Anatomy

Question 1

What 7 bones make up the orbit of the eye?

Answer 1

Frontal
Zygomatic
Maxilla
Palatine
Sphenoid
Ethmoid
Lacrimal

Question 2

Does the nasal bone make up part of the orbit?

Answer 2

No

Question 3

What passes through the optic canal?

Answer 3

Optic nerve
Ophthalmic artery

This opening is found on the sphenoid bone.

Question 4

Which cranial nerves are responsible for movement of the eye?

Answer 4

CNIII (trigeminal)
CNIV (trochlear)
CNVI (abducens)

Question 5

What is a blowout fracture?

Answer 5

When major force is exerted on the orbital rim, the pressure is transferred from the thicker bones to the thinner bones.

Question 6

What is a complication of a trap-door/blowout fracture?

Answer 6

Contents of the orbit may become trapped.

Question 7

What is the name of the sphincter muscle that completely encircles the orbit?

Answer 7

Obicularis oculi

This is innervated by CNVII (facial nerve).

Question 8

What is the role of the levator palpebra superioris?

Answer 8

Elevation of the upper eyelid.

Question 9

Is the levator palpebra superioris mainly skeletal or smooth muscle?

Answer 9

Mainly skeletal, although has a smooth muscle component.

The area related to smooth muscle control may be called Mueller’s muscle.

Question 10

Which gland is found superolateral to the eye?

Answer 10

Lacrimal gland

This is innervated by CNVII (facial nerve).

Question 11

What is the role of the iris?

Answer 11

It is a diaphragmatic/sphincter-like muscle that controls the amount of light entering the eye.

Question 12

What 2 parts make up the fibrous layer of the eye?

Answer 12

Cornea
Sclera

Question 13

What are the 3 layers of the eye?

Answer 13

Fibrous
Uvea/Vascular
Retina

Question 14

Which part of the eye is responsible for 2/3rds of the total refractive power?

Answer 14

Cornea

Question 15

What 3 components make up the uvea layer of the eye?

Answer 15

Iris
Ciliary body
Choroid

Question 16

What area of the eye is considered to be the anterior chamber?

Answer 16

All of the structures located anterior to the lens.

Question 17

What area of the eye is considered to be the posterior chamber?

Answer 17

All of the structures behind the lens.

Question 18

What is the limbus?

Answer 18

The angle found between the cornea and the sclera.

Question 19

What is the indocorneal angle?

Answer 19

The angle between the iris and the cornea.

It is important in the pathology of glaucoma.

Question 20

What is the purpose of aqueous humor?

Answer 20

It is a liquid required to provide nutrition to the avascular lens and cornea.

Production occurs in the posterior chamber, by the ciliary body.

Question 21

Where is the aqueous humor resorbed?

Answer 21

Scleral venous sinuses located at the indocorneal angle.

Question 22

If aqueous humor nourishes the cornea from the inside, what provides the surface area nutrition?

Answer 22

Lacrimal fluid (tears).

Question 23

What controls intra-ocular pressure?

Answer 23

The balance between production and resorption of aqueous humor.

Input must be equal to output to prevent issues.

Question 24

What may result from raised intra-ocular pressure?

Answer 24

Ischaemia of the retina
Glaucoma

Question 25

Which artery supplies the majority of bloodflow to the eye?

Answer 25

Ophthalmic artery This is a branch of the internal carotid artery.

Question 26

What is an end artery?

Answer 26

An artery with insufficient anastomoses. This means that blockage of this will leave the tissue supplied by this cut-off from their blood supply. An example is the central retinal artery.

Question 27

Which area of the retina has the greatest density of cones?

Answer 27

The macula. This area is specialised for acute vision.

Question 28

What may result from the complete interruption of the flow to a central artery/vein?

Answer 28

Monocular blindness

Question 29

What are the 7 extraocular muscles?

Answer 29

Superior rectus Inferior rectus Medial rectus Lateral rectus Superior oblique Inferior oblique Levator palpebra superioris

Question 30

How are extraocular muscles innervated?

Answer 30

LR6 SO4 A03 Lateral rectus = Abducens nerve Superior oblique = Trochlear nerve All others = Oculomotor nerve

Question 31

Which movement tests function of the lateral rectus?

Answer 31

Ask patient to look outwards.

Question 32

Where does sympathetic outflow originate?

Answer 32

T1-L2 Referred to as thoracolumbar outflow.

