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YR2: Head, Neck and Spine > Session 6: Anatomy of the Orbit > Flashcards

Session 6: Anatomy of the Orbit Flashcards

1
Q

Which bones make up the roof, floor and lateral wall of the orbit?

A

Roof: orbital plate of frontal bone
Floor: orbital plate of maxillary bone
Lateral wall: greater wing of the sphenoid bone + zygoma

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2
Q

Which bones make up the medial wall of the orbit?

A

Frontal process of maxilla
Lacrimal bone
Orbital plate of ethmoid
Lesser wing of sphenoid

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3
Q

Which structures pass through the optic canal?

A

Optic nerve

Ophthalmic artery

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4
Q

Which structures pass through the inferior orbital fissure?

A

Zygomatic branch of the maxillary division (V2) of trigeminal nerve
Infraorbital vessels

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5
Q

Which structures pass through the superior orbital fissure?

A 
Oculomotor 
Trochlear 
Ophthalmic division (V1) of trigeminal  
Abducens  
Ophthalmic vessels
Sympathetic fibres
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6
Q

Name the 4 recti muscles and state their origin and insertion.

A

Superior, Inferior, Lateral, Medial
Origin: common tendinous ring (at back of orbit)
Insertion: Sclera, 5 mm behind corneal margin

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7
Q

State the innervation of the 6 extrinsic eye muscles

A

Lateral Rectus= Abducens (CN 6)
Superior Oblique = Trochlear (CN 4)
Medial Rectus, Superior Rectus, Inferior Rectus,
Inferior Oblique = Oculomotor (CN 3)

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8
Q

State the origin and insertion of the inferior oblique.

A

Origin: orbital surface of maxilla
Insertion: postero-lateral inferior quadrant of the globe

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9
Q

State the origin and insertion of the superior oblique.

A

Origin: body of sphenoid
Insertion: via the trochlea to the postero-lateral superior quadrant of the globe

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10
Q

Which muscle is responsible for elevating the eyelid?

A

Levator palpebrae superioris

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11
Q

Where is the origin and insertion of the levator palpebral superioris?

A

Origin: lesser wing of sphenoid
Insertion: superior tarsal plate + skin of the eyelid

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12
Q

Describe the innervation of the levator palpebral superioris

A

Oculomotor + sympathetic to smooth muscle

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13
Q

Describe the isolated muscle action of the oblique muscles.

A

Superior oblique = depresses + abducts

Inferior oblique = elevates + abducts

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14
Q

Describe the isolated muscle action of the superior and inferior recti.

A

Superior rectus = elevates + adducts

Inferior rectus = depresses + adducts

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15
Q

Describe how you would test the muscle actions of superior rectus and inferior rectus.

A

Superior rectus = make patient abduct their eye + then elevate it
Inferior rectus = make patient abduct their eye + then depress it

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16
Q

Describe how you would test the muscle actions of superior oblique and inferior oblique.

A

Superior oblique = make patient adduct their eye + then depress it
Inferior oblique = make patient adduct their eye + then elevate it

17
Q

Which nerve axons make up the optic nerve?

A

Retinal ganglion cell axons

18
Q

What types of fibres are found within the oculomotor nerve?

A

Motor fibres to MR, SR, IR, IO + LPS
Parasympathetic fibres
The oculomotor nerve has 2 rami

19
Q

What are the branches of the ophthalmic division of the trigeminal nerve? Which branch is biggest?

A

Nasociliary
Lacrimal
Frontal – this is the largest

20
Q

What structure do the cranial nerves pass through before reaching the superior orbital fissure?

A

Walls of Cavernous sinus

21
Q

Which of the nerves passing through the cavernous sinus, passes through the middle of it rather than passing through the walls? What else passes through here?

A

Abducens (CN 6)

Internal carotid artery also passes through here

22
Q

What are the branches of the branches of the ophthalmic division of the trigeminal nerve?

A

Lacrimal (no branches)
Nasociliary:
Branch to ciliary ganglion, Ethmoidal, Infratrochlear
Frontal: Supratrochlear + Supraorbital

23
Q

What limb of the autonomic nervous system is the ciliary ganglion involved in?

A

PARASYMPATHETIC

24
Q

Which fibres enter the ciliary ganglion and which fibres leave the ciliary ganglion?

A

Fibres entering the ciliary ganglion: preganglionic fibres in the inferior ramus of the oculomotor nerve
Fibres leaving the ciliary ganglion: postganglionic fibres in the short ciliary nerves

25
Q

What do the fibres leaving the ciliary ganglion innervate?

A

Sphincter pupillae

Ciliary muscle

26
Q

What are the 6 branches of the ophthalmic artery?

A 
Supratrochlear 
Supraorbital 
Lacrimal 
Ciliary 
Muscular branches
Central artery of the retina
27
Q

Name the 2 ophthalmic veins and state where they drain.

A

Superior ophthalmic vein: cavernous sinus (potential route of intracranial infection)
Inferior ophthalmic vein: pterygoid plexus

28
Q

Describe the location of the lacrimal glands.

A

Anterolateral superior orbit

29
Q

Describe the innervation of the lacrimal glands.

A

Parasympathetic secretomotor fibres of Facial Nerve (CN 7) from the pterygopalatine ganglion via the zygomaticotemporal + finally, lacrimal nerves

30
Q

Where do the tears initially drain?

A

Lacrimal Sac

31
Q

Via which duct do the tears drain from the Lacrimal sac and where does this duct empty?

A

Nasolacrimal duct – empties into the inferior nasal meatus

32
Q

What is the corneal reflex?

A

Stimulation of the cornea causes involuntary blinking in both eyes

33
Q

What is Horner’s syndrome and how does it manifest itself in patients?

A

It is caused by a disorder of the sympathetic nerves in the brainstem or cervical region
Presents as:
Ptosis
Miosis
Anhydrosis (lack of sweating around the eye)

34
Q

Where does the nasolacrimal duct drain?

A

Inferior nasal meatus

35
Q

What is the technical term for abnormal alignment of the eyes (having a squint)?

A

Strabismus

36
Q

What are the different types of strabismus?

A

Hypotropia – one eye turns down
Hypertropia – one eye turns up
Exotropia – one eye turns out
Esotropia – one eye turns in

37
Q

Describe the isolated muscle actions of the lateral and medial rectus muscles

A

Lateral: Abduction
Medial: Adduction

38
Q

What may infection or thrombosis in cavernous sinus cause?

A

Direct effects on the cranial nerves passing through

YR2: Head, Neck and Spine (6 decks)

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