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37 Cards in this Set
- Front
- Back
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How many layers of tissue make up the eyeball?
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3 layers:
-outer fibrous layer -middle vascular layer -inner sensory layer |
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What makes up the outer fibrous layer of the eye?
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-opaque sclera (posterior 5/6s)
-transparent cornea (anterior 1/6) |
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What makes up the middle vascular layer of the eye?
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-choroid
-ciliary body -iris |
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What makes up the inner sensory layer of the eye?
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Retina, with rods and cones (sensory receptors).
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What refractive media does light pass through before it strikes the retina?
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1. cornea
2. aqueous humor 3. lens 4. vitreous humor 5. retina |
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Describe the aqueous humor.
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In the anterior chamber, continuously produced and absorbed in balance.
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What happens if the production/absorption of aqueous humor is off balance?
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If there is an excess production of aqueous humor, then glaucoma can develop.
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What suspends the lens?
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Tiny ligaments that are attached to the ciliary muscle in the ciliary body.
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What is accommodation of the lens?
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Changing the shape of the lens by contracting or relaxing of the ciliary muscles.
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What does accommodation of the lens do?
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Changes the shape of the lens to focus light rays coming from different distances on the retina.
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What nerve supplies the ciliary muscles?
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Parasympathetic motor fibers in CN III (oculomotor nerve).
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What does the iris contain?
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2 smooth muscles that regulate the size of the pupil:
-sphincter pupillae -dilator pupillae |
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What does the sphincter pupillae muscle do?
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Contracts to make the pupil smaller.
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What is the sphincter pupillae muscle innervated by?
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Parasympathetic motor fibers supplied by CN III (oculomotor nerve).
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What does the dilator pupillae muscle do?
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Contracts to make the pupil larger.
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What is the dilator pupillae muscle innervated by?
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Postganglionic sympathetic motor fibers supplied by the carotid plexus.
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What is the optic nerve?
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CN II. It is attached to the posterior side of the eyeball in a position that coincides with the "blind spot" of the retina.
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What is the "blind spot"?
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The area of the retina where the optic nerve attaches. Does not contain any rods or cones, but does include the central artery of the retina.
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What surrounds the optic nerve?
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All 3 layers of the meninges:
-dura mater -arachnoid membrane -pia mater |
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What happens to the eye if intracranial pressure increases?
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Choked disc. It will apply pressure on the central artery of the retina when pressing on the optic nerve. Can detect by looking for changes in the "blind spot" and the arteries of the retina.
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What is the macula?
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The portion of the retina that has the highest concentration of cones (detect color) and the sharpest vision.
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How many extraocular muscles are on each eye?
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Six, insert into the eyeball (sclera of the eye). These muscles cause the eyeball to move in various directions to track objects in visual field.
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Superior rectus
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Elevates the eye (primary)
Innervated by CN III (oculomotor) |
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Lateral rectus
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Abducts the eye
Innervated by CN VI (abducens) |
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Medial rectus
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Adducts the eye
Innervated by CN III (oculomotor) |
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Inferior rectus
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Depresses the eye
Innervated by CN III (oculomotor) |
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Superior oblique
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Depresses (assists) and abducts the eye
Innervated by CN IV (trochlear) |
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Inferior oblique
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Elevates (assists) and abducts the eye
Innervated by CN III (oculomotor) |
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Levator palpebrae superioris
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Lies on top of the superior rectus
O: roof of the orbit I: 1. superior part - upper eyelid, 2. inferior part (aka superior tarsal muscle) - tarsal plate Inv: 1. oculomotor n., 2. carotid plexus A: elevates the upper eyelid |
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What is the superior tarsal muscle?
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Smooth muscle fibers of the levator palpebrae superioris that insert into the tarsal plate.
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What is oculomotor nerve palsy?
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Paralysis of the levator palpebrae superioris, which means patient cannot voluntarily elevate upper eyelid.
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What is ptosis?
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Drooping of the upper eyelid. Caused by lesions of cervical sympathetic chain ganglia.
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What is Horner's syndrome?
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A condition characterized by ptosis, is a sign of cervical sympathetic trunk injury.
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What artery supplies all contents of the orbit?
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Ophthalmic artery (the first branch of the internal carotid) and all of its branches.
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What is the only blood supply to the retina?
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The central artery of retina, a branch of the ophthalmic a.
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What drains the contents of the orbit?
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Ophthalmic veins, which have connections to the facial vein and the cavernous sinus.
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What is diabetic retinopathy?
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Affects the central artery of retina, causing blindness.
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