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NEUROANATOMY REVIEW. February 24, 2006. BRODMANN’S AREAS. 8 = Frontal Eye Field 6 = SMA & Premotor ctx 5,7 = Post Parietal Ctx (apraxia, dom. side) 4 = Primary motor ctx 3,1,2 = Primary somatosensory ctx 41,42 = Primary auditory ctx (Transverse gyrus of Heschl)

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neuroanatomy review

NEUROANATOMY REVIEW

February 24, 2006

slide2

BRODMANN’S AREAS

8 = Frontal Eye Field

6 = SMA & Premotor ctx 5,7 = Post Parietal Ctx (apraxia, dom. side)

4 = Primary motor ctx

3,1,2 = Primary somatosensory ctx

41,42 = Primary auditory ctx (Transverse gyrus of Heschl)

44,45 = Broca’s speech area (Inf Frontal Lobe; expressive dysprosody)

22 = Wernicke’s speech area (arcuate fasciculus connect to Broca’s; receptive dysprosody)

40 = Supramarginal gyrus (Rt/Lt confusion, dyscalculia, agnosia)

39 = Angular gyrus (dyslexia & dysgraphia)

Inf Parietal Lobe

slide3

PARIETAL LOBE(in addition to Area 3,1,2…general recognition such as ideas, patterns, symbols)

Sup Parietal Lobe (either side)

- contralateral sensory neglect (form of apraxia--constructional, dressing)

Inf Parietal Lobe (Area 40, 39: Gerstmann’s syn on dominant side)

- agnosia (prosopagnosia--faces, anosognosia--unaware of paralysis, Rt/Lt confusion)

- dyscalculia (math), dyslexia & dysgraphia (reading & writing)

- lower quadrantanopia (visual radiations to cuneus)

Inf Parietal Lobe (Area 40, 39: usually for non-dominant hemisphere)

- astereognosis (tactile agnosia)

- apraxia (Areas 5-7, Post Parietal Lobule)

- lower quadrantanopia (visual radiations to cuneus)

TEMPORAL LOBE(HIPP, amygdala, auditory Area 41 42, Meyer’s loop)

Parahippocampal Uncus = (deep to ctx lies amygdala) part of primary olfactory ctx.

Mesial Temporal Sclerosis—seizures can have smell or visual aura.

slide4

Wernicke’s Encephalopathy (Thiamine/Vit B1 defic)

1) Nystagmus 2) Ataxia 3) Mental status change

Korsakoff’s confabulatory syn

1) Mem loss & confabulation

PAPEZ CIRCUIT

HIPP

Septal area

Hypothal

Fornix

VAFP/VAPP (Ansa Lenticularis)

Stria terminalis

Fornix

Ventral AmygdaloFugal Pathway Ventral AmygdaloPetal Pathway

Mamillary body

Amygdala

Mamillothalamic tract

Olfactory, Sensory, Autonomic

Ant nuc of thalamus (MD)

Ant limb of internal capsule

Cingulate gyrus

Perforant pathway

Cingulum

Entorhinal ctx

slide5

AMYGDALA

Helps integrate complex sensory, emotional, and autonomic input for behavioral/emotional response.

Output via Stria Terminalis posteriorly by tail of caudate and arches over thalamus to anterior hypothalamus.

Output via Ventral Amygdalofugal Pathway (VAFP) to Caudate(BG)/Septal Area.

1. Central (integration of viscerosensory info with basal forebrain: septal nuc, nuc basalis of Meynert, & diagonal band of Broca) 2. Corticomedial (appetitive behaviors such as feeding, drinking, & reproduction with hypothalamus) 3. Basolateral (emotions, learning, & planning; with HIPP/limbic & BG)

Klüver-Bucy Syndrome

(bilateral ablation of ant temporal lobes containing amygdala)

  • Docility
  • Hypersexuality
  • Hyperphagia
  • Visual agnosia
slide6

HYPOTHALAMUS Homeostasis (autonomic, endocrine, & limbic systems)Can survive with half of hypothalamus

slide7

Ant Hypothal Nuc (“AH” dissipates heat, parasympathetic)

Post Hypothal Nuc (conserves heat, sympathetic)

