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Anatomy class > Unit 14: The eye > Flashcards

Unit 14: The eye Flashcards

1
Q

What is the orbital margin and the orbital walls?

A

Margin - The anterior-most circle (the base of the pyramid)
Walls - the bones within the orbit heading backwards towards the brain (think of as sides of the pyramids)

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2
Q

What makes up the supraorbital margin of the orbit?

A

Frontal bone

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3
Q

What makes up the laterla margin of the orbit?

A

The frontal bone
The zygomatic bone

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4
Q

What makes up the infraorbital margin of the orbit?

A

The maxilla
The zygomatic bone

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5
Q

What makes up the medial margin of the orbit?

A

The maxilla (anterior lacrimal crest)
The frontal bone

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6
Q

What is the role of the medial wall or the orbit?
What makes it up?

A

Division between the orbit and the nasal cavity
Passage for arteries and nerves.
Made from the maxilla, lacrimal bone, ethmoid bone, sphenoid bone body.

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7
Q

What is the floor of the orbit and what is its function?

A

Separates the orbit from the maxillary sinus, prevents content from spreading between these structures
Made from the maxilla (orbital process), the zygomatic bone and the palatine bone (orbital process) .

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8
Q

What is the roof of the orbit made from?
What is its function?

A

Wall between orbit, cranial fossa and potentially the frontal sinus
Made from the frontal bone and the sphenoid bone.
Contains the trochlear fovea - connects to trochlear cartilage to act as pully for superior oblique anteromedially and the lacrimal fossa anterolateral for the lacrimal gland.

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9
Q

What is the lateral wall of the orbit made from?
What is its function?

A

Zygomatic bone
Greater wing of the sphenoid
Contains the superior orbital fissure - communicate with cranial fossa
Contains inferior orbital fissure for communication with the pteyrgoid palatine fossa
Enables nerves and vessels to reach the orbit

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10
Q

Why is it significant that the eyes face anteriorly?

A

Anatomical - anterior facing eye
However long axis of orbit is slightly lateral. (the cardinal position of the eye)
This means there must be tonic activity of the muscles of the eye to hold the eye in place - this is mainly down by tonic contraction of medial rectus.

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11
Q

What is the function of the levator palpebrae superioris?

A

Originates from lesser wing of sphenoid and inserts into superior tarsal plate of superior eyelid.
Elevates the superior eyelid.

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12
Q

What nerve innervates the levator palpebrae superioris muscle?

A

The oculomotor nerve.

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13
Q

What are the seven different extra-ocular eye muscles?

A

Superior rectus
Inferior rectus
Medial rectus
Lateral rectus
Superior oblique
Inferior oblique

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14
Q

What is the origin of the s/m/i/l rectus muscles of the eye?

A

The common tendinous ring
Then insert onto their appropriate aspect of the sclera

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15
Q

What do all extra-ocular muscles (minus the levator palpebrae superior) insert onto?

A

The sclera.

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16
Q

What is the function of rectus muscles of the eye?

A

Superior - elevates the eye
Inferior - depresses the eye
Medial - adducts the eye
Lateral - abducts the eye

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17
Q

Describe the innervation to the extra ocular muscles of the eye?

A

SO4 LR6 AO3
Superior oblique by CN4
Lateral lectus by CN6
All others by oculomotor nerve

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18
Q

What is the function of the superior oblique muscle in the eye?

A

Depresses, abducts and intorts the eye
Intorsion is the primary function in the anatomical position
(attaches to back of eye)

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19
Q

What is the function of the inferior oblique muscle of the orbit?

A

Elevates, abducts and extorts the eye
Extorsion is the primary function in the anatomical position
(attaches to back of eye)

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20
Q

What is the unique anatomy of the insertion of the inferior rectus?
Has does this affect its function?

A

Passes obliquely from the common tendinous ring
Enables to depress as the primary function in anatomical position but can also adduct and extort the eye (down and out).

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21
Q

What is unique about the anatomy of the insertion of the superior rectus and how does this affect its function?

A

Passes obliquely through the orbit
Can elevate the eye as its primary function in the anatomical position but can also adduct and intort the eye.

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22
Q

What is the origin of the superior oblique muscle?

A

Originates from the sphenoid bone
Passes into orbit
Has tendinous middle - that loos around a fibre cartilage that is attached to the trochlear of the frontal bone
It continues posteriorly laterally as muscle to attach to the eye

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23
Q

What co-ordination contraction produces elevation of the eye?

A

Superior rectus and inferior oblique

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24
Q

What co-ordination contraction produces depression of the eye?

A

The inferior rectus and the superior oblique.

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25
Q

How does the optic nerve get to the eye?

