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Head and Neck Anatomy > Anatomy of the Brainstem and Cranial Nerve > Flashcards

Anatomy of the Brainstem and Cranial Nerve Flashcards

1
Q

Name the components of the brainstem?

A
  1. Midbrain – First part of Brainstem
  2. Pons – Most anterior part of posterior cranial fossa
  3. Medulla Oblongata – Upper Roots of Cranial Nerves IX – XII attached here
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2
Q

Name the 3 parts of the midbrain?

A
  1. tectum
  2. periaqueductal grey matter
  3. tegmentum
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3
Q

Describe the tectum?

A

Location: Area dorsal to the aqueduct (of Sylvius)
Components: Has 4 dorsal prominences (corpora quadrigemina)
> Two superior colliculi – visual reflexes
> Two inferior colliculi – auditory reflexes
- Cranial nerve IV is attached between them
Function: preliminary processing of the visual or auditory stimuli before they reach their corresponding primary processing centers

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4
Q

Describe the periaqueductal grey matter?

A

Components: Contains nuclei of CN III (OCCULOMOTOR) and IV (TROCHLEAR)
Function: modulate pain by releasing endogenous opioids
- where distinction between the expected and actually perceived pain is made

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5
Q

Describe the tegmentum?

A

Location: Area ventral to the aqueduct
Components:
1. Has the red nucleus
> Passage of impulses to and from cerebral cortex from dentate nucleus through superior cerebellar peduncle to red nucleus (dentato-rubro-thalamic tract)
> Also connected to the spinal cord (rubrospinal, spinorubral tracts)
2. Has Substantia nigra (Latin: Black substance)
> dark area in the tegmentum; one of basal ganglia
> associated with Parkinson’s disease

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6
Q

Describe the pons?

A

Location: Where cerebellum and CN V are attached
Contents:
1. Contains nuclei of CN V, VI, VII, VIII
2. Locus coeruleus (latin: blue place) – pigmented area in the dorsal pons
> concerns with the limbic system and autonomic functions
> a focus for drug action

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6
Q

Describe the anterior aspect of the medulla?

A

4 swellings are visible: 2 on either side of the midline
1. Pyramid: medial swelling on each side
> Contains descending motor corticospinal tracts
2. Olive: lateral swelling on each side
> Contains the inferior olivary nucleus which like the red nucleus is an outpost of the cerebellum

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7
Q

Describe the posterior aspect of the medulla?

A

2 tubercles are visible on each side: concerned with sensation from the spinal cord
1. Gracile: medial tubercle
2. Cuneate: lateral tubercle
Note: Nuclei – Hypoglossal, vagus

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8
Q

What are the cerebellar peduncles?

A

3 paired cerebellur peduncles (bundles of nerve fibers)
> Connect cerebellum to brainstem

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9
Q

Describe the superior peduncle?

A
  • Connects cerebellum with midbrain & pons
  • Contains both afferent & efferent fibers eg:
    > Trigeminocerebellar tract
    > Cerebello – thalamic tract
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10
Q

Describe the middle peduncle?

A
  • Connects cerebellum to pons
  • Contains afferent fibers only
    > e.g. Pontocerebellar fibers
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11
Q

What are the 12 cranial nerves?

A

I - olfactory (smell)
II - optic (sight)
III - oculomotor (motor/parasympathetic)
IV - trochlear (motor)
V - trigeminal (sensation/motor)
VI - abducent (motor)
VII - facial (motor/parasympathetic)
VIII - vestibulo-cochlear (balance/hearing)
IX - glossopharyngeal (sensation/parasympathetic)
X - vagus (parasympathetic/motor/sensory)
XI - accessory (motor)
XII - hypoglossal (motor)

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12
Q

Which parts of the brain do the cranial nerves directly attach to?

A
  1. cerebrum = I and II
  2. midbrain = III and IV
  3. pons = V, VI, VII, VIII
  4. medulla = IX, X, XI, XII
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13
Q

Which parts of the brain do the cranial nerves directly attach to?

