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B12 MSK > Cranial Nerves and Special Senses > Flashcards

Cranial Nerves and Special Senses Flashcards

1
Q

What is the function of each of the 12 cranial nerves

A

I - OLFACTORY - smell
II - OPTIC - vision
III - OCULOMOTOR - eye movements and pupil constriction
IV - TROCHLEAR - superior oblique
V - TRIGEMINAL - sensation of face; muscles of mastication
VI - ABDUCENS - lateral rectus
VII - FACIAL - muscles of facial expression; taste to anterior 1/3 of tongue
VIII - VESTIBULOCOCHLEAR - hearing and balance
IX - GLOSSOPHARYNGEAL - taste to posterior 2/3 of tongue; innervation of pharynx
X - VAGUS - parasympathetic innervation of viscera; laryngeal muscles
XI - ACCESSORY - sternocleidomastoid and trapezius
XII - HYPOGLOSSAL - tongue muscles

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2
Q

Where do the following structures relay information to and from:

  1. optic nerve
  2. optic tract
  3. optic radiation
A
  1. from retina to optic chiasm
  2. from optic chiasm to lateral geniculate nucleus in the thalamus
  3. from LGN to the primary visual cortex
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3
Q

Which hemisphere are the following visual fields represented?

  1. left
  2. right
A
  1. right hemisphere

2. left hemisphere

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4
Q

What is the result of the following lesions:

  1. optic nerve lesions
  2. optic chiasm lesions
  3. optic tract lesions
  4. partial optic radiation lesion
  5. primary visual cortex lesion
A
  1. total blindness of ipsilateral eye
  2. bilateral hemianopsia (loss of right visual field in right eye and left visual field in left eye)
  3. contralatal homonymoys hemoanopsia ( loss of same visual field in bot eyes)
  4. quadrantopia
  5. bilateral hemianopsia
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5
Q
  1. What does the fibrous later of the eye consist of? (2)
  2. What are the functions of the fibrous layer?
  3. What are the three components of the vascular layer of the eye and their functions
A
  1. sclera and cornea
  2. provide shape to the eye and support deeper structures
  3. CHOROID - connective tissue and blood vessels. Provides nourishment
    IRIS - circular structure with aperture in the centre (pupil)
    CILIARY BODY - ciliary muscle and ciliary processes. Controls shape of lens and contributes to formation of aqueous humor
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6
Q
  1. Where are the anterior and posterior chambers of the eye located?
  2. what are these chambers filled with?
  3. What is the space between the lens and the retina filled with?
A
  1. Anterior - between cornea and iris
    Posterior - between iris and ciliary processes
  2. Aqueous humour
  3. vitreous humour
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7
Q
  1. What is gaze stabilisation?
  2. What is gaze shifting?
  3. What are conjugate movements?
  4. What are disconjugate movements?
  5. Describe the following movements:
    a) vestibulo-ocular
    b) optokinetic
    c) saccade
    d) smooth pursuit
    e) vergence
A
  1. eye movements to maintain gaze on visual target
  2. eye movements to move the eyes to a visual target
  3. eye movements in the same direction
  4. eye movements in the opposite direction

5a) conjugate eye movements, initiated by vestibular mechanisms during rapid head movement
5b) initiated by visual mechanisms during slow head movement
5c) directs eyes towards visual target
5d) follows moving visual target
5e) disconjugate movement that adjusts eyes for different viewing distance

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8
Q
  1. Which muscles are innervated by the occulomotor nerve
  2. which muscles are innervated by the trochlear nerve?
  3. Which muscles are innervated by the abducens nerve?
  4. Which muscles are responsible for the following eye movements
    a) elevation
    b) depression
    c) adduction
    d) abduction
    e) intorsion
    f) extortion
A
  1. medial rectus, superior oblique, inferior oblique, superior rectus, inferior rectus
  2. superior oblique
  3. lateral rectus

4a) superior rectus, inferior oblique
4b) inferior rectus, superior oblique
4c) medial rectus
4d) lateral rectus
4e) superior oblique and superior rectus
4f) inferior oblique and inferior rectus

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9
Q

What fibres innervate:

  1. sphincter pupillae?
  2. dilator pupillae?
  3. What is the term given to pupils of two different sizes?
A
  1. Parasympathetic fibres - OCCULOMOTOR NERVE
  2. Sympathetic fibres
  3. anisocoria
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10
Q
  1. Where is aqueous humour produced?