A

Originate from optic chiasma
Through optic canal
Through common tendinous ring

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26
Q

What nerves enter the orbit through the superior orbital fissure and go outside the tendinous ring?

A

The lacrimal nerve
The frontal nerve
The trochlear nerve
The oculomotor ( superior division)

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27
Q

What nerves enter the orbit through the superior orbital fissure and go inside the tendinous ring?

A

The nasocillary nerve
The oculomotor nerve (inferior division)
The abducens nerve

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28
Q

What is the role of the lacrimal nerve in the orbit?

A

Is a branch of the opthalmic division of the trigeminal nerve
Passes inferiorly and laterally, contains sensory and PANS fibres for the lacrimal glands.

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29
Q

What is the role of the frontal nerve in the orbit?

A

Is a branch of the ophthalmic division of the trigeminal nerve.
Passes superiorly and medially to the forehead

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30
Q

What is the role of the trochealr nerve in the orbit?

A

Innervates superior oblique muscle

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31
Q

What is the role of oculomotor nerve superior division in the orbit?

A

Innervates levator palpebrae superioris and superior rectus

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32
Q

What is the role of the nasocillary nerve in the orbit?

A

Branch of ophthalmic division of the trigeminal nerve.
Long ciliary nerves - sensory for ciliary body, iris and corner, post ganglionic sympathetic to dilate pupil
Short ciliary nerves - extend from autonomic ciliary ganglion, contain autonomic fibres, sympathetic for the vasculature, parasympathetic for ciliary body and sphnicter pupillae.

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33
Q

What is the anatomy of the nasociliary nerve?

A

Medial wall of the orbit
Gives off posterior and anterior ethmoid nerves that enter into the nasal cavity.
infratrochlear nerve branch just before anterioe thmoid extends towards the bridge of the nerve.

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34
Q

What is teh function of the oculomotor nerve inferior division in the orbit?

A

Innervates the medial rectus, inferior rectus and inferior oblique.

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35
Q

What is the role of the abducens nerve in the orbit?

A

Innervates the lateral rectus muscle.

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36
Q

What branches from the maxillary division of the trigeminal nerve supply the orbit?

A

The zygomatic (zygomaticotemporal and zygomaticofacial
The infraorbital nerve

37
Q

How does the maxillary nerve enter the orbit?

A

Exits the cranium through the foramen rotunudm, enters the pterygopalatine fossa, enters the orbit through the inferior orbital fissure.

Supplies the skin

38
Q

What are the branches of the opthalmic nerve to supply the eye?

A

The supratrochlear nerve
The supraorbital nerve

Supply the skin

39
Q

What is the main arterial supply to the orbit?

A

Opthalmic artery is a branch of the internal carotid artery.

40
Q

What are the branches of the ophthalmic artery within the orbit?

A

Gives rise to:
central retinal artery which pierces the optic nerve and runs within it to reach the retina
Short posterior ciliary x2- pierce sclera posteriorly and supply posterior choroid.
Long posterior ciliary arteries x2 - pierce and supply anterior choroid, iris and ciliary bodies.
Also anterior ciliary arteries - supply the anterior choroid anastomose with the long ciliary arteries.
Lacrimal artery - lacrimal gland and lateral eye.

41
Q

What is the venous drainage of the eyeball?

A

The central retinal accompanies the central retinal vein.
Superior vorticose drain (x2 L +R) into superior opthalmic vein
inferior vorticose veins (x2 L and R) into inferior opthalmic vein.
All eventually drain into the cavernous sinus (within the sphenoid vein.

42
Q

What is the presentation of oculomotor nerve palsy?

A

Only unaffected muscles are superior oblique and lateral retucs
Results in a depressed and abducted eyeball with partial ptosis on affected side.
Dilated pupil - no PANs to sphincter pupillae.

43
Q

What does trochlear nerve palsy affect the eyeball?

A

Action of superior oblique muscle is lost.
Often no obvious eye movement as compensated for by lateral and inferior rectus muscles
May complain of health tilt away from affected side and diplopia (double vision)

44
Q

What is the gross optic circuitry for passage on information from the eye to the primary visual cortex?

A

Exits the eye travels through a defect in the lamina cribosa of the sclera
Travels through bony orbit and into middle cranial fossa through the optic canal.
Travles along floor of mid cranial fossa through medial aspect of cavernous sinus
The left and right optic nerve then converge at the optic chiasm.
Temporal fibres remain on the ipsilateral side whilst nasal fibres desciate to the contralteral side.
Now termed optic tract/
Projects to the thalamus synapse at the lateral genicular nuclues in the thalamus (bilateral)
Optic radiations then project to the occipital lobe and terminate in the calcarine sulcus of the occpital lobe where the cortical visual centre in located

45
Q

What is the passage of information from photoreceptors to the optic nerve?