Parvocellular PVN

PVN & SON (produce oxytocin & ADH/vasopressin, destructionDI, PVNCRH)

SUPRAOPTICO- HYPOPHYSIAL TRACT to post pituit

Magnocellular PVN

Preoptic area (Medial Preoptic Nuc) (sexually dimorphic, regulates gonadotropic hormones)

Suprachiasmatic nuc (direct retinal input, circadian rhythms)

OPTIC CHIASM

Dorsomedial Nuc (stim causes obesity & savage behavior)

Neuro- hypophysis

Adeno- hypophysis

Lat Nuc (appetite center, stim induces eating, destruction causes starvation)

VMN

Arcuate Nuc (DA-ergic neurons inhib prolactin release) TUBERO- HYPOPHYSIAL TRACT to ant pituit

Ventromedial Nuc (VMN) (satiety center, stim stops eating, destruction causes obesity & savage behavior)

slide8

HYPOTHALAMIC FIBER SYSTEMS

Fornix

From HIPP to mamillary nuclei (then Mamillothalamic tract to Ant Thal Nuc)

Medial Forebrain Bundle (MFB)

  • in lat portion of hypothalamus, lat to fornix
  • unmyelinated, major connection b/n cerebral ctx & BS
  • no synaptic relay through thalamus
  • receives monominergic neurons from the locus coeruleus (NE), raphé nuclei (5-HT), and ventral tegmental area (DA).

Hypothalamo-spinal tract

Descending autonomic fibers for sympathetic neurons (thoracolumbar lateral horn) and parasympathetic neurons (sacral lateral horn)

Lesion or interruption above T1 can cause Horner’s syndrome (miosis, ptosis, anhidrosis, & apparent enophthalmos)

slide9

HYPOTHALAMIC FIBER SYSTEMS

Stria terminalis…

Stria terminalis--Amygdala to hypothalamus/septal area. STRIA = STRANDS (sup to fornix at border of caudate/thalamus)

Lamina terminalis--from anterior commissure in rostral 3rd ventricle down to optic chiasm; closure of ant neuropore; anencephaly) LAMINA = LAYER

Stria medullaris thalami--Habenular nuclei (in epithalamus) to hypothalamus/septal area (in 3rd ventricle roof inf to fornix; relay between midbrain reticular formation and limbic forebrain). STRIA = STRANDS, MEDULLARIS is also in the MEDULLA THALAMI lies completely on thalamus

Stria medullaris of 4th ventricle--runs from arcuate nuc of pyramids (out through the central sulcus) to Inf Cereb Ped between Pons & Medulla.

Sulcus Limitans--divides Alar & Basal plates. SULCUS = GROOVE

slide10

EMBRYOLOGIC DEVELOPMENT

Neural Tube (CNS, pregang ANS)

Neural Crest (PNS including DRG, postgang ANS)

Sulcus Limitans SULCUS = groove (divides Alar & Basal plates)

Alar plate (sensory)

Basal plate (motor)

Rhombencephalic lip (in roof of 4th ventricle becomes Cerebellum)

Retinoic acid (Vit A) = expression of dev’tal genes like Hox (rostral-caudal segm.) Folic acid = prevent neural tube problems. SHH (Sonic Hedgehog) = notochord for dorsal/ventral axis.

slide11

EMBRYOLOGIC DEVELOPMENT

Cephalic flexure

Pontine flexure

Cervical flexure

PRIMARY VESICLES

SECONDARY VESICLES

Telencephalon (lateral ventricles)

Prosencephalon

Diencephalon (3rd ventricle)

Mesencephalon (cerebral aqueduct)

Mesencephalon

Metencephalon (upper 4th ventricle)

Rhombencephalon

Myelencephalon (lower 4th ventricle, central canal)

thalamus

THALAMUS

BLOOD SUPPLY

1. PCA (post circulation) 2. PCOM (ant circulation) 3. Ant Choroidal (ant circulation)

slide13

Ant+MD/DM (Papez—limbic emotion)

VA/VL (GP+SN—EPS motor)

VPL (sensory--body)

VPM (sensory--head)

LGN (vision, Light)

MGN (hearing)

Pulvinar (sensory association)

