. The cortex contains
billions of neurons.
– The cortex contains gyri (convolutions), deep grooves
called fissures, and shallower sulci. (Figure 14.11a)
• Beneath the cortex lies the cerebral white matter, tracts that
connect parts of the brain with itself and other parts of the
nervous system.
• The cerebrum is nearly separated into right and left halves,
called hemispheres, by the longitudinal fissure.
– Internally it remains connected by the corpus callosum, a
bundle of transverse white fibers. Figure 14.12)
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Cerebrum
(Cerebral Hemispheres)
• Cerebral cortex is gray matter
overlying white matter
– 2-4 mm thick containing
billions of cells
– grew quickly; formed folds
(gyri) and grooves (sulci or
fissures)
• Longitudinal fissure separates
left & right cerebral hemispheres
– Corpus callosum is a
commisure (band of white
matter) connecting left and
right cerebral hemispheres
• Each hemisphere is subdivided
into 4 lobes
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Lobes
• Each cerebral hemisphere is further subdivided into four
lobes by sulci or fissures (Figure 14.11 a,b)
– frontal, parietal, temporal, and occipital.
• A fifth part of the cerebrum, the insula, lies deep to the
parietal, frontal, and temporal lobes and cannot be seen in
an external view of the brain.
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Lobes and Fissures
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• Longitudinal fissure
(green)
• Frontal lobe
• Central sulcus
(yellow)
– precentral &
postcentral gyrus
• Parietal lobe
• Parieto-occipital
sulcus
• Occipital lobe
• Lateral sulcus (blue)
• Temporal lobe
• Insula
58
Insula within Lateral Fissure
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White Matter
• The white matter is under the cortex and consists of
myelinated axons running in three principal directions
(Figure 14.12).
– Association fibers connect and transmit nerve impulses
between gyri in the same hemisphere.
– Commissural fibers connect gyri in one cerebral
hemisphere to the corresponding gyri in the opposite
hemisphere.
– Projection fibers form ascending and descending tracts
that transmit impulses from the cerebrum to other parts of
the brain and spinal cord.
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Cerebral White Matter
• Association fibers between gyri in same hemisphere
• Commissural fibers from one hemisphere to other
• Projection fibers form descending & ascending tracts
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Basal Ganglia
The basal ganglia are paired masses of gray matter in
each cerebral hemisphere (Figure 14.13).
• Connections to red nucleus, substantia nigra &
subthalamus
• Input & output with cerebral cortex, thalamus &
hypothalamus
• Control large automatic movements of skeletal
muscles
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Caudate nucleus
• Lentiform and cuadate nuclei are known as the corpus
striatum.
– Nearby structures functionally linked to the basal ganglia
are the substantia nigra and the subthalamic nuclei.
– They are responsible for helping to control muscular
movements.
• Damage to the basal ganglis results in tremor, rigidity, and involuntary
muscle movements. In Parkinson’s disease neurons from the substantia
nigra to the putamen and cuadate nucleus degenerate.
• Basal ganglia also help initiate and terminate some cognitive
processes. Obsessive compulsive disorder, schizophrenia, chronic
anxiety are thought to involve dysfunction of the circuits between the
basal ganglis and limbic system
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Limbic System
• The limbic system is found in the cerebral hemispheres and
diencephalon (Figure 14.14).
– limbic lobe
– dentate gyrus
– amygdala
– septal nuclei
– mammilary bodies, mammilothalmic tract
– anterior and medial nuclei of the thalamus,
– olfactory bulbs
– fornix, stria terminalis, stria medulllaris,
– medial forebrain bundle
• It functions in emotional aspects of behavior and memory,
and is associated with pleasure and pain.
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Limbic System
• Emotional brain--intense pleasure & intense pain
• Strong emotions increase efficiency of memory
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Brain Injuries
• Brain injuries are commonly associated with head injuries
and result, in part, from displacement and distortion of
neuronal tissue at the moment of impact and in part from the
release of disruptive chemicals from injured brain cells.
• Various degrees of brain injury are described by the terms
– concussion, contusion, and laceration.