A

Photorecepotrs - electrical signals generated
Synapse with retinal bipolar cells - rods on a many to :1 ratio and cones on a 1:1 ratio
Synapse to retinal ganglion cells
Converge at the optic disk forming the optic nerve

46
Q

What are the different pattern of travel of the optic radiations from the thalamus to the visual cortex related to the visual field?

A

Loops through the parietal lobe - relate to the upper visual fields
Loops through the temporal bone (Meyers loop) relate to the lower visual fields.

47
Q

Draw a diagram to represent the visual neural circuitry from the visual field to the primary visual cortex

A
48
Q

What defect in the neural circuitry would result in right eye total blindness?

A

Right optic nerve damage

49
Q

What is bitemporal heteronmymous hemianopia?
What defect in neural circuitry causes it?

A

Loss of temporal visual fields in both the left and right visual field
Damage to the optic chiasm, preventing desication of fibres.

50
Q

What is right eye nasal hemianopia?
What defect in the neural circuitry would result in this vision loss?

A

Loss of vision in the right nasal field only.
Damage to part of the right optic nerve originating from the temporal right retina.

51
Q

What is left homonymous hemianopia?
What damage to the neural circuitry could result in this visual defect?

A

Vision loss in the left temporal and the right nasal visual field.
Damage to the right optic tract.

52
Q

What is left lower quadrantic anopia?
What defect in neural circuitry can cause this visual defect?

A

Vision loss in the left lower temporal visual field in the left eye and the left lower nasal visual field in the right eye.
Caused by defect in the superior radiation fibres in the right parietal lobe.

53
Q

What is left upper quadrantic anopia?
What defect in neural circuitry can cause this vision loss?

A

Loss of vision in the left temporal upper quadrant in the left eye and the left nasal upper quadrant in the right eye
Caused by damage to the optic radiation in the right temporal lobe.

54
Q

Describe the location of the orbit.

A

Sits inferior to the anterior cranial fossa and anterior to the middle cranial fossa.
Is pyramidal in shape with the base anteriorly and the apex extending posteromedially.

55
Q

What is the content of the orbit?

A

Contains the eyeball, orbital fat and fascia, extra-ocular muscles, lacrimal apparatus and the associated neurovasculature.

56
Q

What are the seven bones that make up the bony orbit?

A

The maxilla
The frontal
Zygomatic
Ethmoid
Lacrimal
Sphenoid
Palatine

57
Q

What are the features within the medial wall of the orbit?

A

Contains the anterior and posterior ethmoidal foramina.
These are conduits for the ethmoidal vessels.
The lacrimal groove - which contains the lacrimal sac.

58
Q

What are the features of the fllor of the orbit?

A

The inferior orbital fissure
This is a conduit for the inferior ophthalmic vein

59
Q

What are the features of the lateral wall or the orbit?

A

Formed from the zygomatic and sphenoid bones
Contains the superior orbital fissure

60
Q

What is found within the superior orbital fissure?

A

The trochlear nerve
The oculomotor nerve
The opthalmic nerve
The adbudence nerve
The superior ophthalmic vein

61
Q

What is the apex of the bony orbit?

A

The body and the lesser wing of the sphenoid.
Perforated by the optic canal.

62
Q

What is found within the optic canal?

A

The optic nerve
The ophthalmic artery.

63
Q

What are the important division of the trigeminal nerve for the eye?

A

The trigeminal nerve
CNV1 - opthalmic division
Which then divides into three section:
The lacrimal nerve - sensory and parasympathetic to the lacrimal gland.
The frontal nerve. - forehead sensation
The nasociliary - to the ciliary muscles

64
Q

In the anatomical position what is the primary movement of each of the extra-ocular eye muscles?

A

Superior rectus - elevation
Inferior rectus - depression
Medial rectus - adduction
Lateral rectus - abduction
Superior oblique - intorsion
Inferior oblique - extorsion

65
Q

How is the function of the rectus muscles change as you move in/out of the cardinal position of the eye?

A

The medial and lateral rectus muscle function is not affected by the position of the eye.
The superior and lateral rectus are most effective in the cardinal position of the eye.
When moving out of cardinal position ( adduction of eye), the superior and inferior rectus are distorted in shape and are no longer functional, therefore the oblique muscles become the primary elevators/depressors of the eye.

66
Q

Draw a diagram to show how different muscles are responsible for moving the eyes from the anatomical position

A
67
Q

Draw a diagram to show how different muscles are responsible for moving the eye from the cardinal position when testing gaze clinically (h test)

A
68
Q

What are the three layers of the gross anatomy of the eye?

