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Transcript
Anatomy Written Exam #2
1. Cranial Nerves
a. Introduction
 Embryological Development
1. Alar Plate
o Spinal Cord
i. Becomes dorsal horn
ii. Nuclei of termination
iii. GSA and GVA
o Brainstem
i. Gives rise to nuclei of termination
ii. GSA, GVA, SVA, and SSA
2. Basal Plate
o Spinal Cord
i. Becomes ventral horn
ii. Nuclei of origin
iii. GSE and GVE
o Brainstem
i. GSE, SVE, and GVE
CN I
CN II
CN III
GSE, GVE
CN IV
GSE
CN V
SVE, GSA
CN VI
GSE
CN VII
SVE, GVE
CN VIII
CN IX
SVE, GVE
CN X
SVE, GVE
CN XI
SVE
CN XII
GSE
 Corticobulbar Projections
1. From the cerebral cortex to brainstem
2. Arise from neurons in premotor, primary motor, and somatosensory
cortices
3. Usually bilateral, except for nerves innervating facial expression and
tongue muscles
b. CN III
 Oculomotor Nerve
 GSE Component
1. Location: midbrain
2. Course of LMN: exit oculomotor nucleus and enters IPSILATERALLY into
oculomotor nerve
3. Innervate: extraocular muscles
4. No direct corticobulbar projections to brainstem motor nuclei
 GVE Component
1. Location: Preganglionic, parasympathetics in Edinger-Westphal nucleus
o Postganglionics in ciliary ganglion of orbit
1
Anatomy Written Exam #2
2. Innervate: sphincter pupillae and ciliary muscles, which function to
constrict pupil and in accommodation
 Reflexes
1. Pupillary Light Reflex
2. Accommodation Reflex
 Lesions
1. Ptosis
2. Lateral strabismus- eye abducted and inferiorly rotated
3. Mydriasis
4. Loss of light and accommodation reflexes
5. Inability to laterally gaze to side opposite lesion without double vision
(diplopia)
c. CN IV
 Trochlear Nerve
 GSE
1. Location: midbrain
2. Course of LMN: decussate and exit brainstem on dorsal surface
3. Innervate: CONTRALATERAL superior oblique muscle
4. No direct corticobulbar projections to the brainstem motor nuclei
 Lesions
1. Eye is elevated at rest
2. Diplopia in vertical plane
3. To test: have patient look medially and then inferiorly to examine
superior oblique muscle functioning
d. CN V
 Trigeminal Nerve
 Location: lateral aspect of mid-level basilar pons
 Functions: transmission of vibration, touch, conscious and unconscious
proprioceptive, pain, and temperature sensations from the head
1. Motor innervation to muscles of mastication
 GSA
1. Function: general sensations of the face, oral and nasal cavities, dura
mater, and proprioception of muscles
o Similar to dorsal columns, anterolateral system, and
spinocerebellar tracts
2. Three Nuclei:
o Spinal Trigeminal Nucleus
i. Location: lateral tegmentum of medulla and caudal
pons
ii. Function: pain, temperature, and crude touch
1. Analogous to anterolateral system
o Chief Sensory Nucleus
i. Location: dorsolateral pontine tegmentum
ii. Function: fine touch, 2-point discrimination, vibratory,
and conscious proprioception
1. Analogous to dorsal column system
o Mesencephalic Nucleus
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Anatomy Written Exam #2
i. Location: rostral pons and caudal midbrain
ii. Function: unconscious proprioception information
1. Analogous to spinocerebellar system
 SVE
1.
2.
3.
4.
5.
Motor nucleus
Location: dorsolateral pontine tegmentum
Innervate: muscles of mastication and several others
Corticobulbar projections to trigeminal nucleus bilaterally
Lesion: paralysis of muscles of mastication, jaw protrusion to side of
lesion, and absent jaw jerk reflex
 Reflexes
1. Corneal Reflex- unilateral stimulation of the cornea results in reflex
blinking and eye closure
o Direct response- stimulated eye closes
o Consensual response- nonstimulated eye closes
2. Lacrimal Reflex- unilateral stimulation of cornea results in tear
production
e. CN VI
f.
 Abducens Nerve
 GSE
1. Caudal pons
2. Course of LMN: exit brainstem at pontomedullary junction
3. Innervate: IPSILATERAL lateral rectus muscle
4. No direct corticobulbar projections to the brainstem motor nuclei
 Lesions
1. Medial strabismus- adducted
2. Inability to laterally gaze to side of lesion without double vision
CN VII
 Facial Nerve
 SVE
1. Location: caudal pons
2. Course of LMN: exit facial motor nucleus to enter IPSILATERAL motor
root of facial nerve
3. Innervate: muscles of facial expression
4. Subdivided into innervation of upper facial muscles BILATERALLY and
lower facial muscles CONTRALATERALLY
 GVE
1. Location: preganglionic, parasympathetics in superior salivatory nucleus
in pons
o Postganglionic located in IPSILATERAL pterygopalatine and
submandibular ganglia
2. Innervate: mucous glands of oral and nasal cavities, lacrimal gland, and
submandibular and sublingual salivary glands
 Lesions
1. To LMN: complete ipsilateral facial flaccid paralysis
o fasciculations
3
Anatomy Written Exam #2
2. To UMN: paresis of contralateral lower face and disuse atrophy over
time
g. CN IX
 Glossopharyngeal Nerve
 SVE
1. Location: nucleus ambiguous of medulla
2. Course of LMN: enter IPSILATERAL glossopharyngeal nerve
3. Innervate: stylopharyngeus muscle
4. Bilateral corticobulbar projections
 GVE
1. Location: preganglionic, parasympathetic in inferior salivatory nucleus
and enter IPSILATERAL glossopharyngeal nerve
o Postganglionic join auriculotemporal branch of mandibular
nerve
2. Innervate: parotid gland
 Lesions
1. Loss of parotid gland secretions
2. Test: gag reflex
h. CN X
 Vagus Nerve
 SVE
1. Location: nucleus ambiguous
2. Course of LMN: enter IPSILATERAL vagus nerve
3. Innervate: soft palate and muscles of pharynx and larynx
4. Bilateral corticobulbar projections
 GVE
1. Location: preganglionic, parasympathetics in dorsal motor nucleus of
vagus in medulla
o Postganglionic in ganglia of pharynx, larynx, thoracic and
abdominal viscera
2. Innervate: mucous membranes of pharynx, larynx, and smooth muscle
and glands of thoracic and abdominal viscera
 Lesion
1. Unilateral
o Ipsilateral paralysis of soft palate, causing it to droop and not
rise in phonation
i. Deviation of uvula to intact side
o Ipsilateral vocal cord palsy: hoarseness and coughing
2. Bilateral
o Vocal cord paralysis may lead to death by asphyxiation
o May increase HR to point of death
i.
