Brainstem Structure and Cranial Nerve Nuclei Flashcards

1
Q

Brainstem Components (3):

A
  • Midbrain
  • Pons
  • Medulla
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2
Q

What are the general areas of a brainstem cross section?

A
  • The portion posterior to the ventricular space
  • The portion anterior to the ventricular space
  • Additional structures on the anterior surface
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3
Q

Brainstem Functions:

Integrative functions

A
  • performed by a diffuse nucleus within the core of the brainstem
    • reticular formation
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4
Q

Brainstem functions:

Reticular formation

A
  • Helps regulate consciousness
  • Respiratory & cardiovascular centers
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5
Q

What is the brainstem’s role for the sensory and motor tracts?

A
  • Serves as a conduit for ascending sensory and descending motor tracts
  • Corticospinal tract
    • voluntary movement of limbs
  • Spinothalamic tract
    • transmits sensory information
    • pain and temperature
  • Posterior column / Medial lemniscus system
    • transmits sensory information
    • touch, vibration, pressure and proprioception
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6
Q

Brainstem functions:

Cranial Nerves

A
  • Cell bodies of neurons clustered in “nuclei” throughout the brainstem
    • origins of motor CNs
    • terminations of sensory CNs
  • Nuclei are bilateral
  • CN Nuclei are arranged in functional columns
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7
Q

Describe briefly how the nervous system develops:

A
  • NS develops from neural tube
  • Neural tube has basal plate (motor) and alar plate (sensory)
    • divided by sulcus limitans
  • Brainstem development is similar to spinal cord development
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8
Q

Brainstem Nuclei:

Somatic Motor (Red)

  • Function
  • Brainstem Nuclei ⇒ CNs
A
  • Function: Innervate skeletal muscles in the head and neck that are derived from myotomes
  1. Oculomotor ⇒ CN III
  2. Trochlear ⇒ CN IV
  3. Abducens ⇒ CN VI
  4. Hypoglossal ⇒ CN XII
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9
Q

Brainstem Nuclei:

Branchial Motor (orange)

  • Function
  • Brainstem Nuclei ⇒ CNs
A
  • Function: Innervate skeletal muscles derived from branchial arches
    • muscles of mastication, facial expression, pharynx, larynx, middle ear, trapezius m.
  1. Motor nucleus of V ⇒ CN V
  2. Facial nucleus ⇒ CN VII
  3. Nucleus ambiguus ⇒ CN IX and CN X
  4. Spinal Accessory nucleus ⇒ CN XI
    • Located in spinal cord
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10
Q

Brainstem Nuclei:

Visceral Motor (Yellow)

  • Function
  • Brainstem nuclei ⇒ CNs
A
  • Fucntion: Preganglionic parasympathetic innervation to cardiac m., smooth m. and glands
  1. Edinger-Westphal ⇒ CN III
  2. Salivatory ⇒ CN VII
  3. Inferior Salivatory ⇒ CN IX
  4. Dorsal motor nucleus of X ⇒ CN X
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11
Q

Brainstem Nuclei:

Visceral Sensory (Green)

  • Function:
  • Brainstem nuclei ⇒ CNs
A
  • Function:
    • Special – Taste
  • Rostral Nucleus solitarius (gustatory nucleus) ⇒ CN VII, IX and X
  • Function:
    • General – Control of cardiorespiratory and digestive functions
  • Caudal nucleus solitarius (cardiorespiratory nucleus) ⇒ CN IX & CN X
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12
Q

Brainstem Nuclei:

Somatic Sensory (B​lue)

  • Function:
  • Brainstem nuclei ⇒ CNs
A
  • Function: Convey touch, pain, temperature, position and vibration from skin, muscles and joints of the head
  • Trigeminal nuclei ⇒ CN V, VII, IX and X
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13
Q

Brainstem Nuclei:

Special Sensory (Purple)

  • Function:
  • Brainstem nuclei ⇒ CNs
A
  • Function:
    • Hearing
    • Cochlear nucleus ⇒ CN VIII
  • Function:
    • Balance
    • Vestibular nuclei ⇒ CN VIII
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14
Q

