SPECIAL SENSES

Question 1

What is the cranial nerve of smell

Answer 1

olfactory nerve (CN 1)

sensory

Question 2

What is the cranial nerve of sight

Answer 2

Optic nerve (CN 2)

sensory

Question 3

What is the cranial nerve of hearing

Answer 3

vestibulocochlear nerve (CN 8)

sensory

Question 4

What are the cranial nerves of taste

Answer 4

Facial nerve (CN 7)
sensory and motor

Glossopharyngeal nerve (CN 9)
sensory and motor

Question 5

what cells secrete mucous

Answer 5

respiratory type epithelium cells which contain seromucus glands

Question 6

What are the borders of the nasal cavity

Answer 6

external/anterior openings = nares

posterior openings = choanae

medial wall = septum

lateral walls = cartilage and cranial bones (conchae and meatus)

floor = hard palate

roof = cranial bones + olfactory region

Question 7

Explain the nerves of smell

Answer 7

Olfactory nerve fibres and receptors in olfactory epithelium pass into cranial bones to olfactory bulbs

bulbs become olfactory nerve tracts (CN 1) and project to olfactory cortex of temporal lobe

Question 8

What is the orbit

Answer 8

bony cavity for eye made of 7 cranial bones.

orbicularis oculi: circular muscles that close eyelids

extra ocular muscles: move eye and open eyelid

lacrimal apparatus: production, drainage of fluid from eye (tears)

Question 9

List the parts of the eye

Answer 9

Cornea
conjunctiva
iris
lens
anterior and posterior cavities

Question 10

Outline the cornea

Answer 10

refracts bends light

anterior and posterior surfaces are epithelium

anterior surface continuous with conjunctiva

avascular

Question 11

Outline the conjunctiva

Answer 11

Provides mechanical protection and lubrication

epithelium, secretory cells, fibrous tissue and blood vessels.

covers posterior surface of eyelids and reflects to cover anterior surface of eyeball

extends over the anterior sclera

Question 12

Outline the iris

Answer 12

Regulates amount of light entering eye

thin diaphragm of tissue on lens

sphincter papillae arranged circularly around pupil, constrict, parasympathetic

dilator papillae arranged radially, dilate, sympathetic

Question 13

Outline the lens

Answer 13

Refracts/bends light onto retina to focus on images

avascular biconvex disc

CT capsule

suspensory ligaments anchor edges of lens to ciliary smooth muscles which contract to adjust lens

parasympathetic

flatter = distant
rounder = closer

Question 14

Outline anterior cavity

Answer 14

Anterior: contains fluid aqueous humor and supplies nutrients to avascular cornea and lens

maintains intraocular pressure ans shape of anterior eye

fluid continuously produced

Question 15

Outline posterior cavity

Answer 15

Gelatinous mass called vitreous humor

Formed in development, not replaced

Stabilises shape of eye due to muscles

Question 16

Outline the layers of the eye

Answer 16

fibrous tunic (sclera, white of eyes): protects eye, muscle attachment

vascular tunic (choroid): vascularised, smooth muscles of ciliary and iris, blood vessels enter at optic nerve to supply retina/pupils/lens

Neural tunic: explained in another

Question 17

Describe the neural tunic (retina)

Answer 17

innermost, avascular

macula: all cones, no rods
fovea: within macula, densest conc of cones

optic disc: where optic nerve attaches to eye

Question 18

What are the photoreceptors of the eye

Answer 18

rods: sensitive to light, night, no colour distinction
cones: red, green and blue, require light to function

Question 19

Explain the nerves of sight

Answer 19

Visual info of photoreceptors sent to optic nerve, then primary visual cortex of occipital lobe.

partial decussation at optic chiasm

Question 20

Describe the outer ear

Answer 20

auricle/pinna: funnels sound into the auditory meatus

external auditory meatus/acoustic canal: traps foreign particles a by hair cells and ceruminous glands which secrete ear eax. Protect tympanic membrane

Tympanic membrane: Lateral side epidermis, medial side thin mucous membrane, separate external and middle ear

Question 21

Describe the middle ear

Answer 21

Tympanic cavity: contains oval window

pharyngotympanic tube: opens to equilibrate pressure in cavity with outside

auditory ossicles: amplify sound. malleus, incus, stapes. connect to tympanic membrane and oval window. skeletal muscles prevent excessive movement

Question 22

Describe the internal ear

Answer 22

Oval window: connects to series of cavities like bony labyrinth

Bony labyrinth: vestibule, three semicircular canals and cochlea, lined with periosteum

Membranous labyrinth: suspended within the fluid, cochlear duct

Cochlea and cochlear duct: in another

Question 23

Describe the cochlea and cochlear duct

Answer 23

cochlea: transduces sound, curls, contains clear lymphatic fluid and cochlear duct

cochlear duct: contains hair cells/stereocilia, clear lymphatic fluid

Question 24

explain the nerves and physiology of hearing

Answer 24

Auricle directs sound into auditory meatus

Waves hit tympanic membrane converting sound to mechanical movement

Ossicles movement cause vibration of oval window

Oval window vibration generates wave in lymphatic fluid, travels through cochlea

Waves bend stereocilia which are detected by receptors of the cochlear nerve fibres

Cochlear nerve branch of vestibulocochlear nerve that sends info to primary auditory cortex

Question 25

Describe the 4 papillae of the tongue

Answer 25

Vallate/circumvallate: largest, V-shaped
line anterior to the terminal groove. many receptors

Foliate: folds on lateral surfaces of tongue anterior to terminal groove. few receptors

Fungiform: small, found on dorsum of tongue. Some receptors

Filiform: smallest, cone-shaped projections. No receptors

Question 26

What are the receptors of the tongue papillae

Answer 26

Gustatory receptors

Question 27

What are the 5 tastes

Answer 27

sweet
salty
sour
bitter
umami

Question 28

Outline the nerves involved in taste

Answer 28

Gustatory receptors project to facial nerve for the body of tongue (anterior 2/3) and glossopharyngeal nerve for the root of tongue (posterior 1/3). Project to gustatory cortex