The brain stem

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The brain stem

• ??????? ?????
• ???

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The brain

• Telencephalon ??
• Diencephalon??
• Cerebellum ??
• Brain stem ??

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The brain stem ??

• Consists of
• Midbrain ??
• Pons ??
• Medulla oblongata??

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Medulla oblongata??

• Ventral surface
• Pyramid?? contain pyramidal tract (corticospinal
  tract)
• Decussation of pyramid???? formed by crossing
  fibers of corticospinal tract
• Olive?? produced by underlying inferior olivary
  nucleus
• Anterolateral sulcus???? rootlets of hypoglossal
  nerve emerge from it
• Retroolivary sulcus???? rootlets of
  glossopharyngeal, vagus and accessory nerves
  emerge from it

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Medulla oblongata ??

• Dorsal surface
• Lower portion
• Gracile tubercle???? produced by underlying
  gracile nucleus
• Cuneate tubercle???? marks the site of cuneate
  nucleus
• Inferior cerebellar peduncle ????
• Obex ?
• Upper portion forms the lower half of rhomboid
  fossa

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Pons ??

• Ventral surface
• Basilar part ???
• Basilar sulcus ???
• Bulbopontine sulcus ????? from medial
  to lateral, the abducent, facial and
  vestibulocochlear nerves appear
• Middle cerebellar peduncle ????
• Trigeminal nerve ????
• Pontocerebellar trigone ?????? the junction
  of medulla, pons and cerebellum

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Pons ??

• Dorsal surface
• Superior cerebellar peduncle ????
• Superior medullary velum ???
• Trochlear nerve ????

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Midbrain ??

• Ventral surface
• Crus cerebri ????
• Interpeduncular fossa ??? oculomotor nerves
  emerge from medial of crus cerebri
• Posterior perforated substance ???

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Midbrain??

• Dorsal surface
• Superior colliculus ??constitute centers for
  visual reflexes
• Inferior colliculus ??associated with auditory
  pathway
• Brachium of superior colliculi ???
• Brachium of inferior colliculi ???

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Fourth ventricle ????
Central canal ?fourth ventricle ?mesencephalic
aqueduct?third ventricle

• Position
• Situated ventral to cerebellum, and dorsal to
  pons and cranial half of medulla

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• Boundaries
• Inferolateral gracile and cuneate tubercles,
  inferior cerebellar peduncle
• Superolateral superior cerebellar peduncle
• Lateral recess

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• Features
• Median sulcus ???
• Sulcus limitans ??
• Vestibular area??? overlies vestibular nuclei
• Acoustic tubercle???overlying dorsal cochlear
  nucleus
• Medial eminence ????
• Striae medullares ??

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• Facial colliculus???? overlies nucleus of
  abducent n. and genu of facial nerve
• Hypoglossal triangle ?????? verlying
  hypoglossal nucleus
• Vagal triangle?????? overlies dorsal nucleus of
  vagus nerve
• Funiculus separans???
• Area postrema ???
• Locus ceruleus ??

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• Roof
• Anterior part formed by superior cerebellar
  peduncle and superior medullary velum
• Posterior part formed by inferior medullary
  velum and choroid plexus of fourth ventricle
• Three apertures
• Median aperture of fourth ventricle ???????
• Two lateral apertures of fourth ventricle ???????

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Tela choroidea and choroid plexus????????
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Internal structures

• Gray matter
• Cranial nerve nuclei
• Relay nuclei

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General somatic motor nuclei ???????

• Nucleus of oculomotor n.?????
• Nucleus of trochlear n. ?????
• Nucleus of abducent n. ????
• Nucleus of hypoglossal n.?????

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General somatic motor nuclei
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Special visceral motor nuclei ???????

• Motor nucleus of trigeminal n. ???????
• Nucleus of facial n. ????
• Nucleus ambiguus ??
• Accessory nucleus ????

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Special visceral motor nuclei
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General visceral motor nuclei ???????

• Accessory oculomotor nucleus ??????
• Superior salivatory nucleus ????
• Inferior salivertory nucleus ????
• Dorsal nucleus of vagus n. ??????

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General visceral motor nuclei
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Visceral sensory nuclei ( general and special )

• Nucleus of solitary tract ???

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Visceral sensory nuclei ( general and special )
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General somatic sensory nuclei

• Mesencephalic nucleus of trigeminal n. ???????
• Pontine nucleus of trigeminal n.
  ???????
• Spinal nucleus of trigeminal n.
  ???????

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General somatic sensory nuclei
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Special somatic sensory nuclei

• Cochlear nuclei ????
• Vestibular nuclei ?????

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Special somatic sensory nuclei
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Relay nuclei ?????

• Gracile nucleus ???
• Cuneate nucleus ???
• Inferior olivary nucleus ????
• Superior olivery nucleus ????
• Pontine nucleus ???
• Nucleus of inferior colliculus???
• Gray matter layers of superior colliculus
  ?????
• Red nucleus ??
• Substantia nigra ??
• Pretectal area ????

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Non-cranial nerve nuclei
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White matter

• Ascending tracts
• Medial lemniscus ????
• Spinal lemniscus????
• Trigeminal lemniscus ????
• Lateral lemniscus????

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Medial lemniscus ????
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• Spinal lemniscus
• ????

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• Trigeminal lemniscus
• ????

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Descending tracts

• Corticospinal tract ?????
• Rubrospinal tract ?????
• Tectospinal tract ?????
• Vestibulospinal tract ?????
• Reticulospinal tract ?????

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• Lateral lemniscus
• ????

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Reticular formation of brain stem

• Ascending reticular activating system (ARAS)
  ????????
• Motor central and vital centres
• Reticulospinal tract
• Cardiovascular center and respiratory center
• Serotonergic rapheal nuclei

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The characters of internal structure of brain stem
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Medulla oblongata

• Lower part (closed part)
• Two decussations
• Decussations of medial lemniscus
• Decussations of pyramid

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Medulla oblongata

• Upper part (open part)
• Appearance of inferior olivary nuculeus and
  inferior cerebellar peduncle
• Enlargement of central canal to form the fourth
  ventricle floor

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Pons

• Tegmentum of pons ????directed upward
  continuation of medulla oblongata
• Basilar part ???
• contain both longitudinal and transverse
  fibers intermixed with pontine nuclei

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Midbrain

• Rectum of midbrain???? includes superior and
  inferior colliculi
• Cerebral peduncle ???
• Tegmentum ??
• contain ascending tracts, central gray
  matter, recticular formation and so on
• Substentia nigra ??
• Crus cerebri ????
• Pyramidal tract???- middle three-fifths of the
  crus
• Frontopontine tract??? medial one-fifth
• pariatotempopontine tract ????lateral one-fifth

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