orbital cavity

Question 1

what are the bony features of the orbit

Answer 1

-frontal bone
-zygomatic
-maxilla
-lacrimal
-sphenoid
-paletine
-ethmoid

Question 2

what sinuses is the orbital cavity bounded by

Answer 2

-medially: ethmoid paranasal sinuses
-laterally: maxillary paranasal sinuses

Question 3

describe the accessory structures of the eye

Answer 3

-eyebrows: skin, supra-orbital ridge
-eyelids: (palpebrae); separated by a palpebral fissure and reinforced by dense CT bands or tarsi
-meet eachother at medial or lateral angles
-levator palpebra superioris: lifts the superior eyelid
-orbicularis oculi: closes the eyelids, facial muscle innervated by the facial nerve

Question 4

what is the transparent mucous membrane that covers the inner surfaces of the eyelids (palpebral) and the anterior surface of the eyeball (bulbar)

Answer 4

conjunctiva

Question 5

lacrimal apparatus

Answer 5

glands and ducts that drain lacrimal fluid to the nasal cavity

Question 6

lacrimal gland

Answer 6

produces lacrimal fluid (tears), lies in a fossa in the superolateral orbit

Question 7

lacrimal duct

Answer 7

fluid conveys to the conjunctival sac

Question 8

lacrimal canalicula

Answer 8

connect to nasalacrminal duct. fluids leads to the nasal cavity

Question 9

lacrimal production innervation

Answer 9

parasympathetic impulses of CN VII

Question 10

function of the eyeball

Answer 10

-protect and supports the photoreceptors
-gather, focus, and proces light into precise images

Question 11

3 layers of the eye

Answer 11

-fibrous, vascular, and inner

Question 12

the internal cavity of the eye has

Answer 12

fluids (humors); light enters through

Question 13

describe the fibrous layer of the eye

Answer 13

-external layer, has 2 regions of CT that provide shape and resistance
-cornea: anterior 1/6th of the fibrous coat, transparent, allows light to enter eye
-sclera: posterior 5/6th of the coat, white obaque region. provides shape and a sturdy anchoring site for extrinsic and intrinsic muscles

Question 14

vascular layer of the eye

Answer 14

1. chorotid: vascular, dark pigmented membrane. lines the sclera, preventing scattering of the light rays.
2. ciliary body: ring, muscular vascular thickening that provides attachment to the lens. smooth muscles focus the lens.
3. iris: visible colored part of the eye. contracts as it has smooth muscle fibers to focus the pupil.
   -pupil: central opening of the iris, allows light to enter. contracted by the iris

Question 15

smooth muscles of the iris and the ciliary body

Answer 15

sphincter pupillae: of the iris, circularly arranged. constricts pupil size (parasympathetic)
dilator pupillae: radially arranged, dilates the pupil (sympathetic)

Question 16

dilation innerv

Answer 16

post-synaptic sympathetic

Question 17

constricted inner

Answer 17

post-synaptic parasympathetic nerve

Question 18

inner layer, visual layer

Answer 18

-retina: site where light photoreceptor cells are located
-2 parts:
optic layer: sensitive to visual light rays and composed of 2 layers, neural and pigmented
nonvisual layer: anterior continuation of the pigmented area

Question 19

inner layer components

Answer 19

-optic disc: circular layer of retina where sensory fibers and vessels conveyed by the optic nerve CNII, enter the eyeball. contains no chemoreceptors and is insensitive to light
-macula: small area with special chemoreceptors cones for vision
-fovea centralis: depression at the center of the macula, best area of acute vision

Question 20

types of photoreceptors in the retina

Answer 20

-rod cells: more sensitive to light, allow vision in dim light, no sharp/color
-cone cells: operate best in bright light, high color vision.

Question 21

divisions of the lens

Answer 21

-anterior: filled with aqueous humor. clear watery solution that provided nutrients for the vascular lens and cornea
-posterior: filled with vitreous humor. transmits light, holds retina in place, and supports the lens

Question 22

describe the light pathway

Answer 22

cornea-aqueous humor-lens-vitreous humor

Question 23

ciliary muscle function and vision due to shape change of the lens

Answer 23

changes shape of the lens
-stretches, thinner lens: brings more distant objects into focus
-relaxed lens, thick: near vision

Question 24

intraretinal space

Answer 24

separates the layers of a developing retina
correlated with retinal detachment: may result from a blow to the eye and seepage of fluid between the layers

Question 25

general review of extra-ocular muscles of the orbit

Answer 25

-levator palpebrae superioris
-4 recti
-2 obliques
-origin: walls of the orbit
-insert: outer surface of the eyeball
-common tendinous ring: origin of 4 recti, surrounds optic canal

Question 26

levator palpebrae superioris

Answer 26

covers eyelid
-action: elevates superior eyelid
-innerv: Optic Nerve CN II

Question 27

recti muscles

Answer 27

-lateral: abducts
-medial: adducts
-superior: elevates
-inferior: depresses

Question 28

oblique muscles

Answer 28

function: rotational movement
-superior oblique: originates posteriorly, runs anterior along the orbital wall and loops through the trochlea. insert: posterolateral eye surface
action: abducts (lateral) and depresses
inferior oblique: abducts and elevates the pupil

Question 29

nerves of the orbit:

Answer 29

-general sensory: (skin) trigeminal CN V1 nerve
-special sensory: vision, Optic nerve CN II
-branchial motor: facial nerve CN VII
-somatic motor: move eye
1. oculomotor nerve CN III: levator palpebrae superioris, superior rectus, inferior rectus, medial rectus, and inferior oblique
2. trochlear nerve CN IV: superior oblique
3. abducent nerve CN VI: to lateral rectus
-visceral motor: parasympathetic and sypathetic to dilator pupil muscle and sphincter; ciliary muscle

Question 30

arteries of the orbit

Answer 30

ophthalmic artery: branch off the internal carotid artery
-central retinal artery: terminal branch, occlusion causes instant blindess