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MBBS II HNNS > L04 - Brainstem > Flashcards

L04 - Brainstem Flashcards

1
Q

What are the boundaries of the brainstem (anterior and posterior)

A

Anterior = Optic tract (sup.), C1 spinal nerve (inf.)

Posterior = Superior colliculus (sup.), C1 spinal nerve (inf.)

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2
Q

3 major functions of the brainstem.

A

1) Passed through by all ascending, descending pathways
2) Where nuclei of most cranial nerve are located (e.g. 5 senses, facial expression)
3) Where many important life centers (reticular formation) are located, e.g. heartbeat, breath, blood pressure, ascending activating system, blood pH

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3
Q

What are the main regions of the brainstem

A

Diencephalon

Midbrain

Pons

Medulla oblongata

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4
Q

List some major external structures of Diencephalon.

A

Thalamus

Lateral and Medial geniculate body

Pineal gland Optic tract

Mammillary body

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5
Q

List some major external structures of Midbrain.

A

Superior colliculi + Inferior colliculi = Corpora quadrigemina

Superior and inferior cerebral peduncle

Trochlear nerve

Oculomotor nerve

Interpenducular sulcus

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6
Q

List some major external structures of Pons.

A

Superior, middle and inferior cerebellar peduncle

Medial eminence

Rhomboid fossa of 4th ventricle

Hypoglossal and Facial trigone

CN V, VII, VIII

Basilar sulcus (ant.) Median sulcus, Stria medullares, Sulcus limitans (post.)

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7
Q

List some major external structures of Medulla oblongata

A

Olive Pyramid (+ decussation of pyramid at inf. border)

Cuneate fasciculus

Gracile fasciculus

CN IX, X, XI, XII

Anterior median fissure

Posterior median fissure

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8
Q

List all the cranial nerves found in midbrain.

A

CN 2-4

Optic tract

Oculomotor nerve

Trochlear nerve

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9
Q

List all the cranial nerves found in Pons

A

CN 5 - 8

Trigeminal nerve

Facial nerve

Abducens nerve

Vestibulocochlear nerve

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10
Q

List all the cranial nerves found in Medulla oblongata

A

CN9 - 12

Glossopharyngeal nerve

Vagus nerve

Accesory nerve

Hypoglossal nerve

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11
Q

Which cranial nerve separates midbrain and pons.

A

Oculomotor nerve

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12
Q

Which cranial nerves separate pons and medulla oblongata?

A

CN VI, VII, VIII

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13
Q

What pathways go through the medulla oblongata?

A

Dorsal: Dorsal - Medial Lemniscus tract (ascending sensory)

Ventral: Corticospinal tract (descending motor)

Middle: Reticular formation

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14
Q

List the internal structures found at the inferior medulla oblongata.

A

Dorsal:

  • Nucleus Gracilis (lower limb sensory) + fasciculus
  • Nucleus Cuneatus (upper limb sensory) + fasciculus
  • Nucleus of Trigeminal nerve
  • Internal arcuate fibers (decussation for Dorsal Column Medial Lemniscal pathway)

Ventral:

  • Anterior gray column
  • Medullary pyramids + pyramidal decussation
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15
Q

List the internal structures found at the middle medulla oblongata.

A

Dorsal:

  • Nucleus Gracilis. Nucleus Cuneatus
  • Nucleus of trigeminal nerve
  • Nucleus of Hypoglossal nerve

Ventral:

  • Inferior olivary nucleus (hearing)
  • Medial meniscus (relay mechanical sensory info from nucleus gracilis and cuneatus to thalamus)
  • Corticospinal tract
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16
Q

List the internal structures found at the superior medulla oblongata.

A

Dorsal:

  • Vestibular nucleus
  • Vagus nucleus
  • Trigeminal nerve
  • Ambiguus nucleus (IX, X, XI)
  • Inferior cerebellar peduncle
  • Reticular formation (moved from middle to post)
  • Spinothalamic tract (lateral)

Ventral:

  • Medial lemniscus (Dorsal Column Medial Lemniscal pathway)
  • Corticospinal tract
  • Inferior olivary nucleus
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17
Q

List the internal structures found at inferior pons.

A

Dorsal:

  • Abducens nucleus - Facial nerve
  • Middle cerebellar peduncle
  • Reticular formation
  • Medial lemniscus (DMLT)

Ventral:

  • Corticospinal tract
  • Pontine nucleus >> pontocerebellar fibers >> Middle cerebellar peduncle
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18
Q

List the internal structures found at superior pons.

A

Dorsal:

  • Superior cerebellar peduncle
  • Medial lemniscus

Lateral: Pontine nucleus

Middle: Trochlear nucleus Reticular formation

Anterior: Corticospinal tract (antero-lateral, scattered between pontocerebellar fibers from pontine nucleus)

19
Q

List the structures found at the midbrain. (Tectum and different areas of Tegmentum)

A

Tectum (dorsal):

  • Superior and inferior colliculus

Tegmentum (posterior):

  • Cerebral aqueduct + Periaqueductal gray
  • Oculomotor nucleus

Tegmentum (middle):

  • Medial lemniscus - Reticular formation - Red nucleus (motor) - Cerebral peduncle

Tegmentum (anterior):

  • Corticospinal tract (lateral) - Oculomotor nerve* (through interpeduncular fossa) - Substantia nigra (controls basal ganglia)
20
Q

Functions of the Medulla Oblongata?

