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M2 NENTE Anatomy > 4.3 Brainstem & Cranial Nerves > Flashcards

4.3 Brainstem & Cranial Nerves Flashcards

1
Q

Where does the midbrain lie?

A

lies above the pons and continues superiorly with the forebrain

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2
Q

where does the pons lie?

A

above the medulla oblongata

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3
Q

where does the medulla oblongata lie?

A

continues inferiorly as the spinal cord at the forum megnum

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4
Q

what is the posterior relation of the brainstem?

A

cerebellum

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5
Q

what is the anterior relation of the brainstem?

A

clivus

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6
Q

[Medulla Oblongata: Anterior]
The anterior aspect of the medulla oblongata possesses 2 longitudinal sections (pyramids) on either side of the midline, formed by the _______________
• Lateral to the pyramids are the __________ (one on each side) → inferior olivary nuclei lie deep to the olives

A

fibres of the corticospinal tract;

elevated olives

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7
Q

[Medulla Oblongata: Anterior]

Which nerve emerges between the pyramids and olives?

A

Hypoglossal nerve (CN X11)

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8
Q

[Medulla Oblongata: Anterior]

What is the order of nerves that emerge lateral to the olives from top to bottom?

A

glossopharyngeal nerve (CN IX), vagus nerve (CNX), cranial part of accessory nerve (CNXI)

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9
Q

[Pontomedullary junction: Anterior ]
Within the pontomedullary sulcus (of the pontomedullary junction between the pons and medulla oblanga], what are the nerves that emerge from medil to lateral?

A

abducens nerve (CN Vi), facial nerve (CNVII), vestibulocochlear nerve (CNVIII)

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10
Q

[Pons: Anterior]
The anterior aspect of the pons possesses a vertical groove (basilar sulcus) along the midline, which contains the basilar artery (formed by union of ___________________)
- Lateral aspect of the pons gives the attachment to the _____________ which consists of the smaller motor root and larger sensory root
• Basilar artery bifurcates into two terminal branches (________________)

A

left and right vertebral arteries;

trigeminal nerve (CN V);

posterior cerebral arteries

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11
Q

[Midbrain: Anterior]
The cerebral peduncles lie on either side of the midbrain, serving to hold the rest of the cerebral cortex onto the brainstem, and carries the ________________________ in the spinal cord (voluntary motor control):
• Interpeduncular fossa lies between the cerebral peduncles, and the _________________ emerges from this fossa

A

main corticospinal fibres (motor) down to the primary alpha motor neurones;

oculomotor nerve (CN III)

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12
Q

[Medulla Oblongata: Posterior]
The posterior aspect of the medulla oblongata possesses the posterior median sulcus:
• Fasciculus gracilis and fasciculus cuneatus contain the _______________ and lie lateral to the ________________
o Superior part of the fascicles possess the _______ and ____________ respectively

  • Inferior part is known as the closed part (contains the _________); superior part is known as the open part (central canal expands to form ___________)
  • Contains the ____________ (superior) and the ______________ (inferior) → respective cranial nerve nuclei lie deep to these trigones
A

dorsal column (ascending) tracts;

posterior median sulcus ;

gracile tubercles;

cuneate tubercles;

central canal;

4th ventricle;

hypoglossal trigone;

vagal trigone

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13
Q

[Pons: Posterior]
The posterior surface of the pons forms the _______________, while the cerebellum forms the __________________:
• Contains the facial colliculus → ___________________ lies deep to it

A

floor of the 4th ventricle (contains CSF);

roof of the 4th ventricle;

abducens nerve (CN VI) and facial nerve (CN VII) nuclei

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14
Q

[Midbrain: Posterior]
The midbrain has 4 elevations (superior and inferior colliculi) with 2 on either side:
• Superior colliculi: involved in ___________________
• Inferior colliculi: involved in _____________________
• Pineal body is found between the superior colliculi in the midline, and secretes ____________ (vital for circadian rhythms and hormonal release)
The ________________ is the only cranial nerve which emerges on the posterior aspect of the brainstem inferior to the inferior colliculi.

A

primitive visual reflexes (e.g. coordinating the neck and eye movement to track a ball during sports);

auditory reflexes (e.g. coordinating reflex during loud noise to look towards the side of the noise);

melatonin;

trochlear nerve (CN IV)

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15
Q

[Medulla oblongata: Anterior, level of pyramidal decussation (caudal closed medulla)]
____________ containing corticospinal fibres (lower motor neurones from primary motor cortex):
• Pyramidal decussation: 90 – 95% of corticospinal fibres cross over to the other side (passing _________) to form the descending corticospinal tracts
• Corticospinal tracts: supply the ____________

A

Pyramids;

dorsolaterally;

lower motor neurones

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16
Q

[Medulla oblongata: Posterior, level of pyramidal decussation (caudal closed medulla)]

What are the structures?