CN XI
 Spinal Accessory Nerve
 SVE
1. Location: ventral horn of spinal cord C1-C5; medulla
2. Course of LMN: enter IPSILATERAL spinal accessory nerve
3. Innervate: ipsilateral sternocleidomastoid and trapezius muscles
4
Anatomy Written Exam #2
 Lesion
1.
2.
3.
4.
j.
Ipsilateral shoulder sag
Inability to elevate upper limb above horizontal plane
Plegia when point chin away from side of lesion
Chin points to side of lesion
CN XII
 Hypoglossal Nerve
 GSE
1. Location: hypoglossal nucleus in medulla
2. Course of LMN: enter IPSILATERAL hypoglossal nerve
3. Innervate: ipsilateral intrinsic and extrinsic muscles of tongue
4. Contralateral corticobulbar projections
 Lesions
1. LMN
o Paralysis of ipsilateral tongue muscles
o Deviation of tongue to side of lesion
o Atrophy of ipsilateral muscles
o Fasciculations
2. UMN
o Contralateral paresis in tongue muscles
o Deviation of tongue to side opposite the lesion
o Disuse atrophy
o No fasciculations
k. Alternating Motor Systems
 Hallmark of brainstem lesions
 Alternating Hemiplegias
1. Lesion of a CN and the corticospinal tract
2. Usually associated with paramedian lesions
3. Ipsilateral LMN signs for CN
4. Contralateral UMN signs for corticospinal tract
 Alternating Hypoglossal Hemiplegia
1. Aka “medial medullary syndrome”
2. Associated with infarct of paramedian branch of anterior spinal artery
and medial portion of ventral medulla
3. Contralateral loss of tactile sensation and conscious proprioception
4. LMN signs for ipsilateral hypoglossal nerve
5. UMN signs for corticospinal tract
 Alternating Abducens Hemiplegia
1. Associated with infarct of pontine branches of basilar artery and medial
portion of ventral pons
2. LMN signs for abducens nerve
3. UMN signs for corticospinal tract
 Alternating Oculomotor Hemiplegia
1. Aka “Weber’s Syndrome”
2. Associated with an infarct of the basal branch of the posterior cerebral
artery and medial portion of ventral midbrain
3. LMN signs for oculomotor nerve
5
Anatomy Written Exam #2
4. UMN signs for corticospinal tract
_____________________________________________________________________________________
2. Thalamus
a. Diencephalon
 Forebrain- consists of diencephalon and cerebral hemispheres
 Consists of:
1. Thalamus
o Largest part
o Gateway to cerebral cortex
i. Consists of numerous nuclei
1. Transmit general and special sensory
information to regions of sensory cortices
2. Receive impulses from cerebellum and basal
ganglia and interface with motor regions of
frontal lobe
3. Have connections with associative and limbic
areas of cortex
o Forms dorsal part of third ventricle
2. Hypothalmus
o Forms ventral part of third ventricle
3. Subthalamus
o Inferior to thalamus, medial to internal capsule, and lateral to
hypothalamus
o Contains
i. subthalamic nucleus- important for control of
movement
ii. zona incerta- small sheet of gray matter interposed
between thalamic nucleus and thalamus
1. function unknown, but believed to recognize
thirst and stimulate drinking
4. Epithalamus
o Includes the pineal gland and habenular nuclei
o Small
 Location: between brainstem and cerebral hemisphere
1. Continuous with rostral part of midbrain
2. Forms lateral wall of third ventricle
o Dorsal part formed by thalamus
o Ventral part formed by hypothalamus
b. Topographical Anatomy of the Thalamus
 External Features
1. Hypothalamic sulcus- faint groove that mares the transition between
the thalamus and hypothalamus
2. Interthalamic adhesion/mass intermedia- joins two thalami together
3. Stria medullaris thalami- nerve fibers with limbic connections that
course along dorsomedial margin of thalamus
o Fine ridge of white matter
o Associated with feelings of pleasure
6
Anatomy Written Exam #2
4. Anterior pole extends to interventricular foramen
5. Posterior limb of internal capsule lies LATERAL to the thalamus
6. Head of caudate nucleus lies ANTEROLATERAL to thalamus
7. DORSAL part of thalamus forms floor of lateral ventricle
 Internal Organization
1. Contains the internal medullary lamina, a thin layer of nerve fibers
composed of both afferent and efferent connections
o Y-shape provides basis for dividing thalamus into three masses:
i. Anterior Group
ii. Medial Group
iii. Lateral Group
o Contains intralaminar nuclei, which includes:
i. Centromedian Nucleus- largest
1. Afferents from globus pallidus
2. Efferents to stratium
ii. Parafascicular Nucleus- similar to centromedian
2. External Medullary Lamina- lateral to main mass of thalamic nuclei
o Thin sheet of nerve fibers
o Consists of:
i. Thalamocortical fibers
ii. Corticothalamic fibers
o Reticular Nucleus- between lateral medullary lamina and
internal capsule
i. Afferents from thalamus and cerebral cortex
ii. GABA efferents back to thalamus
c. Functional Organization of Thalamic Nuclei
 All thalamic nuclei, except or the reticular nucleus, project to IPSILATERAL
cerebral cortex
1. Specific Nuclei- have point to point projections between individual
thalamic nuclei and restricted cortical zones
o Have well-defined sensory and motor functions
2. Non-specific Nuclei- receive less functionally distinct afferent input
o Connect wider areas of cortex, such as the associative and
limbic domains
 Lateral Nuclear Group
1. Contains all specific thalamic nuclei in ventral part of complex
o Includes:
i. Ventral Anterior Nuclei
1. Occupies rostral part of lateral nuclear mass
2. Afferents are from IPSILATERAL basal ganglia
3. Has reciprocal connections with motor regions
of frontal lobe
4. Important part of mechanism by which basal
ganglia exert influence on normal movement
