Orbit and nasal cavity

Question 1

Superior oblique muscle

Answer 1

Extra- ocular muscle responsible for:

• Depression
• Abduction

Innervated by Trochlear nerve

Question 2

Superior rectus

Answer 2

Extra- ocular muscle responsible for:

• Elevation
• Abduction

Innervated by CN3

Question 3

Inferior oblique

Answer 3

Extra- ocular muscle responsible for:
- Elevation

Innervated by CN3

Question 4

Inferior rectus

Answer 4

Extra- ocular muscle responsible for:

• Depression
• Adduction

Innervated by CN3

Question 5

Medial rectus

Answer 5

Extra- ocular muscle responsible for:
- Adduction

Innervated by CN3

Question 6

Lateral rectus

Answer 6

Extra- ocular muscle responsible for:
- Abduction

Innervated by CN6- abducens

Question 7

Levator palpebrae

Answer 7

Muscle responsible for the elevation and retraction of the eyelid.

Question 8

Orbits of the eye

Answer 8

Vertical
- Abduction and adduction

Transverse

• Elevation
• Depression

Anteroposterior
- Intorsion and extorsion

The natural orbit always leans outwards

Question 9

Bones of the nose

Answer 9

Frontal

2x nasal

2x maxilla

Septum

Question 10

Cartilage of the nose

Answer 10

Lateral

Major and minor alar

Question 11

Internal projections of the nasal cavity

Answer 11

Superior, middle and inferior conchae

• directs flow of air
• warms the air

Lined with epithelium

Question 12

Olfaction

Answer 12

‘Smelling’

Mechanism:

• Odiferous gases in the air are dissolved in mucosal fluid secreted by epithelium
• Conchae help to direct air
• Odiferous gases are sensed by receptors connected to CN1.

Question 13

Nervous supply to the nose

Answer 13

• Olfactory, CN1
• CN V1, ophthalmic
• CN V2, maxillary

Question 14

Blood supply to nose

Answer 14

Supplied by branches from:

• Ophthalmic
• Maxillary

Question 15

Frontal paranasal sinus

• Drainage
• Innervation

Answer 15

Located on the frontal bone
- Drains into the frontonasal duct–> middle nasal meatus

Innervation
- Supraorbital nerve [from frontal nerve, CN V1]

Question 16

Ethmoidal air cells

• Drainage
• Innervation

Answer 16

Located within the ethmoidal bone

Drainage:
- Anterior and middle ethmoidal sinus—-> drains into middle meatus

• Posterior—> into superior meatus

Innervation
- Nasocillary nerve [CN V1]

Question 17

Sphenoid paranasal sinus

• Drainage
• Innervation

Answer 17

Located within the sphenoid bone

• Drains into the spheno-ethmoidal recess–> above the superior concha

Innervation
- Branch of nasocillary nerve [posterior ethmoidal], CN V1

Question 18

Maxilla paranasal sinus

• Drainage
• Innervation

Answer 18

Located within the maxilla bone
- Drains into middle meatus

Innervation

• Superior alveolar nerve [CN V2]
• Infraorbital nerve [CN V2]

Question 19

CN II

• Type
• Exit
• Innervation

Answer 19

Optic nerve
- Sensory

Exits- Optic canal

Innervates:
- Vision [transmits visual information from the retina]

Question 20

Eye anatomy

Answer 20

Outer layer

• Sclera [eye white]
• Cornea [avascular]

Middle:

• Vascular layer
• Iris

Inner:
Retina

Posterior chamber: Below lens
Anterior chamber: Above lens

Question 21

Bones of the orbit

Answer 21

Nasal
Lacrimal
Ethmoidal
Frontal
Sphenoid
Temporal-Zygomatic
Maxilla

Question 22

CN III

• Type
• Exit
• Innervation

Answer 22

Oculomotor
- Somatic motor

Exit: Superior orbital fissure

Innervation: Extra-ocular muscles

• Superior rectus
• Medial rectus
• Inferior rectus
• Inferior oblique

Ciliary body and sphincter pupillae
- Via parasympathetic ciliary nerve.

Question 23

CN IV

• Type
• Exit
• Innervation

Answer 23

Trochlear nerve
- Somatic motor

Exits superior orbital fissure

Innervates superior oblique muscle [Depression + abduction]

Question 24

CN VI

• Type
• Exit
• Innervation

Answer 24

Abducens nerve
- Somatic motor—-> Lateral rectus [abduction]

Exits superior orbital fissure

Question 25

Anosmia

Answer 25

Loss of the sense of smell\ Can be temporary [Mucus filled from a cold] or permanent [Trauma, Parkinson's abscess].

Question 26

Blood supply to the eye [3]

Answer 26

Ophthalmic [From Internal carotid] Infra-orbital [From maxillary] Central retina [From ophthalmic]

Question 27

Inability of specific eye movements- clinical consideration

Answer 27

Depression= Problem with CN 3/ CN 4 Elevation= CN3 Abduction= CN 3/6 Adduction = CN3

Question 28

Pupil dilation [blown pupil]- clinical consideration

Answer 28

Indicates impairment of CN3 | - CN3 supplies sphincter pupillae via parasympathetic fibres

Question 29

Ptosis

Answer 29

Drooping eyelid Indicates impairment of CN3 - CN3 innervates levator palpebrae [which opens eyelids]

Question 30

Aneursym in cerebral artery affects CN...

Answer 30

3

Question 31

An orbital fracture can impair CN...

Answer 31

4

Question 32

Cavernous sinus lesion can impair CN...

Answer 32

6

Question 33

Lacrimal apparatus

Answer 33

Enables crying. 1. Lacrimal gland secretes lacrimal fluid. 2. Lacrimal fluid flows into lacrimal papilla 3. Fluid enters lacrimal sac than inferior meatus via naso-lacrimal duct.

Question 34

Nervous supply to lacrimal apparatus

Answer 34

Secremotor - Parasympathetic----> follows CN VII Vasconstrictive - Sympathetic----> follows interal carotid from superior cervial ganglion

Question 35

Parasympathetic supply to lacrimal gland

Answer 35

Facial nerve at internal acoustic meatus travels - Joins with lacrimal nerve [CN V1] into gland CN VII----> Greater petrosal nerve----> Deep petrosal nerve [from internal carotid plexus]-----> Nerve of pterygoid canal synapses at ganglion