Anatomy Flashcards
What is telecanthus?
increased distance between the medial canthi of the eyelids.
What is phthiriasis palprebrarum?
infection of the eyelashes caused by pthiriasis pubis
A lesion on the eyelid has telangiectasia, what is it?
BCC
What is the thinnest layer of skin in the body?
eyelid
does the eyelid skin contain fat?
no
What are the layers of the eyelid?
- skin
- subcutaneous areolar
- orbicularis
- sub muscular areolar
- orbital septum
- posterior muscular system
- tarsal plate
- palpebral conj
What is the subcutaneous areolar layer? What does it contain?
loose connective tissue
The upper lid’s subcutaneous areolar layer contains the levator aponeurosis as it travels to inset into the tarsal plate and skin
what is another name for muscle of riolan?
pars ciliaris
What causes paralysis of the orbicularis muscle? Why does this happen? What is the result?
- Bell’s palsy
- sarcoid
orbicularis is innervated by zygomatic branch of CN 7 (voluntary motor), paralysis causes it to loose its laxity leading to ectropion
What is the main cause of Bell’s palsy? what do patient’s normally complain of?
idiopathic
extropion, tearing, exposure keratopathy
what is another name for Horner’s?
pars lacrimalis
What is the function of Horner’s muscle?
pump tears
What receptors are on muellers?
alpha-2- receptors
= sympathetic receptors
what receptors are located on the dilator?
alpha-1-receptors
What drug works on alpha 2 receptors and what drug works on alpha 1 receptors?
alpha -2 receptors: upneeq = agonist
alpha -1- receptors: phenylephrine
What is located in the sub muscular areolar layer?
levator aponeurosis + the palpebral part of the lacrimal gland + peripheral & marginal arcades
What is the function of the orbital septum?
barrier to the orbit, prevents fat from falling onto the lid margins and keeps infections localized to anterior part of the eyelid
what is the orbital septum/ where is it attached?
Periorbita - part that covers bones projects forward and becomes the septum. It also moves backwards and fuses with the dura
mater of the ONH.
ie. the orbital septum is continuous with the periorbita and the periosteum of the skull.
medially it attaches to the posterior lacrimal crest
superiorly, it is an insertion point for the levator aponeurosis
where does the levator originate?
lesser wing of the sphenoid
What does the posterior muscular system contain?
LPS, superior(Mueller’s) and inferior tarsal muscle
What is mueller’s muscle
superior tarsal muscle. It originates from Mueller’s and goes into the tarsal plate
In TED, what causes the stare appearance?
retraction of Mueller’s
What is the normal interpalprebral fissure distance?
10-12 mm
What is the function of the tarsal plate? what is it made of? what condition occurs if the tarsal plate is not working?
rigidity to the eyelids
connective tissue
floppy eyelid syndrome
what is in the palpebral portion of the conj?
- epithelial layer
a. goblet cells - stroma = vascularized CT
a. immune cells, IgA, macrophage, mast, esosinophils, PMNs
b. accessory lacrimal glands - glands of wolfing
what is the function of goblet cells? where are they found?
make mucin
inferior nasal fornix and bulbar conj
What condition/ drug affects meibomian glands?
accutane ( decreases the size and oil selection leading to dry eye)
rosacea
sebaceous gland carcinoma ( seen more on the UL because contains more meibomian glands)
OIS
lack of oxygen to the carotid artery, leads to entire eyeball problem
NOTE: diff from sleep apnea!!
what is holocrine, apocrine and merocrine secretion?
holocrine: whole cell is shed into the lumen
apocrine: part of the plasma membrane buds off and enters the lumen. for secretion
merocrine: cells secrete substances via exocytosis. The cells are intact
what are the sensory nerves of the eyelids?
upper eyelid - frontal (supraorbital/supratrochlear) and lacrimal branches of V1
lower eyelid: infraorbital and zygomaticofacial branches of V2
infratrochlear nerve (branch of the nasocilliary nerve - branch of V1) innervates medical aspect of the upper and lower eyelids
blood supply of the eye - CRA, PCA, ACA
ICA -> ophthalmic artery -> CL MS LSE
CRA-> supplies ON from point to entry to the inner retinal layers
PCA -> SPCA & LPCA
- SPCA piece the ONH around it and then travel in the suprachoridal space (between Choroid & sclera)
-anastomose in the sclera and make the circle of zin - haller (supplies laminar part of the ON)
- supply the choroid up to the equator
- supply the sclera
- LPCA travel in the suprachoroidal space to the ciliary body
- supplies the sclera
- join with the ACA to form MACI (supplies iris and CB)
- once reaches the ORA, send recurrent branches back to supply the choroid anterior to the equator
ACA
- ICA -> Ophthalmic -> muscular (7) supplies the recti muscles ( LR only one with 1) -> become the ACA (which start after muscles are supplied by muscular artery till past the recti muscles) -> bifurcate (some go under the bulbar conj) or some piece the sclera and join the LPCA to make MACI )
- note: before making MACI, recurrent branches are sent off to supply the choroid anterior to the equator
blood supply of the eye - lacrimal artery
Ophthalmic -> lacrimal artery
- supplies the lacrimal gland -> then pierces the orbital septum and terminates as the lateral palpebral arteries (2) .