and abnormalities of movement
ii. Ventral Lateral Nuclei
1. Lies immediately caudal to ventral anterior
nucleus
7
Anatomy Written Exam #2
2. Subcortical afferents to nucleus originate from
IPSILATERAL globus pallidus and substantia
nigra and CONTRALATERAL dentate nucleus
3. Efferents project to primary motor cortex of
precentral gyrus
iii. Ventral Posterior Nucleus
1. Lies between ventrolateral nucleus and pulvinar
2. Termination of all ascending pathways rom
spinal cord and brainstem carrying general
sensory information from contralateral half of
body to conscious level
a. Spinothalamic Tract (lateral part of
nucleus)
b. Medial Lemniscus Tract (lateral part of
nucleus)
c. Trigeminothalamic Tract (medial part of
nucleus)
3. Projects to primary somatosensory cortex in
postcentral gyrus of parietal lobe
iv. Ventral Medial Nuclei
v. Lateral Geniculate Nuclei
1. Part of visual system
2. Site of termination of optic tract
3. Each nucleus receives axons that originated in
IPSILATERAL temporal hemiretina and
CONTRALATERAL nasal hemiretina
4. Projects to primary visual cortex of occipital
lobe
vi. Medial Geniculate Nuclei
1. Part of auditory system
2. Receives ascending fibers from inferior
colliculus of midbrain
3. Projects to primary auditory cortex of temporal
lobe
2. Also has non-specific nuclei in dorsal part
o Lateral Dorsal Nucleus- part of limbic system
i. Afferents from hippocampus
ii. Efferents to cingulate gyrus
o Lateral Posterior Nucleus- has connections with sensory
association cortex
o Pulvinar- largest thalamic nucleus
i. Extensive connections with parietal-occipital-temporal
association cortex
_____________________________________________________________________________________
Study Break:
TOP TEN THINGS YOU DON'T WANT TO HEAR IN SURGERY
1 Don't worry. I think it is sharp enough.
8
Anatomy Written Exam #2
2 Nurse, did this patient sign the organs donation card?
3 Damn! Page 84 of the manual is missing!
4 Everybody stand back! I lost a contact lens!
5 Hand me that...uh...that uh.....thingie
6 Better save that. We'll need it for the autopsy.
7 "Accept this sacrifice, O Great Lord of Darkness"
8 Whoa, wait a minute, if this is his spleen, then what's that?
9 "Ya know, there's big money in kidneys. Hell, he's got two of'em
10 What do you mean "You want a divorce?"
_____________________________________________________________________________________
3. Cerebellum
a. Largest part of hindbrain
 Overlies fourth ventricle
 Connected to brainstem by three pairs of fiber bundles:
1. Inferior Cerebellar Peduncle- connects cerebellum to medulla
2. Middle Cerebellar Peduncle- connects cerebellum to pons
3. Superior Cerebellar Peduncle- connects pons to midbrain
b. Functions: entirely motor and operates at unconscious level
 Maintenance of Equilibrium
 Posture and Muscle Tone
 Coordinates Movements
c. Consists of two laterally located hemispheres joined by vermis at midline
 Lies beneath tentorium cerebelli
 Surface is highly convoluted with folds known as folia
d. Fissures divide the cerebellum into three lobes
 Lobes include:
1. Anterior Lobe
2. Posterior Lobe
3. Flocculonodular Lobe
 Primary Fissure- separates anterior lobe from posterior lobe
 Posterolateral Fissure- separates flocculus and nodule
e. Internal Structure
 Outer layer of gray matter known as cerebellar cortex
1. Contains cell bodies, dendrites, and synaptic connections
2. Uniform organization: Three Layers
o Molecular Layer- outer
i. Fiber rich
9
Anatomy Written Exam #2
o
Purkinje Layer- intermediate
i. Consists of unicellular layer of purkinje neurons soma
o Granular Layer- inner
 Inner core of white matter that is made up of afferent and efferent fibers
1. Deep within this white matter is four pairs of nuclei
o Dentate Nucleus- largest nuclei and only one that can be seen
with naked eye
i. Thin layer of nerve cells folded into a “crinkled bag”
ii. Receives afferent fibers rom inferior olivary nucleus
o Emboliform Nucleus
o Globose Nucleus
o Fastigial Nucleus
o Don’t Eat Greasy Food
o Fat Guys Eat Doughnuts
f. Afferent Projections
 Originates from spinal cord, inferior olivary nucleus of medulla, vestibular
nuclei, and pons
 Usually terminate in cerebellar cortex and are excitatory to cortical neurons
 Fibers enter cerebellum through one of the peduncles and proceed to cortex as
either mossy fibers or climbing fibers
 Those from the spinal cord, vestibular nuclei, and pons end as mossy fibers,
which branch to supply several folia and end in granular layer
1. Axons of granule cells pass towards cortex and enter molecular layer,
where they bifurcate and form parallel fibers
 Those from inferior olivary nucleus provide excitatory input to purkinje cells as
climbing fibers
1. Also excitatory to deep cerebellar nuclei
g. Efferent Projections
 Dendritic arborizations extend towards cortex into molecular layer
1. Parallel fibers go to purkinje cells, giving cells an excitatory synaptic
input
2. Axons of the purkinje cells are the only axons to leave cerebellar cortex
3. Project to deep cerebellar nuclei
 Destinations of efferent fibers from cerebellar nuclei include:
1. Reticular and vestibular nuclei of medulla and pons
2. Red nucleus of midbrain
3. Ventral lateral nucleus of thalamus
_____________________________________________________________________________________
4. Limbic System
a. Introduction
 Brain tissue that surrounds the brainstem and lies beneath the neocortical
mantle
 Includes:
1. Hippocampus
2. Cortical Structures
3. Olfactory Structures
10
Anatomy Written Exam #2
4.
