11 - Head & Neck - The Eye 3 + The Ear Flashcards Preview

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Flashcards in 11 - Head & Neck - The Eye 3 + The Ear Deck (33):
1

How will the optic disc appear during fundoscopy if there is raised intracranial pressure?

Papilloedema = swelling of the optic nerve
- Optic disc = swollen with blurred margins

2

How will the optic disc appear during fundoscopy if there is raised intra-ocular pressure?

Optic disc cupping

3

What is optic disc cupping?

Increased diameter of central cup of optic nerve, due to increased intra-ocular pressue
* sign of glaucoma

4

What is a Meibomian cyst? How is this different to a stye?

Blocked Meibomian gland within tarsal plate
Stye = blocked sebaceous gland at base of eyelash (infected hair follicle)

5

Outline the consensual pupillary light reflex:

- Light shone in left eye
- Sensory afferent from L retina via CN II
- To Pretectal nucleus (brainstem)
- To BOTH L + R Edinger-Westphal nuclei
- Parasympathetic fibres hitchhike on CN III
- Innervate both sphincter pupillae
= Both L + R pupils constrict

6

What are the afferent and efferent nerves of the pupillary light reflex?

Afferent = CN II
Efferent = CN III

7

Why might someone not be able to look up if they have a blow-out fracture?

Blow-out fracture = fractured floor of orbit
- Orbital fat can prolapse and ocular-muscles can become trapped
- Haematoma may form in inferior rectus
- Inferior rectus contracts in response to damage, preventing patient from looking up

8

Why might someone with a blow-out fracture have reduced sensation over their cheek?

- Damage to the inferior orbital branch of CN V2
--> Emerges below orbit via infra-orbital foramen

9

What are the effects on lacrimation if orbicularis oculi is damaged?

- Inferior eyelid retracts, exposing cornea
- Cornea becomes dry and unprotected
- Constant corneal irritation increases lacrimal secretion
- Risk of ulceration

10

Which nerve stimulates the lacrimal gland?

Parasympathetic fibres associated with CN VII
-> via Greater petrosal to pteygopalatine ganglion to gland

11

How can thrombophlebitis of the facial veins spread into the cranial cavity?

Facial veins drain directly into internal jugular vein,
BUT have anastamoses with superior + inferior ophthalmic veins which drain into cavernous sinus

12

What are the afferent and efferent nerves of the corneal blink reflex?

Afferent = CN V1 (Ophthalmic)
Efferent = CN VII

13

How is visual acuity tested?

Snellen chart

14

Name the 4 parts of the temporal bone:

- Squamous part
- Petromastoid part
- Tympanic plate
- Styloid process

15

The external acoustic meatus lies within which part of the temporal bone?

Tympanic plate

16

Describe the epithelium of the external acoustic meatus:

Keratinised squamous
- Cartilaginous outer 1/3rd = is lined with hairs + produces cerumen (+ dead cells = wax)

17

When examining the ear, how should the pinna be manipulated for ideal view of the tympanic membrane?

Child = Down + back
Adult = UP, OUT + BACK

18

The middle and inner ear lie in which part of the temporal bone?

Petromastoid part

19

What is the function of the external ear?

Collect, transmits + focuses sound waves onto tympanic membrane

20

What is the approx. length of the external acoustic meatus?

~ 2.5 cm long

21

What is the approx. diameter of the tympanic membrane?

~ 1 cm

22

Which nerve innervates the internal surface of the tympanic membrane?

CN IX

23

What structures does the middle ear cavity communicate with anteriorly and posteriorly?

Ant = nasopharynx via eustachian tube
Post = Mastoid air cells

24

Why is it important for the middle ear cavity to be connected to the nasopharynx?

- Allows equalisation of air pressure between middle ear + atmosphere
- Allows drainage + ventilation

25

When is the Eustachian tube opened?

During swallowing
- opened due to pull of palate muscles

26

Name the ossicles:

Malleus
Incus
Stapes

27

Which ossicle is attached to the tympanic membrane?
Which ossicle articulates with the bony labyrinth of the inner ear (via oval window)?

Malleus
Stapes

28

What is the function of the ossicles?

Amplify and concentrate sound energy from eardrum to oval window

29

Which muscles reduce sound amplitude by resisting ossicle movement? Which nerves innervate them?

- Stapedius - CN VII
- Tensor tympani - CN V3

30

The membranous labyrinth of the ear sits within the bony labyrinth. Name the fluid which separates these structures:

Perilymph

31

Name the fluid contained within the membraneous labyrinth:

Endolymph

32

Which organ lies within the cochlear, and is reponsible for hearing?

Spiral organ of Corti

33

Describe the process of hearing:

- Sound waves are transmitted down the external ear, causing vibration of the tympanic membrane
- Vibration of the ossicles results in transmission of the sound waves to the oval window
- Causes wave motion of the endolymph within the membranous labyrinth
- Stimulates hair cells triggering AP in CN VIII > Brain