EENT

Question 1

what does the EENT system enable?

Answer 1

enables sensation of the external environment through the special senses
– sight, hearing, balance, smell and taste

Question 2

what does EENT stand for?

Answer 2

• eyes
• ears
• nose
• throat

Question 3

what muscles allow the eyes to move?

Answer 3

extraocular muscles

Question 4

how do our eyes see images?

Answer 4

• Waves of light are reflected into the eyes by objects we see
• Objects absorb some wavelengths and reflect the colour the object appears to be

Question 5

how many extraocular muscles are there?

Answer 5

6 extrinsic muscles

Question 6

what 2 muscles control the eyelids?

Answer 6

• Levator palpebrae – lifts eyelid
• Orbicularis oculi – closes eye

Question 7

what is conjunctiva?

Answer 7

membranous lining of the eyelids and front of eye (forms a closed sac)

Question 8

what produces tears?

Answer 8

lacrimal glands

Question 9

where do the tears drain?

Answer 9

Tears drain down the nasolacrimal duct into the nasal cavity

Question 10

what is the outer layer of the eye made up of?

Answer 10

fibrous layer of sclera and cornea

Question 11

what does the middle vascular layer of the eye consist of?

Answer 11

Choroid, ciliary body, iris, (lens)

Question 12

what does the inner nervous tissue of the eye consist of?

Answer 12

Retina leading to optic nerve

Question 13

what is the optic disc?

Answer 13

Where the nerve fibres and blood vessels enter / exit the eye (blind spot)

Question 14

what is the iris?

Answer 14

Coloured ring of circular and radial smooth muscle that regulates light entry (via pupil size)

Question 15

what is the lens?

Answer 15

Avascular elastic biconvex disc behind the pupil, separating the anterior and posterior eye
- Bends (refracts) light onto retina (upside down)
- Accommodation: Thickening of lens to focus on near objects

Question 16

what does the anterior eye contain?

Answer 16

The aqueous humour:
- Supplies nutrients / waste removal to avascular structures (cornea / lens)

Question 17

what does the posterior eye contain?

Answer 17

The vitreous humour
- Holds retina against choroid

Question 18

what is the retina?

Answer 18

• Several layers of specialised cells sit on the choroid and pigmented epithelium (black-out)
• Light travels through the nerve cells to the photoreceptors
• Message then sent to occipital lobe of brain (via optic nerve)

Question 19

what are rods for?

Answer 19

• Non-colour vision
• Night vision (low light levels)

Question 20

what are cones for?

Answer 20

• Colour vision
• Needs bright light
• 3 types of cone (in most primates incl Humans) for different wave lengths: blue (short wavelength), green (medium), and red (long)

Question 21

what does binocular vision enable?

Answer 21

better perception of depth, distance, height, width

Question 22

what is visual acuity?

Answer 22

sharpness of vision

Question 23

ears are the organs of what?

Answer 23

hearing and balance

Question 24

what is the function of the outer ear?

Answer 24

collects sound waves

Question 25

what is the function of the middle ear?

Answer 25

Amplifies and transfers sound waves to inner ear

Question 26

what is the function of the inner ear?

Answer 26

• Converts sound waves to nervous impulses
• CNVIII (vestibulocochlear nerve)  brain
• Also contains organs of balance

Question 27

what is the role of the auricle (pinna)?

Answer 27

collects sound waves

Question 28

what is the role of the external acoustic meatus (auditory canal)?

Answer 28

glands secrete earwax

Question 29

what is the tympanic membrane (eardrum)

Answer 29

membrane seperating outer and middle ear

Question 30

what is the anatomy of the middle ear?

Answer 30

• Air filled cavity within temporal bone
• Contains the ossicles: 3 very small bones: Malleus, incus, stapes (smallest bone)

Question 31

what is the role of the ossicles?

Answer 31

amplify signal (~20x)

Question 32

what are the 2 roles of the inner ear?

Answer 32

• Hearing: Cochlea
• Balance: Vestibule and 3 semicircular canals

Question 33

what is the cochlea?

Answer 33

A fluid-filled tube rolled into a spiral.