Flashcards in Head and Neck: Orbit Deck (33):
Orbit bounded anteriorly by what?
What two things protect the cornea/eyeball?
Eyelids + tears
What are the eyelids made of?
Tarsal plates; kind of cartilaginous
Describe the composition of the eyelid
Tarsal plate sandwiched between skin and muscle (orbicularis oculi (palpebral portion)) anteriorly and conjunctiva posteriorly
Name the muscles associated with eyelid?
Orbicularis oculi (palpebral part)
Levator palpebrae superioris
Superior tarsal muscle (smooth muscle)***-> sympathetic innervation
extravasation of blood into subcutaneous tissue and skin of eyelids
What structure produces tears?
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
Where does the nasolacrimal duct drain?
Inferior Nasal Meatus
Where is the lacrimal gland positoned?
Laterally amidst the tendon of levator palpebrae superioris
Orbicularis oculi innervation
Facial N. (CNVII)
Levator palpebrae superioris innervation
Oculomotor N. (CNIII)
Lacrimal gland innervation
CN VII -> greater petrosal nerve -> nerve of pterygoid canal -> pterygopalatine ganglion -> CNVb and CNVa
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
Sensation of upper eyelid
GSA: supratrochlear n
All branches of CNV1
Sensation of lower eyelid
GSA: infraorbital n. -> palpebral branch
Branch of CNV2
Corneal blink reflex afferent limb
V1 from cornea via long and short ciliary nerves -> branches of CNV1
Corneal blink reflex efferent limb
CNVII to orbicularis oculi
Bones of the orbit (7)
Frontal, Zygomatic, Maxillary, Lacrimal, Ethmoid, Sphenoid and Palatine
What are the openings of the orbit?
Superior orbital fissure
Inferior orbital fissure
Contents of optic canal
Optic nerve = CNII and Opthalmic artery (off of ICA)
Wall between orbit and ethmoidal air cells/sinus?
Contents of superior orbital fissure
CN III, CNIV and CNVI
Contents of inferior orbital fissure
CNV2 - infraorbital branch
fracture of orbital walls
Where does the opthalmic vein drain into?
Cavernous sinus but also connects to facial vein so drainage in multiple directions possible
What structures located in cavernous sinus?
CN III, IV and VI
+ V1 and V2 and ICA
Accommodation of the lens
CN III -> parasympathetic stimulation of smooth muscle in ciliary body
Parasympathetic innervation to sphincter pupillae muscle
Sympathetic innervation to dilator pupillae muscle
Elevation of eyelid (involuntary)
Sympathetic innervation to superior tarsal muscle of eyelid
Parasympathetics route to eye
Oculomotor/CNIII to ciliary ganglion -> CNV1 short ciliary nerves to globe