A

Dorsal columns (ascending) tracts carrying information about touch and proprioception from the body

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17
Q

[Medulla oblongata: Lateral, level of pyramidal decussation (caudal closed medulla)]
What are the structures?

A
  • Spinal nucleus (V): pain and sensations from the head & neck
  • Lateral spinothalamic tracts: pain from contralateral areas of body
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18
Q

[Medulla oblongata: Medial , level of sensory decussation (rostral closed medulla)]
What are the structures?
- _______________ lying anteriorly
- Sensory decussation: dorsal column fibres (first order neurones) synapse in the _________________ → second order neurones cross to the opposite side behind the pyramids (then ascend upwards as the medial lemniscus)

A

Pyramids (containing corticospinal fibres);

gracile and cuneate nuclei

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19
Q

[Medulla oblongata: Lateral, level of sensory decussation (rostral closed medulla)]
What are the structures?

A
  • Spinal nucleus (V): pain and sensations from the head & neck
  • Lateral spinothalamic tracts: pain from contralateral areas of body (decussation occurs in the spinal cord)
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20
Q

[Medulla oblongata: Medial, level of rostral (open) part of the medulla]
What are the structures and what are they supplied by?

A

Supplied by the anterior spinal arteries:
• Pyramids (containing corticospinal fibres) lying anteriorly
• Medial lemniscus (from decussation of dorsal column tracts)
• Hypoglossal nucleus/nerve (CN XII)

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21
Q

[Medulla oblongata: Lateral, level of rostral (open) part of the medulla]
What are the structures and what are they supplied by?

A

Supplied by the posterior inferior cerebellar artery (PICA):
• Spinal nucleus (V) and related tracts
• Lateral spinothalamic tract
• Inferior olivary nuclear complex (connected to cerebellum)
•Dorsal nucleus of vagus (X), nucleus ambiguus (IX, X, XI), nucleus solitarius (VII, IX, X)
• Vestibular & cochlear nuclei (VIII)

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22
Q

Medial medullary syndrome: due to occlusion of the __________________
• Involves the pyramids, medial lemniscus, hypoglossal nerve (CN XII)

A

vertebral artery or anterior spinal artery

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23
Q

Lateral medullary syndrome (Wallenberg syndrome): due to occlusion of the __________
• Involves the nucleus ambiguus (CN IX, X, XI), spinal tract of the trigeminal nucleus (V), lateral spinothalamic tract, vestibular nuclei (VIII), hypothalamospinal tract

A

left PICA

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24
Q

[Pons: basilar (anterior), caudal part of the pons]

What are the structures?

A

Pontine nuclei, corticospinal fibres and bundles of transverse fibres

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25
Q

[Pons: tegementum (posterior), caudal part of the pons]

What are the structures?

A
  • Spinal nucleus (V) and related tracts
  • Medial lemniscus
  • Lateral spinothalamic tract
  • Vestibular nuclei (VIII), facial nucleus/nerve (VII) (winds around the abducens nucleus to produce the facial colliculus), abducens nucleus/nerve (VI)
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26
Q

[Pons: cranial (anterior), cranial part of the pons]

What are the structures?

A

Pontine nuclei, corticospinal fibres and bundles of transverse fibres

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27
Q

[Pons: tegementum (posterior), cranial part of the pons]

What are the structures?

A
  • Motor nucleus (V) (muscles of mastication) & principal sensory nucleus (V) (general sensation from the face)
  • Medial lemniscus
  • Lateral spinothalamic tract
28
Q

[Midbrain]
The midbrain consists of ________________ (lateral halves) made of the crus cerebri, tegmentum and tectum:
• Interpeduncular fossa lies between the peduncles (________ emerges from this fossa)
• __________ (melanin pigment; band of grey matter) is involved in motor function (regulation of muscle tone)
• ___________ runs through the centre of the midbrain (surrounded by central grey matter) and connects the 3rd and 4th ventricles

A

two cerebral peduncles;

CN III;

Substantia nigra;

Cerebral aqueduct

29
Q

[Midbrain: level of the inferior colliculi]

What are the structures?

A
  • Crus cerebri (containing descending corticospinal fibres)
  • Substantia nigra (motor fibres controlling muscle tone)
  • Nucleus of inferior colliculus (auditory pathways and reflexes)
30
Q

[Midbrain: level of the inferior colliculi]

What are the cranial nerve nuclei?