Intralaminar CM (diffuse to cerebral ctx, ends in layer I for cortical excit)

Reticular (GABA-ergic to thal)

= ANT-MED (limbic)

= ANT-LAT (EPS)

= POST (sensory)

= NON-SPECIFIC (relay)

slide14

Caudate

Caudate

Fornix

VA (VL)

VA (VL)

Ant

Ant

Interthalamic adhesion

Cerebral peduncle

Cerebral peduncle

Mamillary bodies

Ant

Ant

Pulvinar

Pulvinar

VL

VL

MD

Pineal gland

CM

CM

MD

MD

Sup colliculus

LGN

LGN

VPL

VPL

MGN

MGN

VPM

VPM

Midbrain

Zona Incerta

STN

Pons

LD or DL

LP

hippocampus

HIPPOCAMPUS

HIPPOCAMPAL FORMATION (declarative mem)a) Dentate gyrus—HIPP input & output to HIPP pyramidal cells.b) Hippocampus properor Cornu Ammonis (CA)—to fornix then septal area.c) Subiculum—to fornix then mamillary nuc.

Alzheimer’s Disease affects neurons in Nuc Basalis of Meynert (ACh), Locus Coeruleus (NE), Entorhinal ctx, and CA1/Subiculum of HIPP.

MONOMINERGIC NUCLEI (connections with limbic system, HIPP) 1. Nucleus Basalis of Meynert (ACh) 2. Locus Coeruleus (NE) 3. Raphé Nuclei (5-HT) 4. Ventral Tegmental Area (DA), SNpc, Arcuate/tuberal nuc of hypothalamus

SNpr (GABA)

slide16

Dentate gyrushas afferents & efferents entirely within HIPP formation.

CA1 projects to Subiculum and pre-commissural FORNIX (to septal area).CA3projects to CA1 and pre-commissural FORNIX.CA4(hilus of dentate gyrus) receive afferents from dentate and projects to bilateral dentate gyri (via hippocampal commissure).

Subiculumprovides main efferents to post-commissural FORNIX (to hypothalamus, thalamus, & mamillary bodies).

HIPP proper

slide17

Pyr system (CS tract)

Spastic Paralysis

Flaccid Paralysis

UMN lesion

LMN lesion

1. Weakness 2. No atrophy 3. Inc tone 4. Inc DTR 5. Babinski

STRENGTH MUSCLE TONE REFLEXES BABINSKI

1. Weakness 2. Atrophy (fasciculation/fibrillations) 3. Dec tone (hypotonia) 4. Dec DTR (hyporeflexia) 5. Downgoing toes

Lesions above BS (c/l paralysis of face & body)

Lesions at BS (crossed signs: i/l face, c/l body)

Lesions below BS (no face involvement: hemisection causes crossed sensory signs, i/l touch etc, c/l pain & temp)

slide18

Pyr system (CS tract)

Spastic Paralysis

Flaccid Paralysis

UMN lesion

LMN lesion

1. Weakness 2. No atrophy 3. Inc tone 4. Inc DTR 5. Babinski

STRENGTH MUSCLE TONE REFLEXES BABINSKI

1. Weakness 2. Atrophy (fasciculation/fibrillations) 3. Dec tone (hypotonia) 4. Dec DTR (hyporeflexia) 5. Downgoing toes

EPS (Basal Ganglia)

Cerebellum

  • Chorea (Huntington’s, Syndenham’s)
  • Athetosis (choreoathetosis in HD, Tardive dyskinesia when antipsychotics block DA receptors & make super-sensitive)
  • Hemiballismus (stroke to c/l STN)
  • Parkinson’s vs Diffuse Lewy Body Dz (bradykinesia, truncal instability, resting tremor, dementia)

1. Intention tremor 2. Ataxia (fall towards lesion, gait & trunk dystaxia, dysrhythmokinesia, dysdiadochokinesia, dysmetria) 3. Nystagmus 4. Dec DTR/tone ipsilaterally 5. Asthenia (mm tire easily)

slide19

Lenticular nuc = Put + GP Striatum/Neostriatum = Put + Caud Corpus striatum = Put + Caud + GP