A
  1. cerebrum = I and II
  2. midbrain = III and IV
  3. pons = V, VI, VII, VIII
  4. medulla = IX, X, XI, XII
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14
Q

Which parts of the brain do the cranial nerves directly attach to?

A
  1. cerebrum = I and II
  2. midbrain = III and IV
  3. pons = V, VI, VII, VIII
  4. medulla = IX, X, XI, XII
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15
Q

Where do cranial nerves exit the cranial cavity?

A
  1. olfactory = cribiform plate
  2. optic = optic canal
  3. Oculomotor, Trochlear, Trigeminal (V1 – Ophthalmic), Abducent = superior orbital fissure
  4. trigeminal (V2 - maxillary) = foramen rotundum
  5. trigeminal (V3 -mandibular) = foramen ovale
  6. facial + vestibulo-cochlear = internal acoustic meatus
  7. Glossopharyngeal, Vagus, Accessory = jugular foramen
  8. hypoglossal = hypoglossal canal
16
Q

Describe the point of exit from/entry into skull, distribution/function and dysfunction in case of lesion for the olfactory nerve?

A
  1. foramen - cribriform plate
    > 20 neurons from mucosa of upper part of nasal cavity pass via cribriform foramina amd end as olfactory bulb
  2. function - smell
  3. dysfunction - anosmia > loss of olfaction
    > leakage of CSF through nose (rhinorrhoea)
17
Q

State the origin, course and function of optic nerve?

A
  1. origin - axons of ganglionic cells of retina
  2. course - optic canal
  3. function - vision + accomodation reflexes
18
Q

State the foramen, distribution and dysfunction of the oculomotor nerve?

A
  1. foramen - enter orbit rhough superior orbital fissure
  2. distribution - extraocular muscles
    > superior, inferior, medial recti, inferior oblique and levator palpebral superioris
    > sphincter pupillary muscle of iris and ciliary muscle which Ck instructs pupil and accommodate lens
  3. Dysfunction
    •Eye deviation - down & out
    (Lateral stabismus).
    •Ptosis (drooping of eyelid)
    •Mydriasis (fully dilated pupil)
    •Loss of power of accommodation
    •Diplopia
19
Q

What is Horners syndrome?

A

Damage to sympathetic (“Fight or Flight” response) chain fibres before join oculomotor nerve
- leads to
> Droopy eyelid
> Pupillary constriction
> Absence of sweating

20
Q

State the foramen, distribution and dysfunction of the trochlear nerve?

A

Trochlear Nerve (IV)
• Passes through superior orbital fissure
Distribution: Superior oblique
Dysfunction: Rarely paralysed alone
• Diplopia (double vision) on looking down &
Extorsion

21
Q

What are the 3 divisions of the trigeminal nerve?

A

Ophthalmic Division (V1 ) - superior orbital fissure
Maxillary Division (V2 ) - foramen rotundum
Mandibular Division (V3 ) - foramen ovale

22
Q

Describe the sensory distribution of the trigeminal nerve?

A

• Sensory
- Periodontal ligaments of teeth
- Reflex control of force of bite
- Discriminative tactile: from skin of face, mucous membrane of middle ear, pharygotympanic tube, pharynx, larynx

23
Q

Describe the motor distribution of the trigeminal nerve?

A

• Motor
- Muscles of mastication
- Tensor tympani
- Tensor veli palatine
- Mylohyoid
- Anterior belly of digastric

24
Q

Describe the consequences of trigeminal nerve dysfunction?

A

• Trigeminal Nerve dysfunction
• Trigeminal neuralgia - pain in distribution of maxillary and/or mandibular nerve.
• Decreased forehead pain and touch, corneal reflex (1st sign of lesion of ophthalmic nerve), cheek touch & pain, jaw touch & pain & jerk, and
Weakness of muscles of mastication

25
Q

State the foremen, distribution and dysfunction of the abducens nerve?