2. describe the drainage route of aqueous humour

A
  1. ciliary body
  2. posterior chamber → narrow space between the posterior iris and the anterior lens→ pupil → anterior chamber → trabecular meshwork→ Schlemm’s canal (and into venous system)
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11
Q
  1. Name the two blood circulatory systems in the eye
  2. From which artery are they both derived from?
  3. Where do the retinal arteries enter the eye?
  4. What does the retinal arteries supply?
  5. What does the choroidal blood vessels supply?
A
  1. retinal and choroidal
  2. opthalmic
  3. along with the optic nerve
  4. inner retina
  5. ouuter layers
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12
Q

Describe the following laminar organisation of the retina:

  1. ganglion cell layer
  2. inner nuclear layer
  3. outer nuclear layer
  4. photoreceptor layer
A
  1. cell bodies of ganglion cells
  2. cell bodies of bipolar cells; horizontal anf amacrine cells
  3. cell bodies of photoreceptors
  4. light sensitive elements of photo receptors embedded in a pigment epithelium
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13
Q

How is the fovea adapted for high visual acuity? (3)

A
  1. lateral displacement of cells above the photoreceptors to prevent light scattering
  2. contains exclusively cones
  3. each photoreceptor has its own ganglion cell
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14
Q
  1. Where in the brain is the Lateral Geniculate Nucleus Located?
  2. How many layers make up the magnocellular layer?
  3. What do they receive input from?
  4. What type of visual processing are they involved in?
  5. How many layers make up the parvocellular layer?
  6. What do they receive input from?
  7. What type of visual processing are they involved in?
A
  1. thalamus
  2. bottom two layers
  3. P type ganglion cells
  4. light and dark
  5. top 4 layers
  6. M type ganglion cells
  7. colour processing
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15
Q
  1. Where is the primary visual cortex located?
  2. What is the role of V4?
  3. What is the role of V5?
  4. What are the difficulties of patients with lesions in:
    a) V4
    b) V5
  5. What is the “where” pathway?
  6. What is the “what” pathway?
A
  1. medial surface of the occipital lobe, surrounding the calcarine fissure
  2. colour processing
  3. motion processing

4a) perceiving colour (achromtopsia)
4b) perceiving motion (akinetopsia)

  1. primary visual cortex to dorsal parietal cortex
  2. primary visual cortex to inferotemporal cortex
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16
Q
  1. What is cataracts?

