The Orbit Flashcards
What is the roof, medial wall, lateral wall, and floor of the orbit?
roof: frontal bone, lesser wing of sphenoid
medial wall: ethmoid, lacrimal, maxilla
lateral wall: zygomatic, greater wing of sphenoid
floor: mxilla, zygomatic, palatine
The lacrimal groove is an important landmark in the orbit. What is it between and what does it hold?
between the lacrimal and maxillary bones; lacrimal sac
The optic canal is an important landmark in the orbit. Where at in the orbit is it located and what does it transmit?
at the apex, in the lesser wing of sphenoid; transmits optic nerve and ophthalmic artery
In regards to the composition of the eyelids, a thin palpebral part of the ___ ___ lies anterior to the tarsi and is separated from the skin by a thin layer of loose CT
orbicularis occuli
In regards to the composition of the eyelids, a “skeleton” of the eyelids is formed by dense CT plates known as the superior and inferior ___ for the upper and lower lids respectively
tarsus
In regards to the composition of the eyelids, the ___ glands are embedded in the tarsi, with openings in the margins of the eyelids.
tarsal
What do the tarsal glands secrete?
an oily substance that prevents overflow of tears in normal production
In regards to the composition of the eyelids, the ___ ___ ligament connects the tarsi to the medial margin of the orbit and is the origin for the orbicularis occuli. The ____ ____ ligament connects the tarsi to the lateral margin of the orbit
medial palpebral; lateral palpebral
In regards to the composition of the eyelids, an orbital ____ is continuous with the periosteum and at the level of the orbital margin, extends into the eyelids and fuses with the tarsi
septum
In regards to the composition of the eyelids, the aponeurosis of the ___ ____ ____ attaches to the superior tarsus. Smooth muscle fibers froming the ___ ___ muscle also inserts here. These muscles elevate the eyelid.
levator palpebrae superioris; superior tarsal
The ____ lines the inner surface of the eyelids
conjunctiva
Sebaceous and sweat glands present in the eyelids have openings by the ____
eyelashes
Eyelashes are arranged in 2-3 rows at the free margin of the eyelid from the ___ ____ to the level of the ____ ____. Just medial to this site in the lid margin is the lacrimal ____
lateral canthus; plica semilunaris; papilla
What is the basic structure of the eyelids?
skin, SC tissue, striated muscle, tarsus and orbital septum, smooth muscle, and conjunctiva
The lacrimal gland is situated in the ____ part of the ____ part of the orbit
anterior; superolateral
There are numerous ducts that drain the lacrimal gland, opening into the lateral part of the ____ ____
superior fornix
The tear collects ____ in the lacrimal lake. The lacrimal lake contains an elevated mucosal site called the lacrimal ____ and a vertical fold of conjunctiva, the semilunar fold
medially; caruncle
Tears then flow into the lacrimal ___ of the upper and lower eyelids via their openings, the lacrimal ___.
canaliculi; puncta
The lacrimal puncta are on the elevations known as lacrimal ____, located just medial to the eyelashes
papillae
The lacrimal canaliculi empty into the lacrimal ____ located in the lacrimal groove adjacent to the nose
sac
The lacrimal sac continues inferiorly as the _____ duct that empties into the nasal cavity, guarded by a valve
nasolacrimal
The lacrimal gland receives sensory from the ____ nerve, a branch of the ophthalmic nerve (V1)
lacrimal
The lacrimal gland receives parasympathetic innervation by preganglionic fibers from the ____ nerve synapsing the ____ ganglion.
facial (greater petrosal nerve); pterygopalatine
Postganglionic axons travel ____ then ___ to reach the lacrimal gland
V2; V1
Sympathetic innervation of the lacrimal gland is via postganglionic axons from the ___ ____ ganglion -> deep petrosal nerve + great petrosal nerve = the nerve of the ___ ___ and reach the pterygopalatine ganglion in the pterygopalatine fossa
superior cervical; pterygoid canal
The outer, white, fibrous layer of the globe of the eyeball is the ____.
sclera
The ___ of the eyeball is avascular and is highly sensitive to touch, while the ___ is the site of attachment to extrinsic muscles and is pierced by vessels and nerve
cornea; sclera
The middle, vascular layer of the eyeball (urea) has 3 parts. What are they?
