Orbit and Nasal Cavity

Question 1

THE NOSE

i) what is its function?
ii) what four bones does it contain?
iii) what three main cartilages is it comprised of?
iv) what three projections are found in the interal surface of the lateral wall? what is the function of these structures?
v) what does the nasal cavity open out into?
vi) it gets arterial supply from branches of which two arteries?
vii) which three nerves supply it?

Answer 1

i) to filter dust entering the respiratory system
ii) contains paired nasal bones, maxillae, frontal bone and septum
iii) comprised of lateral, major alar and septal

iv) internal surface of the lateral wall contains superior, inferior and middle conchae
- function to warm area and direct it to the rest of the respiratory tract

v) nasal cavity opens up into the nasopharynx
vi) nose gets arterial supply from branches of opthalmic and maxillary arteries
vii) supplied by olfactory, opthalmic and maxillary nerve

Question 2

label nose structures A-E

Answer 2

A = superior concha 
B = middle concha 
C = lateral nasal cartilage 
D = alar cartilage 
E = nasal bone

Question 3

OLFACTORY NERVE (CN 1)

i) what type of nerve is it?
ii) what is it an extension of?
iii) where does it exit the skull?

Answer 3

i) special afferent - sensory
ii) extension of the forebrain
iii) exits the skull at the cribiform plate

Question 4

OLFACTION

i) what is olfaction aided by?
ii) what is the function of conchae?
iii) where are olfaction receptors found?
iv) what is secreted form the epithelial cells in the nose and what does this allow?
iv) what is anosmia? give three things that may cause this?

Answer 4

i) olfaction is aided by air flow through the nasal cavity
ii) conchae warm and moisten the airr
iii) olfaction receptors are found in the epithelium lining the roof and walls of the nose
iv) epithelial cells secrete mucus and odiferous gases are dissolved into the fluid and then detected by the olfactory nerves

iv) anosmia is absence of olfaction
- can be caused by common cold, trauma or parkinsons

Question 5

PARANASAL SINUSES

i) what are they?
ii) name the four paranasal sinuses - where are they found and what do they drain into?
iii) label sinuses A-C
iv) where does sinus C drain into?
v) name two functions of paranasal sinuses

Answer 5

i) air filled extensions of the nasal cavity

ii) 1) **paired frontal sinuses
- ** found in the frontal bone
- drain through the frontal nasal sinus

2) ethmoidal sinus
- invaginations into the ethmoid bone
- drain into the middle meatus (anterior and middle) or the superior meatus (posterior sinus)

3) sphenoidal sinus
- found in the sphenoid bone
- drain intto tthe spheno-ethmoidal recess

4) paired maxillary sinus
- found in maxilla
- drain into the middle meatus

iii) A = frontal sinus
B = ethmoidal sinus
C = maxillary sinus

iv) middle meatus
v) lighten skull and voice resonance

Question 6

ORBIT ANATOMY

i) label bones A-G
ii) label foramina 1-3

Answer 6

A = frontal, B = zygomatic, C = spehnoid, D = ethmoid, E = maxilla, F = lacrimal, G = nasal

ii) 1 = optic canal
2 = superior orbital fissure
3 = inferior orbital fissure

Question 7

THE EYE & VISUAL FIELDS

i) name the three layers of the eye and their associated structures
ii) how many chambers is it divided into?
iii) which side is information from the R visual field picked up on the retina? why?
iv) what lobe of the brain is the visual cortex found in?