A
  • Trochlear nucleus (IV) within the central grey matter in the inferior colliculi (CN IV runs dorsally → decussates → emerges from dorsal surface → surrounds midbrain and runs ventrally to supply the superior oblique muscle)
  • Mesencephalic nuclei (V): proprioception of TMJ, muscles of mastication
31
Q

[Midbrain: level of the inferior colliculi]

What are the sensory tracts?

A
  • Medial lemnisci (dorsal column tract)
  • Spinal lemnisci (lateral spinothalamic tract)
  • Trigeminal lemnisci
  • Lateral lemnisci (hearing pathways)
32
Q

[Midbrain: level of the superior colliculi]

What are the structures?

A
  • Red nucleus (high vascularity with iron pigment): coordination of muscle tone, body position/posture and gait
  • Substantia nigra (motor fibres controlling muscle tone)
  • Nucleus of superior colliculus (visual reflexes)
  • Pretectal nucleus (visual pathways and light reflexes)
33
Q

[Midbrain: level of the superior colliculi]

What are the cranial nerve nuclei ?

A
  • Oculomotor nucleus (III) within the central grey matter (CN III runs ventrally and emerges from the interpeduncular fossa to supply most of the extraocular muscles except the superior oblique (IV) and lateral rectus (VI))
    • Edinger-Westphal nucleus (III) involved in parasympathetic pathways and light reflexes (travels along CN III to supply ciliaris muscle and sphincter pupillae)
  • Mesencephalic nuclei (V)
34
Q

[Midbrain: level of the superior colliculi]

What are the sensory tracts?

A
  • Medial lemnisci (dorsal column tract)
  • Spinal lemnisci (lateral spinothalamic tract)
  • Trigeminal lemnisci
35
Q

The lower part of the neural tube develops into the spinal cord:
• Neurones in the neural tube proliferate to form the alar plate (dorsal) and basal plate (ventral) with the ____________ between them
• Basal plates develop into _________________
• Alar plates develop into the _______________
• Central cavity shrinks to form the central canal of the spinal cord

The medulla oblongata also develops from the lower neural tube (above spinal cord):
• Central cavity enlarges and spreads laterally to form the _____________
• Alar plates and basal plates move laterally → alar plates lie more laterally (sensory neurones more lateral); basal plates lie medially (motor neurones more medial)

A

sulcus limitans;

the anterior grey columns/horns (motor) ;

posterior grey columns/horns (sensory);

4th ventricle

36
Q

what are the special somatic/ visceral efferent cranial nerves and their nuclei

A
  • CN V, VII, IX, X, XI
  • Nucleus ambiguus (IX, X, XI): pharynx, larynx, soft palate
  • Motor facial nucleus (VII): muscles of facial expression
  • Motor trigeminal nucleus (V): muscles of mastication
37
Q

what are the general visceral efferent cranial nerves and their nuclei?

A

GVE (general visceral efferent) – smooth muscles and glands (parasympathetic)
• CN III, VII, IX, X
• Dorsal nucleus of vagus (X): parasympathetic fibres
• Inferior salivatory nucleus (IX): parotids
• Superior salivatory nucleus (VII): submandibular, sublingual glands
• Edinger-Westphal nucleus (III): sphincter pupillae, ciliaris muscle

38
Q

which nerves are entirely sensory?

A

CN I (olfactory), CN II (optic), CN VIII (vestibulocochlear)

39
Q

which nerves are entirely motor?

A

CN III (oculomotor), CN IV (trochlear), CN VI (abducens), CN XI (accessory), CN XII (hypoglossal)

40
Q

Which nerves are sensory + motor?

A

CN V (trigeminal), CN VII (facial), CN IX (glossopharyngeal), CN X (vagus)

41
Q

Which nerves are parasympathetic?

A

CN III, VII, IX, X

42
Q

Which nerves supply the eye?

A

CN III (most muscles), CN IV (superior oblique), CN VI (lateral rectus)

43
Q

Olfactory (I) *No definite nucleus
- Entirely sensory (to nose); fibres from modified cells of the nasal epithelium

What is the path?

A

enter cranial cavity via the olfactory foramina lateral to the crista galli of the cribriform plate) → olfactory bulbs → tract → striae

44
Q

Optic (II)

  • Entirely sensory (to eyes);
  • Covered by the meninges (true cranial nerve) → can be compressed due to increased ICP (causing papilloedema)

What is the path?

