Brainstem Flashcards

1
Q

Obex

A

apex of fourth ventricle where it narrows it the central canal opens to spinal cord (Medulla)

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2
Q

Pyramidal decussation

A

interrupts anterior median fissure, at junction of brainstem and spinal cord. Contains corticospinal tract, motor fibers form cerebral cortex on their way to the spinal cord. Note pyramid bounded by anterolateral sulcus. (anterior surface)
�Caudal Medulla

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3
Q

CN XII

A
Hypoglossal nerve (cranial nerve XII) rootlet exit via anterolateral or preolivary sulcus
�Rostral MEDULLA
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4
Q

Olive

A

Bulge created by inferior olivary nucleus (MEDULLA)

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5
Q

CN IX and CNX

A

Rootlets of glossopharyngeal (IX) and vagus (X) nerves emerge from the post olivary sulcus, lateral to the olive.
�(MEDULLA)

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6
Q

cuneate tubercle

A

Fasciculus cuneatus extends to cuneate tubercle, marking site of the nucleus cuneatus. Fibers leave these nuclei and travel in an arch across the midline to form the medial lemniscus.
�(MEDULLA)

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7
Q

gracile tubercle

A

Fasciculus gracilus extends to the gracile tubercle which is at the site of nucleus gracilus. Fibers leave these nuclei and travel in an arch across the midline to form the medial lemniscus.
(Medulla)

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8
Q

Sulcus limitans

A

Sulcus limitans: Embryonic dividing line between sensory (now lateral) and motor (now medial) nuclei.
extends down spinal cord
sensory component swins out laterally during development

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9
Q

Hypoglossal trigone

A

triangular swelling in floor of 4th ventricle made by underlying hypoglossal nerve nucleus.
MEDULLA

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10
Q

Vagal trigone

A

triangular swelling in floor of 4th ventricle made by underlying dorsal motor nucleus of the vagus nerve. Vagus nerve is longest nerve
MEDULLA

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11
Q

Facial colliculus

A

Facial colliculus: Actually in pons, but since we are in the floor of the fourth ventricle now we can see it. This little hill is not due to the facial nerve motor nucleus, instead this is the site where the facial nerve loops over the abducens nerve nucleus as it goes on its way out of the brainstem.

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12
Q

Basal pons

A

Large bulge on anterior surface of brainstem. Site of many neurons that receive axons from cerebral cortex, the pontine neurons then send an axon across the midline of the pons (so-called crossing fibers) that collect laterally forming the middle cerebellar peduncle. )This is part of the cerebropontocerebellar pathway; more to come).

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13
Q

Middle cerebellar peduncle (MCP)

A

Major cerebellar input pathway. CAUDAL pons is attached to the cerebellum by the middle cerebellar peduncle

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14
Q

Trigeminal nerve (V):

A

Enters at midpontine level thru middle cerebellar peduncle.

lateral to pons but at midline

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15
Q

Abducens nerve (VI)

A

Exits brainstem at the pontomedullary junction near midline, near edge of pyramid as it emerges from the pons. Motor and sensory component.. Motor is rostral

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16
Q

Facial nerve (VII)

A

Exists lateral the abducens at the pontomedullary junction. Has two parts: motor root that is larger and more medial than the sensory root. Sometime the sensory root is known as the intermediate nerve. Cerebellar pontine angle

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17
Q

Vestibulocochlear nerve (VIII)

A

Exists lateral the facial nerve at the pontomedullary junction. Has two parts: a medially situated vestibular division and a more laterally situated cochlear division. Cerebellar pontine angle

18
Q

Superior cerebellar peduncle (brachium conjunctivum)

A

Forms much of the roof of the fourth ventricle. It emerges from the cerebellum (it is mostly a cerebellar out flow pathway) and moves towards the midline entering the brainstem near the junction of the pons and midbrain. (roof)
Can see the superior cerebellar peduncle (SCP) leaving the cerebellum at ROSTRAL pons. Then enters the CAUDAL midbrain and decussates . After Some superior cerebellar peduncle fibers end in the red nucleus in the ROSTAL midbrain , but most proceed to the thalamus.

19
Q

Lateral lemniscus

A

Band of fibers that covers the superior cerebellar peduncle in the rostral pons that is part of the ascending auditory pathway which terminates in the inferior colliculus, a midbrain structure.

20
Q

Cerebral aqueduct

A

Narrow channel in midbrain the connects the 3rd and 4th ventricles. Remnant of the lumen of the embryonic mesencephalon. Lesions in the aqueduct are not an uncommon cause of CSF obstruction narrow, which can be series as the aqueduct is also the only way CSF fluid can reach the fourth ventricle. Can be seen in midbrain cross sections with periaqueductal gray matter (PAG) around it, which is very important in descending pain control. Opens up into ventricle at ROSTRAL pons making the ventricular opening smaller at this level.

21
Q

Superior colliculus

A

Gray matter mass in roof (tectum) of rostral midbrain. Has roles in directing visual attention and controlling eye movements. Found on poster midbrain

22
Q

Inferior colliculus

A

Gray matter mass in roof (tectum) of caudal and posterior midbrain. It is a major component of the auditory system. It received input from the lateral lemniscus; output goes thru the inferior brachium to the medial geniculate nucleus of the thalamus.