Glutamate

GABA

(Glycine in SC)

Input from Ctx--Net excitation Input from D1 recep—Net excitation

DIRECT PATHWAY

Ctx

Striatum

GPi/SNr

VA/VL thalamus

Ctx

Parkinson’s

D1 recep

SNc

Input from Ctx—Net inhibition Input from D2 recep—Net excitation

INDIRECT PATHWAY

Ctx

Striatum

GPe

STN

GPi/SNr

VA/VL thalamus

Ctx

Parkinson’s

D2 recep

SNc

slide20

Striatum(GABAergic neurons)--have both D1 recep (Gs; contain excitatory Substance P or dynorphin) & D2 recep (Gi; inhibitory Enkephalin or neurotensin).

Net LOSS of excitation in Parkinson’s Dz.

Pallidotomy destroys segments of GPi to reduce inhibition of thalamus (interrupts direct & indirect pathways). GPi and GPe tend to always be on/active.

GPe is constantly on. In Huntington’s chorea, the striatum (ACh & GABAergic medium spiny neurons) are destroyed so GPe overstimulates Ctx.

Damage to STN results in Hemiballismus due to decreased stim of thalamic inhibition to Ctx.

cerebellar peduncles

Cerebellar Peduncles

1. Sup Cerebellar Ped (cerebellum to cerebral ctx = dentatothalamic tract, VSCT)

2. Middle Cerebellar Ped (cerebral ctx to cerebellum = pontocerebellar fibers)

3. Inf Cerebellar Ped (spine to cerebellum = DSCT, CCT, OCT, vestibulocereb…JRB)

cerebellum

CEREBELLUM

Functional vs Anatomical Divisions

cerebellar synonyms

Cerebellar Synonyms

1. VERMIS = Medial zone or (part of) Spinocerebellum

2.PARAVERMIS = Intermediate zone or (part of) Spinocerebellum

3.CEREBELLAR HEMISPHERES = Lateral zone or Cerebrocerebellum (or Pontocerebellum)

4.FLOCCULONODULAR LOBE = Vestibulocerebellum

slide24

Cerebellar Function

1. VERMIS = axial motor fxn; balance (Fastigial nuc) Spinocerebellum

2.PARAVERMIS = distal motor fxn/execution (Globose & Emboliform) Spinocerebellum

3.CEREBELLAR HEMISPHERES = motor planning (Dentate) Cerebrocerebellum

4.FLOCCULONODULAR LOBE = eye mvmt & balance; vestibulo-ocular reflex. Vestibulocerebellum

slide25

4 Cerebellar Deep Nuclei

5 Types of Cerebellar Cells (know if excit or inhib; know if they project out of cerebellum or not)

slide26

Cerebellar Deep Nucleireceive excitatory afferents from Climbing fibers and Mossy fibers (collaterals on their way to the Granule layer).

Purkinje cell (only ones that project out of ctx) inhibitory fibers from Cerebellar Ctx to Cerebellar Deep Nuclei. Climbing fibers from Inf Olivary Nuc via Inf Cerebell Ped.

Granule cell(only excitatory CELL) endings (Parallel Fibers) go to Molecular layer but not out of Cerebellar Ctx. Stellate, Basket, & Golgi cells (inhibitory) do not project out of Cerebellar Ctx either.

slide27

Flocculo-nodular lobe projects to Medial and Lateral Vestibular Nuclei.

Medial Vestibular Nuclei assist coordinating eye movement with body.

Lateral Vestibular Nuclei assist postural control.

Don’t confuse Dentate nuclei (cerebellum) and Dentate gyri (HIPP).

slide28

Rubrospinal tracts (gross mvmts) cross immediately in midbrain.

Rt cerebellum (Decussation of Sup Cereb Ped, then surrounds Red Nuc on BS slides) to Lt Red Nucleus (Rubrospinal tract) crosses to innervate Rt arm & leg.

CEREBELLAR TESTS/SIGNS(cerebellum provides constant feedback & adjustment)

1. Posture/balance maintenance (DYSEQUILIBRUIM or TRUNCAL/GAIT ATAXIA) = fall towards affected side.

2. Voluntary motor activity/coordination (DYS-SYNERGIA) = finger-to-nose (intention tremor & dysmetria), pronator drift with poor adjustment, dysdiadochokinesia, foot tap/heel-shin, nystagmus on extreme gaze.