Question 33

Where does the oculomotor nerve originate?

Answer 33

The junction of the midbrain and the pons.

Question 34

What are the 3 layers of the meninges?

Answer 34

Dura mater Arachnoid mater Pia mater

Question 35

Which nerve supplies the dura mater?

Answer 35

Trigeminal nerve (CNV)

Question 36

Where is the CSF and blood vessels found in the brain?

Answer 36

Subarachnoid space

Question 37

How many ventricles are found in the brain?

Answer 37

2 lateral ventricles 2 midline ventricles

Question 38

Where is the CSF produced?

Answer 38

The choroid plexus of the lateral ventricles and 3rd ventricle.

Question 39

Where is CSF resorbed?

Answer 39

Dural venous sinuses via the arachnoid granulations.

Question 40

What are the 3 branches of the trigeminal nerve?

Answer 40

Ophthalmic nerve (CNV1) Maxillary nerve (CNV2) Mandibular nerve (CNV3)

Question 41

Which branch of the trigeminal nerve is the only one responsible for providing motor function?

Answer 41

Mandibular nerve (CNV2) Responsible for the muscles of mastication.

Question 42

What area of the face is innervated by CNV1 (ophthalmic division of the trigeminal nerve)?

Answer 42

Upper eyelid, cornea, and conjunctiva.

Question 43

What area of the face is innervated by CNV2 (maxillary branch of the trigeminal nerve)

Answer 43

Skin of the lower lid Skin over the maxilla

Question 44

What area of the face is innervated by CNV3 (mandibular division of the trigeminal nerve)?

Answer 44

Skin over the mandible Temporomandibular joint

Question 45

What is a pathologically enlarged pupil called?

Answer 45

Mydriatic pupil

Question 46

What is a pathologically constricted pupil called?

Answer 46

Mitotic pupil Can present in Horner's syndrome.

Question 47

What may cause a fixed 'pin-point' pupil?

Answer 47

Opiate overdose

Question 48

What may cause a fixed dilated pupil?

Answer 48

CNIII pathology

Question 49

Is levator palpebra superioris skeletal or smooth muscle?

Answer 49

Skeletal muscle

Question 50

What is Horner's syndrome?

Answer 50

The loss of parasympathetic supply to the eye. Will result in unilateral pupillary constriction.

Question 51

Which nerve is affected in Bell's palsy?

Answer 51

CNVII (facial nerve) May result in an inability to close the affected eye.

Question 52

Does distant or close light require more refraction?

Answer 52

Close light - these rays diverge more, thus greater refraction is needed to focus properly.

Question 53

Is CNIII afferent or efferent?

Answer 53

Efferent (moves away from brain).

Question 54

Is CNII afferent or efferent?

Answer 54

Afferent (moves towards brain).

Question 55

Where is optic tract pathology located if both eyes are affected by a singular lesion?

Answer 55

May be behind the optic chiasm, or directly affecting the chiasm if causing a bitemporal hemianopia.

Question 56

Where is optic tract pathology located if one eye only affected?

Answer 56

Infront of the optic chiasm.

Question 57

Why is raised ICP a serious clinical problem?

Answer 57

As the skull is a closed compartment, the pressure it exerts can damage the brain/spinal cord.

Question 58

What are the 3 components that contribute to the intracranial volume?

Answer 58

Blood Brain CSF

Question 59

Why is it common for visual problems to present in raised ICP?

Answer 59

As the cranial meninges surround the optic nerve, thus raised pressure seen will be exerted on the nerve itself, resulting in altered vision. Fundoscopy will show papilloedema.

Question 60

What is papilloedema?

Answer 60

Swelling of the optic disc. Results in visual disturbances.

Question 61

What is the largest dural septae?

Answer 61

Falx cerebri Attaches to the crista galli (of the ethmoid bone) anteriorly, and the internal occipital protuberance posteriorly.

Question 62

What is the purpose of dural septae?

Answer 62

To prevent the brain moving within the cranial cavity.

Question 63

How does the eye appear in a CNIII palsy?

Answer 63

Down and out Caused by unopposed activity of superior oblique (CNIV) and lateral rectus (CNVI).

Question 64

What is the only cranial nerve to originate from the dorsal surface of the midbrain?

Answer 64

CNIV (trochlear nerve)

Question 65

What causes ptosis?

Answer 65

A lack of sympathetic innervation to Mueller's muscle - the eyelid will be lifted by LPS alone.