Head and Neck: Orbit Flashcards Preview

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Flashcards in Head and Neck: Orbit Deck (33):
1

Orbit bounded anteriorly by what?

Eyelids

2

What two things protect the cornea/eyeball?

Eyelids + tears

3

What are the eyelids made of?

Tarsal plates; kind of cartilaginous

4

Describe the composition of the eyelid

Tarsal plate sandwiched between skin and muscle (orbicularis oculi (palpebral portion)) anteriorly and conjunctiva posteriorly

5

Name the muscles associated with eyelid?

Orbicularis oculi (palpebral part)
Levator palpebrae superioris
Superior tarsal muscle (smooth muscle)***-> sympathetic innervation

6

Peri-orbital ecchymosis

extravasation of blood into subcutaneous tissue and skin of eyelids

7

What structure produces tears?

Lacrimal gland

8

Describe the path of flow of tears.

Lacrimal gland -> across eye from lateral to medial -> into sup/inf puncta -> canaliculi -> lacrimal sac -> nasolacrimal duct into INFERIOR NASAL MEATUS

9

Where does the nasolacrimal duct drain?

Inferior Nasal Meatus

10

Where is the lacrimal gland positoned?

Laterally amidst the tendon of levator palpebrae superioris

11

Orbicularis oculi innervation

Facial N. (CNVII)

12

Levator palpebrae superioris innervation

Oculomotor N. (CNIII)

13

Lacrimal gland innervation

CN VII -> greater petrosal nerve -> nerve of pterygoid canal -> pterygopalatine ganglion -> CNVb and CNVa

14

Sympathetic innervation

Not of lacrimal gland per se but of vasculature;

Ascends via IC plexus and becomes the DEEP PETROSAL N. and joins parasympathetics to become nerve of pterygoid canal

15

Sensation of upper eyelid

GSA: supratrochlear n
supraorbital n.
lacrimal n.

All branches of CNV1

16

Sensation of lower eyelid

GSA: infraorbital n. -> palpebral branch

Branch of CNV2

17

Corneal blink reflex afferent limb

V1 from cornea via long and short ciliary nerves -> branches of CNV1

18

Corneal blink reflex efferent limb

CNVII to orbicularis oculi

19

Bones of the orbit (7)

Frontal, Zygomatic, Maxillary, Lacrimal, Ethmoid, Sphenoid and Palatine

20

What are the openings of the orbit?

Superior orbital fissure
Inferior orbital fissure
Optic canal

21

Contents of optic canal

Optic nerve = CNII and Opthalmic artery (off of ICA)

22

Wall between orbit and ethmoidal air cells/sinus?

Lamina papyracea

23

Contents of superior orbital fissure

CN III, CNIV and CNVI
CNV1 (NFL)
Opthalmic vein

24

Contents of inferior orbital fissure

CNV2 - infraorbital branch

25

Blowout fracture

fracture of orbital walls

26

Where does the opthalmic vein drain into?

Cavernous sinus but also connects to facial vein so drainage in multiple directions possible

27

What structures located in cavernous sinus?

CN III, IV and VI

+ V1 and V2 and ICA

28

Accommodation of the lens

CN III -> parasympathetic stimulation of smooth muscle in ciliary body

29

Pupil constriction

Parasympathetic innervation to sphincter pupillae muscle

30

Pupil dilation

Sympathetic innervation to dilator pupillae muscle

31

Elevation of eyelid (involuntary)

Sympathetic innervation to superior tarsal muscle of eyelid

32

Parasympathetics route to eye

Oculomotor/CNIII to ciliary ganglion -> CNV1 short ciliary nerves to globe

33

Sympathetics route to eye

Internal carotid plexus and then long ciliary nerve carries it to the globe