Head and Neck: Orbit

Question 1

Orbit bounded anteriorly by what?

Answer 1

Eyelids

Question 2

What two things protect the cornea/eyeball?

Answer 2

Eyelids + tears

Question 3

What are the eyelids made of?

Answer 3

Tarsal plates; kind of cartilaginous

Question 4

Describe the composition of the eyelid

Answer 4

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

Question 5

Name the muscles associated with eyelid?

Answer 5

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

Question 6

Peri-orbital ecchymosis

Answer 6

extravasation of blood into subcutaneous tissue and skin of eyelids

Question 7

What structure produces tears?

Answer 7

Lacrimal gland

Question 8

Describe the path of flow of tears.

Answer 8

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

Question 9

Where does the nasolacrimal duct drain?

Answer 9

Inferior Nasal Meatus

Question 10

Where is the lacrimal gland positoned?

Answer 10

Laterally amidst the tendon of levator palpebrae superioris

Question 11

Orbicularis oculi innervation

Answer 11

Facial N. (CNVII)

Question 12

Levator palpebrae superioris innervation

Answer 12

Oculomotor N. (CNIII)

Question 13

Lacrimal gland innervation

Answer 13

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

Question 14

Sympathetic innervation

Answer 14

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

Question 15

Sensation of upper eyelid

Answer 15

GSA: supratrochlear n
supraorbital n.
lacrimal n.

All branches of CNV1

Question 16

Sensation of lower eyelid

Answer 16

GSA: infraorbital n. -> palpebral branch

Branch of CNV2

Question 17

Corneal blink reflex afferent limb

Answer 17

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

Question 18

Corneal blink reflex efferent limb

Answer 18

CNVII to orbicularis oculi

Question 19

Bones of the orbit (7)

Answer 19

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

Question 20

What are the openings of the orbit?

Answer 20

Superior orbital fissure
Inferior orbital fissure
Optic canal

Question 21

Contents of optic canal

Answer 21

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

Question 22

Wall between orbit and ethmoidal air cells/sinus?

Answer 22

Lamina papyracea

Question 23

Contents of superior orbital fissure

Answer 23

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

Question 24

Contents of inferior orbital fissure

Answer 24

CNV2 - infraorbital branch

Question 25

Blowout fracture

Answer 25

fracture of orbital walls

Question 26

Where does the opthalmic vein drain into?

Answer 26

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

Question 27

What structures located in cavernous sinus?

Answer 27

CN III, IV and VI

+ V1 and V2 and ICA

Question 28

Accommodation of the lens

Answer 28

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

Question 29

Pupil constriction

Answer 29

Parasympathetic innervation to sphincter pupillae muscle

Question 30

Pupil dilation

Answer 30

Sympathetic innervation to dilator pupillae muscle

Question 31

Elevation of eyelid (involuntary)

Answer 31

Sympathetic innervation to superior tarsal muscle of eyelid

Question 32

Parasympathetics route to eye

Answer 32

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

Question 33

Sympathetics route to eye

Answer 33

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