brain division
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BRAIN DIVISION. telencephalon Brain diencephalon cerebellum midbrain brain stem pons mudulla oblongata. I.Brain Stem. - PowerPoint PPT PresentationTRANSCRIPT
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telencephalon Brain diencephalon cerebellum midbrain brain stem pons mudulla
oblongata
BRAIN DIVISION
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1.Location : Being in the skull , it superiorly connects diencephalon , inferiorly conjoins spinal cord
and ventrally lies on the clivus of occiptal bone and posteriorly attaches cerebellum.
I.Brain Stem
2.External Borders (1) ventral surface a. bulbopotine sulcus b. sup border of basilar part in pons (2) dorsal surface a. striae medullares b. lower border of inf colliculi
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3. Parts and Ventral Appearances
Cerebral
peduncles
Interpeduncular fossa
Basilar part of ponsBasilar sulcus
PyramidsDecussation of pyramidInferior olives
Midbrain
Pons
Medulla oblongata
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Superior colliculiBrachiums of superior colliculiInferior colliculiBrachiums of inferior colliculi
4. Parts & Dorsal Appearances(A)
mid
brai
n
Paired Structures
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median sulcus 1sulcus limitensredullary stria 1 medial eminencesfacial colliculivagal-triangles hypoglossal trianglesvestibular areassup, mid & inf cerebellar peducles
Pon
s & M
edu
lla O
blon
gata
Parts & Dorsal Appearances(B)
pai
Paired structures
Rhomboid Fossa(4th ventricle floor)
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3) Names of Cranial Nerve(CN)
I olfactory nII optic n
Ⅲ oculomotor n Ⅳ trochlear n Ⅴ trigeminal n Ⅵ abducent n (dorsal
origin) Ⅶ facial n
Ⅷ vestibulocochlear n
Ⅸ glossopharyngeal n
Ⅹ vagus n
Ⅺ accessory n Ⅻ hypoglossal n
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Pons
Medullaoblongata
Ⅲ oculomotor n Ⅳ trochlear n
Ⅴ trigeminal n
Ⅵ abducent n
Ⅶ facial n Ⅷ vestibulo- cochlear n
Ⅸ glosso- pharyngeal n Ⅹ vagus n
Ⅺ accessory n
Ⅻ hypoglossal n
Midbrain
Connections with Parts
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3.Internal Structure Inclusion: gray matter,white matter &
reticular formation Characteristics of Gray Matter :
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Think about the followimg questions:1.What nuclei exist in midbrain,pons and medulla oblongta, respectively?2.Which are cranial nuclei or non-cranial nuclei? 3.How many kinds of cranial nuclei in brain stem? somatic motor nuclei visceral motor nuclei visceral afferent nuclei somatic afferent nuclei
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Division of
Brain Stem
Somatic Motor Nuclei Lying Immediately Lateral to Median Sulcus
midbrain
pons
medulla oblongata
nucleus of trochlear n
nucleus of abducent n
nucleus of hypoglossal n
nucleus of oculomotor n
Localization of Somatic Motor Nuclei
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Nucleus of trochlear n
Nucleus of abducent n
Nucleus of hypoglossal n
Nucleus of oculomotor n Top-bottom
arrangement
Dorsal surface of brain stem
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Division of
Brain Stem
General Visceral Motor Nuclei of CN Immediately Medial to Sulcus Limitans
midbrain
pons
medulla
oblongata
accessory nucleus of oculomotor n
superior salivary nucleus
inferior salivary nucleus
dorsal nucleus of vagus n
Localization of General Visceral Motor Nuclei
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Accessory nucleus of oculomotor n
Superior salivary n
Inferior salivary n
Dorsal nucleus of vagus n
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motor nucleus of trigeminal n
nucleus of facial n
ambiguous nucleus
accessory nucleus
Division of
Brain Stem
Special Visceral Motor Nuclei of CN Ventrolateral to VMN & Medial to Sulcus Limitans
midbrain
pons
medulla
oblongata
Localization of Special Visceral Motor Nuclei
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Motor nucleus
of trigeminal n
Nucleus of facial n
Ambiguous nucleus
Accessory nucleus
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Division of
Brain Stem General & Special Visceral Sensory Nucleus of CN Immediatedly Lateral to Sulcus Limitans
midbrain
pons
medulla
oblongata nucleus of solitary tract
Localization of General & Special Visceral Sensory Nucleus
none
none
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Nucleus of
solitary tract
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Division of Brain Stem
General & Special Somatic Sensory Nuclei Lateral & Dorsalolateral to GSVSN
midbrain
pons
medulla oblongata
mesencephalic nucleus of trigeminal n
cochlear nuclei
vestibular nuclei
pontine nucleus of trigeminal n
spinal nucleus of trigeminal n
Localization of General & Special Somatic Sensory Nuclei
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Mesencephalic nucleus of trigeminal n
Cochlear & vestibular nuclei
pontine nucleus of trigeminal n
Spinal nucleus of trigeminal n
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Division of Brain Stem
midbrain
nucleus of sup. colliculus
black substance
pontine nucleus
gracile nucleus cuneate nucleus
pons
medulla oblongata
Nuclei of Non-Cranial Nerves
nucleus of inf. colliculus
red nucleus
Localization of Non-Crainal Nuclei
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1.Discern which one is a cranial nucleus, ambiguous or gracile nucleus ?