A

Enters orbit through superior orbital fissure
Distribution: Supplies Lateral rectus
Dysfunction: Medial deviation & diplopia. Cannot look outwards

26
Q

Describe the course of the facial nerve?

A

Course: Internal acoustic meatus to facial canal
• Exits skull through the
Stylomastoid foramen to supply muscles including those of facial expression

27
Q

Describe the distribution of the facial nerve?

A

• Taste from anterior 2/3 of tongue
• Skin of external acoustic meatus
• Mucous membrane of nasopharynx & palate
• Lacrimal, nasal, palatine, submandibular & sublingual glands.

28
Q

Describe the dysfunction of the facial nerve?

A

• Most frequently paralysed of all
cranial nerves
• Infranuclear lesion (LMN) - Bell’s palsy (most common):
- facial muscles
paralysis/weakness with asymmetry of corner of mouth
- Inability to close eye or wrinkle forehead on affected side
- excessive acuteness of hearing (hyperacusis)
• Decreased tearing, salivation & taste

29
Q

State the foremen, functions and dysfunction of the vestibulo-cochlear nerve?

A

• Both pass with CN VII through internal acoustic meatus
.
Functions:
- Vestbular part for balance and posture (Semicircular canals, utricle & saccule).
- Cochlear for Hearing
• Dysfunction
.
Vestibular nerve: Dysequilibrium & vertigo
• Decreased hearing (nerve deafness) - cochlear lesion
• Conduction deafness - external or middle ear
• Tinnitus (noise in ear)

30
Q

State the course, distribution and dysfunction of the glossopharyngeal nerve?

A

• Course: Passes through jugular foramen
• Distribution: Stylopharyngeus, Parotid gland (parasympathetic & sensation), carotid body & sinus, pharynx & middle ear, Taste posterior 1/3 of tongue, Tonsil & palate, Sensation from external ear
• Dysfunction: Decreased Salivation, sensation to back of ear, gag reflex (closure of glottis), taste

31
Q

What is the foremen of the vagus nerve?

A

Jugular foremen

32
Q

Describe the distribution of the vagus nerve?

A

Motor: Pharyngeal constrictor muscles, intrinsic muscles of larynx, muscles of palate.
• Parasympathetic: Smooth muscles of trachea, bronchi, Gl tract, heart
• Sensory: Tongue, pharynx, larynx, thoraco-abdominal viscera, auricle, external auditory meatus, meninges of post cranial fossa.

33
Q

Describe the dysfunction of the vagus nerve?

A

Dysfunction:
.
Recurrent laryngeal nerye palsies are common, from malignant diseases & surgical damage during surgery
heart & lung
on thyroid gland, heck, oesophagus,
. •
Hoarseness and Dysphagia
Decreased gag reflex, sensation in external auditory meatus, pharynx, tachycardia

34
Q

State the foremen, distribution and dysfunction of the accessory nerve?

A

Foremen
Jugular foremen
Distribution
Sternocleidomastoid & Trapezius
muscles
• Dysfunction:
• Wry neck
• Decreased ability to shrug shoulders or turn neck to opposite side

35
Q

State the foramen, distribution and dysfunction of the hypoglossal nerve?

A

Leaves skull through hypoglossal canal
• Distribution: Intrinsic and extrinsic muscles of tonque
.
Dysfunction
Vicarness of tongue movement
.
. On attempted protrusion, tongue deviates
towards affected side
Moderate dysarthria

36
Q

What causes the paralysis of the hypoglossal nerve?

A

• fracture of the occipital condyle
• tumor near the hypoglossal canal

37
Q

What is the consequence paralysis of the hypoglossal nerve?

A

The tongue will deviate towards the side of a peripheral lesion therefore, this is right CN XII paralysis

38
Q

How do you test cranial nerve lesions?

A

Head and Neck Anatomy (37 decks)

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