anatomy Flashcards
what are some anatomical features of the orbit?
supraorbital notch / foramen
orbital plate of ethmoid
infraorbital foramen
superior orbital fissure
optic canal
orbital plate of frontal
which bones make up the orbit?
frontal
zygomatic
maxilla
palentine
sphenoid
ethmoid
lacrimal
what shape is the orbit?
pyramidal
the base is located anteriorly
and the apex is located at the optic canal
which way does the orbit face?
anterolaterally
which bones in the orbit are susceptible to fracture?
orbital plate of ethmoid and maxilla
what is the most external structure of the eyelid?
orbicularis oculi muscle
what is the orbicularis made up of?
the orbital part- responsible for tight squeezing shut of eyes
the palpebral part- responsible for gentle closing of eyelid
what nerve innervates the orbicularis oculi?
CN VII
what helps prevent spread of infection between the deep and superficial eyelid?
the orbital septum
what makes up the deeper eyelid?
lateral palpebral ligament
superior tarsus
inferior tarsus
medial palpebral ligament
tendon of LPS
what kind of muscle is tenon of levator palpebrae superiorus?
skeletal mainly
bit of smooth (superior tarsus muscle/ muellers muscle)- sympathetic innervation
what do tarsal glands secrete?
lipids
where is the lacrimal gland found?
superiolaterally
which nerve innervates production of lacrimal fluid?
CN VII (parasympathetic)
what is the route of lacrimal fluid?
- wash over eye
- pushed towards medial angle
- drains through lacrimal puncta
- eventually reaches inferior meatus
name the seven extraocular skeletal muscles?
superior rectus
inferior rectus
medial rectus
lateral rectus
superior oblique
inferior oblique
LPS
what are the attachments for the rectus muscles?
- all originate from common tendinous ring
- all insert onto sclera
what are the attachments for oblique muscles?
superior oblique
- originates from sphenoid bone
inferior oblique
- originates from orbital plate of maxilla
both insert onto sclera
what is the attachment for LPS?
originates from lesser wing of sphenoid
inserts onto skin and tarsus of superior
eyelid
what is the innervation for extraocular muscles?
LR6 SO4 AO3
lateral rectus CN VI (abducent nerve)
Superior oblique CN IV (trochlear nerve)
All others CN III (oculomotor nerve)
what are the features of the fibrous layer of the eye?
outer layer
2 parts
:sclera – muscle attachment
:cornea – 2/3 of refractive power
what are the features of the uvea (vascular layer) of the eye?
middle layer
3 parts
:iris – pupil diameter
:ciliary body – controls iris, shape of lens and secretion of aqueous humour
:choroid – nutrition and gas exchange
what are the features of the retinal (photosensitive) layer of the eye?
inner area with many parts
what are the features of the anterior segment of the eye?
in front of lens (cornea to iris)
has an anterior chamber and a posterior chamber (iris to vitreous body)
contains aqueous humour
what are the features of the posterior segment of the eye?
behind lens
2/3rds of eye
contains vitreous body which contains vitreous humour
which structure of the eye is completely avascular?
cornea
what is the pathway of circulation of aqueous humour?
Ciliary body
-smooth muscle and blood vessels
-ciliary processes secrete aqueous
- Aqueous circulates
-within posterior chamber
-nourishes lens - Aqueous then passes through pupil
-into anterior chamber
-nourishes cornea - Aqueous reabsorbed
-into scleral venous sinus (Canal of Schlemm)
-at iridocorneal angle
what can cause ischaemia of the retina and glaucoma?
raised intra ocular pressure
which sinus does the internal carotid pass through?
cavernous artery