5.
6.
7.
8.
9.
10.
11.
Basal Forebrain Structures
Parahippocampal Gyrus
Cingulate Gyrus
Septal Area
Thalamic Structures
Amygdala
Hypothalamus
Hippos check out basketball playing chicks since they are hot.
o *borrowed from Christina Regelsberger
 Old part of the brain that is responsible for reactions such as fear, anger, and
emotions associated with sexual behavior
b. Hippocampal Formation
 “sea horse”
 Curved and re-curved sheet of cortex folded into the medial surface of the
temporal lobe
 Three components:
1. Subiculum
o Direct continuation of the anterior parahippocampal gyrus
o Transitional cortex- layering pattern that runs the spectrum
from 6 layers to 3 layers
o Hippocampal Sulcus- separates the subiculum from the dentate
gyrus
2. Hippocampus Proper
o Allocortex
o Three Layers:
i. Molecular- inner
ii. Pyramidal- intermediate
iii. Polymorphic- outer
o “C” shaped, interacting with the shape of the dentate gyrus
o Aka cornu ammonis
3. Dentate Gyrus
o Allocortex
o Three Layers:
i. Molecular- inner
ii. Granule- intermediate
iii. Multiform- outer
o “C” shaped, interacting with the shape of the hippocampus
proper
 “C” shaped in coronal sections
 Pathways
1. Main Afferent
o Perforant Pathway- projection to dentate gyrus
o Alvear Pathway- projection to hippocampus proper
i. Goes around lateral aspect of hippocampus proper
o Dentate Gyrus Projections- axons rom neurons of the granular
layer project to and terminate on dendrites of pyramidal
neurons in hippocampus proper
11
Anatomy Written Exam #2
2. Efferent Pathway
o Fornix- fibers from hippocampus proper and subiculum
i. “C” shaped fiber bundle which projects to
hypothalamus and septal area
ii. Parts:
1. Alveus- thin layer of white matter
2. Fimbria- coalescence of alveus into a compact
bundle to leave the surface of the hippocampal
formation
3. Crus- continuation of fibria that begins at the
posterior limit of the hippocampal formation
beneath the splenium
4. Body- where the two crura join together
a. Runs inferior to corpus callosum and
septum pellucidum
5. Columns- where body splits in two
a. Directed ventrally to hypothalamus
b. Post-commissural fibers- includes most
of fibers
i. Traverse hypothalamus and
terminate in mammillary bodies
and ventromedial hypothalamic
nuclei
c. Pre-commissural fibers- terminate in
septal area, anterior hypothalamus, and
substantia innominate
 Functions
1. No significant olfactory function
2. Stimulation results in changes to autonomics, endocrine, and behavioral
functions
3. Involved with recent memory
o Large, bilateral lesions result in profound impairment of
memory for recent events
i. General intelligence remain unaffected
ii. Unable to learn new facts and skills
iii. Anterograde amnesia- loss of memories taking place
after time of brain damage
o Damage to mammillary bodies
i. Common in alcoholism
ii. Korsakoff’s Psychosis
1. Results in memory deficits
2. Severe anterograde amnesia and cell loss
3. Intact intelligence
4. Confabulatory syndrome- make up answers to
questions to try and conceal extent of memory
loss
5. Damage cannot be repaired
c. Amygdala
12
Anatomy Written Exam #2
 “almond”
 Location
1. Found in mediodorsal portion of temporal lobe, anterior and dorsal to
tip of inferior horn of lateral ventricle
2. Deep to cerebral cortex of uncus
 Subdivisions
1. Corticomedial Group- medial portion of amygdala
o Blends with cortex of uncus
o Receives fibers from olfactory bulb
2. Basolateral Group- largest part of amygdaloid complex
o Widespread connections
 Pathways
1. Stria Terminalis- efferents to septum
o “C” shaped fiber tract
2. Ventral Amygdalofugal-efferents to septum and hypothalamus
3. Brainstem Connections
 Functions
1. Prominent olfactory input, but importance of olfactory is uncertain
2. Stimulation produced pronounced behavioral changes
o Arrest reaction- all spontaneous activity ceases as the animal
assumes an attitude of aroused attention
o Initial phase of fight or flight—interpreting presence of either a
threat or lack of a threat
3. Almost all of the same visceral or somatic activities produced by
hypothalamus stimulation
4. Destruction produced disturbances in emotional behavior
o Placid with not sign of rage, fear, or aggression
o Hypersexuality
o Kluver-Bucy Syndrome- bilateral removal of anterior temporal
lobes
i. Fearless and placid
ii. Absence of emotional reactions
iii. Males become hypersexual and indiscriminate
iv. Extreme curiosity
v. Voracious appetite
vi. Psychic blindness or visual agnosia
d. Septal Area
 Includes both cortical and subcortical nuclei
 Rostral to anterior commissure and preoptic area near base of septum
pellucidum
 Afferent Pathways
1. From hippocampal formation via pre-commissural fibers of fornix
2. From amygdala via stria terminalis
 Efferent Pathways
1. To lateral hypothalamus and midbrain tegmentum via the medial
forebrain bundle
2. To hippocampus via fornix
13
Anatomy Written Exam #2
 Functions
1. Pleasure center
2. Lesions- alterations in sexual and foraging behaviors
e. Miscellaneous Limbic Structures
 Cortical Areas
1. Prefrontal Cortex- areas 9-12 on Brodmann’s
o Function- determines affective reactions to present situations
on the basis of past experiences
2. Cingulate Gyrus- receives inputs from prefrontal cortex
o Projects to hippocampal formation via cingulum bundle
o Functions
i. Stimulation elicits autonomic and somatic effects
ii. Alterations in respiration and circulation
iii. Alterations in peristaltic and gut secretion activities
iv. Pupillary dilation
v. Muscle tone and inhibition of ongoing movements
(arrest behavior)
vi. Stimulation of anterior portion results in aggressive
behavior
1. Lesions to area make them tame and socially
indifferent
 Thalamic Structures
1. Anterior Nucleus- inputs from hypothalamus via mamillothalamic tract
and from hippocampus via fornix
2. Dorsomedial Nucleus- inputs from amygdala and prefrontal cortex
o Projects back to prefrontal cortex
 Basal Forebrain Structures
1. Substantia Innominata- contains Basal nucleus of Meynert
o Projects throughout neocortex, especially the prefrontal cortex