2. Name some risk factors for cataracts

A
  1. opacification of the lens, caused by compaction and protein deposition
  2. aging, trauma, diabetes, smoking, UVB exposure, fam Hx
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17
Q
  1. What is glaucoma?
  2. Name 4 risk factors for glaucoma
  3. What is primary open angle glaucoma caused by?
  4. What is acute, angle closure glaucoma caused?
  5. How is glaucoma treated (5 drugs)
A
  1. raised intraocular pressure (>22mmHg)
  2. hypertension, long term steroid use, severe near sightedness, eye injury/surgery
  3. blocking of the trabecular meshwork
  4. bowing of the iris, which closes the anterior chamber angle and blocks drainage
5. beta blockers
alpha 2 agonists
carbonic anhydrase inhibitors
prostaglandin analogues
muscarinic agonists (miotics)
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18
Q
  1. what is the pinna and its function?
  2. What is the shape of the external auditory meatus?
  3. Where does the external auditory meatus run from and to?
  4. What is the external auditory meatus surrounded by?
  5. What is the most depressed part of the tympanic membrane?
  6. Which of the ossicles attaches to the tympanic membrane?
  7. What is the function of the outer ear?
A
  1. visible part of the ear on the lateral side of the head, involved in catching sound
  2. sigmoid
  3. from pinna to the tympanic membrane
  4. first 1/3 is surrounded by cartilage; second 2/3 is surrounded by bone
  5. umbo
  6. malleus
  7. convert acoustic energy to kinetic energy
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19
Q
  1. Name the three ossicles
  2. What is the function of the ossicles?
  3. What does the eustachian tube connect to?
  4. What is the function of the eustachian tube?
  5. Name the two middle ear muscles
  6. What reflex are these muscles involved in?
  7. What is the innervation of these muscles?
A
  1. malleus, incus and stapes
  2. to concentrate sound energy on a smaller area
  3. connects middle ear to nasopharynx
  4. pressure equalisation between middle and external ear
  5. tensor tympani and stapedus
  6. attenuation reflex - dampens down sound of own voice during speaking
  7. stapedal nerve (branch of facial) innervates stapedus
    mandibular branch of trigeminal nerve innervates tensor tympani
20
Q
  1. what makes up the bony labyrinth?
  2. what is the membranous labyrinth filled with?
  3. what is the bony and membranous labyrinth separated by?
A
  1. petrous part of the temporal bone
  2. endolymph (high [K+])
  3. perilymph (hign [Na+])
21
Q
  1. What structure does the cochlea wind around?
  2. Name the three chambers of the cochlear and what they are filled with?
  3. Name the two membranes that separate these chambers
  4. What does the organ of corti sit on?
A
  1. modiolus
  2. scala media - filled with endolymph
    scala vestibuli (superior) - filled with perilymph
    scala tympani (inferior) - filled with perilymph
  3. reisners membrane separates the scala vestibuli and scala media
    basilar membrane separates the scala media and scala tympani
  4. basilar membrane
22
Q
  1. Describe the process of sound transduction
  2. How does the organ of corti transmit sound?
  3. Where are:
    a) high pitched sounds detected?
    b) low pitched sounds detected?
    c) why?
A
  1. vibration of the ear drum and ossicles; footplate of stapes vibrates in the oval window
    wave along scala vestibul, and then back along the scala tympani to the round window - leads to displacement of basilar membrane
  2. displacement of basilar membrane causes shear of hair cells - causes opening of transduction ion channels

3a) base of cochlear.
3b) helicotrema
3c) stiffest at the base; only high frequency sounds can displace the membrane at the base.

23
Q
  1. describe the auditory pathway from ear to auditory cortex (SLIM)
  2. Where does decussation take place?
  3. How are auditory pathways bilaterally represented?
A
  1. superior olivary complex → lateral lemniscus → inferior coliculus → medial geniculate nucleus
  2. between cochlear nuclei and superior olivary complex
  3. cells in cochlear nucleus have axons that project to the superior olive on both sides of the brainstem.
24
Q
  1. Where is the auditory cortex located?
  2. What brodman areas are these?
  3. How is the auditory cortex tonotopically arranged?
A
  1. temporal lobe
  2. 41 and 42
  3. different layers correspond to different frequencies
25
Q
  1. What does decussation and bilateral representation enable?
  2. What do medial superior olivary nuclei detect?
  3. What do lateral superior olivary nuclei detect?
  4. How is low frequency sound localised?
  5. How is high frequency sound localised?
A
  1. inputs from left and right ears to be compared in the superior olivary nuclei
  2. differences in TIME that sound reaches the ear
  3. differences in SOUND INTENSITy reaching each ear
  4. detection of time differences
  5. detection of sound intensity differences
26
Q
  1. What is conductive hearing loss?

2. What is sensorineural hearing loss?

A
  1. hearing loss caused by problem conducting sound waves through outer ear, eardrum or middle ear
  2. problem in cochlea/organ of corti, vestibulocochlear nerve or auditory cortex
27
Q

WEBER TEST

  1. what does it mean if normal ear hears sound louder?
  2. What does it mean if defective ear hears sound louder?
A
  1. hearing loss is sensorineural

2. hearing loss os conductive

28
Q
  1. define posture

2. what type of tone is required for maintaining posture?