Answer 7

i) outer fibrous = sclera and cornea
vascular = iris
inner = retina

ii) divided into anterior and posterior compartments
iii) info from R visual field is picked on LHS of retina due to crossing at the optic chiasm
iv) visual cortex found in the occipital lobe

Question 8

CN II - OPTIC NERVE

i) what type of nerve is it?
ii) where does it exit the skull?
iii) what embryonic week does it develop? what grows outs and what grows in?
iv) label structures A & B

Answer 8

i) special afferent - sensory
ii) exits skull at the optic canal

iii) develops embryonic week 4/day 22
- optic stalk grows out and the lens vesicle grows in

iv) A = optic stalk
B = lens vesicle

Question 9

MOVEMENT OF THE EYE

i) which movements are the following 7 extraocular muscles responsible for & what is their nerve supply?
1) superior oblique, 2) inferior oblique, 3) superior rectus, 4) inferior rectus, 5) medial rectus, 6) lateral rectus, 7) levator palpebrae

ii) what three axes does the eyeball move in?

Answer 9

i) 1) sup oblique = down (trochlea)
2) inf oblique = up and out (oculomotor sup branch)
3) superior rectus = up and in medially (oculomotor sup branch)
4) inf rectus = down and in medially (oculomotor inf branch)
5) medial rectus = medial (oculomotor sup branch)
6) lat rectus = lateral (abducens)
7) lev palpebrae = lifts eyelid (oculomotor)

ii) eyeball moves in vertical, transverse and anteroposterior

Question 10

EYE MOVEMENTS

which muscles are responsible for movements A > P?

Answer 10

A = inferior rectus
B = superior rectus
C&D = superior rectus & inferior oblique
E = superior rectus
F = inferior oblique
G&H = medial & lateral rectus
I&J = medial and lateral rectus
K = superior oblique
L = inferior rectus
M&N = superior oblique and inf rectus
O = inf rectus
P = sup oblique

Question 11

EYE MOVEMENTS - CLINICAL TESTS

which muscle are being clinically tested in the eye movements A-F?

Answer 11

A = superior rectus 
B = inferior rectus
C = lateral rectus 
D = superior oblique
E = inferior oblique
F = medial rectus

(lateral is rectus muscles on same side but medial movement is oblique muscles on opposite side)

Question 12

CN III - OCULOMOTOR

i) what type of nerve is it to the extra ocular muscles? except which two?
ii) which nerves does it pass via to the cilliary body and sphincter pupillae? what does this cause? what type of nerve is it here?
iii) where does it exit the skull?
iv) which four muscles does the superior branch supply?
v) which muscle does the inferior branch supply?

Answer 12

i) general motor to extra ocular muscles apart from superior oblique (trochlea) and lateral rectus (abducens)

ii) passes via short cilliary nerves to CB and SP - this causes constriction
- general efferent parasympathetic

iii) exits skull at superior orbital fissue
iv) superior branch supplies - lev palp superioris, superior rectus, medial rectus and inf oblique
v) inferior branch supplies inferior rectus

Question 13

NERVE SUPPLY TO THE EYE

i) which nerve is labelled A?
ii) which muscles are labelled B & C?

Answer 13

i) A = oculomotor nerve

ii) B = levator palpebrae
C = inferior oblique

Question 14

CN IV - TROCHLEA NERVE

i) what type if nerve is it?
ii) what extra ocular muscle does it innervate?
iii) where does it exit the skull?
iv) which structure does it emerge next to? is it a thick or thin nerve?

Answer 14

i) somatic motor
ii) innervates the superior oblique
iii) exits skull at superior orbital fissue
iv) emerges next to the cerebellar peduncle and is a thin nerve

Question 15

CN VI - ABDUCENS NERVE

i) what type of nerve is it?
ii) which extra ocular muscle does it innervate?
iii) where does it exit the skull?

Answer 15

i) somatic motor
ii) innervates the lateral rectus
iii) exits the skull through the superior orbital fissue

Question 16

CN INNERVATION TO THE EYE

which nerves are labelled A & B and what do they innervate?

Answer 16

A = trochlea nerve innervates the superior oblique

B = abducens nerve innervates the lateral rectus

Question 17

CLINICAL CONSIDERATIONS

i) which nerves may be implicated in
a) inability to perform specific eye movements (3)
b) dilation of pupil (1)
c) ptosis (drooping of eyelid) (1)
d) abnormal pupil reflex

ii) which nerve may be implicated in
a) aneurysm of cerebral artery
b) orbital fracture
C) cav sinus lesion

iii) which nerve is implicated in the diagram? which muscle isnt working properly?

