HAPE Flashcards
Iris
controls the amount of light allowed to enter the eye through the pupil
Cornea
covers both the pupil and the iris and is continuous with the sclera
The upper eyelid
covers a portion of the iris but does not normally overlay the pupil
Palpebral fissure
the opening between the eyelids
Conjunctiva
Covers the surface of the eye and the inner surfaces of the eyelids
Two Components of Conjunctiva
Bulbar conjunctiva covers most of the anterior eyeball
Palpebral conjunctiva lines the eyelids
Tarsal Plates
Contains parallel rows of meibomian glands (also known as tarsal glands)
Provides oily lubrication to the ocular surface
Levator palpebrae superioris
Primary muscle that raises the upper eyelid
Innervated by the oculomotor nerve, cranial nerve (CN) III
Müller’s muscle (superior tarsal)
Innervated by the sympathetic nervous system
Also contributes to lid elevation
Lacrimal Gland
Tears are produced at the lacrimal gland Drain through the lacrimal puncta Then pass through the canaliculi Into the lacrimal sac On into the nose through the nasolacrimal (tear) duct
Tear Film
protects the conjunctiva and cornea from drying
inhibits microbial growth
gives a smooth optical surface to the cornea
Lens
Suspended by ligaments (zonule fibers) - controls thickness of lens
Allows the eye to adjust focus on near or distant objects (accommodation)
Projects clear image on retina, the sensory part of the eye
Presbyobia
farsightedness caused by loss of elasticity of the lens of the eye, aging problem.
Three Chambers of Fluid in Eye
Anterior chamber (between the cornea and iris) Posterior chamber (between the iris and the lens) Both are filled with aqueous humor Vitreous chamber (between the lens and the retina) Filled with vitreous humor, maintains the shape of the eye
Optic Fundus
The posterior portion of the eye that is seen through the ophthalmoscope
Retina
a layer of tissue in the back of your eye that senses light and sends images to your brain
Macula
Part of the retina in the back of the eye. Fovea is in the middle of macula. Macula surrounds the fovea.
Fovea
Point of central vision. Tiny pit in the macula of the retina that provides the clearest vision of all
Optic Disc
entry point of optic nerve. the round spot on the retina formed by the passage of the axons of the retinal ganglion cells, which transfer signals from the photoreceptors of the eye to the optic nerve, allowing us to see
Choroid
the middle layer of tissue in the wall of the eye
Vitreous
the clear gel that fills the space between the lens and the retina of the eyeball
Pupillary constriction.
Sphincter Pupillae and is a parasympathetic response. Miosis
Pupillary dilation
Dilator pupillae. A sympathetic innervation. mydriasis and raising of upper eyelid (mullers muscle).
Light Test Abnormality
There may be a lesion in the optic tract. The eyes should move consensually. The initial sensory pathways are like those described for vision:
Retina, optic nerve (CN II), and optic tract, which diverges in the midbrain
The constrictor muscles of the iris are transmitted through oculomotor nerves (CN III)
Near Reaction
Pupils constrict
When gaze shifts from far to near object
Mediated by the oculomotor nerve (CN III)
Eyes converge
Bilateral medial rectus movement
Accommodation
Increased convexity of the lenses caused by contraction of the ciliary muscles
Pupillary dilation abnormality.
A lesion anywhere along this pathway may impair sympathetic effects that dilate the pupil and will cause miosis
Dilation Pathway
Starts in the hypothalamus
Passes down through the brainstem and cervical cord into the neck
The neurons travel with the brachial plexus at the lung apex
Returns to the superior cervical ganglion near the mandible
Follows the carotid artery or its branches into the orbit
Hyperobia
Farsightedness