3. Helps in muscle tone maintenance (HYPOTONIA)

*Romberg test = vision, vestibular, DC-ML. (not SC tract or cerebellum, which are for unconsc proprio).

slide29

BV’s & CN’s

Pituitary adenoma

Acoustic neuroma (Schwannoma) at CPA

Berry aneurysms (ACOM, MCA, PCOM, basilar tip)

asymptomatic unless large or rupture (possible death)

rupture—SAH, hemorr stroke (seizures, HCP)

worst HA of life (10/10)

ADPKD, Ehlers-Danlos, Marfan’s

slide30

ICA-MCA aneurysm can put pressure on side of optic chiasm.

Basilar tip aneurysm can put pressure on CN3’s.

Lat striate or Lenticulostriate aa of cerebral hemorrhage (internal capsule).

Occlusion of PCA distal to PCOM can result in Ant choroidal to Post choroidal aa.

Labyrinthine a from AICA or Basilar a.

Post Spinal a from PICA or Vertebral a.

slide31

Autoregulation allows constant blood flow over wide bp range (local metabolite control).

Pupillary light reflex CN2 afferent & CN3 efferent.

CN2 lesionpreserves consensual reflex. CN3 lesion causes blown-pupil (mydriasis), down-and-out eye, droopy eyelid, & no light reflex on affected side (no direct or consensual).

Corneal blink reflex CN5 (V1) afferent & CN7 efferent.

DTR’s

Ankle jerk = S1 Knee ext = L2,3,4 Brachiorad = C5 Biceps = C6 Triceps = C7

Abdominal = T8-T12 Babinski = L5-S1

slide32

Internal Capsule

BLOOD SUPPLY

ANT LIMB = ACA (medial striate) + MCA (lateral / lenticulostriate)

GENU = ICA (Ant Choroidal)

POST LIMB = ICA (Ant Choroidal) + MCA (lateral / lenticulostriate)

FIBERS

ANT LIMB = cerebral ctx to/from thalamus (rest of Int Capsule too)

GENU = CB tract

POST LIMB = CS tract (A-T-L), DC-ML, ALS

slide33

1. Epidural lens 2. Subdural falx 3. Subarachnoid (ventricles) 4. Intraparenchymal bleeds

Scalp infections down through valveless emissary vv.

Pineal tumors (Perinaud’s syn) block cerebral aqueduct & impose on sup colliculus

slide34

HCP ex-vacuo (big ventricles, nml ICP, shrunken brain)

NPH (big ventricles, nml ICP)

Pseudotumor cerebri (nml or slit ventricles, inc ICP)

Communicating vs Non-communicating Hydrocephalus (HCP)

Above or below 4th ventricle

Choroid plexus Creates CSF, Arachnoid villi/granulations Absorb CSF

slide35

HERNIATION SYNDROMES

Subfalcine

Transtentorial

Foraminal

slide36

TEMPORAL

NASAL

TEMPORAL

Ipsilateral blindness

Nasal hemianopia

Contralateral hemianopia with macular sparing

Bitemporal hemianopia

to LGN, optic radiations, then occipital lobe

Contralateral hemianopia

slide37

LGN

Crossed fibers to layers 1, 4, 6

Uncrossed fibers to layers 2, 3, 5

to LGN, optic radiations, then occipital lobe

slide38

Temporal lobe visual radiations (Meyer’s loop) to lingual gyrus

Contralateral upper quadrantanopia

LGN to OCCIPITAL LOBE

Parietal lobe visual radiations to cuneate gyrus

Contralateral lower quadrantanopia

Calcarine fissure

to LGN, optic radiations, then occipital lobe

slide39

Constricted field (glaucoma)

Central scotoma (optic neuritis in MS)

Lower altitudinal hemianopia (bilateral cuneate gyri)

to LGN, optic radiations, then occipital lobe

Upper altitudinal hemianopia (bilateral lingual gyri)

slide40

Sup Colliculus

Vertical gaze

MLF

coordinates CN3 & CN6

(internuclear ophthalmoplegia in MS)

