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ANAT242 > Lecture 7- Brainstem and Cranial Nerves 2 > Flashcards

Lecture 7- Brainstem and Cranial Nerves 2 Flashcards

1
Q

What is bitemporal hemianopia? What is it caused by?

A
  • Visual field defect: bitemporal hemianopia is when lose outer vision in both eyes this occurs from a cut at the optic chiasm
  • Tumors in the pituitary or the hypothalamus can damage vision.
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2
Q

What is the optic nerve?

A

Axons of the retinal ganglion cells

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3
Q

What is the optic chiasm?

A

fibers originated from nasal retina cross over to the opposite side

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4
Q

What is the optic tract?

A

contains crossed axons from nasal retina & uncrossed axons from
temporal retina

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5
Q

What is the optic tract?

A

contains crossed axons from nasal retina & uncrossed axons from
temporal retina

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6
Q

What is the Lateral geniculate nucleus of the thalamus/ it’s role in vision?

A

Processes & relays visual information to visual cortex

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7
Q

What is the Superior colliculus and it’s role in vision?

A

visual reflex centres controlling the extrinsic eye muscles

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8
Q

Where is the primary visual cortex and what is its role in vision?

A
  • In the occipital lobe
  • processes basic visual information (contrast information & object orientation)
  • conscious perception of visual images
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9
Q

Where is the visual association areas and what is their role in vision?

A
  • Also in occipital lobe

- Processes visual information concerned with shape, colour & movement

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10
Q

How do different lobes of the brain contribute to complex visual processing?

A

Ventral parts of the temporal lobe - identify objects in the visual field (what)

Parietal cortex - assess the spatial location of objects (where)

Frontal cortex - uses visual information to guide movement

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11
Q

What is the third cranial nerve? Where does it sit/ extend to?

A
  • Oculomotor nerves

- Axons extend from ventral midbrain & pass through the superior orbital fissure to the eye

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12
Q

Are the oculomotor nerves considered motor sensory of mixed?

A

Mixed or chiefly motor

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13
Q

What do the different parts of the oculomotor nerves do?

A

Somatic motor axons

  • to four of the six extrinsic eye muscles (inferior oblique muscle and superior, inferior and medial rectus muscles)= move eyeball
  • to levator palpebrae superior muscle= raising upper eyelid

Parasympathetic (autonomic) motor axons
- to constrictor muscles of iris= causing pupil to constrict
- to ciliary muscle= controlling shape of lens for visual
focusing

• Sensory (proprioceptor) afferents - from eye muscles to midbrain

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14
Q

What is the primary purpose of the oculomotor nerves? What therefore is the result of damage?

A 
Provide most of the movement of each eye
Also 
- opening of eyelid
- constriction of pupil
- focusing

Damage causes drooping upper eyelid, dilated pupil, double vision, difficulty focusing & inability to move eye in certain directions

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15
Q

What is cranial nerve number four? Where does it emerge from and run to?

A

-Trochlear Nerves
-Axons emerge from dorsal midbrain, course ventrally
around midbrain, pass through the superior orbital
fissure to the eye
**Only cranial nerve emerging from dorsal brainstem

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16
Q

Are the trochlear nerves motor, sensory or mixed?

A

Motor

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17
Q

What are the functions of the trochlear nerves and therefore what does damage cause?

A
  • Supply somatic motor axons to (& carry proprioceptor axons from) the superior oblique muscle (which rotates the eye downward & laterally) [SO4]
  • This muscle has a tendon that hooks around a pulley called a trochlea
  • Provide eye movement
  • Damage causes double vision & inability to rotate eye inferolaterally (out and down)
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18
Q

What is cranial nerve number 5? Where does it sit/ run to?

A
  • Trigeminal nerves
  • Axons extend from face to pons (S) & pons to muscles (M)
  • Cell bodies of sensory neurons are located in large trigeminal ganglion
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19
Q

Why are the trigeminal nerves called trigeminal?

