Eye and Orbit 2 Flashcards
7 bones that make up the orbit
frontal, maxilla, zygomatic, sphenoid, ethmoid, lacrimal, palatine
why are the floor and medial wall of the orbit weaker
because there are sinuses on the other side
what sit behind the eye occupying the rest of the orbit
fat
what feature of someones eyes may suggest they are in starvation
sunken eyeballs (loss of fat behind eyes)
what disease can cause hypertrophy of fat behind eyes
thyroid eye disease
glands at eyelashes
sebacous glands secrete oily
why is the tarsal plate needed
to prevent the eyelid from being scrunched up. palpebra and oculi would have a naturally scrunched up tone
glands within the tarsal plate
meibomian glands
structure that lies posterior to the tarsal plate
conjunctiva
3 sections of conjunctiva
palperbral, superior/inferior fornix, ocular
what structure on the front of the eye does the conjuctiva not cover and why
the cornea. conjunctiva is a very vascular membrane and vessels often leak, don’y want it affecting the quality of light passing through this transparent structure
what is the conjunctiva
a thin vascular membrane covering the inside surface of the eyelids and sclera
what does the conjunctiva look like over the sclera
transparent and containing blood vessels
where is the lacrimal gland
in the superior orbit slightly lateral and quite anterior
innervation of lacrimal gland
para-sympathetic, by facial nerve VII
course of the tears/lacrimal fluid
secreted from gland through duct into conjunctival sac where it is spread across eye surface. Collected in medial corner and drained into the lacrimal sac by superior and inferior punctae. lacrimal sac drains into nasolacrimal duct which drains into the inferior meatus
effect of blinking on lacrimal sac
orbicularis muscle pull on lacrimal sac opening it, creating a negative pressure to pull in fluid
intrinsic muscles of eye
ciliaris muscle and dilator and constrictor pupillae
innervation of ciliaris muscle and constrictor pupillae
III occulomotor (parasympathetic)
innervation of dilator pupillae
sympathetic
6 extrinsic muscles
lateral, medial, superior and inferior rectus and superior and inferior oblique
little pulley of superior oblique
trochlea
origin insertion of rectus muscle
annular fibrous ring at apex of orbit
which is the only extrinsic muscle to originate from the front of the orbit
inferior oblique
nerve supply of lateral rectus
abducent VI (as in abduct, like the action of the lateral rectus)
nerve supply of superior, inferior, medial rectus and inferior oblique
oculomotor III
nerve supply of superior oblique
trochlear IV
which are the only two extrinsic muscles not to be innervated by III oculomotor
lateral rectus and superior oblique
