principles of human anatomy and physiology, 11e1 chapter 14 the brain and cranial nerves lecture...

Principles of Human Anatomy and Physiology, 11e 1

Chapter 14

The Brain and Cranial Nerves

Lecture Outline


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.


Chapter 14The Brain and Cranial

Nerves

• Largest organ in the body at almost 3 lb.• Brain functions in sensations, memory, emotions, decision making,

behavior


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


Principal Parts of the Brain

• Cerebrum• Diencephalon

– thalamus & hypothalamus• Cerebellum• Brainstem

– medulla, pons & midbrain


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


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.


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.


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.


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


CEREBROSPINAL FLUID

• Cerebrospinal fluid (CSF) is a clear, colorless liquid that protects the brain and spinal cord against chemical and physical injuries.


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


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.


Origin of CSF

• Choroid plexus = capillaries covered by ependymal cells– 2 lateral ventricles, one within each cerebral hemisphere– roof of 3rd ventricle– fourth ventricle


Drainage of CSF from Ventricles

• One median aperture & two lateral apertures allow CSF to exit from the interior of the brain


Flow of Cerebrospinal Fluid


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

– 20 ml/hour reabsorption rate = same as production rate


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


THE BRAIN STEM


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.


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


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


XII = Hypoglossal Nerve

• Controls muscles of tongue during speech and swallowing

• Injury deviates tongue to injured side when protruded

• Mixed, primarily motor


XI = Spinal Accessory Nerve

• Cranial portion– arises medulla– skeletal mm of throat & soft

palate• Spinal portion

– arises cervical spinal cord– sternocleidomastoid and

trapezius mm.


X = Vagus Nerve

• Receives sensations from viscera

• Controls cardiac muscle and smooth muscle of the viscera

• Controls secretion of digestive fluids


IX = Glossopharyngeal Nerve

• Stylopharyngeus m. (lifts throat during swallowing)

• Secretions of parotid gland• Somatic sensations & taste

on posterior 1/3 of tongue


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)


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


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).


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


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


VI = Abducens Nerve

• Lateral rectus eye muscle


V = Trigeminal Nerve

• Motor portion– muscles of mastication

• Sensory portion– touch, pain, &

temperature receptors of the face

• ophthalmic branch• maxillary branch• mandibular branch


Midbrain

• One inch in length• Extends from pons

to diencephalon• Cerebral aqueduct

connects 3rd ventricle above to 4th ventricle below


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


Dorsal Surface of Midbrain

• Corpora quadrigemina = superior & inferior colliculi– coordinate eye movements with visual stimuli– coordinate head movements with auditory stimuli


IV = Trochlear Nerve

• Superior oblique eye muscle


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


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


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


Cerebellum

• Transverse fissure between cerebellum & cerebrum• Cerebellar cortex (folia) & central nuclei are grey matter• Arbor vitae = tree of life = white matter


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


THE DIENCEPHALON


Diencephalon Surrounds 3rd Ventricle

• Surrounds 3rd ventricle• Superior part of walls is thalamus

• Inferior part of walls & floor is hypothalamus


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.)


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


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)


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.


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


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.


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


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.


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.


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)


Cerebrum (Cerebral Hemispheres)

• Cerebral cortex is gray matteroverlying 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


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.


Lobes and Fissures• Longitudinal fissure

(green)• Frontal lobe• Central sulcus (yellow)

– precentral & postcentral gyrus

• Parietal lobe• Parieto-occipital sulcus• Occipital lobe• Lateral sulcus (blue)• Temporal lobe• Insula


Insula within Lateral Fissure


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.


Cerebral White Matter

• Association fibers between gyri in same hemisphere• Commissural fibers from one hemisphere to other • Projection fibers form descending & ascending tracts


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


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


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.


Limbic System

• Emotional brain--intense pleasure & intense pain• Strong emotions increase efficiency of memory


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.


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


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


Sensory Areas of Cerebral Cortex

Receive sensory information from the thalamusPrimary somatosensory area = postcentral gyrus = 1,2,3Primary visual area = 17Primary auditory area = 41 & 42Primary gustatory area = 43


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)


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


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)


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)


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


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.


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


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.


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


II -- Optic Nerve

• Connects to retina supplying vision


I -- Olfactory Nerve

• Extends from olfactory mucosa of nasal cavity to olfactory bulb

• Sense of smell


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


Dorsal View of Neural Groove


Development of Principal Parts• By end of 4th week, 3 anterior enlargements occur

– prosencephalon– mesencephalon– rhombencephalon


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


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


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


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


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)


Alzheimer Disease (AD)


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.


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.


Cranial Nerve Review


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principles of human anatomy and physiology, 11e1 chapter 14 the brain and cranial nerves lecture...

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