A

Because they are three fold. The divisions are:

  • Ophthalmic division (V1)
  • Maxillary division (V2)
  • Mandibular division (V3)
20
Q

What does the Ophthalmic division (V1) of the trigeminal nerve do?

A

-Axons run from face to pons via superior orbital fissure

-Convey sensory impulses from skin of anterior scalp,
upper eyelid & nose, & from nasal cavity mucosa,
cornea & lacrimal (tear) gland

21
Q

What does the Maxillary division (V2) of the trigeminal nerve do?

A

•Axons run from face to pons via foramen rotundum
• Convey sensory impulses from nasal cavity mucosa,
palate, upper teeth, skin of cheek and upper lip

22
Q

What does the Mandibular division (V3) of the trigeminal nerve do?

A
  • Axons pass through skull via foramen ovale
  • Convey sensory impulses from anterior tongue (except taste buds), lower teeth, skin of chin, & temporal region of scalp
23
Q

Which division of the trigeminal nerves also has a motor output and what does this do?

A
  • Mandibular division (V3)

- Supply motor axons to (carry proprioceptor axons from) muscles of mastication

24
Q

Overall are the trigeminal nerves motor, sensory or mixed?

A

Mixed nerves (mainly sensory)

  • Largest cranial nerves
  • Main sensory nerve from face (transmitting afferent impulses from touch, temperature & pain receptors)
  • Supply motor axons to muscles of mastication (motor)
25
Q

What does damage to the trigeminal nerves cause?

A

-Loss of sensation & impaired chewing

Tic Douloureux (Trigeminal Neuralgia)
• excruciating pain
• provoked by a sensory stimulus in area of supply
• inflammation of trigeminal nerve (pressure on nerve root)
• analgesics - partially effective
• Nerve cut in severe case to relieve pain (but causing sensation loss)

26
Q

What nerves are anaesthetised during dental procedures?

A

Trigeminal nerves

27
Q

What is cranial nerve number 6 and what is it’s function?

A

-Abducens nerve

  • Axons leave inferior pons & pass through superior orbital fissure to eye (lateral rectus muscle)
  • Provide eye movement (abducts the eyeball)
  • Damage results in inability to rotate eye laterally & at rest eye rotates medially
28
Q

What is cranial nerve number 7 and where does it sit/ run through?

A

-Facial nerves
-Axons emerge from pons, enter temporal bone via
internal auditory meatus and run within bone (through
inner ear cavity) before emerging through stylomastoid
foramen; course to lateral aspect of face

29
Q

What 5 branches are there of the facial nerves?

A
  • Temporal
  • Zygomatic
  • Buccal
  • Mandibular
  • Cervical

(think a hand with each finger labelled)

30
Q

Are the facial nerves sensory, motor or mixed? + functions related to these labels….

A

Mixed nerves

  • Major motor axons of the face
  • Supply motor axons to (convey proprioceptor impulses from) skeletal muscles of face (muscles of facial expression), except for chewing muscles served by cranial nerve V
  • Transmit parasympathetic (autonomic) motor impulses to lacrimal (tear) glands, nasal & salivary glands
  • Convey sensory impulses from taste buds of anterior 2/3 of tongue
31
Q

What happens if you damage the facial nerves? Causes? Treatment?

A

-Damage produces sagging facial muscles (mask like face) & disturbed sense of taste (missing sweet, salty & umami)

-A specific condition is bell’s Palsy:
• characterized by paralysis of facial muscles (affected side) & partial loss of taste sensation.
• viral infection causing inflammation of facial nerve
• symptoms: lower eyelid droops, corner of mouth sags,
tears drip continuously, eye cannot be completely closed,
paralysed face is ‘pulled’.
• Treatment: steroids, rest

32
Q

What is cranial nerve number 8? Where does it sit/ run?

A
  • Vestibulocochlear Nerve
  • Axons arising from hearing & equilibrium apparatus within inner ear of temporal bone, passing through internal acoustic meatus to enter brainstem at the pons medulla border
33
Q

Are the vestibulocochlear nerves motor, sensory or mixed? How does this relate to function?