Caudal Midbrain

A
  1. Cerebral aqueduct
  2. Raphe nuclei
  3. Trochlear nucleus
  4. Trochlear nerve fibers, on their way to the contralateral superior oblique
  5. Inferior colliculus ​
    • Site of termination of the lateral lemniscus and site of origin of the brachium of the inferior colliculus
  6. Lateral lemniscus ending in the inferior colliculus
  7. Anterolateral pathway
  8. Medial lemniscus
  9. Cerebral peduncle
  10. Substantia nigra
  11. Decussation of the superior cerebellar peduncles (DSCP)
  12. Pontine nuclei
  13. Central tegmental tract
  14. Medial longitudinal fasciculus (MLF)
  15. Mesencephalic trigeminal tract
  16. Periaqueductal gray
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15
Q

Rostral Midbrain (level of superior colliculus)

A
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16
Q

Midpons

A
  1. Fourth ventricle
  2. Medial longitudinal fasciculus (MLF)
  3. Superior cerebellar peduncle
  4. Anterior spinocerebellar tract
  5. Mesencephalic trigeminal tract and nucleus
  6. Trigeminal main sensory nucleus
  7. Trigeminal motor nucleus
  8. Anterolateral pathway
  9. Medial lemniscus
  10. Trigeminal nerve
  11. Pontocerebellar fibers
    • from pontine nuclei of one side to the opposite middle cerebellar peduncle
  12. Corticospinal, corticobulbar, and corticopontine fibers from ipsilateral cerebral cortex
  13. Pontine nuclei
  14. Trapezoid body
  15. Central tegmental tract
  16. Superior olivary nucleus
  17. Lateral lemniscus
  18. Middle cerebellar peduncle
  19. Raphe nuclei
  20. Superior vestibular nucleus
  21. Inferior cerebellar peduncle entering the cerebellum
17
Q

Caudal Pons

A
  1. Vermis of the cerebellum
  2. Fourth ventricle
  3. Medial longitudinal fasciculus (MLF)
  4. Raphe nuclei
  5. Abducens nucleus
  6. Superior cerebellar peduncle
  7. Inferior cerebellar peduncle entering the cerebellum
  8. Abducens nerve fibers, on their way to the ipsilateral lateral rectus
  9. Solitary tract and its nucleus
  10. Spinal trigeminal tract
  11. Spinal trigeminal nucleus (oral nucleus)
  12. Middle cerebellar peduncle
  13. Lateral lemniscus
  14. Anterolateral pathway
  15. Errant avian
  16. Corticospinal, corticobulbar, and corticopontine fibers, from ipsilateral cerebral cortex
  17. Pontocerebellar fibers
  18. Pontine nuclei
  19. Trapezoid body
  20. Medial lemniscus
  21. Central tegmental tract
  22. Superior olivary nucleus
  23. Facial motor nucleus
  24. Anterior spinocerebellar tract
  25. Facial nerve fibers
  26. Lateral vestibular nucleus (VIII)
    • ​​source of the lateral vestibulospinal tract
  27. Juxtarestiform body
  28. Superior vestibular nucleus
  29. Internal genu of the facial nerve.
    • Facial nerve fibers, most of them on their way to ipsilateral muscles of facial expression.
  30. Dentate nucleus
  31. Interposed nucleus
  32. Fastigial nucleus
18
Q

Rostral Medulla

A
  1. Fourth ventricle
  2. Medial longitudinal fasciculus (MLF)
  3. Hypoglossal nucleus
  4. Dorsal motor nucleus of X
  5. Nucleus of the solitary tract
  6. Solitary tract
  7. Nucleus cuneatus
  8. Lateral cuneate nucleus
  9. Inferior cerebellar peduncle
  10. Posterior spinocerebellar tract entering the inferior cerebellar peduncle
  11. Location of nucleus ambiguus
  12. Anterolateral pathway
  13. Vagus nerve (CN X)
  14. Internal arcuate fibers
  15. Hypoglossal nerve fibers
  16. Pyramid
  17. Raphe nuclei
  18. Medial lemniscus
  19. Inferior olivary nucleus (medial accessory nucleus)
  20. Inferior olivary nucleus (principal nucleus)
  21. Fibers of the central tegmental tract reaching the inferior olivary nucleus
  22. Inferior olivary nucleus (dorsal accessory nucleus)
  23. Anterior spinocerebellar tract
  24. Spinal trigeminal tract
  25. Spinal trigeminal nucleus (interpolar nucleus)
  26. Inferior vestibular nucleus with bundles of vestibular primary afferents running through it
  27. Medial vestibular nucleus
19
Q