o Major link between limbic system and neocortex
o Shows marked cell loss in Alzheimer’s
2. Nucleus Accumbens- where the caudate and putamen are continuous
ventrally
o Modulatory role in regulating motivationally based motor
behaviors
o Primary brain interface between motivational state and motor
behavior
o Role in mediating certain addictions
f. Papez Circuit
 Nerve impulses proceed in both directions around the ring of the limbic lobe
_____________________________________________________________________________________
Study Break:
The following quotes were taken from actual medical records dictated by physicians.
o
o
o
o
By the time he was admitted, his rapid heart had stopped, and he was feeling better.
Patient has chest pain if she lies on her left side for over a year.
On the second day the knee was better and on the third day it had completely disappeared.
She has had no rigors or shaking chills, but her husband states she was very hot in bed last night.
14
Anatomy Written Exam #2
o
o
o
The patient has been depressed ever since she began seeing me in 1983
Patient was released to outpatient department without dressing.
I have suggested that he loosen his pants before standing, and then, when he stands with the
help of his wife, they should fall to the floor.
o The patient is tearful and crying constantly. She also appears to be depressed.
o Discharge status: Alive but without permission.
o The patient will need disposition, and therefore we will get Dr. Blank to dispose of him.
o Healthy appearing decrepit 69 year-old male, mentally alert but forgetful.
o The patient refused an autopsy.
o The patient has no past history of suicides.
o The patient expired on the floor uneventfully.
o Patient has left his white blood cells at another hospital.
o The patient's past medical history has been remarkably insignificant with only a 40 pound
weight gain in the past three days.
o She slipped on the ice and apparently her legs went in separate directions in early December.
o The patient experienced sudden onset of severe shortness of breath with a picture of acute
pulmonary edema at home while having sex which gradually deteriorated in the emergency
room.
o The patient had waffles for breakfast and anorexia for lunch.
o Between you and me, we ought to be able to get this lady pregnant.
o The patient was in his usual state of good health until his airplane ran out of gas and crashed.
o Since she can't get pregnant with her husband, I thought you would like to work her up.
o She is numb from her toes down.
o While in the ER, she was examined, X-rated and sent home.
o The skin was moist and dry.
o Occasional, constant, infrequent headaches.
o Coming from Detroit, this man has no children.
o Patient was alert and unresponsive.
o When she fainted, her eyes rolled around the room.
o MD during a physical exam, stated, in my ears, "I am unable to arouse this woman", personally, I
really don't think he should have bragged about it
_____________________________________________________________________________________
5. Higher Cortical Functions
a. Corticocortical Connections
 Two Classes:
1. Association Fibers- from same hemisphere
o Most numerous fiber type
o Arise from neurons in supragranular layers of cerebral cortex
and terminate in similar layers in ipsilateral hemisphere
o Fiber Tracts:
i. Unnamed fibers that connect cortical areas within same
gyrus
ii. ‘U’ fibers that connect adjacent fibers
iii. Superior Longitudinal Fasciculus
1. Course from frontal lobe to parietal, occipital,
and parietal lobes
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Anatomy Written Exam #2
2. Link between cortical areas involved with
sensory and motor skills of language
iv. Superior Occipitofrontal Fasciculus
1. Connects the frontal and occipital lobes
v. Inferior Occipitofrontal Fasciculus
1. Connects the frontal lobe with temporal and
occipital lobes
vi. Cingulum- within cingulate gyrus
1. Connects septal area and parahippocampal
gyrus
2. Commissural Fibers- from contralateral hemisphere
o Arise from neurons in supragranular layers of cerebral cortex
and terminate in similar layers in contralateral hemisphere
o Anterior Commissure- small, compact bundle that crosses
midline rostral to columns of fornix
i. Connects regions of middle and inferior temporal gyri as
well as olfactory tracts and bulbs
o Corpus Callosum- largest fiber bundle
i. Interconnect homologous regions of cortex in the two
hemispheres
ii. Four components:
1. Rostrum- anterior wall of third ventricle
2. Genu- interconnecting the anterior parts of the
frontal lobes
3. Body- interconnecting the remainder of the
frontal and parietal lobes
a. Connects primary motor cortices
4. Splenium – interconnecting regions of the
temporal and occipital lobes
a. Connects visual pathways
iii. Allow for interhemispheric integration of information
o Posterior Commissure- at diencephalonic-mesencephalic
junction
i. Connect the pretectal nuclei
ii. Functions in pupillary light reflexes
o Hippocampal Commissure- where fornix-hippocampal efferents
cross midline
b. Hemispheric Asymmetry
 Lateral fissure extends father posterior on left side than on the right and it rises
more steeply on the right
 Planum temporale is larger on the left side
1. Larger in people with perfect pitch
 Male brains are less symmetrical
 Females tend to have larger, more bulbous spleniums of corpus callosums
c. Cerebral Dominance
 Dominant Hemisphere- hemisphere that is more important for the
comprehension and production of language
1. Functions:
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Anatomy Written Exam #2
o Language and speech
o Math
o Problem solving in sequential, logical manner
o Sign language
2. Has Two Cortical Areas For Language:
o Broca’s Area- area 44 and 45
i. On inferior frontal gyrus
ii. “motor speech” area
iii. Motor skills necessary for generation of propositional
language—grammar, syntax, and semantics
iv. Projects to areas of primary motor cortex for the
execution of the articulation and phonation of speech
v. Receives inputs from Wernicke’s area
