11 Orbit Anatomy Flashcards
Avg volume of orbit
30 cm3
Avg depth of orbit
40-50 mm
Whats unique about anatomy of Asian eyelid
levator muscle lacks attachment to pretarsal skin resulting in absent pretarsal fold
What divides the lacrimal gland into 2 lobes
levator aponeurosis
What provides static support to lower lid
tarsal plate and its assoc medial and lateral canthal tendons
What provides dynamic support to lower lid
adhesion of pretarsal portion of orbicularis to tarsal plate
What structure in lower lid is analogous to levator aponeurosis of upper lid
capsulopalpebral fascia
what are the lower eyelid retractors
capsulopalpebral fascia and inferior tarsal muscle
What lines the posterior surface of eyelid
palpebral conjunctiva
what creates gray line in lid margin
muscle of riolan
what does the gray line divide
anterior and posterior lamella
What is the origin of the superior tarsal muscle (of Muller)
Deep side of the levator palpebrae superioris
What structure forms the medial canthal tendon
superficial head of the pretarsal fibers of the orbicularis oculi muscle
What are the 3 limbs of the medial canthal tendon
Superior, anterior, posterior
What limb of the medial canthal tendon covers the lacrimal fossa
superior
What is Whitnall’s tubercle
insertion site of lateral canthal tendon
Which part of lacrimal system is most vulnerable to injury
The inferior canaliculus near the medial canthal tendon
In relation to the anterior lacrimal crest, where are the anterior and posterior ethmoid arteries and the optic canal
24-12-6 rule
What does the medial epicanthal fold cover?
lacrimal lake
What is the fnc of the deep head of the orbicularis oculi?
inserts on posterior lacrimal crest and provides structural support to lid
what happens with disruption of deep head of orbicularis oculi
lateral and anterior displacement of the medial canthal angle
where does the lateral canthal tendon insert
orbital tubercle located 5 mm posterior to the lateral orbital rim
what is the fleshy pink mound of tissue in medial canthus
lacrimal caruncle
what glands are contained w/in tarsal plates
tarsal glands (meibomian)
which muscles are innervated by superior division of CN III
superior rectus and levator palpebrae superioris
which muscles are innervated by inferior division of CN III
inferior oblique, inferior rectus, medial rectus
What passes through superior orbital fissue
CN III, IV, VI, V1
Superior ophthalmic vein
what is trichiasis
abnl direction of eyelashes
what is gross asymmetry of eye mvmt
heterotropia
What is an Argyll Robertson pupil
Accomodates but doesnt react (reacts to accomodation but not light) a/w syphilis