  • carries info from pontine Horizontal Gaze Centers (PPRF) to oculomotor complex in midbrain.
  • Helps during turning of head (conjugate gaze); inc activity during mvmt.
slide41

Voluntary Conjugate Gaze

One-and-a-half Syndrome

Argyll-Robertson’s pupils (syphilis) brachium of sup colliculus

Optic radiation

Visual ctx

Rt Pontine Paramedian Reticular Formation (PPRF; lat gaze center)

Lt Medial Longitudinal Fasciculus (MLF)

Lt Area 8 (FEF)

Rt CN6

Lt CN3

[Rt Gaze]

Pupillary Light Reflex

Optic n/chiasm/tract (CN2)

Sup Colliculi (pretectal area)

Ciliary ganglia (CN3 Edinger-Westphal)

LGB

Accommodation

Optic n/chiasm/tract (CN2)

Sup Colliculi (pretectal area)

Ciliary ganglia (CN3 Edinger-Westphal)

LGB

slide42

HEARING

  • Medial Sup Olivary Nuc (SON) is 1st place with binaural processing (ipsilat & contralat distribution to Lateral Lemniscus). Lesion after cochlear nuclei will decrease hearing bilaterally (more in contralateral ear).
  • Lateral Sup Olivary Nuc (SON) has intensity differences for horizontal position orientation.
  • The Inner hair cells transduce sound, and Outer hair cells modify sound(olivocochlear efferents). Scala media (endolymph—high K+).
  • The high frequencies are closest to Oval window/Stapes at the sound entry point(base of cochlea at scala vestibule and NOTround window at the end of the scala tympani)a.k.a. tonotopic organization, and high freq is dorsomedial in cochlear nuclei.
healing

ANTEROGRADE degeneration is Wallerian degeneration—axons & myelin sheaths disappear. (e.g., Pt dies from mid-thoracic crush of spine. Stain of cervical spine shows Wallerian degeneration of…fasciculus gracilis.)

  • RETROGRADE degeneration is Chromatolysis—loss of Nissl substance (RER & free polyribosomes at cell body and dendrites are lost b/c axons no longer need NT)
  • In the CNS, glial scars formed by astrocytes inhibit healing(reactive astrogliosis).
  • For successful axonal repair, macrophages must clean debris.
  • 5. Axonal elongation is 2-4 mm/d in the CNS (oligodendrocytes) or PNS (Schwann cells).

HEALING

healing1

Nerve Growth Factor (NGF) is a target-derived neurotrophic factor (peptide for DRG, ANS, and basal forebrain ACh neurons in CNS)

  • tropic (differentiation; turning toward stim)
  • trophic (growth & survival)
  • Other target-derived neurotrophic factors include…Neurotrophins (NGF, BDNF, NT3) and IGF1 + FGF + GDNF + CNTF + TGF-beta.
  • BDNF is synthesized in cell body & transported anterogradely down the axons (unlike NGF or GDNF).

HEALING

neurohistology

Sensory neurons = Pseudounipolar, myelinated

(DRG and CN 5, 7, 9, 10)

Neurohistology

Special senses = Bipolar (smell is unmyelinated-slow, hearing is myelinated-fast)

(CN 1, 2, 8)

Motor neurons = Multipolar

(αMN, ANS)

6 layered neocortex

AFFERENT (Layer IV is big in Brodmann Area 3,1,2)

EFFERENT (Layer V is big in Brodmann Area 4)

granular layers (II,IV = in)

pyramidal layers (III,V,VI = out)

Layer I (Molecular)

Layer II (External Granular)—cortico-cortical fibers in.

Layer III (External Pyramidal)—cortico-cortical fibers out.

Layer IV (Internal Granular)—thalamocortical fibers in (VPL, VPM, LGN).

Layer V (Internal Pyramidal)—CS/CB, & corticostriatal fibers out. (Betz giant pyramidal cells)

Layer VI (Multiform)—corticothalamic fibers out.

6-Layered Neocortex

sensory motor homunculi

SENSORY & MOTOR HOMUNCULI

Lots to lips, tongue, hand, & index finger

Paracentral lobule = feet/legs

retrograde transport rabies

Rabies (Rhabdovirus) enters a peripheral nerve & travels retrograde to the DRG.

