Session 6: Anatomy of the Orbit Flashcards Preview

Y2 HNS Anatomy (LCRS2) > Session 6: Anatomy of the Orbit > Flashcards

Flashcards in Session 6: Anatomy of the Orbit Deck (39)
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1

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

Roof – orbital plate of frontal bone

Floor – orbital plate of maxillary bone

Lateral wall – greater wing of the sphenoid bone + zygomatic bone

2

Which bones make up the medial wall of the orbit?

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

3

Which structures pass through the optic canal?

Optic nerve Ophthalmic artery

4

Which structures pass through the inferior orbital fissure?

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

5

Which structures pass through the superior orbital fissure?

Oculomotor Trochlear Ophthalmic division (V1) of trigeminal Abducens Ophthalmic veins (superior and inferior) Sympathetic fibres

6

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

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)

7

State the innervation of the 6 extrinsic eye muscles?

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

8

State the origin and insertion of the inferior oblique.

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

9

State the origin and insertion of the superior oblique.

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

10

Which muscle is responsible for elevating the eyelid?

Levator palpebrae superioris

11

Where is the origin and insertion of the muscle responsible for elevating the eyelid?

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

12

Describe the innervation of the muscle responsible for elevating the eyelid?

Oculomotor and sympathetic to smooth muscle

13

Describe the isolated muscle action of the oblique muscles.

Superior oblique = depresses AND abducts Inferior oblique = elevates AND abducts

14

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

Superior rectus = elevates AND adducts Inferior rectus = depresses AND adducts

15

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

Superior rectus = make the patient abduct their eye and then elevate it

Inferior rectus = make the patient abduct their eye and then depress it

16

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

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

Which nerve axons make up the optic nerve?

Retinal ganglion cell axons

18

What types of fibres are found within the oculomotor nerve?

Motor fibres to MR, SR, IR, IO and LPS Parasympathetic fibres The oculomotor nerve has two rami

19

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

Lacrimal Nasociliary Frontal – this is the largest

20

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

Cavernous sinus

21

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

Abducens (CN 6)

22

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

Lacrimal – no branches

Nasociliary -  Branch to ciliary ganglion, Ethmoidal, Infratrochlear

Frontal  - Supratrochlear, Supraorbital

23

What limb of the autonomic nervous system is the ciliary ganglioninvolved in?

PARASYMPATHETIC

24

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

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

What do the fibres leaving the ciliary ganglion innervate?

Sphincter pupillae Ciliary muscle

26

What are the SIX branches of the ophthalmic artery?

◦central artery of the retina

◦muscular branches

◦ciliary

◦lacrimal

◦supratrochlear

◦supraorbital

27

Name the two ophthalmic veins and state where they drain.

Superior ophthalmic vein = cavernous sinus Inferior ophthalmic vein = pterygoid plexus

28

Describe the location of the lacrimal glands.

Anterolateral superior orbit

29

Describe the innervation of the lacrimal glands.

parasympathetic secretomotor fibres (from CNVII) from pterygopalatine ganglion via zygomaticotemporal and lacrimal nerves    

30

Where do the tears initially drain?

Lacrimal Sac

31

Via which duct do the tears then drain and where does this duct empty?

Nasolacrimal duct – empties into the inferior nasal meatus

32

What is the corneal reflex?

Stimulation of the cornea causes involuntary blinking in both eyes

33

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

It is caused by a disorder of the sympathetic nerves in the brainstem or cervical region

Presents as:

Ptosis (drooping upper eyelid)

Miosis (pupil constriction)

Anhydrosis (lack of sweating around the eye)

34

Where does the nasolacrimal duct drain?

Inferior nasal meatus

35

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

Strabismus

36

What are the different types of strabismus?

Hypotropia – one eye turns down

Hypertropia – one eye turns up

Exotropia – one eye turns out

Esotropia – one eye turns in

37

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