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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
Q

trochlear nerves cross

A
  • 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
Q

down and out pupil

A

trochlear nerve

superior oblique muscle

27
Q

the right trochlear nerve is made of axons from the

A

left trochlear nucleus. and left nerve is from the right nucleus.

28
Q

ventral to the periaqueductal gray

A

in the lower midbrain: trochlear nuclei

in the upper midbrain: oculomotor nuclei

29
Q

abducens nerve innervates:
trochlear nerve innervates:
oculomotor nerve innervates:

A

abducens: lateral rectus
Trochlear: superior oblique (lower midbrain)
oculomotor: superior rectus, inferior rectus, medial rectus, inferior oblique (upper midbrain)

30
Q

medial longitudinal fasciculi

A
  • 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
Q

oculomotor nerves

A

oculomotor nuclei extend ventrad and exit the ventral surface of he upper midbrain between cerebral peduncles (interpeduncular fossa)

32
Q

the medial longitudinal fasciculi exchange fibers with

A

vestibular nuclei, oculomotor nuclei, trochlear nuclei, and abducens nuclei

33
Q

inferior olivary nucleus of the medulla

A

-recieves input from the ipsilateral red nucleus of the upper midbrain via the central segmental tract

34
Q

the central segmental tract

A
  • 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
Q

red nucleus

A
  • 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
Q

right side of cerebellum

A

synapse on left red nucleus or continue and synapse on left side of thalamus

37
Q

the right side of the thalamus receives projections from

A

the left side of the cerebellum (contralateral)

38
Q

if axons in the superior cerebellar peduncle do not synapse on the red nucleus they will synapse

A

pass the red nucleus on the lateral side and synapse in the thalamus

39
Q

reticular formation

A
  • 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
Q

remnant of the anterolateral system

A

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
Q

spinothalmaic tracts

A

-between the reticular formation and the surface of the lower midbrain

42
Q

the alternating input to the upper motor neurons in the pontine and medullary reticular formation

A
  • produce unconscious walking

- from the midbrain reticular formation

43
Q

unconscious walking

A

-coordinated by neurons in the reticular formation of the midbrain

44
Q

nucleus of the inferior colliculus: location, importance, projections

A

-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
Q

the trochlear nuclei are embedded in

A

the medial longitudinal fasciculus in the lower midbrain

46
Q

automatic tracking of a moving object

A

programmed by the superior colliculi in the upper midbrain

47
Q

the inferior and superior colliculi make up the

A

quadrigeminal plate or the tectum of the midbrain

48
Q

largest things in the the tegmentum of the upper midbrain

A

red nuclei

49
Q

largest projection to the red nuclei

A

superior cerebellar peduncles which crossed in the tegmentum of the lower midbrain

50
Q

largest projections to the red nuclei in humans

A

-central tegmental tract which ends in the inferior olivary nucleus of the medulla

51
Q

base of the midbrain is mostly occupied by

A

corticospinal tracts

52
Q

the medial leminiscus

A

passes through the lateral part of the tegmentum of the midbrain without synapsing

53
Q

the spinothalamic tract is dorsal to

A

the lateral edge of the medial leminiscus in the midbrain

Neuroanatomy (19 decks)

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