the choroid, ciliary body, and iris
This is the largest part of the vascular layer of the eyeball. It provides the inner retinal layer with an oxygen supply and nutrients
choroid
This is the anterior continuation of the choroid, forming a ring-like thickening that contains muscles as we’ll as vessels, and connects to the iris.
ciliary body
Folds of tissue project from the inner surface of the ciliary body forming ciliary processes that are attachment sites for the ___ via ___ fibers that form the suspensory ligament of the lens, and also secrete aqueous humor
lens; zonular
The ___ projects from the ciliary body as a circular aperture that lies on the anterior surface of the lens. It is the site for color of the eyes and contains muscle fibers that can either increase or decrease the pupil.
iris
Muscle fibers arranged in a circular pattern in the iris form the ___ ____ and are innervated by parasympathetic fibers. Muscle fibers arranged radially form the ____ ___ which is innervated by sympathetic fibers
sphincter pupillae; dilator pupillae
The inner layer of the eyeball is the ___ which consists of a large posterolateral optic part and a smaller anterior non-visual part. The two parts are continuous as a jagged line, the ora serrata.
retina
This part of the retina is sensitive to light and has two layers: an outer pigmented layer attached to the choroid and an inner neural layer attached to the pigmented layer only at the optic nerve and ora serrata
optic part
What occurs in the condition known as detached retina?
the inner neural layer separates from the pigment layer
The posterior part of the optic part of the retina contains the ___ ___ where the optic nerve leaves which is also the site of the branching of the ___ artery of the retina
optic disc; central
The highest visual sensitivity of the retina is at the ___ ___ with the ___ ___, located lateral to the disc
macula lutea; fovea centralis
The non-visual part of the retina covers what?
the inner surface of the ciliary body and iris
This is the space between the cornea and iris, and is filled with aqueous humor
anterior chamber
This is the space between the posterior surface of the iris and the anterior surface of the lens and also contains aqueous humor
posterior chamber
Aqueous humor is produced in the ____ chamber by the ___ ___
posterior; ciliary processes
After starting in the posterior chamber, where does aqueous humor flow?
through the pupil into the anterior chamber where it is taken up by the scleral venous sinus at the iridiocoroneal angle
Reduced uptake of aqueous humor leads to increased intraocular pressure. This condition is known as what?
glaucoma
The vetoer body (humor) is permanent and is traversed by the ____ canal, the remnant of an embryonic blood vessel that nourished the lens
hyaloids
The ___ is a transparent biconvex structure that is highly elastic
lens
Opacity of the lens is referred to as a ____
cataract
The fascial sheath of the eyeball forms a socket for the eyeball, separating it from ___ and attaching it to the ___
fat; sclera
Medial and lateral expansions of the sheath of the eyeball form medial and lateral ___ ligaments that limit abduction and adduction of the eyeball.
check
The blending of the check ligaments inferiorly with muscle coverings forms the ___ ligament of the eyeball
suspensory
The apex of the orbit points ____
posteriorly
The medial walls of the orbits are ___, lateral walls are at approximately ____ degrees
parallel; 90
____ muscles are involved with movements of the eyeball. ____ muscles control the shape of the lens and size of the pupil
extrinsic; intrinsic
What is the action, origin, insertion, and innervation of orbicular occuli?
action: palpebral portion closes eyelids gently (sleep and blinking)
origin: medial palpebral ligament
insertion: superior and inferior tarsus
innervation: facial nerve
What is the action, origin, insertion, and innervation of levator palpebrae superioris?
action: raises upper eyelid
origin: lesser wing of sphenoid
insertion: superior tarsus, and skin of the upper eyelid
innervation: occulomotor nerve and inferior lamella
What is the innervation of the superior tarsal muscle (smooth muscle)?
superior cervical ganglion (sympathetic)
What is the action and innervation of superior rectus?
action: elevates, adducts, intort eyeball
innervation: occulomotor (sup. branch)
What is the action and innervation of inferior rectus?
action: depresses, adducts, extorts eyeball
innervation: occulomotor (inf. branch)
What is the action and innervation of medial rectus?
