Orbit-Ear Flashcards
MOD3-ANAT SMU PA
What are the three parts of the ear? boundaries between them? composition and their contents
External- Boundary tympanic membrane.
Composition: Auricle- collects sound waves, cartilage
External auditory meatus- conducts sound waves to TM vibrates.
Middle - transfer acoustic air waves to fluid waves. Uses pharyngotympanic tube (audity eustachina) to talk to nasopharynx
Boundary TM, oval window
Composition: Ear ossicles: malleus, incus, stapes
Muscles: Stapedius (CNVII), Tensor Tympani (CNV3)
Nerves: Chorda tympani (CNII, Tympanic plexus CNII, IX, sympathetics)
Internal-Boundary- oval window boneorgans for hearing and balance
Cochlea- hearing
Semicircular canals- balance
Vestibule- oval window, works w/ cochlea and semicircular canals
What are the bones that contribute to the formation of the orbit and what lies external to them?
Frontal Lacrimal Sphenoid zgoma maxilla
What are the foramina that communicate with the orbit and what they transmit?
Supraorbital foramen- supraorbital VAN
Nasolacrimal canal- nasalacrimal duct
Optic canal- Optic n. Central vn of retina
Opthalmic a.
Sup. orbital fissure- Nerves; Oculomotor, Ophthalmic, Trochlear, Abducens, Superio ophthalmic v.
Inf. orbital fissure: infraorbityal n. (CNV2), brance of inf. ophthalmic v.
Infraorbital Foramen: infraorbital VAN
Name the three layers of the eyeball and their components
Outer fibrous layer- sclera, cornea
Middle Vascular Layer: ciliary body/m, iris, pupil
Inner Layer: Retina
What are the parts of the lacrimal apparatus and the pathway of lacrimal fluid•
Secretes lacrimal fluid: w/i superolateral orbit fossas in frontal bone
- Lateral inferior lacrimal ducts transfer fluid from glands in to conjuctiva sac on surface of the eye
- Lacrimal canaliculi transfers fluid from medial eye to lacrimal sac
- Lacirmal sac is dialted to inferior meatus of nasal cavity.
What are the innervation, location, and function of the intraocular muscles•
ALL SMOOTH M.
Dilator pupillae- GVEs DILATES pupil dim light.
Sphincter pupillae- GVEp CONSTRICTS pupil. circular under dilator m.
Cilary m. (SPINCHTER) RELAXED (thus HOLE FLAT) Lens TENSED so focus on FAR DISTANT
Cilary m. (SPINCHTER) CONTRACTED (thus HOLE OPEN small) Lens RELAXED so focus on NEAR DISTANT
What are the innervation, action and function of the extraocular muscles•
CN IV
Insert on sclera of eyeball
Levator palpebrae superioris: inserts upper eyelid- elevates Fx- rotates eye around 3 axis Sup. rectus: elevate, ADD, intort Medial recuts: ADD Inf. rectus: depress, ADD, extort Lat. rectus- ABD (CN VI)
Sup. oblique: depress, ABD, intort
Inf. oblique- elevate, ABD, extort
Name the sensory innervation (GSA & SA) of the eyeball and the fibre pathways of special sensory innervation (CN II)•
Dilator pupillae- GVEs dilates pupil, dim light
Sphincter pupillae-GVEp constricts pupil, bright light
Cillary musle- RELAXED- Lens is tensed focus on distant object. TENSED-Lens is relaxed focus on near- GVEp
Name the blood supply of orbital structures.
Ophthalmalic a.- branc ICA 1- supratrochlear a.- scalp 2-supraorbital a. scalp 3- Lacrimal 4-Post. ciliary a.- eyeball 5- Central a. of retina
Infraorbital a. -Branch of maxillary a., supplies orbit
What are the clinically relevant venous communications?)
Superior Ophthalmic vein- drains from facial vein to sup. orbital fissure into cavernous sinus.
Inferior Ophthalmic vein- drains to superior ophthalmic vein, also to pterygoid plexus.
Central v. of retina- inside optic nerve, drains to cavernous sinus. BLOCKAGE cause blindness)
Are there anastomoses in the eye?
Central a. of the retina travels w/ optic nerve
END ARTERY
NO ANASTOMOSE w/ any other blood vessels
DAMAGE = BLINDNESS
Tunnel vision
Bitemporal Hemianopsia
(Both TEMPORAL SIDES damaged)
Damage to chiasm bc Chaism only for the crossing of Temporal/perpherial field.
Blind in one eye
IF lesion to optic nerve (division after chiasm) on one side
Lateral and media eye blind
Homonymous Hemianopsia
Damage to optic tract (posterior division)
Can see lateral or one and and medial of other eye
Still can see from lateral nasal field of affected eye
Identify palsies of cranial nerves III (nerve testing)•Oculomotor palsy
GSE, GVEp
Eye ABD because medial rectus damaged
Eye depressed bc CN IV trochlear still works
Ptosis (drooping upper eyelid) bc levator palbebra super is damaged
Dilated nonreactive pupil- Cilliary muscle (GVEp) damaged
Test- reaction to light, accommodation, movement