A
  1. relative position of various parts of the body with respect to one another, the environment, and gravity
  2. extensor tone
29
Q
  1. Name three sensory inputs involved in maintaining posture

2. Name the four descending tracts involved in controlling posture

A
  1. somtosensory receptors
    visual system
    vestibular system
  2. vestibulospinal tract
    tectospinal tract
    pontine reticulospinal tracts
    medullary reticulospinal tracts
30
Q

What is the sensory input, origin, and function of the following descending tracts:

  1. vestibulospinal
  2. tectospinal
  3. pontine reticulospinal
  4. medullary reticulospinal
A
  1. sensory input from vestibular labyrinth
    originates from vestibular nuclei
    facilitates extensor tone of legs
  2. sensory input from eye
    originates from superior colliculus
    facilitates orientating response
  3. input from cerebellum and cortex
    arises from pontine reticular formation
    facilitates extensors of lower limbs
  4. input from cerebellum and cortex
    arises from medullary reticular formation
    liberates antigravity muscles
31
Q

name the two vestibular apparatus and what they detect

A
  1. Otolith organs - detect force of gravity and linear tilts of the head
  2. semicircular canals - detects rotation of the head
32
Q
  1. What are the two otolith organs called?
  2. What is the sensory epithelium of the otolith organs called?
  3. What do the two components detect?
  4. Describe the structure of the otolith organs
  5. Name the two types of cilia on hair cells
  6. How are these hair cells directionally sensitive?
  7. What is the striola?
  8. How are cillia orientated towards the striola?
A
  1. utricle and saccule
  2. macula
  3. utricle - horizontal movement
    sacule - vertical movement
  4. hair cells of the macule have cillia that penetrate into a gelatinous cap. The surface of the gelatinous cap is encrusted with calcium carbonate crystals
    head movements cause the gelatinous cap to sag, causing the cilia to bend
  5. stereocilia - short
    kinocillium - long
  6. movement that bends the hair cell away from the kinocilium > hyperpolarisation
    movement that bends the hair cell towards the kinocilium > depolarisation
  7. line that bisects the macula
  8. utricle - kinocilia are orientated towards the striola
    saccule - kinocilia are orientated away from the striola
33
Q
  1. What are the semicircular canals filled with?
  2. what is the main sensory structure of the semicircular canals?
  3. How are head movements transmitted into neural signals by the semicircular canals?
A
  1. endolymph
  2. cupula - a gelatinous cap into which the hair cells are embedded
  3. due to the inertia of the endolymph, with angular rotation, the cupula bends in the opposite direction. This causes the hair cells to bend and depolarise
34
Q
  1. What is the vestibulo-ocular reflex?
  2. Describe the reflex
  3. Why is the reflex important?
A
  1. compensatory movement of the eyes in the opposite direction of head rotation
  2. left horizontal canal excited as head moves left
    signal sent to vestibular nuclei then occulomotor nuclei
    right abducens nerve flexes the right lateral retctus
    eyes turn to the right
  3. allows image to remain steady on the retina, despite head movements
35
Q
  1. What is the aim of protective postural reflexes?
  2. what is the positive supporting reaction
  3. what is the hopping reaction?
A
  1. to regain the centre of mass over the base of support
  2. placing a limb on the ground initiates a set of reflexes that stiffen the limb
  3. momentary destabilisation of the body causes hopping to a new position where a stable posture is possible
36
Q
  1. What is anticipatory postural control
  2. Is it conscious, learned or automatic?
  3. What is feedforward control?
  4. What neural structure is important for feedforward control?
  5. What is feedback control?
  6. What neural structures are important for feedback control?
  7. What is vestibular plasticity?
A
  1. ability to anticipate changes in posture, and to be able to activate the postural system in the absence of vestibular input
  2. must be learned, but then becomes automatic
  3. postural adjustments made before voluntary movements
  4. reticular formation
  5. responses to sensory stimuli following postural disturbance
  6. vestibular nuclei
  7. adaptation of postural reflexes in order to optimise performance
37
Q
  1. What is Meniere’s syndrome?
  2. name 3 symptoms of meniere’s syndrome
  3. how is it managed?
A
  1. increase in the volume of endolymp, which disrupts the membranous labyrinth of the inner ear
  2. temporary attacks of vertigo, deafness and tinitus
  3. antiemetics - prochlorperazine and antihistamines
38
Q
  1. What is benign paroxysmal positional vertigo?
  2. What are the symptoms?
  3. How is it treated?
A
  1. dislodging of calcium carbonate crystals of the otolith organs, disrupting the flow of endolymph in the semicircular canals
  2. dizziness when moving head in certain direction; nausea and vomiting
  3. semont manoeuvre to reposition crystals
    exercises to ignore dysfunctional signals and maintain balance.
39
Q