Caudal Medulla

A
  1. Dorsal motor nucleus of X
  2. Nucleus gracilis
  3. Nucleus cuneatus
  4. Fasciculus cuneatus
  5. Lateral cuneate nucleus
  6. Spinal trigeminal nucleus (caudal nucleus)
  7. Spinal trigeminal tract
  8. Posterior spinocerebellar tract
  9. Anterolateral pathway
  10. Location of nucleus ambiguus
  11. Anterior spinocerebellar tract
  12. Inferior olivary nucleus
  13. Pyramid
  14. Raphe nuclei
  15. Medial lemniscus
  16. Medial longitudinal fasciculus (MLF)
  17. Hypoglossal nucleus
  18. Hypoglossal nerve fibers
  19. Internal arcuate fibers
  20. Fibers of the vagus nerve
  21. Solitary tract and its nucleus
  22. Central canal
20
Q
  • What supplies the lateral apsects of the rostral medulla?
  • What happens if these vessels are occluded?
A
  • Vessels that supply the lateral rostral medulla:
    • VERTEBRAL A.
    • posterior inferior cerebellar a. (PICA)
  • Occlusion ⇒ lateral medullary syndrome (of Wallenberg)
21
Q
  • What supplies the medial aspect of the rostral medulla?
  • What happens if the vessels are occluded?
A
  • Vessels that supply the medial aspect of rostral medulla:
    • anterior spinal a.
    • penetrating branches of the VERTEBRAL A.
      • also supplies the corticospinal tract (medullary pyramid)
  • Occlusion ⇒ medial medullary syndrome
22
Q

What supplies the lateral aspect of the caudal medulla?

A
  • Vessels that supply the lateral caudal medulla:
    • POSTERIOR SPINAL A. (vertebral a.)
23
Q

What supplies the medial aspect of the caudal medulla?

A
  • Vessels that supply the medial caudal medulla:
    • ANTERIOR SPINAL A.
    • penetrating branches of the vertebral a.
      • also supply the corticospinal tract (medullary pyramid)
24
Q
  • What supplies the lateral aspect of the rostral pons?
  • What happens if the vessels are occluded?
A
  • Vessels that supply the lateral rostral pons:
    • SUPERIOR CEREBELLAR A.
      • also supplies the middle and superior cerebellar peduncles
    • Basilar a. ⇒ short circumferential branches
  • Occlusion of superior cerebellar a. ⇒ Lateral pontine syndromes
25
Q
  • What supplies the medial aspect of the rostral pons?
  • What happens if the vessels are occluded?
A
  • Vessels that supply the medial rostral pons:
    • Penetrating branches of the BASILAR A.
      • i.e. paramedian arteries
      • also supply the pontine nuclei, medial lemniscus and corticospinal tract
  • Occlusion of basilar a. ⇒ medial pontine syndromes
26
Q
  • What supplies the pontine tegmentum and dorsolateral quadrant of the pons?
  • What happens if the vessels are occluded?
A
  • Vessels that supply the pontine tegmentum and dorsolateral quadrant of the pons:
    • ANTERIOR INFERIOR CEREBELLAR A. (AICA)
    • long circumferential branches of the basilar a.
    • SUPERIOR CEREBELLAR A.
  • Occlusion of AICA ⇒ Lateral pontine syndromes
27
Q
  • What supplies the supply the lateral aspects of the midbrain?
  • What supplies the supply the medial aspects of the midbrain?
  • What happens if these areas are occluded?
A
  • Lateral Midbrain:
    • ​POSTERIOR CEREBRAL A. (PCA)
    • SUPERIOR CEREBELLAR A.
    • Occlusion of PCA ⇒ Weber’s syndrome
  • Medial Midbrain:
    • BASILAR A.
    • POSTERIOR COMMUNICATING Artery