ANS, visual, hearing pathways

Question 1

outer layer of eye

Answer 1

cornea - transparent, a-vascular, refraction

sclera - white opaque area, muscles insert for eye movement

Question 2

middle, vascular layer of eye

Answer 2

choroid- vascular, nourishes cornea, retina
iris- pigmented, vascular, muscles which change diamater of pupil
ciliary body- controls shape of lens via suspensory ligaments
lens- biconvex, A-vascular

Question 3

inner layer of eye

Answer 3

retina (extension of diencephalon)

Question 4

features of non-neuronal layer of retina

Answer 4

pigmented epithelium, sitting against choroid of eye.

absorbs light

maintains the metabolic activity of photoreceptors

provides cap. to the photoreceptors

Question 5

features of neuronal layer of retina

Answer 5

photoreceptors

1st order bipolar neurones

2nd order ganglion nuerones

optic disk –> point where axons of ganglion neurones leave the retina to become the optic nerve

interneurones: horizontal and amacrine interneurones

photochemical reactions occur here

Question 6

features of rods

Answer 6

20 x more common, sensitive to light, vision in dim-light, high level of convergence
found everywhere

Question 7

features of cones

Answer 7

colour vision, high visual acuity, lower levels of convergence , at macula= one cone for every ganglion cell
found in macula/ fovea/ not in periphery

Question 8

the visual pathway is a 3 neurone chain. the optic nerves will combine to cross at …

Answer 8

the optic chiasm: hemi-decusation (nasal fibres will cross, temporal will not)

Question 9

location of the visual cortex

Answer 9

above and below the calcarine sulcus, extending to the occipital pole

Question 10

our eyes are binocular. what does this mean

Answer 10

both of our eyes see the same thing

Question 11

what is fixation point

Answer 11

point of visual acuity corresponding to the fovea. it where all quadrants of visual field meet

Question 12

define scotoma

Answer 12

localised patch of blindness

Question 13

define anopia and give examples of 2 types

Answer 13

the loss of one or more quadrants of the visual field

e. g. hemianopia= one HALF of the visual field is lost (both of upper and lower on that half are lost)
e. g. quadrantanopia= one QUADRANT of the visual field is lost only

Question 14

define homonymous

Answer 14

visual field losses are on same side for both eyes

Question 15

define heteronymous

Answer 15

visual field losses are on different sides for both eyes

Question 16

3 examples of visual defects

Answer 16

monocular blindness (completely blind in ONE eye)

bi-temporal hemianopia (outer half BOTH right and left visual field is missing)

homonymous hemianopia (visual field loss on same side of both eyes)

Question 17

which region of the external ear is bony/cartilaginous

Answer 17

lateral 1/3= cartilaginous

medial 2/3= bony

Question 18

tympanic membrane may be called the eardrum. what is its function

Answer 18

to separate the external and middle ear.

–> it is part of middle ear

Question 19

middle ear is high risk space why?

Answer 19

1. eustachian tube connects it to naso-pharynx= prone to infection
2. connected to mastoid air cells= infection spread to middle cranial fossa
3. inferior is the IJV= risk of thrombosis
4. anterior is the internal carotid artery= risk of pulsatile tinnitus
5. transversed by facial nerve and canal= infection spread to facial muscles

Question 20

3 features of the auditory pathway

Answer 20

polysynpatic (many neurones/ synpases)

tonotopically organised

bilateral (recieve sound from both ears)

Question 21

auditory centres in brainstem are…

Answer 21

cochlear nuclei
SUPERIOR olivary nuclei
inferior colliculus
MEDIAL geniculate nucleus

Question 22

cell bodies of the cochlear nerve (CN8) are in the

Answer 22

spiral ganglion. will travel into the dorsal/ventral cochlear nuclei

Question 23

where are low and high frequency sound recieved in cochlear and projected in the heschl’s gyrus

Answer 23

base= high
apex=low

low= antero-lateral part of heschl's gyrus
high= postero-medial part of heschl's gyrus

Question 24

secondary auditory areas

Answer 24

brocas- anterior of frontal, motor production of speech

wernickes - posterior of temporal, understanding of speech

Question 25

define anxiety

Answer 25

a FEELING of worry, nervousness, unease –> typically about an imminent even or something with an uncertain outcome BUT it has physical effects (racing heart, heaving breathing, sweating, dry mouth)

Question 26

function of autonomic NS

Answer 26

to monitor the VISCERAL ACTIVITY to maintain homeostasis

Question 27

distinct feature of somatic and autonomic MOTOR efferent fibres

Answer 27

in ANS, the visceral motor efferent fibres leave the spinal cord via the LATERAL GREY HORN which is present only within the segmental spinal nerves T1-L2 and S2-4

Question 28

in the ANS there is a 2 neurone chain- not seen in somatic. what are the names of neurones and where are they located

Answer 28

pre-ganglionic neurone- somewhere in CNS

post-ganglionic nuerone going to target organ- somewhere in the PNS

NB. synapse at the ‘autonomic ganglion’

Question 29

outflow of symp and para are..

Answer 29

sympathetic= thoracolumbar outflow, T1-L2

para= cranio-sacral outflow, S2-S4 (occulomotor, facial, glossopharyngeal, vagus)

Question 30

which neurotransmitter is released by symp/para fibres

Answer 30

para=acetylcholine released by BOTH neurones. localised effects (1:1 of pre and post neurones)

symp= acetylcholine by pre and then noradrenaline by post-ganglion neurone BUT sweat glands post-ganglionic neurones release a different neurotransmitter