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Brain Injuries
• Causes of damage
– displacement or distortion of tissue at impact
– increased intracranial pressure
– infections
– free radical damage after ischemia
• Concussion---temporary loss of consciousness
– headache, drowsiness, confusion, lack of concentration
• Contusion--bruising of brain (less than 5 min
unconsciousness but blood in CSF)
• Laceration--tearing of brain (fracture or bullet)
– increased intracranial pressure from hematoma
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Sensory Areas
• The sensory areas of the cerebral cortex are concerned with
the reception and interpretation of sensory impulses.
• Some important sensory areas include
– primary somatosensory area,
– primary visual area,
– primary auditory area, and
– primary gustatory area
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Sensory Areas of Cerebral Cortex
Receive sensory information from the thalamus
Primary somatosensory area = postcentral gyrus = 1,2,3
Primary visual area = 17
Primary auditory area = 41 & 42
Primary gustatory area = 43
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Motor Areas
• The motor areas are the regions that govern muscular
movement.
• Two important motor areas are
– primary motor area and
– Broca’s speech area. (Figure 14.15)
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Motor Areas of Cerebral Cortex
• Voluntary motor initiation
– Primary motor area = 4 = precentral gyrus
• controls voluntary contractions of skeletal muscles on other side
– Motor speech area = 44 = Broca’s area
• production of speech -- control of tongue & airway
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Association Areas of Cerebral Cortex
•
•
•
•
•
•
Somatosensory area = 5 & 7 (integrate & interpret)
Visual association area = 18 & 19 (recognize & evaluate)
Auditory association area(Wernicke’s) = 22(words become speech)
Gnostic area = 5,7,39 & 40 (integrate all senses & respond)
Premotor area = 6 (learned skilled movements such as typing)
Frontal eye field =8 (scanning eye movements such as phone book)
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Association Areas
• The association areas are concerned with complex
integrative functions such as memory, emotions, reasoning,
will, judgment, personality traits, and intelligence. (Figure
14.15)
– Injury to the association or motor speech areas results in
aphasia, an inability to use or comprehend words.
(Clinical Application)
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Aphasia
Language areas are located in the left cerebral hemisphere of most
people
Inability to use or comprehend words = aphasia
• nonfluent aphasia = inability to properly form words
– know what want to say but can not speak
– damage to Broca’s speech area
• fluent aphasia = faulty understanding of spoken or written words
– faulty understanding of spoken or written words
• word deafness = an inability to understand spoken words
• word blindness = an inability to understand written words
– damage to common integrative area or auditory association
area
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Hemispheric Lateralization
• Although the two cerebral hemispheres share many
functions, each hemisphere also performs unique functions.
• hemispheric lateralization (Figure 14.16).
– The left hemisphere is more important for right-handed
control, spoken and written language, and numerical and
scientific skills.
– The right hemisphere is more important for left-handed
control, musical and artistic awareness, space and
pattern perception, insight, imagination, and generating
mental images of sight, sound, touch, taste, and smell.
• Table 14.3 summarizes some of the distinctive functions
that are more likely to reside in the left or right hemisphere.
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Hemispheric Lateralization
• Functional specialization
of each hemisphere
more pronounced in men
• Females generally have
larger connections
between 2 sides
• Damage to left side
produces aphasia
• Damage to same area
on right side lead to
speech with little
emotional inflection
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Brain Waves
• An EEG may be used to diagnose epilepsy and other
seizure disorders, infectious diseases, tumors, trauma,
hematomas, metabolic abnormalities, degenerative
diseases, and periods of unconsciousness and confusion; it
may also provide useful information regarding sleep and
wakefulness.
• An EEG may also be one criterion in confirming brain death
(complete absence of brain waves in two EEGs taken 24
hours apart).
• Figure 14.17 shows four kinds of brain waves that can be
recorded from normal individuals.