Replicates/infects the CNS (encephalitis) with neurologic symptoms leading to coma & respiratory/cardiac arrest (fast retrograde transport via neurotubules & dynein: also herpes simplex virus, poliovirus, tetanus toxin).

Retrograde Transport: RABIES

brainstem spinal cord

BRAINSTEM & SPINAL CORD

February 24, 2006

slide50

Weber syndrome

BRAIN STEM LESIONS

MIDBRAIN(PCA, SCA, basilar)

a) Weber (PCA) = CN 3 nuc + CB/CS tract

b) Benedikt (PCA) = CN 3 nuc + CB/CS tract + ML + Sup Cereb Ped (a.k.a. paramedian midbrain syn)

c) Parinaud (pineal tumor) = dorsal midbrain (defect in upward gaze) + HCP (a.k.a. dorsal midbrain syn)

Wallenberg or Lat Medullary syndrome

PONS(basilar, AICA)

a) Millard-Gubler (basilar pontine br) = CN 6/7 + CS tract

b) Med Inf Pontine (paramedian basilar) = CN 6 + CS tract + ML

c) Lat Inf Pontine (AICA) = CN 5/7/8 nuc + ALS + Mid/Inf Cereb Ped + Hypothalamospinal tract

Wallenberg syndrome

Med medullary syndrome

MEDULLA(vertebral, PICA)

a) Med Medullary (vertebral) = CN 12 + ML + CS tract

b) Wallenberg/Lat Medullary (PICA) = Nuc Ambiguus (CN 9/10/11) + ALS + SC tract

slide51

SPINAL CORD TRACTS

Fasciculus gracilis

Fasciculus cuneatus

Proprospinal pathways

Lateral corticospinal tract

Dorsal spinocerebellar tract

Rubrospinal tract

Ventral spinocerebellar tract

Lateral spinothalamic tract

Vestibulospinal tract

Ventral/Anterior spinothalamic tract

Ventral/Ant white commissure

Ventral/Medial corticospinal tract

slide52

CORTICOSPINAL TRACT

lat CS tract (85-90% crossed)

med

lat

lat

head

arms

trunk

ventral/med CS tract (10-15% uncrossed)

legs

Area 4 (primary motor ctx) Area 6 (premotor ctx) Area 3,1,2 (primary sensory ctx)

corona radiata

post limb of IC

crus cerebri (cerebral peduncles)

pontine CS fibers

pyramids (decussation)

slide53

post (post limb)

DORSAL COLUMN - MEDIAL LEMNISCUS

Post limb of IC

ant (genu, ant limb)

ML (midbrain)

post

lat

med

ant

ML (pons)

ML (medulla)

post

lat

med

ant

med

legs

lat

lat

arms

Area 3,1,2 (primary sensory ctx)

VPL of thalamus

internal arcuate fibers cross…

nucleus gracilis & cuneatus

HATL (Head-Arms-Trunk-Legs)

fasciculus gracilis & cuneatus

exception = Dorsal Columns

nucleus proprius (lamina III-V)

slide54

ANTEROLATERAL SYSTEM (SPINOTHALAMIC TRACTS)

Lissauer’s tract (lamina I) (dorsolateral fasciculus)

med

Substantia gelatinosa (lamina II)

lat

lat

Ventral/Ant White Commissure

Area 3,1,2 (primary sensory ctx)

VPL of thalamus

Ant & Lat Spinothalamic Tracts (ALS)

slide55

SPINOCEREBELLAR TRACTS

sup cerebellar peduncle

inf cerebellar peduncle

ventral spinocerebellar tract

dorsal spinocerebellar tract

Cuneocerebellar tract (C1-C8) = UE

nucleus dorsalis of Clarke (T1-L2) = LE

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SPINAL CORD LESIONS

  • SENSORY LOSS
  • Tabes dorsalis
  • Pernicious anemia (SCD)

Poliomyelitis

Gullain-Barré syndrome

  • MOTOR LOSS
  • Poliomyelitis
  • Amyotrophic Lateral Sclerosis (ALS)

Tabes dorsalis

ALS

  • MIXED MOTOR & SENSORY LOSS
  • Gullain-Barré syndrome
  • Syringomyelia
  • Trauma
    • Anterior Cord syndrome
    • Central Cord syndrome (like syringomyelia)
    • Brown-Séquard syndrome

Brown-Séquard syndrome

Anterior Cord syndrome

Pernicious anemia (SCD)

Syringomyelia

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Gross motor & Postural mm.