o Wernicke’s Area- area 22
i. In temporal gyri
ii. “sensory speech” area
iii. Contains the mechanisms for the understanding,
comprehension, and formulation of propositional
language
iv. Receives inputs from auditory, visual, and
somatosensory cortices
 Functions of Non-dominant Hemisphere
1. Recognition and appreciation of simple, spatial relationships
2. Music and poetry
3. Artistic ability
4. Emotion
 Wada Test- done prior to neurosurgery to localize functions within cerebral
hemisphere
1. Have patient lay down with arms raised in air
o Have them count out loud backwards
o Temporarily anesthetize one hemisphere
o In non-dominant hemisphere- arm on opposite side falls down
and patient stops counting for a few seconds and then resumes
o If dominant hemisphere- arm on opposite side falls down and
patient stops counting for a few minutes
d. Speech
 Ability to vocalize by coordinating the muscles controlling the vocal apparatus
 Mechanical aspect of oral communication
 Components to Assess During Exam
1. Volume- may be increased or decreased
2. Rate- normal is 100-150 wpm
o Increased in Wernicke’s aphasia
o Decreased in Broca’s aphasia
3. Articulation
o Defects may result in errors such as repeating the same errors
when trying to produce certain sounds (dysarthria)
4. Prosody- inflection, affective intent, and pragmatic intent
5. Initiation- timing of speech initiation
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Anatomy Written Exam #2
e. Speech Disorders
 Dysarthria- disturbance in articulation
1. Inability to form or produce understandable speech due to lack of
motor control over peripheral structures
2. Forms:
o Flaccid- due to LMN disease
o Spastic- due to UMN disease
o Ataxic- due to cerebellar disease
 Dysphonia- disturbance in vocalization or phonation
1. Inability to vocalize due to a disorder of the larynx or its innervation
2. Most common: laryngitis
 Phonic Tics and Vocalizations
1. Simple Tics- inarticulate noises and sounds
2. Complex Tics- expressed as articulate words, phrases, or sentences
o Ex- Tourette’s
o Types:
i. Echolalia- involuntary repetition of the last sound,
word, phrase, or sentence of another person
ii. Coprolalia- involuntary utterance of socially
unacceptable or obscene words, phrases, or sentences
3. Other Tics
f.
 Stutter
1. Most commonly developmental
2. More common in males
3. Involuntary repetition of first syllable of a word
4. Stutter- machine-gun like repetition
5. Stammer- initial vocalization followed by prolonged silence
6. May be the result of a struggle for cerebral dominance
Language
 Cognitive aspect of symbolic communication
 Ability to converse, comprehend, repeat, read, and write
 Six Parts of Examination
1. Expressive Speech- spontaneous or conversational speech
2. Comprehension
3. Repetition
4. Naming
5. Reading
6. Writing
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Anatomy Written Exam #2
g. Language Disorders
 Aphasia- language dysfunctions caused by neurological disorders
 See attached table.
 Alexia- loss of ability to read
1. Visual information has lost access to Wernicke’s area
2. Lesion usually to connections in and around angular gyrus
3. Dyslexia- incomplete alexia
 Agraphia- loss or impairment of the ability to produce written language due to
brain dysfunction
1. Lesion usually to inferior parietal lobule, especially angular gyrus
 Prosopagnosia- inability to recognize familiar faces
 Aprosodia- problems with prosody, the rhythmic and musical aspects of speech
1. Motor- inability to convey emotions by voice or gestures; monotone
2. Sensory- difficulty comprehending emotional content of speech or
gestures
h. Agnosia
 Inability to recognize or be aware of an object when using a given sense, even if
that sense is functionally intact
 Sensory or Tactile
1. Lesions in superior parietal lobe
2. CONTRALATERAL loss of sensory discrimination
3. Inability to recognize objects by touch alone
 Visual
1. Lesions of visual association cortices
2. Inability to recognize objects by sight alone
i. Apraxia
 Inability to correctly perform certain learned, skilled movements on command
 Usually able to perform same action in a different context, such as a reflex
 Three Common Types:
1. Kinetic- lesion of premotor cortex
o Difficulties in fine motor control
o Loss of ability to make finely graded, precise individual finger
movements
2. Ideomotor- lesion of supramarginal gyrus
o Inability to perform many complex tasks on command
3. Ideational- seen in degenerative dementia
o Inability to perform a series of acts to obtain a goal
j. Prefrontal Cortex
 Does not elicit somatic motor movements when stimulated
 Helps determine affective reactions to present situations based upon past
experiences
 Monitors behaviors and exercises control based on higher mental faculties
 Lesions
1. Inappropriate social behavior
2. Difficulties in adaptation and loss of initiative
k. Neglect Syndromes
 Lesion of the non-dominant parietal lobe
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Anatomy Written Exam #2
 Lack of appreciation of spatial aspects of all sensory input from
CONTRALATERAL side of body and visual field
 Patients sometimes ignore half of their body
 Often deny deficit
l. Split-Brain Syndromes
 Severing the corpus callosum
 Exhibit no neurological deficits, they look and act normally
 Inability of blindfolded patient to match an object held in one hand with object
held in other hand
m. Alexia without Agraphia
 Lesion of posterior cerebral artery and destruction of visual cortex and splenium
 Can write but not read
_____________________________________________________________________________________
6. Motor Pathways—Integration
a. Basal Ganglia are sometimes referred to as components of the ‘extrapyramidal motor
system’
 Both pyramidal and extrapyramidal systems are intimately related rather than
separate
b. Two Main Roles of Basal Ganglia
 Facilitate movements that are required and appropriate in any particular
context
 Inhibit unwanted or inappropriate movements
c. When a movement is initiated from the cerebral cortex….