Answer 17

i) a) trochlea, oculomotor and abducens
b,c,d) oculomotor

ii) a) OM
b) trochlea
c) abducens

iii) abducens as the lateral rectus isnt working so eye sits in a medial position

Question 18

CRYING

i) what two parts does the lacrimal gland consist of?
ii) when lacrimal fluid is secreted across the eye, what does it pass to? (3) what duct is this via?
iii) what supplies a) parasympathetic and b) sympathetic to the lacrimal gland? what function does each have?

Answer 18

i) lacrimal gland consists of orbital and palpebral

ii) lacrimal secreted across the eye to the lacrimal papilla, lacrimal sac and to the inferior meatus
- via the nasolacrimal duct

iii) psym = facial nerve = secretomotor
sym = sup cervical ganglion = vasoconstrictive

Question 19

PSYM SUPPLY TO THE LACRIMAL GLAND

i) which foramen does the facial nerve pass through?
ii) what does it then branch into? what artery does this run closely to?
iii) which two nerves join into the pterygoid canal and what does this pass to?
iv) which two nerves do the fibres jump around to reach the lacrimal nerve?
v) which nerve is the lacrimal nerve a branch of?

Answer 19

i) facial nerve passes through the internal acoustic meatus
ii) facial branches into the greater petrosal nerve which runs closely to the internal carotid artery
ii) greater petrosal and deep petrosal nerve join to make the pterygoid canal which passes to the pterygopalatine ganglion
iv) nerve fibres jump around maxillary V2 and the zygomatic nerve to reach the lacrimal
v) lacrimal nerve is a branch of V1 trigeminal

Question 20

LACRIMAL PSYM SUPPLY

name structures labelled A-D

Answer 20

A = greater petrosal nerve
B = deep petrosal nerve
C = pterygopalatine ganglion
D = lacrimal V1

Question 21

ORBIT ANATOMY

i) which ANS branch governs pupil dilation?
ii) which ANS branch governs pupil constriction?
iii) which three arteries supply the orbit?

Answer 21

i) dilation = sympathetic
ii) constriction = parasympathetic
iii) opthalmic artery, infraorbital artery and the central artery

Question 22

CN V - TRIGEMINAL

i) what are the three branches and what foramina do they pass through?
ii) what two types of nerves does it contain?
iii) which branches are labelled in green, orange and blue?

Answer 22

i) opthalmic V1 = superior orbital fissue
maxillary V2 = rotundum
mandibular V3 = ovale

ii) contains general sensory and somatic motor to derivates of 1st pharyngeal arch

iii) green = opthalmic V1
orange = maxillary V2
blue = mandibular V3

Question 23

V1 OPTHALMIC

i) what structures does it send sensory fibres to? (5)
ii) what three sections does it branch into? which one of these contains psym fibres from CNVII?
iii) where does it exit the skull?
iv) label the branches A-D

Answer 23

i) sensory fibres to skin, mucous membranes, conjunctiva, front of head and nose

ii) branches to lacrimal, frontal and nasocillary
(lacrimal also contains psym from facial nerve)

iii) exits skull at superior orbital fissue

iv) A = trigeminal ganglion
B = trochlea
C = frontal > supraorbital
D = lacrimal

Question 24

BLOOD SUPPLY TO THE EYE

i) what major artery does it originate from and where does this pass through?
ii) after passing through the optic canal what does it branch into?
iii) what are the four branches of this artery?
iv) which two veins drain the eye

Answer 24

i) originates from the internal carotid which passes through the cavernous sinus
ii) passes optic canal and branches to opthalmic artery
iii) opthalmic artery branches to the central retina, lacrimal. long & short post cilliary arteries and the supraorbital artery
iv) superior and inferior opthalmic veins