Anatomy Flashcards

1
Q

What 7 bones make up the orbit of the eye?

A

Frontal
Zygomatic
Maxilla
Palatine
Sphenoid
Ethmoid
Lacrimal

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2
Q

Does the nasal bone make up part of the orbit?

A

No

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3
Q

What passes through the optic canal?

A

Optic nerve
Ophthalmic artery

This opening is found on the sphenoid bone.

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4
Q

Which cranial nerves are responsible for movement of the eye?

A

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

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5
Q

What is a blowout fracture?

A

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

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6
Q

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

A

Contents of the orbit may become trapped.

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7
Q

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

A

Obicularis oculi

This is innervated by CNVII (facial nerve).

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8
Q

What is the role of the levator palpebra superioris?

A

Elevation of the upper eyelid.

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9
Q

Is the levator palpebra superioris mainly skeletal or smooth muscle?

A

Mainly skeletal, although has a smooth muscle component.

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

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10
Q

Which gland is found superolateral to the eye?

A

Lacrimal gland

This is innervated by CNVII (facial nerve).

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11
Q

What is the role of the iris?

A

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

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12
Q

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

A

Cornea
Sclera

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13
Q

What are the 3 layers of the eye?

A

Fibrous
Uvea/Vascular
Retina

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14
Q

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

A

Cornea

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15
Q

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

A

Iris
Ciliary body
Choroid

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16
Q

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

A

All of the structures located anterior to the lens.

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17
Q

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

A

All of the structures behind the lens.

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18
Q

What is the limbus?

A

The angle found between the cornea and the sclera.

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19
Q

What is the indocorneal angle?

A

The angle between the iris and the cornea.

It is important in the pathology of glaucoma.

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20
Q

What is the purpose of aqueous humor?

A

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

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

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21
Q

Where is the aqueous humor resorbed?

A

Scleral venous sinuses located at the indocorneal angle.

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22
Q

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

A

Lacrimal fluid (tears).

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23
Q

What controls intra-ocular pressure?

A

The balance between production and resorption of aqueous humor.

Input must be equal to output to prevent issues.

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24
Q

What may result from raised intra-ocular pressure?

A

Ischaemia of the retina
Glaucoma

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25
Q

Which artery supplies the majority of bloodflow to the eye?

A

Ophthalmic artery

This is a branch of the internal carotid artery.

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26
Q

What is an end artery?

A

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.

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27
Q

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

A

The macula.

This area is specialised for acute vision.

28
Q

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

A

Monocular blindness

29
Q

What are the 7 extraocular muscles?

A

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

30
Q

How are extraocular muscles innervated?

A

LR6 SO4 A03

Lateral rectus = Abducens nerve
Superior oblique = Trochlear nerve
All others = Oculomotor nerve

31
Q

Which movement tests function of the lateral rectus?

A

Ask patient to look outwards.

32
Q

Where does sympathetic outflow originate?

A

T1-L2

Referred to as thoracolumbar outflow.

33
Q

Where does the oculomotor nerve originate?

A

The junction of the midbrain and the pons.

34
Q

What are the 3 layers of the meninges?

A

Dura mater
Arachnoid mater
Pia mater

35
Q

Which nerve supplies the dura mater?

A

Trigeminal nerve (CNV)

36
Q

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

A

Subarachnoid space

37
Q

How many ventricles are found in the brain?

A

2 lateral ventricles
2 midline ventricles

38
Q

Where is the CSF produced?

A

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

39
Q

Where is CSF resorbed?

A

Dural venous sinuses via the arachnoid granulations.

40
Q

What are the 3 branches of the trigeminal nerve?

A

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

41
Q

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

A

Mandibular nerve (CNV2)

Responsible for the muscles of mastication.

42
Q

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

A

Upper eyelid, cornea, and conjunctiva.

43
Q

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

A

Skin of the lower lid
Skin over the maxilla

44
Q

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

A

Skin over the mandible
Temporomandibular joint

45
Q

What is a pathologically enlarged pupil called?

A

Mydriatic pupil

46
Q

What is a pathologically constricted pupil called?

A

Mitotic pupil

Can present in Horner’s syndrome.

47
Q

What may cause a fixed ‘pin-point’ pupil?

A

Opiate overdose

48
Q

What may cause a fixed dilated pupil?

A

CNIII pathology

49
Q

Is levator palpebra superioris skeletal or smooth muscle?

A

Skeletal muscle

50
Q

What is Horner’s syndrome?

A

The loss of parasympathetic supply to the eye.

Will result in unilateral pupillary constriction.

51
Q

Which nerve is affected in Bell’s palsy?

A

CNVII (facial nerve)

May result in an inability to close the affected eye.

52
Q

Does distant or close light require more refraction?

A

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

53
Q

Is CNIII afferent or efferent?

A

Efferent (moves away from brain).

54
Q

Is CNII afferent or efferent?

A

Afferent (moves towards brain).

55
Q

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

A

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

56
Q

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

A

Infront of the optic chiasm.

57
Q

Why is raised ICP a serious clinical problem?

A

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

58
Q

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

A

Blood
Brain
CSF

59
Q

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

A

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.

60
Q

What is papilloedema?

A

Swelling of the optic disc.

Results in visual disturbances.

61
Q

What is the largest dural septae?

A

Falx cerebri

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

62
Q

What is the purpose of dural septae?

A

To prevent the brain moving within the cranial cavity.

63
Q

How does the eye appear in a CNIII palsy?

A

Down and out

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

64
Q

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

A

CNIV (trochlear nerve)

65
Q

What causes ptosis?

A

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

66
Q
A