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Y2 LCRS 2 - HNS Anatomy > 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 + zygomatic bone

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2
Q

Which bones make up the medial wall of the orbit?

A

Lacrimal bone
Orbital plate of ethmoid
Frontal process of maxilla
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 veins (superior and inferior)  
Sympathetic fibres
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6
Q

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

A

Superior Rectus, Inferior Rectus, Lateral Rectus, Medial Rectus
Origin: common tendinous ring at the back of the eye
Insertion: 5 mm behind the corneal margin (onto the sclera)

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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 this muscle?

A

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

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12
Q

Describe the innervation of this muscle.

A

Oculomotor and sympathetic to smooth muscle

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13
Q

Describe the isolated muscle action of the oblique muscles.

A

Superior oblique = depresses AND abducts

Inferior oblique = elevates AND abducts

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14
Q

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

A

Superior rectus = elevates AND adducts

Inferior rectus = depresses AND 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 the patient abduct their eye and then elevate it
Inferior rectus = make the patient abduct their eye and 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 the patient adduct their eye and then depress it
Inferior oblique = make the patient adduct their eye and 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 and LPS
Parasympathetic fibres
The oculomotor nerve has two 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

Cavernous sinus

21
Q

Which of the nerves passing through the cavernous sinus, passesthrough the middle of it rather than passing through the walls?

A

Abducens (CN 6)

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 ganglioninvolved 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 SIX branches of the ophthalmic artery?

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

Name the two ophthalmic veins and state where they drain.

A

Superior ophthalmic vein = cavernous sinus

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 and, finally, lacrimal nerves

30
Q

Where do the tears initially drain?

A

Lacrimal Sac

31
Q

Via which duct do the tears then drain 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

Y2 LCRS 2 - HNS Anatomy (6 decks)

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