A
  • House discerte nuclei (i.e. CN 5, 9 - 12) in internal gray matter
  • Connect with spinal cord via ascending DCML, spinothalamic and descending corticospinal tracts
  • regulates: heart rate, blood vessel diameter, respiration, swallowing, vomiting, hiccupping, coughing, sneezing
  • Pyramid and Olive functions
21
Q

Function of pyramids in Medulla Oblongata?

A

descending nerve tracts on the anterior surface.

Inferiorly fibers decussate; thus each half of the brain controls the opposite half of the body

22
Q

Function of olives in Medulla Oblongata?

A

rounded; protrude from anterior surface.

regulate balance, coordination, modulation of sound from inner ear

23
Q

Function of Pons?

A
  • Host fiber tracts to connect with cerebellum
  • House Pontine nuclei + Cranial nerve V-IX
  • Sleep and Respiratory center
  • House ascending and descending fibers
24
Q

Function of midbrain tectum?

A

2 superior colliculi involved in visual reflexes (receive information from inferior colliculi, eyes, skin, cerebrum)

2 inferior colliculi involved in hearing

25
Q

Function of midbrain tegmentum?

A

House nerve tracts:

  • Ascending tracts (e.g. spinal and medial lemniscus from spinal cord to brain)
  • Descending: cerebral peduncles from cerebrum through brainstem to spinal cord
26
Q

Function of midbrain red nuclei and substantia nigra?

A

– Red nuclei of tegmentum: aid in unconscious regulation and coordination of motor activities

– Substantia nigra: pigmented with melanin; interconnected with basal nuclei of the cerebrum (motor)

27
Q

Outline the outflow of Corticospinal tract through the brain stem.

A

Motor cortex

>> Cerebral peduncle in midbrain

>> Pyramids in medulla oblongata >> pyramidal decussation

>> Lateral corticospinal tract + Anterior corticospinal tract

28
Q

Define reticular formation.

A

Diffusely interconnected neurons in brainstem (vs. more distinct nuclei associated with cranial nerves)

29
Q

Function of reticular formation?

A
  • INTEGRATE INFO: sensory, visceral, limbic, and motor functions, and project throughout the CNS
  • MODULATE FUNCTIONS: autonomic regulation of vital organ system, behavior, somatic motor activities, sleep cycles, alertness, pain modulation
30
Q

What are the 4 types of reticular formation?

A

Ascending reticular activating system (ARAS):

  • Norepinephrine system
  • Serotonin system
  • Ach system
  • Dopamine system
31
Q

Outline the basic functions of the 4 types of reticular formation?

A
  • Norepinephrine system = Alertness, fight or flight
  • Serotonin system = Mood and emotions
  • Pontine- Ach system = wakefulness
  • Dopamine system = habitual and working memory + incentive emotion
32
Q

Wakefulness is maintained by neuronal activity in which parts of the brain?

A

maintained by cholinergic neuronal activity in 2 main arousal centers (Ach):

  1. Brainstem: supplies acetylcholine for thalamus, brainstem
  2. Forebrain: supplies acetylcholine for cerebral cortex
33
Q

Pathology of Wallenberg syndrome?

A

Occlusion of the posterior inferior cerebellar artery supplying the LATERAL aspect of the medulla

34
Q

What internal structures of the brainstem are affected by Wallenberg syndrome?

A

Affect lateral medulla:

  • CN V, IX, X
  • Spinothalamic tract
  • Ambiguus nucleus
  • Sympathetic nerve
35
Q

Damage to CN V in Wallenberg syndrome causes what symptoms?

A

ipsilateral analgesia, thermoanesthesia

36
Q

Damage to Spinothalamic tract in Wallenberg syndrome causes what symptoms?

A

contralateral analgesia, thermoanesthesia below neck

37
Q

Damage to ambiguus nucleus in Wallenberg syndrome causes what symptoms?

A

ipsilateral paralysis in palatal, laryngeal muscles

38
Q

Damage to sympathetic nerves in Wallenberg syndrome causes what symptoms?

A

Horner’s syndrome

Drooping eyelids, reduced pupil size

39
Q

Pathology of Medial Medullary Syndrome?

A

Occlusion of the branches of vertebral artery supplying the MEDIAL aspect of the medulla

40
Q

What internal structures are affected in Medial Medullary Syndrome?

A
  • Medial lemniscus
  • Corticospinal tract
  • CN XII
41
Q

Contralateral impaired sensations of position and movement and tactile discrimination seen in Medial Medullary Syndrome is due to damage to what?

A

Medial lemniscus, damage DCML pathway

42
Q

Contralateral hemiparesis seen in Medial Medullary Syndrome is due to damage to what?

A

Corticospinal tract

43
Q

Damage to CN XII in Medial Medullary Syndrome causes what symptoms?

A

Ipsilateral paralysis of tongue muscles with deviation to the paralyzed side when tongue is protruded

44
Q

Degeneration of which brainstem region causes Parkinsonism?

A

Substantia nigra in Midbrain

MBBS II HNNS (57 decks)

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