A

The fibrous layer
The vascular layer or uvea
The inner later or retina.

69
Q

What makes up the fibrous layer of the eye?

A

The outermost structures of the eye
The sclera - attachment for extraocular muscles, penetrated by nerves and vessels e.g optic nerve
The cornea - transparent, anterior and central continuation, responsible for refraction of light.
Both layers provide shape to the eye and support deeper structures.

70
Q

What makes up the vascular layer of the eye?

A

Also called the uvea
Consists of the choroid, ciliary body and the iris.

71
Q

What is the choroid of the eye?

A

Part of the vascular layer.
Just superficial to the retina, contains blood vessels and connective tissue to provide nourishment to the outer layers of the retina.

72
Q

What are the features of the ciliary body of the eye?

A

Made from the ciliary muscle and the ciliary process
Ciliary muscle - smooth muscle with three different orientations of fibres (longitudinal, circular and radial), contract and relax to control circular ciliary body size
What is the ciliary process - connects the lens to the ciliary body via zonular fibres (termed suspensory ligament of the lens), this alters the lens shape when ciliary muscles contract.

73
Q

How does contraction of the ciliary muscle affect lens shape?

A

Contraction of ciliary muscle - reduce ciliary body circular diameter - less tension of the suspensory ligaments of the lens - lens more convex in shape (shorter and wider), enables to focus on closer located objects.

74
Q

How does relaxation of the ciliary muscles affect the lens hence vision?

A

Relaxation of ciliary muscles, increases the circular diameter of the ciliary body, this puts more tension in the suspensory ligament of the lens, leads to a stretched retina, thinner and longer - better for focusing on objects that are far away.

75
Q

What are the features of the iris?

A

Iris makes up coloured component of eye contains muscles to control dimension of pupil (central aperture) in response to light conditions.
Muscles are - sphincter pupillae muscle and the dilator pupillae muscle.

76
Q

What are the features of the sphincter pupillae muscle?

A

In the iris, made from circular fibres
Under parasympathetic control
ACh binds to M3, PLCbeta, inc Ca2+ leads to contraction,
This leads to pupillary contraction, to reduce the light influx into the eye.

77
Q

What are the features of the dilator pupillae muscle?

A

Located in the iris
Made from radial fibres
Under sympathetic innervation, adrenaline to alpha 1, PLCbeta, inc Ca2+ cause contraction
Leads to pupillary dilation, inc light entering the eye.

78
Q

What are the different layers of the retina?
Where is each retinal layer found?

A

Has a neural and pigemented layer.
Neural - contains photoreceptors and neurovasculature - located posterior and laterally.
Pigemented - superfical to the neural layer, attached to choiroid layer, supports the neural layer, found around the whole circumference of the retina.

79
Q

What is meant by the optic retina?

A

The posterior and lateral aspects of the retina that contains both the pigmented and neural layers of the retina.
Is viewed during fundoscopy.

80
Q

What is meant by the non-visual retina?

A

Found anteriorly where the pigmented layer of the retina exists and the neural layer does not.

81
Q

What is the macula lutea?

A

A feature of the retina
Responsible for central vision, contains a depression called the fovea with the highest concentration of cones on the retina for high acuity central vision (fovea has no rods)

82
Q

What is the optic disk of the retina?

A

The blind sport of the eye - contains no photoreceptors
Where the optic nerve enters the retina
Branches of the central retinal arteries radiate out of here.

83
Q

What are the features of the anterior cavity of the eye?

A

Consists of an anterior chamber - from cornea to Iris
Also a posterior chamber from iris to lens
These are connected by the pupipillary opening and filled with aqueous humour, clear and nourishes and protects the eye.

84
Q

What is the most common route of aqueous humour flow?

A

Seceretes by ciliary body into posterior chamber of anterior cavity
Moves into anterior chamber via pupillary opening
Drains into the canal of schlemm located in the chamber angle (between the iris and the cornea)

85
Q

What fluid is found in the posterior cavity of the eye?

A

Vitreous humour
Fills the posterior cavity from the lens to the retina.

86
Q

What are the different arteries that supply the eye?

A

All branches of the opthalmic artery
- short posterior ciliary arteries - posterior choroid
- posterior long ciliary arteries - anterior choroid
- anterior ciliary arteries - anastamose with lpca in choroid
Central retinal artery - up the middle of the optic nerve to supply the retina. (note does not supply the optic nerve)

87
Q

Where are the CN3,4 and 6 nuclei located in the brainstem?

A

3 - medial midbrain
4 - Midbrain
6 - pontomedullary junction

88
Q

What is meant by visual gaze?

A

The coordinate movements of the right and left eyes to a visual target.

Anatomy class (42 decks)

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