eyes and visual pathway Flashcards
what are the 5 structures of the external eye
- lacrimal caruncle
- semilunar fold
- sclera
- pupil
- iris
what 3 structures are part of the palpebral tissue ( area between open eyelids)
- iris
- sclera
- pupil
what is the role of eyelahses
- stop particles getting into eye and scratching cornea
- contain lipid-rich secretion to stop eyelids sticking together, we blink to spread tears over the surface of eye to keep it
why do we have the semilunar fold (when its useless)
evolutional remnant from when we has secondary eyelids like lizards
what are the 6 internal structures of the eye (not including iris and pupil)
- tarsal plate (inner side of eyelid)
- lens
- cillary body
- retina
- choroid
- sclera
the sclera, choroid and sclera are 3 layers of the body of the eyeball, what are the functions of these
sclera - white of eye, fibrous tunic
choroid - vascular
retina - pigmented to capture light info
explain how we see images/ how our eyeball depicts images
- light travels in straight line
- lens is required to bend the light so it can focus on the retina
- this explains why image is upside down, due to depth of eyeball
- info detected by retina and sent along optic nerve
describe how the rays of light differ coming from a distant or nearby object
- nearly parallel rays coming from DISTANT object
- divergent rays coming from CLOSE object
what are the 7 bones that make up the orbits
- frontal
- zygomatic
- lacriminal
- sphenoid
- ethmoid
- palatine
- maxilla
what are the 3 apertures/ foramen found in the orbits
superior/infeiror orbital fissure
optic canal
find diagram and label all bones of orbits
what is the lacrimal apparatus
structures that secrete tears and drain them from the surface of the eyeball
what is the lacrimal gland and where is it found
- almond sized and found in the upper outer margin of each orbit
- primary function of secreting the aqueous portion of the tear
(aprox a dozen small darts lead from each gland and drain into conjunctivae)
what is the lacrimal canal
small channels that empty into lacrimal sacs
what is the lacrimal sac
located in a groove in lacrimal bone
- collect tears that drain out of your eyes through your lacrimal puncta
what is the lacrimal puncta
the openings that pump tears out of your eyes/ or drain them
what is the nasolacrimal ducts
- small tubes that extend from the lacrimal sac into the inferior meatus of nose
(thats why nose runs when u cry)
find image of lacrimal apparatus and label each structure
what are the 6 muscles of the eye
- lateral and medial rectus
- inferior and superior rectus
- inferior oblique and superior oblique rectus
what movement does the lateral and medial rectus muscle allow fro
outward and inward movement (left and right)
what movement does the inferior and superior rectus muscle allow for
up and down
what movement does the inferior/superior oblique rectus muscle allow for
inferior oblique = upwards and outwards
superior oblique = downwards and outwards
what are the 3 ligaments of the eye
- medial and lateral check lig
- suspensory lig
what maintains the vertical position of the eyeball
suspensory ligament
what maintains the anteroom-posterior position of the eyeball
lateral/medial check ligament, fascial sheath and orbital fat
what is the main muscle located in the eyelid and what is its function
- levator palpebrae superioris
- controls elevation and retraction of eyelids
find and label orbital and nearby structures on CT/MRI scan
what 2 arteries supply the orbit
- ophthalmic artery
- internal carotid artery
define visual field
The visual field refers to the total area in which objects can be seen in the side (peripheral) vision as you focus your eyes on a central point.
what 2 halves can the retina be split into
temporal and nasal retina
which sides of the retina are responsible for the left or right visual field
nasal retina = left visual field
temporal retina = right visual field
what is the optic chasm
the part of the brain where the optic nerves cross
what is the sella turcica
a depression in the sphenoid bone, containing the pituitary gland
how does the optic chasm and sella turcica sit relative to each other
the optic chiasm is sat above the sella turcica
why is vision affected if there is a pituitary tumour
the growth of the pituitary tumour within the sella turcica will press against the optic chiasm
what is acromegaly
abnormal growth of the hands, feet, and face, caused by overproduction of growth hormone by the pituitary gland.
what are the optic radiations
- a projection tract that connects the lateral geniculate nucleus to the primary visual cortex in the occipital lobe.
- It functions to transmit visual input coming from the retina, the optic nerve, and the optic tract.
which lobe of the brain o the inferior optic radiations pass through
temporal
which lobe of the brain do the superior optic radiations pass through
parietal
how can lesions in the parietal or temporal lobe lead to affected sight
- they will interrupt the inferior or superior optic radiations, iand affect the transmission of visual input from the retina
in which lobe is visual information processed
occipital
where/how pathway = posterior parietal cortex
what pathway = inferior temporal cortex
what artery supplies the occipital lobe
posterior cerebral artery
look through axial stack of visual pathway, screenshotted