A

fibres from the optic vesicle pass through the optic canal (with ophthalmic artery) and decussate at the optic chiasm

45
Q

Oculomotor (III)
- Entirely motor; carry parasympathetic preganglionic fibres

Where does it arise from? What does it supply?

A
  • arise from nuclei in midbrain at the level of superior colliculus
    • Oculomotor nucleus: extraocular muscles (except superior oblique and lateral rectus), levator palpabrae superioris (upper eyelids)
    • Edinger-Westphal nucleus (parasymp): sphincter pupillae, ciliaris
46
Q

Trochlear (IV)
- Entirely motor

Where does it arise from? What does it supply?

A

decussate before emerging from dorsal side (arise from nuclei in midbrain at the level of inferior colliculus):
• Trochlear nucleus (GSE): superior oblique muscles (rotates eyeball medially downwards)

47
Q

What does the motor trigeminal nucleus (pons) supply?

A

muscles of mastication, mylohyoid, anterior belly of digastric, tensor palatini

48
Q

what does the spinal (medulla) and principal sensory (pons) nuclei of trigeminal nerve supply?

A

general sensation from face, anterior scalp, oral/nasal cavities, orbit

49
Q

What does the mesencephalic trigeminal nucleus supply?

A

proprioception from TMJ and muscles of mastication

50
Q

Abducens (VI)
- Entirely motor

Where does it arise from? What does it supply?

A

Entirely motor (arise from nuclei deep to facial colliculus in the pons): • Abducens nucleus (GSE): lateral rectus muscle (abducts the eyes)

51
Q

What does the facial motor nucleus (SVE) supply?

A

facial muscles, stylohyoid, posterior belly of digastric, stapedius

52
Q

What does the superior salivatory and lacrimatory nucleus (GVE) from facial (VII) supply?

A

secretomotor to submandibular, sublingual and lacrimal glands

53
Q

What does the nucleus solitarius (SVA) from facial (VII) supply?

A

taste (anterior two-thirds of tongue)

54
Q

What does the Vestibulocochlear (VIII) supply?

A

Entirely sensory • Vestibular + cochlear nuclei (SSA): hearing, balance

55
Q

[Glossopharyngeal (IX)]

What does Nucleus ambiguus (SVE) supply?

A

stylopharyngeus

56
Q

[Glossopharyngeal (IX)]

What does Inferior salivatory nucleus (GVE) supply?

A

secretomotor to parotids

57
Q

[Glossopharyngeal (IX)]

What does Nucleus solitarius (GSA) supply?

A

chemoreceptors, baroreceptors

58
Q

[Glossopharyngeal (IX)]

What does Spinal trigeminal nucleus (GSA) supply?

A

posterior oral cavity, tonsillar region, middle ear, auditory tube

59
Q

[Vagus (X)]

What does Nucleus ambigus (SVE) supply?

A

pharyngeal constrictors, muscles of soft palate and larynx

60
Q

[Vagus (X)]

What does Dorsal motor nucleus of vagus (GVE) supply?

A

parasympathetic to heart, lungs, most of GI tract

61
Q

[Vagus (X)]

What does Nucleus solitarius (SVA) supply?

A

taste from palate and epiglottis

62
Q

[Vagus (X)]

What does Nucleus solitarius (GSA) supply?

A

chemoreceptors, baroreceptors

63
Q

Accessory (XI) GSE

What does Cranial part (nucleus ambiguus): supply?

A

soft palate muscles

64
Q

Accessory (XI) GSE

What does Spinal part (C1 – C5 part of spinal cord) supply?

A

SCM, trapezius

65
Q

Hypoglossal (XII) GSE
- Entirely motor (arise from nuclei in the medulla):

What does hypoglossal nucleus (GSE) supply?

A

all extrinsic and intrinsic muscles of the tongue (except palatoglossus)

66
Q

The brainstem reticular formation is a complex intermingling of loosely defined nuclei and tracts which extends through the ______________:
• Intimately associated with the ascending and descending tracts as well as the cranial nerve nuclei
• Receives input from all parts of the nervous system (exerts widespread influence on every CNS function)

A

central part of medulla, pons and midbrain

67
Q

The locus cerules is a dark-coloured nucleus with melanin-containing neurons located under the _____________:
• Axons are distributed to the __________________
• Noradrenergic projections: regulation of attention, cortical arousal, sleep-wake cycle, learning, memory,
anxiety, mood → norepinephrine increases brain responsiveness and speeds up information processing

A

lateral part of the floor of the rostral pontine 4th ventricle;

cerebral cortex, thalamus, hypothalamus, cerebellar cortex, brainstem, and spinal cord

M2 NENTE Anatomy (24 decks)

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