Where are the nuclei for the cranial nerves located?

A 
I - cerebrum
II - cerebrum
III - midbrain (dorsal surface)
IV - midbrain
V - pons
VI - pons 
VII - pons
VIII - pons
IX - medulla
X - medulla
XI - medulla
XII - medulla
40
Q
  1. Where are neurons of the primary motor cortex supplying the
    a) inferior body found?
    b) superior body found?
  2. How do fibres coming from the following descend?
    a) lateral cortex
    b) medial cortex
  3. Which motor tracts do not decussate? What do they supply?
A

1a) medially
1b) laterally

2a) medially
2b) laterally

  1. anterior corticospinal tracts
    supply the axial muscles
41
Q
  1. What sensory modalities do the dorsal columns carry?
  2. Describe the pathway that the first order neurons of the dorsal columns take
  3. Where do the dorsal columns decussate?
  4. What sensory modalities do the spinothalamic tracts carry?
  5. Where do they decussate?
A
  1. fine touch, proprioception, vibration
  2. from upper limb - travel in fasiculus cuneatus to nucleus cuneatus in medulla
    from lower limb - travel in fasiculus gracialis to nucleus gracialis in medulla
  3. medulla
  4. pain, crude touch, temperature
  5. two vertebral levels above, in the spinal cord
42
Q

Name features of cerebellar dysfunction (VANISHED)

A 
Vertigo
Atazia
Nystagmus
Intention Tremor
Slurred Speech
Hypotonia
Dysdiadochokinesis
43
Q
  1. What is glioblastoma multiforme?
  2. Name 2 signs of this
  3. What is Weber’s syndrome?
  4. What is it caused by?
  5. What is wallenburg syndrome?
  6. Name some symptoms
A
  1. Most malignant of primary brain tumours
  2. contralateral motor signs; frontal lobe lesion signs
  3. oculomotor nerve palsy
  4. caused by stroke
  5. syndrome caused by stroke of the brainstem
  6. impaired gag reflex, ipsilateral facial sensory loss, ipsilateral horner’s syndrome, vertigo, ataxia, altered taste
44
Q
  1. Describe the three signs of an occulomotor nerve lesion
  2. What is Horner’s syndrome caused by?
  3. Name 4 signs of Horner’s Syndrome
  4. What are the signs of a trochlear nerve palsy?
  5. What are the signs of an Abducens nerve palsy?
A
  1. down and out
    pupil is dilated
    partial ptosis
  2. damage to sympathetic trunk (C8/T1 pathology)
  3. miosis. partial ptosis. anhydrosis. Enopthalmos
  4. difficulty looking down and in
  5. difficulty abducting eye on affected side
45
Q

When is the forehead spared? Upper or Lower Motor Neuron lesions?

A

Upper motor neuron lesions

forehead tends to be spared in stroke but not in bells palsy

46
Q
  1. What is decorticate posturing?

2. What is decerebrate posturing?

A
  1. flexed arms, legs extended. Indicates damage to cerebral hemispheres, internal capsule and thalamus
  2. arms and legs extended, head arched back. Indicates brainstem damage
47
Q
  1. What is brown sequard syndrome?
  2. What does the anterior spinal artery supply?
  3. What happens in anterior spinal artery syndrome?
A
  1. hemicord lesion. Ipsilateral motor and dorsal column signs and symptoms. Contralateral spinothalamic signs
  2. anterior 2/3 of the spinal cord
  3. motor loss, spinothalamic loss; dorsal columns are spared

B12 MSK (12 decks)

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