A
  • Purely sensory
  • Provide hearing (cochlea nerves) and sense of balance (vestibular nerves)
  • Damage produces deafness, dizziness, nausea, loss of balance and nystagmus (rapid involuntary eye movements)
34
Q

Label the diagram on OneNote showing the auditory pathway…

A

Answers there

35
Q

What is the cranial nerve number 9 called? Where do they sit?

A

Glossopharyngeal Nerves

Axons emerge from medulla & leave skull through
jugular foramen

36
Q

Are the glossopharyngeal nerves motor, sensory or mixed? What is their function related to this?

A

Mixed nerves

-Supply motor axons to (carry proprioceptor fibers from) a pharyngeal muscle= stylopharyngeus
-Provide parasympathetic motor axons to parotid salivary gland
-Sensory axons conduct taste & general sensory impulses
from pharynx & posterior 1/3 of tongue
-Conducting sensory impulses from chemoreceptors in
the carotid body & pressure receptors of carotid
sinus
-Provide control over swallowing, salivation, gagging,
sensations from posterior 1/3 of tongue, control of
blood pressure & respiration

37
Q

What does damage to the glossopharyngeal nerves cause?

A

Damage results in loss of bitter & sour taste, and impaired swallowing

38
Q

What is cranial nerve number 10? Where does it sit/ pass through?

A

Vagus Nerve
-Axons emerge from medulla, pass through skull via
jugular foramen, descend through neck region into
thorax & abdomen

39
Q

Are the vagus nerves sensory, motor or mixed?

A

-Mixed nerves

-Supply motor axons to (carry proprioceptor fibers from)
skeletal muscles of pharynx & larynx
- Parasympathetic motor fibers supply heart, lungs
& abdominal viscera

Sensory axons:
-conducting sensory impulses from thoracic &
abdominal viscera
-transmitting sensory impulses from chemoreceptors
in the carotid & aortic bodies, & pressure
receptors of carotid sinus
- conducting sensory impulses from taste buds of
posterior tongue & pharynx

40
Q

How is the vagus nerve special in terms of its location?

A

The only cranial nerve extending beyond the head &

neck to the thorax & abdomen

41
Q

Complete the major of motor axons in the vagus nerve are…

A

Parasympathetic

42
Q

What is the general function of the vagus nerve and therefore the result if they are damaged?

A
  • Provide swallowing & speech; regulate activities of major viscera
  • Damage causes hoarseness or loss of voice, impaired swallowing & digestive system mobility. If both are cut it’s fatal as critical to keeping heart and lungs going.
43
Q

What is cranial nerve number 11?

A

-Accessory nerve

44
Q

Are the accessory nerves primarily motor, sensory or mixed? What is there function and result of damage?

A

-Mixed nerves (primarily motor)

-Cranial root joins with axons of vagus nerve (X) to supply motor axons to larynx, pharynx & soft palate. Damage causes hoarseness or loss
of voice & impaired swallowing.

-Spinal root supplies motor axons to (conveys proprioceptor
impulses from) trapezius & sternocleidomastoid muscles, therefore
provides head, neck & shoulder movement. Damage causes impaired head, neck & shoulder movement. eg. unable to shrug on one side if unilateral injury

45
Q

What is cranial nerve number 12? Where does it sit?

A

-Hypoglossal nerves
-Axons arise by a series of roots from medulla, exit from
skull via hypoglossal canal to tongue. Axons emerge between the pyramid & olive

46
Q

Are the hypoglossal nerves motor, sensory or mixed? What is the function and result of damage?

A
  • Primarily motor

-Supply somatic motor axons to (convey proprioceptor
impulses from) intrinsic & extrinsic muscles of
tongue
-Damage causes difficulties in speech & swallowing
Both sides - inability to protrude tongue
One side - tongue deviates (leans) towards injured side & results in ipsilateral atrophy eventually

ANAT242 (25 decks)

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