23
Q

Cerebral peduncles:

A

Large bundle of white matter at the base of the midbrain located anteriorly. It contains tightly packed fibers from the cerebral cortex on their way to the brainstem and spinal cord.
Base that connects cerebrum and brainstem

24
Q

Oculomotor nerve (III)

A

Lower motor neurons for extraocular muscles and contains preganglionic parasympathetic neurons that control pupillary sphincter and ciliary muscles. Nucleus is located in rostral midbrain and emerges from space between the cerebral peduncles (aka the interpeduncular fossa)

25
Q
Trochlear nerve (IV)
�
A

Found in caudal and dorsal midbrain. The nerve leaves the dorsal aspect of the brainstem (the only one that does this) just below the inferior colliculus Innervates the superior oblique muscle.

26
Q

Inferior brachium (a.k.a. brachium of inferior colliculus):

A

Part of ascending auditory pathway. Contains fibers from the inferior colliculus that project to the medial geniculate nucleus of the thalamus.

27
Q

Tegmentum

A

Tissue anterior to ventricle

28
Q

Tectum

A

(“roof”): Tissue posterior to ventricle

29
Q

What is a peduncle?

A

A bundle of white matter that connects different parts of the brain. Cerebellar ones connect cerebellum to brain stem and cerebral ones connect cerebral cortex to brainstem

30
Q

Corticospinal tract

A

Descending tract and most anterior.. The nerve axons travel from the cortex through the cerebral peduncle and into the brainstem and anterior medulla. Discrete in midbrain then breaks up in pons into noticeable bundles then discrete again in medulla in large anterior pyramids. Bound by the anterolateral sulcus, forming the pyramids of the medulla. Majority of Axons cross over at the pyramidal decussation before continuing in the spinal cord. The nerve axons traveling down the tract are referred to as upper motor neurons and will synapse either directly with lower motor neurons or interneurons first.

31
Q

Spinothalmic tract

A

Spinothalmic is ascending. Joins up with medial lemniscus at level of the pons. Anterolatera l

32
Q

Medial lemniscus

A

These fibers crossing the midline are known as internal arcuate fibers or the sensory decussation. Fibers from gracile nucleus and cuneate nuclease come in.
Pathway: Internal arcuate fibers form medial lemniscus in the CAUDAL medulla. In the medulla the medial lemniscus is arranged so that fibers carrying cervical information are most posteriorly situated. As it travels through the pons, information from the feet is lateral and cervical areas are near the midline. Horizontally oriented in the pons as well. Note that as the ML moves laterally and it approaches the spinothalmic tract in the rostral pons, which is a good thing as these tracts will proceed together to the thalamus.

33
Q

Lateral or external cuneate nucleus

A

Embedded in fasciculus cuneatus this serves as the arm’s equivalent of Clarke’s nucleus (proprioception) and the axons of the neurons here join up with the posterior cerebellar tract in the inferior cerebellar peduncle at a more rostral level.

34
Q

Inferior olivary nucleus (IO):

A

This nucleus make the bump we call the olive on the external surface of the medulla. Fibers leave the hilum of the inferior olivary nucleus and cross the midline to reach the inferior cerebellar peduncle; these are the internal arcuate fibers. Internal arcuate fibers form medial lemniscus in the ROSTRAL medulla

35
Q

pontine nucleus

A

The pontine nuclei are a part of the pons involved in motor activity. They are anteriorly located and in the basal pons. They are numerous and scattered about crossing fibers and are is the gray matter found amongst the coritcospinal tract.. The crossing fibers collect at the lateral pons and form the middle cerebellar peduncle at the CAUDAL end of the pons

36
Q

Substantia nigra (SN):

A

Nucleus that contains neurons that use dopamine as a neurotransmitter and heavily innverate the putamen and caudate of the cerebrum. Neuronal loss results in Parkinson’s disease. First found in the ROSTRAL midbrain immediately posterior to the cerebral peduncles.

37
Q

red nucleus

A

The red nucleus is a structure in the rostral midbrain involved in motor coordination. Found anterior to periaqueductal gray matter. Some superior cerebellar peduncle fibers end in the red nucleus , but most proceed to the thalamus.

38
Q

What artery supplies medial medulla?

A

paramedian branches of vertebral artery and anterior spinal artery

39
Q

What artery supplies lateral medulla?

A

PICA!!!!

  1. ) Arises from the vertebral artery at the level of the medulla
  2. ) supplies lateral medulla and inferior cerebellum (olive)
40
Q

What artery supplies lateral pons?

A

AICA and SCA
1.) AICA: level of caudal pons
lateral caudal pons and small region of cerebellum
2.) SCA: Level of rostral pons
supplies superior cerebellum and rostrolateraldorsal pons

41
Q

What artery supplies midbrain?

A

POSTERIOR CEREBRAL ARTERY!

42
Q

What artery supplies medial pons?

A

paramedian branches of the basilar artery