These supple the skin & conj of the lateral 1/2 of the upper and lower eyelids
blood supply of the eye - supraorbital artery
passes forward above the levator palpebrae superiors and supplies the (LPS, SR, SO)
exits orbit via supraorbital foramen
supplies the skin, muscles of the forehead and scalp
joins with the superficial temporal and supratrochlear arteries in the scalp
medial palpebral artery
branch off of the ophthalmic artery
supply: the medial 1/2 of the upper and lower eyelids and conj.
palpebral arcades
made from the joining of the medial and lateral palpebral arteries.
marginal palpebral arcades - closer to the eyelid
peripheral palpebral arcades - supply formic, posterior conj. also join with the ACA to supply anterior conj
facial artery
branches off of the ECA prices circulation to the superficial areas of the eyelid
Why do patient’s with uveitis experience circumlimbal injection and decreased aqueous humor production?
because the ACA provide circulation to the bulbar conj and the CB
lymph nodes
both mimic the veins which mimic the arteries
located in the conj
lateral lymphatics drain into the parotid/pre-auricular lymph node
medial lymphatic drain into the submandibular lymph node
what causes a swollen lymph node?
PET PIG
P - parunauds oculoglandular syndrome
E - EKC (#1 reason)
T - trachoma
P - pubic lice
I - inclusion conjunctivitis
G - gonorrhea
does bacterial conjunctivitis cause pre-auricular lymphadenopathy?
NOOO
What prevents back flow from the lacrimal sac onto the eye?
valve of reosenmueller
what events nasal fluid to back flow back into the eye?
valve of hasher
what bone is the lacrimal gland located in?
frontal bone
how does the lacrimal gland produce tears?
via parasympathetic innervation from
CN 7-> Vivian nerve -> pterygopalatine Ganglion -> lacrimal gland
what is another name for the pterygopalatine ganglion?
sphenopalatine gagnolino
What is the lacrimal papilla?
puncta îs located here and keeps the puncta open
What is the spiral of tillaux? What does this mean for the muscles?
the recti muscles insertion in the orbit form this
the closer the limbus the muscles attaches, the stronger its pull
Where does the medial rectus insert?
5.5 mm from the limbus
ie. this is the longest
Where does the lateral rectus insert?
6.9 mm from the limbus
Where does the inferior rectus insert?
6.5 mm from the limbus
Where does the inferior rectus insert?
6.5 mm from the limbus
Where does the SR muscle insert? How is it related to the LPS?
7.7 mm from the ring. This is the shortest
sheath covering SR is connected to sheath covering LPS and the superior conj fornix. Why eyelid retracts when looking up
EOMs compared to other muscles in our body
more blood and nerves
faster and more fatigue resistant
Adipose tissue compartments in the orbit
intraconal - ie. in the muscle cone of the 4 recti muscles (separates recti muscles from the ON)
extraconal - b/w the EOMs and wall
what recti originate from the dural sheath surrounding the ONH?
SR and MR
this is why during optic neuritis (inflammatory response against the optic nerve’s myelin) we get pain on eye movement due to the pulling of these muscles on the ON’s inflamed coverings
What in the origin and insertion for the superior oblique?
origin: lesser wing of the sphenoid . Note moves forward and goes through the troche before inserting on the superior lateral globe behind the equator
what is the trochlea?
physiologic origin of the SO
What in the origin and insertion for the inferior oblique?
ordinates anteriorly at the maxillary bone and inserts on the inferior lateral globe behind the equator
how much can the eye abduct and adduct?
adduct 51-54 degrees
abduc 23 degrees
when the eye is adducted , what are the muscles used for depression and elevation?
what about when the eye is abduct?
adduct: SO and IO
abduct: SR and IR
Versions follow which law?
hering’s law for yolked muscles
What inhibits versions?
trauma
INO
what is INO and what causes it?
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