2. Distinguish the category of the following nuclei:
black substancered nucleus cochlear
nuclei
vestibular nuclei
accessory nucleus
dorsal nucleus of vagus nnucleus of hypoglossal n
Test Yourself
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3.How many nuclei are there in medullar oblongata ?
4.Which nucleus is in pons?
( memorize nuclei according to their positions )
Black substance
Red nucleus Cochlear nuclei
Vestibular nucleiAccessory nucleus
Dorsal nucleus of vagus N.
Nucleus of hypoglossal N.
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5.Which one is somatic nucleus? (to memorize four kinds of cranial N respectively according to their functions)
Nucleus of oculomotor N
Accessory nucleus of oculomotor N
Spinal nucleus of trigeminal N.
Nucleus of solitary tract
Nucleus of facial N
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6.Four pairs of parasympathetic nuclei exsit in brain stem:
accessory nucleus of oculomotor n
superior salivary nucleus
inferior salivary nucleus
dorsal nucleus of vagus n
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7.Relationships between nuclei & cranial nerves
1) one nucleus connects 1 nerve 2) one nucleus connects 2 or more nerves nucleus of solitary tract Ⅶ、
Ⅸ 、
Ⅹ ambiguous nuleus Ⅸ、
Ⅹ 、
Ⅺ
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3) Two or more nuclei connect one nerve:
a. oculomotor nu, accessory nu of oculomotor n---Ⅲ
b. sensory & motor nus of trigeminal n---------------Ⅴ
c. facial nu, sup. salivary nu, solitary tract nu------Ⅶ
d. ambiguous , inf.salivary,solitary tract nus------Ⅸ
e. ambiguous nu, dorsal nu of vagus n, solitary tract nu, spinal nu of trigeminal n------------- - Ⅹ
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Cranial N and Relative Nuclei
III
V
VIVIII
XI
IX
X
XII
IV
VII
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White Matter of Brain Stem
Ascending tracts :1.medial lemniscus2.spinal lemniscus3.trigeminal lemniscus4.lateral lemniscus
Descending tracts:1.corticospinal tract2.corticonucleus tract3.extrapyramid tract
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Overview of Microstructures of White Matter
1. White matter consists of numerous nerve fibers.
2. The certain bundle fibers with the same origin,
course,end & functions form a tract.
3. The fiber tracts of brain include both ascending
& descending ones(ascending –blue;descending –red).4. Focus on the names (according to origin & end )
formations ( Which nucleus receives or sends the
bundled fibers ? ), locations ( Where do the fibers
pass via the brain stem ? ) and functions ( What
information do the fibers transmit ? ) of the main
tracts. Descending Tract
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1.Medial Lemniscus
medial lemniscus
↑
decussation of
med lemniscus
↑
gracile nucleus
cuneate nucleus
↑
fasciculus gracilis
fasciculus cuneatus
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2.Spinal Lemniscus
anterior spinal lemniscus
lateral spinal lemniscus
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3.Trigeminal Lemniscus
trigeminal lemniscus
↑
decussation of trigeminal lemniscus
↑
pontine nucleus & spinal nucleus of trigeminal n
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4.Lateral Lemniscus
lateral lemniscus
↑
↑ uncrossed
↑ crossed
trapezoid body
↑
cochlear nuclei
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Descending Tract 1. Pyramidal Tract 1) corticonuclear tract 2) corticospinal tract
2. Extrapyramidal System
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1) Corticonuclear Tract a.inf.part of precentral gyrus ↓ motor nuclei in brain stem
b.The tract dominates the most nuclei on both sides of brain stem. c.Lower-half parts of facial nu & hypoglossal nu only receive the control of the tract from opposite side. d.The tract controls voluntarily
muscular movements of head, face and neck .
