8.0 eye anatomy Flashcards
where are most sensory receptors located
70% aof all sensory receptors are in the eye
what are the accessory structures of the eye
Eyebrows
Eyelids
Conjunctiva
lacrimal apparatus
extrinsic eye muscles
what is the purpose of eye brows?
what controlls them
- coarse hairs that overlie the supraorbital margins
- shade the eye from sun and prevent perspiration from reaching the eye
controlled by corrugator supercilii (move eyebrown medially), orbicularis oculi (depresses brows)
role of palpebrae (eyelids)
separated by Palpebral fissure
- commissures: medial and lateral angles (connection point for eyelid)
- levator palpebae superioris msucle controlles upper eyelid
what are tarsal glands
- accessory palpebrae (eyelids)
- embedded in tarsal plates, theri ducts open at the eyelid edge
- produce an oily secretion to lburicate edges of eyeball
describe the conjunctiva
- lines eyelids as the palpebral conjunctiva
- coveres whites of eyes as ocular (bulbar) conjunctiva
- lubricates and protects the eye
describe the lacrimal apparatus
- lacrimal glands secrete tears
- > Contain mucus, antibodies, and lysozyme
- > teats exit via excretory ducts
- > collect at lacrimal punctum
- > drain into nasolacrimal duct
*lacrimal caruncle contains glands that secrete a whitish oily secretion
Describe extrinsic Eye Muscles
- enable the eye to follow moving objects and maintain the shape
- four rectus muscles originate from the annular ring (superior, inferior, medial and lateral)
- two oblique muscles move eye in vertical plane (superior and inferior)
what cranial nerves control the different muscles of the eye
LR6SO4R3
Lateral Rectus: moves eye laterally CN VI
Medial rectus: moves eye medially CN III
Superior rectus: elevates eye and turns it medially CN III
Inferior rectus: depresses eye and turns it medially CN III
Inferior oblique: elevates eye and turns laterally CN III
Superior oblique: depresses eye and turns laterallu CN IV
structure of eye ball
What is the fibrous tunic
-f orms the outermost coat of eye, is composed of:
opaque sclera: protects the eye and anchord extrinsic muscles
Clear cornea: anterior, lets light enter the eye
Describe the vascular tunic, what are the parts?
*choroid region
- has 3 regions; choroid, ciliary body, and iris
- Choroid region
- dark bron memrbane that forms the posterior portion of uvea and supplied blood to all eye tunics
- Ciliary body
- thickened ring of tissue surrounging the lens
- anchord suspensory ligaments that holds the lens in place
- iris
- close/brige light -> pupils constrict
- distant/dim light -> pupils dilate
- changes in emotional state can also cause populs to dilate
what muscles cause pupils to dilate vs constrict? What system regualtes this
constriction: sphincter pupillae muslce, reg by parasympathetic
Dilation: dilator pupillae muscle, reg by sympathetic
where are photo receptors located? what are the two layers?
- located in the retina
- Outer pigmented later:
- absorb light and prevents it from scattering in the eye
- acts as phagocytes to remove dead or damaged photoreceptor cells
- Transparent inner neural layer
- out pocket of the brain, retina contains millsion of photoreceptors
what does light cross when comes through retina
- through ganglion cells
- neuclei of bipolar cells
- then gets to nuceli of rods and cones
what is macula lutea
- area of eye without blood vesels on surface
- improtant for high cirspnedd of eye, done want anyhitng to block that
describe macular degeneration
- foten age related (AMD)
- involved buildup of visual pigments in the retina
Dry MD: degredation and los of pigmented epithelial layer
Wet: abnormal blood vessel growth
describe retinopathy
- can happen in diabetes patients
- vessels have weak walls, causes hemorrhaging and blindness
- > BV leakage, if enough leakage will get blindness
- body cant clear clots bc fluid is not renewably, its jelly like and will stay there
describe the inner chambers and fluids of the eye: posterior segment
* lens separates the anterior and posterior segments
- posterior is filled with vitreous humor
- > clear gel that allows for the transmission of light
- > intraocular pressue (IOP) helps hold the neural retina firmly against the pigmented layer
Describe the anterior segment of the eye
- anterior segment has 2 chambers: anterior ( between cornea and iris) and posterior (between iris and lens)
- filled with aqueous humour that is produced by cilliary process
- > plasma fluid that fills the anterior segment
- > drains via the scleral venous sinus
- > supports, nourishes and removes waste
What collacts aqueous humour
Scleral venous sinus
what is the anterior segment filled with, how is it produced
aqueous humour
- small amount is produced constantly by silliary process (folws fromposterior -> anterior chambers)
- equal amount flows out of eye through microscopic drainage system - trabecular meshwork (collects it)
0 then goes to Schelmm’s canal or Scleral venous sinus
what is glaucoma
Disease of the optic nerve
- blind spots develop & usually go undetected until optic nerve is significantly damaged
- Leading cause of blindness, especially for older people
*due to changes in intraocular pressure which damages optic nerve
- aqueous humour does not flow thoruhg trabecular meshwork properly -> voertime, IOP increases, damaging the optic nerve fibers
what is the lens attached to? what happens when it contracts vs when it is relaxed
lens is attached to ciliary muscle by inelastic ligaments (zonules)
- when relaxed: ligaments pull on and flatten the lens (see objects farther)
- when contracts: it releases tension on ligaments and lens becomes more rounded (see closed obejcts)
