Orbit and Nasal Cavity

Question 1

nose function

Answer 1

filters dust entering the respiratory system

Question 2

nose bones

Answer 2

paired nasal bones
maxillae
frontal bone
septum

Question 3

nose cartilages

Answer 3

3 main lateral: major, alar, septal

Question 4

nose internal surface

Answer 4

lateral wall has 3 projections:

superior, middle and inferior conchae

Question 5

nose blood supply

Answer 5

branches from opthalmic and maxillary arteries

Question 6

nose nerve supply

Answer 6

olfactory and opthalmic nerves

Question 7

cranial nerve 1

Answer 7

olfactory
special afferent - sensory (olfaction)
exit = cribriform plate

Question 8

olfaction

Answer 8

aided by air flow through nasal cavity
conchae help warm and moisten air
olfaction receptors detect ‘smell’

Question 9

olfaction receptors

Answer 9

in epithelium lining roof and walls of nasal cavity
secrete mucus fluid
odoriferous gases dissolve in fluid
gases are detected by olfactory nerves

Question 10

anosmia

Answer 10

lack of smell

can be temporary (cold) or permanent (trauma, Parkinson’s)

Question 11

paranasal sinuses

Answer 11

air filled extensions of nasal cavity 
frontal sinuses 
ethmoidla cells 
sphenoidal sinuses 
maxillary sinuses

Question 12

frontal sinuses

Answer 12

paired
in frontal bone
drain through frontonasal duct

Question 13

ethmoid cells

Answer 13

invaginations in ethmoid bone

drain into middle meatus (anterior/middle) or superior meatus (posterior)

Question 14

sphenoidal sinuses

Answer 14

in sphenoidal bone

drain into spheno-ethmoid recesses

Question 15

maxillary sinuses

Answer 15

paired
in maxilla
drain into middle meatus

Question 16

orbit bones

Answer 16

frontal
maxilla
ethmoidal
lacrimal 
sphenoidal 
temporal-zygomatic 
nasal

Question 17

eye

Answer 17

contains optical apparatus for visual system
located in orbit - suspended by muscles
3 layers
divided into anterior and posterior chambers

Question 18

eyeball layer

Answer 18

outer fibrous - sclera and cornea
vascular - iris
inner - retina

Question 19

cranial nerve II

Answer 19

optic
special afferent - sensory (sight)
exit = optic canal
special embryology: optic stalk grows out, lens vesicle grows in

Question 20

extraocular muscles

Answer 20

levator palpebrae 
superior oblique
superior rectus 
medial rectus
lateral rectus
inferior rectus 
inferior oblique

Question 21

eye movement

Answer 21

controlled by 7 extraocular muscles surrounding globe of the eye
movement occurs around 3 axes: vertical, transverse, anteroposterior

Question 22

superior oblique

Answer 22

pulls eye down and out (depression/abduction)

nerve supply = trochlear

Question 23

superior rectus

Answer 23

pulls eye up and in (elevation/adduction)

nerve supply = oculomotor

Question 24

medial rectus

Answer 24

pulls eye in (adduction

nerve supply = oculomotor

Question 25

lateral rectus

Answer 25

pulls eye out (abduction) | nerve supply = abducens

Question 26

inferior rectus

Answer 26

pulls eye down and in (depression/adduction) | nerve supply = oculomotor

Question 27

inferior oblique

Answer 27

pulls eye up and out (elevation/abduction) | nerve supply = oculomotor

Question 28

cranial nerve III

Answer 28

oculomotor somatic motor to extra-ocular muscles (NOT superior oblique/lateral rectus) and ciliary body and sphincter pupillae (via short ciliary nerves) exit = superior orbital fissure

Question 29

cranial nerve IV

Answer 29

trochlear somatic motor to superior oblique very small exit = superior orbital fissure

Question 30

cranial nerve VI

Answer 30

abducens somatic motor to lateral rectus very small exit = superior orbital fissure

Question 31

orbit nerve supply

Answer 31

CN II, III, V1, VI, VII sympathetic - stimulates dilator pupullae to let more light in parasympathetic - stimulates constrictor pupillae to let less light in

Question 32

orbit blood supply

Answer 32

opthalmic artery infra-orbital artery central artery

Question 33

orbit clinical considerations

Answer 33

inability of specific eye movements (CN III, IV, VI) dilated pupil/abnormal pupil reflex (CN III) ptosis - drooping eyelid (CN III) lesion CN III aneurysm of cerebral artery CN IV: orbital fracture CN VI: cavernous sinus lesion

Question 34

lacrimal gland

Answer 34

2 parts: orbital and palpebral secretes lacrimal fluid which passes across the eye into lacrimal papilla, lacrimal sac and to inferior meatus via nasolacrimal duct

Question 35

lacrimal gland nerve supply

Answer 35

sensory from lacrimal branch of V1 parasympathetic - secretomotor (CN VII) sympathetic - vasconstrictive (superior cervical ganglion, via internal carotid)