Rubrospinal tract (for gross motor fxn)

Vestibulospinal & Reticulospinal tracts (postural mm for truncal stability)

Postural mm are antigravity (trunk & leg extensors, arm flexors)

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CN 7

Central palsy

Bell’s palsy

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CN 10

Uvula deviates away from deficit

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CN 12

Tongue deviates towards deficit

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GSE (CN 3,4,6,12)

SVE (CN 5,7,9,10,11)

Trigeminal= Tensor tympani, Tensor veli palatini, Mylohyoid, Mastication mm, Ant belly digastric.

Facial (Seven)= Stapedius, Stylohyoid, Buccinator, Platysma, Post belly digastric.

Glossopharyngeal = Stylopharyngeus.

Vagus= Pharynx, Larynx, & Esophageal mm.

Extraocular mm

Intrinsic tongue mm

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Brief Cranial Nerve Basics

*THREE Pure Sensory:CN 1 (SVA) CN 2, 8 (SSA)

*FOUR MIXED Pharyngeal/Branchial Arch I-IV/VI: CN 5 (GSA + SVE) CN 7 (GSA + SVE) and (SVA taste, GVE cry/spit) CN 9 (GSA + SVE) and (SVA taste, GVE spit, GVA mucosa/carotid) CN 10 (GSA + SVE) and (SVA taste, GVE to GI tract, GVA mucosa)

tongue sensation = CN 5, 9, 10 tongue taste = CN 7, 9, 10

GVE CN 7 (crying) = sphenopalatine gang to lacrimal gl GVE CN 7 (spit) = submandibular gang to submandib & sublingual glGVE CN 9 (spit) = otic gang to parotid glGVE CN 10 (to GI tract) = prevertebral gang to Auerbach’s myen & Meissner’s submuc pl

*FIVE Pure Motor: CN 3 (GSE + GVE) CN 4, 6 (GSE) CN 11 (SVE) CN 12 (GSE)

tongue

glands

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Nuc Ambiguus (motor)

Nuc Solitarius (sensory)

CN 9,10,11 = swallow

CN 7,9,10 = taste

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Trigeminal Nuclei(simplify)

Mesencephalic (unconscious proprioception)to cerebellum and the CN 5 motor & principal sensory nuclei (cell bodies in nuc instead of CN 5 ganglion)

Principal Sensory (fine touch, vibration, kinesthesia) to ipsilateral Dorsal Trigeminothalamic Tract & contralateral Ventral Trigeminothalamic Tract

Motor nuc is Medial to the principal sensory nuc (mvmt)

Spinal—pars oralis, interpolaris, caudalis (pain & temp) to contralateral Ventral Trigeminothalamic Tract

like SC tract

like DC-ML

like CS tract

like ALS

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CN 8 (cochlear)

Know components of pathway & the start of b/l input (SON)

Areas 41,42 Primary auditory ctx (transverse gyrus of Heschl)

MGB

Inferior colliculus

Lateral lemniscus

SON

Dorsal & Ventral cochlear nuclei

Trapezoid bodies

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CN 8 (vestibular)

PONS:

Sup Vestibular Nuc (direct vestibular input for eye mvmt)

Lat Vestibular Nuc to Lat Vestibulospinal Tract throughout spine (postural control)

MEDULLA:

Med Vestibular Nuc to MLF & Med Vestibulospinal Tract of C-spine (coordinates eye mvmt with neck mvmt)

Inf (Spinal) Vestibular Nuc to MLF & vestibulocerebellar pathways (eye mvmt & postural control)

Vestibulo-ocular reflex with MLF & Flocculo-nodular lobe

Utricles, Saccules, Semicircular Canals… more for CNS Physiology