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Electroencephalogram (EEG)
• Brain waves are millions of
nerve action potentials in
cerebral cortex
– diagnosis of brain
disorders (epilepsy)
– brain death (absence of
activity in 2 EEGs 24
hours apart)
• Alpha -- awake & resting
• Beta -- mental activity
• Theta -- emotional stress
• Delta -- deep sleep
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II -- Optic Nerve
• Connects to retina supplying
vision
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I -- Olfactory Nerve
• Extends from olfactory
mucosa of nasal cavity to
olfactory bulb
• Sense of smell
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Developmental Anatomy of the NS
• Begins in 3rd week
– ectoderm forms thickening (neural
plate)
– plate folds inward to form neural
groove
– edges of folds join to form neural tube
• Neural crest tissue forms:
– spinal & cranial nerves
– dorsal root & cranial nerve ganglia
– adrenal gland medulla
• Layers of neural tube form:
– marginal layer which forms white
matter
– mantle layer forms gray matter
– ependymal layer forms linings of
cavities within NS
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Dorsal View of Neural Groove
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Development of Principal Parts
• By end of 4th week, 3 anterior enlargements occur
– prosencephalon
– mesencephalon
– rhombencephalon
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Development of Principal Parts
• By 5th week, 5 enlarged areas exist
• Prosencephalon
– telencephalon
– diencephalon
• Mesencephalon
• Rhombencephalon
– metencephalon
– myelencephalon
• Neural tube defects
– associated with low levels of folic acid (B vitamins)
– spina bifida is failure to close of vertebrae
– anencephaly is absence of skull & cerebral
hemispheres
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Aging & the Nervous System
• Years 1 to 2
– rapid increase in size due to increase in size of
neurons, growth of neuroglia, myelination &
development of dendritic branches
• Early adulthood until death
– brain weight declines until only 93% by age 80
– number of synaptic contacts declines
– processing of information diminishes
– conduction velocity decreases
– voluntary motor movements slow down
– reflexes slow down
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DISORDERS: HOMEOSTATIC IMBALANCES
• The most common brain disorder is a cerebrovascular
accident (CVA or stroke).
• Third leading cause of death after heart attacks and cancer
• CVAs are classified into two principal types:
– ischemic (the most common type), due to a decreased
blood supply
– hemorrhagic, due to a blood vessel in the brain that
bursts.
• Common causes of CVAs are intracerebral hemorrhage,
emboli, and atherosclerosis.
• Tissue plasminogen activator (t-PA) used within 3 hours of
ischemic CVA onset will decrease permanent disability
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Transient Ischemic Attack (TIA)
• Episode of temporary cerebral dysfunction
• Cause
– impaired blood flow to the brain
• Symptoms
– dizziness, slurred speech, numbness, paralysis on one
side, double vision
– reach maximum intensity almost immediately
– persists for 5-10 minutes & leaves no deficits
• Treatment is aspirin or anticoagulants; artery bypass grafting
or carotid endarterectomy
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Alzheimer Disease (AD)
• Dementia = loss of reasoning, ability to read, write, talk,
eat & walk
• Afflicts 11% of population over 65
• Great loss of neurons in specific regions (e.g.,
hippocampus and cerebral cortex); loss of neurons that
release acetylcholine
• Plaques of abnormal proteins deposited outside neurons
(amyloid plaques).
• Tangled protein filaments within neurons (neurofibrillary
tangles).
• Treated with acetylcholinesterase inhibitors (Aricept
(donepezil), Reminyl (galantamine), and Exelon
(rivastigmine)
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Alzheimer Disease (AD)
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Tumors
• Brain tumor is an abnormal growth of tissue it may be
malignant or benign.
• Attention Deficit Hyperactivity Disorder (ADHD) is a laerning
disorder characterized by poor attention span, hyperactivity
and inappropriate impulsiveness.
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CRANIAL NERVE Review
• Twelve pairs of cranial nerves originate from the brain
(Figure 14.5)
– named primarily on the basis of distribution and
numbered by order of attachment to the brain.
• Some cranial nerves (I, II, and VIII) contain only sensory
fibers and are called sensory nerves. The rest are mixed
nerves because they contain both sensory and motor fibers.
• Figures 14.18 – 14.27 illustrate the distribution of many of
the cranial nerves.
• Table 14.4 presents a summary of cranial nerves, including
clinical applications related to their dysfunction.
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Cranial Nerve Review
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Cranial Nerve Review
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Cranial Nerve Review
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Cranial Nerve Review
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Cranial Nerve Review
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Cranial Nerve Review
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Cranial Nerve Review
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Cranial Nerve Review
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Cranial Nerve Review
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Cranial Nerve Review
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end
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