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Neuroanatomy > Ch. 29 The Midbrain > Flashcards

Ch. 29 The Midbrain Flashcards

1
Q

midbrain

A

between the forebrain and the pons

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2
Q

the cerebral aqueduct

A
  • connects the 3rd and 4th ventricle
  • surrounded by periaquedectal gray matter region
  • tectum of the midbrain is its roof (dorsal to it)
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3
Q

mesencephalic tract

A

-trigeminal nerve continues into the midbrain in lateral edge of periaquedecutal gray

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4
Q

the roof of the 4th ventricle

A

cerebellum

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5
Q

midbrain tectum

A
  • roof of the cerebral aqueduct and periaqudeuctal gray

- also dorsal to the lateral portion of the midbrain tegmentum

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6
Q

midbrain tegmentum

A

lateral and ventral to the periaqueductal gray

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7
Q

pons tegementum

A

ventral to the 4th ventricle

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8
Q

cerebral peduncles of the midbrain

A

-formed by the substantia nigra and the corticospinal tracts (crus cerebri)

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9
Q

base of the pons

A

formed by the

  1. corticospinal fiber white matter (ventral)- heavily myelinated
  2. pontine nuclei gray matter
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10
Q

crus cerebri

A

(aka corticospinal tract or basis pedunculi)

  • white matter
  • separated from the tegmentum of the midbrain by gray matter of the substantia nigiri
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11
Q

substansia nigri

A

gray matter that separates the crus cerebra from the tegementum of the midbrain

  • ventral to the tegmentum of the midbrain
  • dorsal to the crus cerebri
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12
Q

the cerebellum projects

A

to the opposite side of the midbrain and thalamus through superior cerebellar peduncles

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13
Q

the superior cerebellar peduncles

A
  • cross ventral to the periaqueductal gray in the tegmentum of the lower midbrain
  • helps cerebellum project to the opposite side of midbrain and thalamus
  • crossing is called decussation
  • half the fibers synapse in the red nucleus of the upper midbrain after crossing the lower midbrain
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14
Q

midbrain tectum divisions

A
  • divided into 4 small colliculi (2 inferior, 2 superior)

- upper tectum is the 2 superior, lower tectum is the 2 inferior

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15
Q

the nucleus of the inferior colliculus

A
  • large mass of gray matter formed by inferior colliculi in lower midbrain
  • recieves auditory information from superior olivary nucleus on the same side via the lateral leminiscus
  • receives direct input from the opposite cochlear nuclei and indirect input from both cochlear nuclei
  • receives auditory information from both ears and relays it to the medial geniculate nucleus of the thalamus
  • nuclei of inferior colliculus are connected via commissure of inferior colliculi
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16
Q

upward projections of the superior olivary nucleus are

A

ipsilateral

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17
Q

projections of the nucleus of the lateral leminiscus are

A

bilateral

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18
Q

nucleus of the superior colliculus receives direct input from

A
  • the ipsilateral superior olivary nucleus

- both nuclei of lateral leminiscus

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19
Q

the anterior and posterior cochlear nucleus

A

gives direct auditory information to the contralateral inferior colliculi via the lateral leminiscus

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20
Q

the lateral leminiscus

A

passageway for the A and P cochlear nuclei and superior olivary to send auditory information to the inferior colliculi

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21
Q

medial geniculate nucleus of the thalamus

A

the nucleus of the inferior colliculus relays information from the ears via the brachium of the inferior colliculus

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22
Q

the brachium of the inferior colliculus

A

send information from the inferior colliculi to the medial geniculate nucleus of the thalamus and pretecal nucleus for pupillary reflex

23
Q

trochlear nerve

A
  • only cranial nerve of the lower midbrain
  • only cranial nerves to exit the dorsal surface of the brainstem
  • only cranial nerves that cross (between inferior colliculi)
  • lower motor neurons project to the superior oblique muscle
  • run dorsrad to the periaqueductal gray
  • exit the lower midbrain between the superior colliculi
24
Q