 Impulses discharge through corticospinal, corticobulbar, and corticostriatal
pathways to neostriatum, which causes excitation of striatal neurons
 Striatum has two routes to control basal ganglia output:
1. Direct Pathway
o Consists of striatopallidal and striatonigral neurons
o Inhibits medial pallidal or pars reticulate neurons
i. Leads to disinhibition of target neurons, the VA and VL
nuclei of thalamus
ii. Results in increase in thalamic neuron activity and
excitation of cerebral cortex
o Effect: support or facilitate ongoing movements
2. Indirect Pathway
o Via subthalamic nucleus
o Efferents rom striatum terminate in lateral pallidal segment,
inducing inhibition of neurons
i. Caused disinhibited subthalamic nucleus
ii. Results in an increase in discharge of subthalamic
neurons
iii. Activates medial pallidal and nigral neurons
iv. Inhibition of thalamic and cortical cells, which inhibits
unwanted movement
d. Pathophysiology of Basal Ganglia Disorders
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Anatomy Written Exam #2
 Normally, dopamine appears to exert an excitatory influence on striatal neurons
of direct projection and an inhibitory effect on neurons of indirect pathway
 Loss of striatal dopamine causes underactivity of direct pathway and
overactivity of indirect pathway
1. Leads to disinhibition of subthalamic nucleus
 Causes akinesia- absence or loss of voluntary movements
e. Basal Ganglia Diseases
 Parkinson’s Disease
1. A neurodegenerative disease, usually in the elderly with an unknown
cause
2. Akinesia, flexed posture, rigidity, and a resting tremor
3. Hallmark: degeneration of dopaminergic neurons of pars compacta of
substantia nigra and depletion of striatal dopamine levels
4. Most effective treatment is levodopa
o Immediate metabolic precursor of dopamine
o Converted to dopamine and restores normal striatal function
o Long term complication: levodopa induced dyskinesia
5. When drug therapy fails- neurosurgical ablation or electrical stimulation
of subthalamic nucleus or medial segment of globus pallidus
 Huntington’s Disease
1. Excessive, unwanted, abnormal movements
2. Autosomal dominant
3. Chorea and progressive dementia
4. Progressive degeneration of striatum and cerebral cortex
5. Within striatum, attrition of cells that project to lateral segment of
globus pallidus
o Leads to disinhibition of lateral pallidol neurons and inhibition
of subthalamic nucleus
o Medial pallidal neurons become underactive, resulting in
unwanted, involuntary movements
f. Terms for Basal Ganglia Syndromes
 Unilateral basal ganglia lesions produce effects on CONTRALATERAL side of body
 Does not cause paralysis, sensory loss, or ataxia
 Leads to abnormal motor control, alterations in muscle tone, and emergence of
abnormal, involuntary movements
1. Bradykinesia- slowness of movement
2. Hypokinesia/akinesia- poverty of movement
3. Normal posture cannot be maintained and limb movements when
walking are lost
 Dyskinesias describe abnormal movements, not underlying disease
1. Tremors- to and fro sinusoidal movement
2. Chorea- sequence of rapid, asymmetrical, and fragmented movements
usually affecting distal limbs
3. Dystonia- sustained muscular contractions that give rise to abnormal
postures or contortions
4. Athetosis- slow, sinous, writhing movements
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Anatomy Written Exam #2
5. Myoclonus- sudden, shock like movements, which are usually bilateral
and affect upper limbs
6. Tics- stereotyped movements influenced by emotional stress
g. Other Basal Ganglia Diseases
 Hepatolenticular Degeneration
1. Aka Wilson’s disease
2. Autosomal recessive
3. Disorder of copper metabolism
4. Choreo-athetosis and progressive dementia in childhood and youth
 Sydenham’s Chorea
1. Manifestation of rheumatic fever in young females
2. Abnormal behavior and generalized chorea
 Hemiballism
1. Violent choreiform movements of limbs on one side of body
2. Caused by lesion of contralateral subthalamic nucleus
 Dystonia
1. Syndrome of abnormal muscle contraction that produces repetitive
involuntary twisting movements and abnormal posturing
2. Affect the arm and hand (writer’s cramp), leg, neck (torticollis), or face
and mouth (orofacial dyskinesia)
_____________________________________________________________________________________
Study Break:
A man was walking home alone late one night when he hears a BUMP... BUMP... BUMP... behind him.
Walking faster he looks back, and makes out the image of an upright coffin banging its way down the
middle of the street towards him ... BUMP... ....BUMP... ....BUMP...
Terrified, the man begins to run towards his home, the coffin bouncing quickly behind him ... faster...
faster... BUMP... BUMP... BUMP. He runs up to his door, fumbles with his keys, opens the door, rushes
in, slams and locks the door behind him.