action: adduction of eyeball
innervation: occulomotor (inf. branch)
What is the action and innervation of lateral rectus?
action: abducts eyeball
innervation: abducens nerve
The superior oblique arises from the sphenoid and reaches the ____
trochlea (attached to frontal bone)
What is the action and innervation of superior oblique?
action: intorsion, depress, and abduct eyeball
innervation: trochlear nerve
note: SOLID = Supeior Oblique Lateral movement (abduction) Intorsion Depression
The inferior oblique is the only extrinsic eye muscle that does not arise from the ___ part of the orbit.
posterior
note: its origin is from the medial side of the floor of the orbit, the orbital surface of the maxilla just lateral to the nasolacrimal groove. It inserts just inferior to the lateral rectus
What is the action and insertion of the inferior oblique?
action: extorsion, elevates, abducts eyeball
inervaiton: occulomotor (inf. branch)
For each of the following nerves, give the movements or actions that indicate a clinical issue
occulomotor
trochlear
abducens
occulomotor: down and out, ptosis, pupil dilation
trochlear: down and in
abducens: inability to abduct the eye
The ophthalmic artery is a branch of the ___ that enters the orbit though the optic canal.
ICA
This branch of the ophthalmic artery travels with the optic nerve to the retina
central artery of the retina
This branch of the ophthalmic artery supplies the lacrimal gland, lateral sides of the eyelids, and zygomatic branches
lacrimal
This branch of the ophthalmic artery travels through the supraorbital notch to the forehead and scalp to vertex
supraorbital
This branch of the ophthalmic artery supplies ethmoidal air cells and superior nasal cavity
posterior ethmoidal
This branch of the ophthalmic artery gives off anterior meningeal; then supplies nasal cavity including nasal septum and lateral wall. It ends as the lateral nasal artery.
anterior ethmoidal
This branch of the ophthalmic artery supplies the forehead and is one of two terminal branches
supratrochlear
This branch of the ophthalmic artery supplies the upper surface of the nose and is one of the two terminal branches
dorsal nasal
This branch of the ophthalmic artery becomes the anterior ciliary artery
muscular to intrinsic muscles
This branch of the ophthalmic artery supplies the medial area of the upper and lower eyelid including the nasolacrimal duct
medial palpebral
The superior and inferior ophthalmic veins drain into the ___ sinus
cavernous
The superior ophthalmic vein communicates with ____ and ___ veins (triangle of danger)
supraorbital; angular
The inferior ophthalmic vein communicates with the ____ plexus of veins, ____ ___ vein and the ___ sinus
pterygoid; superior ophthalmic; cavernous
The bulb of the eyeball is drained by 4 ___ veins which empty into the ophthalmic veins
vorticose
An increase in CSF pressure surrounding the optic nerve will cause what?
bulging of the optic disc
This nerve is the smallest of the cranial nerves but has the greatest intracranial length.
trochlear
The nucleus of the trochlear nerve is found where?
caudal midbrain
The trochlear nerve exits the dorsal surface of the brainstem and winds anteriorly to enter the lateral wall of the ____ sinus
cavernous
Injury of the trochlear nerve causes weakness of ____ eye movement and ___
downward (vertical diplopia); torsion (response to tilting head sideways)
The abducens nerve nucleus is located in the ___ on the floor of the ___ ventricle
pons; 4th
Aneurysms of the ICA can damage what nerve?
abducens
Abducens nerve dysfunction induces ____, a convergent squint on a distant object
esotorpia
note: patient may turn face towards side of the affected eye
The oculomotor nerve originates form the oculomotor nucleus at the level of the midbrain and form the _____-___ nucleus.
Edinger-Westphal
The oculomotor nerve carries what two types of fibers?
somatic motor and visceromotor
A branch to the ciliary ganglion carries preganglionic ____ fibers from Edinger-Westphal nucleus to the ciliary ganglion.
parasympathetic
The ciliary ganglion is located between the ____ nerve and the ____ ___ muscle
optic; lateral rectus
Horner’s syndrome is damage to the superior cervical ganglion causing a triad of problems. Name them.
ptosis - drooping of eyelid
miosis - consrticted pupil
anhydrosis - loss of hemifacial sweating
