Lecture 9- The Orbit Flashcards
What is the name for the small reddish body containing modified sebaceous and sweat glands at the medial corner of the eye?
Lacrimal canuncle
What is the only eyelid muscle that is not under conscious control?
superior tarsal muscle
What is the name for the opening of the lacrimal canal to which tears drain from the eye?
lacrimal puncta
What is the name for the swelling/projection on the eyelid near the lacrimal puncta?
Lacrimal papilla
What is the white part of the eye called?
sclera
What is the opening between the eyelids called?
palpebral fissure
What prevents the eyelids from sticking together?
tarsal glands-produce fluid
tarsal plates contain glands
Which direction do tears move across the eye?
lateral to medial
Name the four structures that tears pass through after they leave the lacrimal gland and travel across the eye?
- drain into superior & inferior lacrimal puncta
- into the superior & inferior lacrimal caniculi
- into the lacrimal sac
- into nasolactrimal duct
lacrimal puncta->lacrimal canicula->lacrimal sac-> nasolacrimal sac
What muscle divides the lacrimal gland and thus movement of this muscle “milks” the lacrimal gland?
levator palpebrae superioris
Name two ways that tear release is triggered from the lacrimal gland.
parasympathic innervation
milking by the tendon of the levator palpebrae superioris muscle
Which nerve moderates tear production?
facial nerve (CN VII)
Describe the pathway of the parasympathetic fibers to the lacrimal gland.
presynaptic fibers from greater petrosal nerve (VII)
become nerve to pterygoid canal
synapse in pterygopalatine ganglion
postsynaptic fibers run with branches of V (zygomatic->zygomaticotemporal->lacrimal)
Where do parasympathetic of the lacrimal gland synapse?
pterygopalatine ganglion
How does paralysis of CN VII affect the eyes?
inability of blinking
What nerve controls levator palpebrae superioris?
oculomotor (CN III)
What does damage to CN III cause?
ptosis
What is the function of the superior tarsal muscle? How is it controlled?
elevates eyelid during sympathetic response
sympathetics
Which nerves control the corneal (blink) reflex?
afferent- long & short ciliary (V1)
efferent- VII to orbicularis oculi
What is the purpose of the corneal (blink) reflex?
prevent cornea from drying out
contact with foreign objects
Name the 7 bones that make up the orbit.
Frontal Zygomatic Maxilla Sphenoid Ethmoid Lacrimal Palatine
What is the name of the membrane that surrounds the inner surface of the orbit?
periorbita
Name the 7 muscles that move the eye or eyelid.
Levator palpebrae superioris Superior rectus Inferior rectus Lateral rectus Medial rectus Superior oblique Inferior oblique
Which muscle abducts the eye?
Lateral rectus
Which muscle is innervated by the abducens nerve?
Lateral rectus (CN VI)
Which muscle is innervated by the trochlear nerve (CN IV)?
Superior oblique muscle
Which muscle opens the eye?
levator palpebrae superioris
Which nerve controls opening of the eye?
oculomotor nerve (CN III)- levator palpebrae superioris
What is the name for the clinical test used to test individual eye muscles?
H Test
What is diploblia?
double vision
What muscle is being tested when looking “laterally and upward”?
superior rectus
What muscle is being tested when looking “laterally and downward”?
inferior rectus
What muscle is being tested when looking “laterally”?
lateral rectus
What muscle is being tested when looking “medially”?
medial rectus
What muscle is being tested when looking “medially and upward”?
inferior oblique
What muscle is being tested when looking “medially and downward”?
superior oblique
What are the 4 functions of the eye that are mediated by autonomics?
Accomodation
Constriction of pupil
Dilation of pupil
Involuntary elevation of eyelid
What muscle controls accommodation (focusing)?
ciliary muscle
What nerves control accommodation?
parasympathetic short ciliary nerves (V1) from ciliary ganglion (fibers originated in oculomotor III)
What type of innervation controls constriction of the pupil?
parasympathetic
What type of innervation controls dilation of the pupil?
sympathetic
Which muscle causes involuntary elevation of the eyelid?
superior tarsal muscle (sysmpathetics)
What is the colored part of the eye called?
iris
What is the transparent covering over the iris?
cornea
What is miosis?
maximum constriction
What is mydriasis?
maximum dilation
What is Horner’s Syndrome?
compression of the sympathetic trunk
How does Horner’s Syndrome affect the eye?
miosis (constriction)
What are four causes of miosis?
light
fatigue
horner’s syndrome
morphine
What are four causes of mydriasis?
dark
excitement, pain
oculomotor palsy
migraine
Where do the sympathetic fibers to the eye synapse?
superior cervical ganglion
Where do the parasympathetic fibers in the orbit originate from?
oculomotor (synapse in ciliary ganglion and travel with short ciliary of V1 to eye muscles)
What are 3 symptoms of Horner’s Syndrome?
ptosis of eyelids
Miosis of pupil
anhydrosis (lack of sweating)
Which muscle of the eye has lost function in Horner’s Syndrome?
Superior tarsal muscle
Name 5 nerve branches that travel in the cavernous sinus.
III IV V1 V2 VI
What are 5 symptoms of cavernous sinus thrombosis.
- Bulging eyeballs
- Cannot move eye in certain direction
- Drooping eyelids
- Headaches
- Vision loss