However, the coffin crashes through his door, with the lid of the coffin clapping ... clappity-BUMP...
clappity-BUMP... clappity-BUMP... on the heels of the terrified man.
Rushing upstairs to the bathroom, the man locks himself in.
His heart is pounding; his head is reeling; his breath is coming in sobbing gasps. With a loud CRASH the
coffin breaks down the door. Bumping and clapping towards him. The man screams and reaches for
something, anything ... but all he can find is a bottle of cough syrup!
Desperate, he throws the cough syrup at the coffin ...
.... and of course ... the coffin stops
_____________________________________________________________________________________
7. Sensory Pathways—Integration
a. Etiology of Neurological Disease
 Four Major Types:
1. Extrinsic
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Anatomy Written Exam #2
o
o
Treated with neurosurgery
Lead to compression of the brain, spinal cord, nerve roots, and
peripheral nerves
o Investigation: CNS/PNS prior to surgery
o Delay in decompression can lead to permanent paralysis,
sensory loss, and incontinence
2. Systemic
o Treated with medicine
i. Can lead to cure
o Primarily disorder of organs instead of nervous system
o Disrupt neurological function by abnormal metabolism
o Caused by:
i. Intoxication with drugs
ii. Dietary deficiency
iii. Failure of cardiorespiratory system, liver, or kidneys
iv. Hormonal disorders
v. Abnormalities in calcium and potassium balance
o Investigation: hematological
3. Vascular
o Treated with cardiology
o Damage of circulation to nervous system
o Thrombosis- occlusion of vessels
o Infarction- restricting blood and oxygen supply
o Hemorrhage- bleeding into nervous tissues
4. Intrinsic
o Treated with neurology
o Primary disorders of the nervous system itself
o Uncommon
o Often chronic and irreversible
o Usually genetic
i. Paroxysmal Disorders- episodic loss of consciousness,
excessive sleep, and headache
ii. Inborn Errors of Metabolism- lead to mentally
subnormality and disability in children
1. Usually caused by deficiencies in specific
enzymes
iii. System Degenerations- lead to premature death of
certain neuromuscular components
o In youth: often have obvious genetic cause
o In adults: often more sporadic
o Systemic degenerations are selective
 Causes ranked in order of clinical priority to detect common, life-threatening
diseases, or reversible are either established or excluded first
 Neoplasia- excessive uncontrolled growth of tissues, forming a benign or
malignant tumor
1. Primary- arise in neuromuscular tissues themselves
2. Secondary- spread in circulation from other primary organ sites
 Inflammation of neuromuscular tissue may results from…
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Anatomy Written Exam #2
1. Infection
2. Immune Disorders
o Most common is multiple sclerosis
3. Investigate with microbiological and serological tests of blood and CSF
4. Treat infection with antimicrobials and suppression of immune
responses
 Site of Lesion and Clinical Syndromes
1. In order to understand the relationship between neuroanatomy and
clinical signs:
o Know routes of major sensory and motor pathways
i. Tactile and proprioceptive information passes
IPSILATERALLY in the dorsal columns of spinal cord
before decussating in lower brain stem and passing via
the thalamus to the CONTRALATERAL sensory cortex
ii. Sensory pathways for pain and temperature decussate
within the spinal cord and travel to CONTRALATERAL
spinothalamic column before reaching the contralateral
sensory cortex
iii. Dissociated sensory loss- damage of one pathway but
other pathway is spared
o Lesions of LMN and UMN
i. LMN
1. Weakness and paralysis of individual muscles
2. Wasting
3. Fasciculation
4. Hypotonia
5. Diminution or loss of deep tendon reflexes
ii. UMN
1. Weakness or paralysis of specific movements
(pyramidal weakness)
2. NO wasting
3. Spasticity and initial resistance to muscular
stretching followed by relaxation
4. Hyperreflexia
5. Babinski reflex
o General functions of cerebellum, basal ganglia, and cerebral
cortex
i. Cerebellar Pathways
1. Plan of an intended movement is transmitted to
cerebellum from cerebral cortex and basal
ganglia
2. Compares intended movements with actual
movements of limbs in space
3. Able to correct deviant movements
4. Lesions:
a. Incoordination of movements (ataxia)
of head, neck, and limbs in the absence
of weakness or loss of sensation
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Anatomy Written Exam #2
b. Unilateral lesions lead to IPSILATERAL
loss off coordination
5. Cerebellar Syndrome- nystagmus, dysarthria,
intention tremor of upper limbs, and gait ataxia
ii. Basal Ganglia
1. Receive sensory and motor information from all
parts of cerebral cortex, brain stem, and spinal
cord
2. Facilitate useful, purposeful movements and
inhibit unwanted movements
3. Control of posture and muscle tone
4. Lesion:
a. Loss of control over voluntary
movements and posture
b. Unilateral lesions cause
CONTRALATERAL symptoms
c. Do NOT lead to loss of sensation,
power, or coordination
iii. Cerebral Cortex
1. Functions of language, perception, spatial
analysis, learned skilled movements, memory,
and problem solving are organized here
2. Language functions organized in frontal,
parietal and temporal lobes adjacent to lateral
fissure
3. Primary visual processes organized in occipital
lobes
4. Perception or recognition of objects and faces
are organized in projections to temporal lobes
5. Spatial ability to navigate limbs and body in
space is organized in parietal lobes
6. Premotor areas of frontal lobes govern
enactment of learned, skilled movements of
head, neck, and limbs
7. Structure in medial aspects of temporal lobes
are responsible for learning new information
and recollecting from experience
8. Organization of behavior is organized in
prefrontal areas of frontal lobes
2. Examine:
o Cranial nerves and motor system
o Reflexes
o Sensations
o Coordination
GOOD LUCK!!!!
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