trochlear nuclei

A
  • ventral to the periaqueductal grey of the lower midbrain
  • midline of the tegmentum of the midbrain
  • cut into the MLF
25
trochlear nerves cross
- above the commissure of the inferior colliculi. - right trochlear nucleus is the source of the left trochlear nerve - left trochlear nuclei is the source of the right trochlear nerve (opposite)
26
down and out pupil
trochlear nerve | superior oblique muscle
27
the right trochlear nerve is made of axons from the
left trochlear nucleus. and left nerve is from the right nucleus.
28
ventral to the periaqueductal gray
in the lower midbrain: trochlear nuclei | in the upper midbrain: oculomotor nuclei
29
abducens nerve innervates: trochlear nerve innervates: oculomotor nerve innervates:
abducens: lateral rectus Trochlear: superior oblique (lower midbrain) oculomotor: superior rectus, inferior rectus, medial rectus, inferior oblique (upper midbrain)
30
medial longitudinal fasciculi
- heavily myelinated - midline of the tegmentum of the upper midbrain - white matter tracts - stretch from the lower forebrain tot he sacral cord - ventral side of trochlear nuclei in the lower midbrain - lateral side of the oculomotor nuclei in the upper midbrain - in the lower pons, runs between abducens nuclei - coordinates eye movement with each other and with movement of the head
31
oculomotor nerves
oculomotor nuclei extend ventrad and exit the ventral surface of he upper midbrain between cerebral peduncles (interpeduncular fossa)
32
the medial longitudinal fasciculi exchange fibers with
vestibular nuclei, oculomotor nuclei, trochlear nuclei, and abducens nuclei
33
inferior olivary nucleus of the medulla
-recieves input from the ipsilateral red nucleus of the upper midbrain via the central segmental tract
34
the central segmental tract
- extension of the red nucleus in the tegmetum of the upper midbrain - leaves red nucleus on the dorsal side in the upper midbrain (starts here) - runs lateral to the MLF in the lower midbrain - ventral to the periaqueductal gray - dorsal to the decussation peduncles in the lower midbrain
35
red nucleus
- round structure in the tegmentum of the upper midbrain - half the fibers in each superior cerebellar peduncle synapse in the red nucleus - fibers from the right side o cerebellum synapse on the LEFT red nucleus. (contralateral side of cerebellum to red nucleus)
36
right side of cerebellum
synapse on left red nucleus or continue and synapse on left side of thalamus
37
the right side of the thalamus receives projections from
the left side of the cerebellum (contralateral)
38
if axons in the superior cerebellar peduncle do not synapse on the red nucleus they will synapse
pass the red nucleus on the lateral side and synapse in the thalamus
39
reticular formation
- makes up a large portions the the tegmentum of the midbrain - necessarly lateral to the decussation of the superior cerebellar peduncles and the central segmental tract in the lower midbrain - medial to the spinothalmic tract and lateral to the central tegmental tract (both the lower and upper midbrain)
40
remnant of the anterolateral system
further lateral, between the reticular formation and the surface of the lower midbrain -remaining fibers synapse in the thalamus and are called he spinothalamic tracts
41
spinothalmaic tracts
-between the reticular formation and the surface of the lower midbrain
42
the alternating input to the upper motor neurons in the pontine and medullary reticular formation
- produce unconscious walking | - from the midbrain reticular formation
43
unconscious walking
-coordinated by neurons in the reticular formation of the midbrain
44
nucleus of the inferior colliculus: location, importance, projections
-in the tectum of the lower midbrain -processing enter for hearing -recieves auditory information via the lateral leminiscus project to the thalamus via the brachium of the lateral inferior colliculus
45
the trochlear nuclei are embedded in
the medial longitudinal fasciculus in the lower midbrain
46
automatic tracking of a moving object
programmed by the superior colliculi in the upper midbrain
47
the inferior and superior colliculi make up the
quadrigeminal plate or the tectum of the midbrain
48
largest things in the the tegmentum of the upper midbrain
red nuclei
49
largest projection to the red nuclei
superior cerebellar peduncles which crossed in the tegmentum of the lower midbrain
50
largest projections to the red nuclei in humans
-central tegmental tract which ends in the inferior olivary nucleus of the medulla
51
base of the midbrain is mostly occupied by
corticospinal tracts
52
the medial leminiscus
passes through the lateral part of the tegmentum of the midbrain without synapsing
53
the spinothalamic tract is dorsal to
the lateral edge of the medial leminiscus in the midbrain

Neuroanatomy (19 decks)

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