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Anatomy > Midbrain > Flashcards

Midbrain Flashcards

1
Q

External features of ventral surface of midbrain

A
  1. 2 cerebral peduncles: crus cerebri, substantia niagra, tegmentum
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2
Q

External features of dorsal surface of midbrain

A
  • called tectum/ corpora quadrigemina
  • separated from each other by cruciform sulcus
  • vertical limb of sulcus forms depression lodging pineal body above, and frenulum veli below
  • sup. brachium connects sup. colliculus to lat. geniculate body, made of optic fibres
  • inf. brachium connects inf. colliculus to med. geniculate body, made of auditory fibres
  • Trochlear N emerges after decussation at superior medullary velum
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3
Q

Crus cerebri

A

Middle 3/5: Corticospinal, corticonuclear
Medial 1/5: Frontopontine
Lateral 1/5: Temporopontine, parietopontine, occipitopontine

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4
Q

Substantia niagra

A
  • b/w tegmentum and crus cerebri
  • dorsal pars compacta - sends nigrostriatal fibres to caudate nucleus and putamen
  • ventral pars reticularis
  • cells contain melanin and iron
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5
Q

Grey matter of midbrain at level of inferior colliculus

A
  1. Trochlear N nucleus: posterior to MLF
  2. Mesencephalic N of trigeminal N
  3. Substantia niagra
  4. Reticular formation b/w medial lemnisci and central grey matter
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6
Q

White matter of midbrain at level of inferior colliculus

A
  1. Decussation of superior cerebellar peduncles
  2. Medial, trigeminal, spinal, lateral lemniscus - medial to lateral
  3. MLF
  4. Tectospinal tracts
  5. Rubrospinal tracts ventral to cerebellar decussation
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7
Q

Grey matter of midbrain at level of superior colliculus

A
  1. Occulomotor nucleus
  2. Edinger Westphal nucleus supplies sphincter pupillae and ciliary muscles
  3. Mesencephalic N of trigeminal nerve
  4. Nucleus of superior colliculus
  5. Pretectal nucleus
  6. Red nucleus
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8
Q

White matter of midbrain at level of superior colliculus

A
  1. Dorsal tegmental decussation of Meynert
  2. Ventral tegmental decussation of Forel
  3. MLF
  4. All lemnisci except lateral
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9
Q

Connections of superior colliculus

A

Afferent:
1. Retina through lat. geniculate body, sup. brachium
2. Spinal cord through spinotectal tract
3. Frontal and occipital visual cortex
4. Inferior colliculus
Efferent:
1. Tectospinal and tectobulbar tracts for reflex mvmts of eye, head, neck in response to visual stimuli

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10
Q

Unilateral lesion of superior colliculus

A
  1. Neglect of visual stimuli

2. Inability to track moving objects in contra. field

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11
Q

Pretectal nucleus

A

Aff: from optic tract
Eff: to Edinger Westphal nucleus
Function: part of pupillary and consensual light reflex
Lesion: Argyll Robertson pupil - accommodation reflex intact, light reflex lost

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12
Q

Red nucleus

A
  • ovoid mass of grey matter
  • dorsomedial to substantia niagra
  • red due to high vascular supply
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13
Q

Connections of red nucleus

A

Afferents:
1. Cerebellorubral from contra. dentate nucleus
2. Corticorubral from ipsi. motor area
3. Pallidorubral from ipsi. globus pallidus
Efferents:
1. Rubrospinal
2. Rubrobulbar
3. Rubroreticular
* These fibres form ventral decussation of Forel
4. Rubroolivary

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14
Q

Medial Longitudinal Fasiculus

A
  • tract in paramedian plane of brainstem
  • extends cranially to interstitial nucleus of Cajal
  • caudally contd. with anterior intersegmental fasiculus of SC
  • contains fibres from vestibular nuclei
  • fibres interconnect nuclei of 3, 4, 5, 6 and spinal nucleus of accessory N
  • coordinates mvmts of eyes, head and neck using vestibulocochlear stimulus
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15
Q

Blood supply of midbrain

A
  1. Basilar
  2. Posterior cerebral
  3. Superior cerebellar
  4. Anterior choroidal
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16
Q

Weber’s syndrome

A
  • Lesion in cerebral peduncle due to occlusion of posterior cerebral A
  • Lesion involves occulomotor N and crus cerebri
    1. Ipsi. lateral squint
    2. Contra. hemiplegia
    3. Contra. paralysis of lower part of face and tongue
    4. Ptosis
    5. Dilated pupil
17
Q

Benedikt’s syndrome

A
  • Ischemia of tegmentum
  • Involves medial, spinal lemniscus, red nucleus, cerebellar peduncle, occulomotor N
    1. Ipsi. lateral squint and ptosis
    2. Contra. loss of pain and temp.
    3. Contra. loss of tactile, muscle, joint, vibration senses
    4. Contra. tremors, involuntary mvmts
18
Q

Parinaud syndrome

A

Lesion of superior colliculus

1. Loss of upward gaze

Anatomy (23 decks)

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