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2) Corticospinal Tract
c.The tract controls movements of voluntary muscles in trunk and limbs.
superior & middle part of precentral gyrus
↓
ant horn cells of spinal cord
a.Most fibers decussate at decussation of pyramid.
b.Fewer fibers decussate at ant white commissure.
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All the descending tracts except pyramidal tracts dominating the vuluntarily muscular movements, are subordinated to the system. The functions of the system are to modulate the voluntarily muscular movements. The conbination of the two system enables the body to carry out the appropriate, precise , effective, harmonious & temporospatial
movements so as to reliably respond to the stimuli from external or internal enviroments.
Extrapyramidal System
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Reticular Formation of Brain Stem
Raphe nuclei locates in median line of brain stem.
Functions :1) ascending : helping sleep2) descending: alleviating pain
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Ascending Reticular Activating System--ARAS
Location :
dorsolateral area of pons and medullar oblongata
Functions:(1)~(3)
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Fiber projection
targets of ARAS
(1)Receives the informations transmitted by the numerous lateral branches given off by the responding specific sensation conduction tracts. (2)converts these specific messages into non-specific ones ,and then sends them to most areas of cortex of cerebrum via its projection fibers. (3) thus makes the cortex be conscious or vigilant states so as to be able to recognize and distinguish the various afferent messages.
Lateral branches
Sensory pathwayspons
bolb
Fibers to cortex
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Functions of Reticular Formation a.Regulating somatic movements: strengthen or weaken muscular tensions . b.Performing the behavioral arousal function. c.Controlling the activities: vomiting center;regulating visceral reflexes(DS&RS); centers for vital movements , including cardiovascular motor center & respiratory center----controlling heartbeat, BP& R. d.5-TH ascending projection to cerebral cortex inhibits activities of the cortex and induces human to sleep.5-TH descending projection to the spinal cord plays roles in modulating cardiovascular activities and pain sensation.
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Relationship between External Appearance & Internal Structure
1.Dorsal Surfacesup colliculus---—-------------------- ----its nulceus inf colliculus--------------------------------its nucleus vestibular area-------------------vestibular nucleus facial colliculus------------------abducens nucleus
hypoglossal triangle-----------------------its nucleus vagal triangle-----------------dorsal nucleus of X n
acoustic tubercle----------------dorsal nuclei of VIII nlocus ceruleus-----------------------------its nucleus gracile tubercle----------------------------its nucleus cuneate tubercle---—---------------------its nucleus
aera postrema---chemical receptor –activative vomiting center; the relay stops ofviceral information exchange & visceral reflexes;an area controlling neuroendocrine secretion.
obex---
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Relationship between External Appearance & Internal Structure
2.Ventral Surface
pyramid-corticospinal tract
pyramidal decussation--lateral corticospinal tract(ventral crossding;decussation of medial lemniscus-dorsal crossing,,both approximately at the same level in oblongata)
olive---inferior olivary nucleus
pontine base—pontine nucleus
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Cerebellum
Location:
lying in posterior cranial fossa & attachingdorsum of brain stem
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External Features 2 parts ,1 tonsil& significance
cerebellar hemisphere
vermis
tonsil of cerebellum
If intracranial pressure
sharply increases ,the tonsil
will be pressed toward
oblongata (tonsillar hernia),
leading to sudden death.
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Lobes and Their FunctionsFlocculonodular lobe-----keeps the balances of bodyAnterior lobe-----regulates muscular tension. Posterior lobe-----coordinates the movements of voluntary muscles
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Internal Structures of Cerebelluncortex : three layers . sends fibers to central nucleimedulla : central nuclei of cerebellum(four pairs )
Dentate N
emoliformGlobse N
Fastigial N
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Fiber Connections of the Cerebellum
1. Three pairs of
cerebellar peduncles:
superior, middle,inferior
2. Fiber connection circuit:
Primary afferent fibers from
other parts in CNS first enter
the cortex of cerebellum (Piriform cells /Purkinjie cells which are the only efferent neurons in the cortex receive the afferents and then send their own fibers to central nuclei in medulla, and finally the central nuclei send their efferent fibers from medulla of cerebellum to other parts in CNS.Complete the transmission !
Infer.cereb. ped
Mid. cereb. ped
Sup.cereb. ped
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Vestibular N
Vestibular ganhlion
Cortex of cerebellum
Vestibulospinal tract
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