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111 Cards in this Set
- Front
- Back
Bones of the Orbit
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Lesser wing of sphenoid
Superior orbital fissure Greater wing of sphenoid Frontal bone Optic Canal Ethmoidal foramina Ethmoid Bone |
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The shape of the orbit is almost _____
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pyramidal
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Medial walls of the orbit are ____. Lateral walls are __________.
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parallel; at right angles
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The orbit is comprised of all or part of ____ bones and lined with_________which forms a funnel shaped fascial sheath that encloses the orbital contents.
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Seven; periorbita (orbital periosteum)
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Orbital margin of the orbit
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Frontal bone
Maxilla Zygomatic bone |
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Superior wall or roof
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Frontal bone (orbital plate)
Lesser wing of the sphenoid bone (Posterior part) |
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Medial wall of orbit
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a. Ethmoid - lamina papyracea
b. Frontal bone c. Lacrimal bone d. Sphenoid bone |
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Inferior wall - or Floor; separated from lateral wall by the inferior orbital fissure
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a. Maxilla - orbital surface
b. Zygomatic bone c. Palatine bone – (orbital process) |
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Lateral Wall of orbit
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a. Zygomatic bone - frontal process
b. Sphenoid bone - greater wing |
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Orbital margin fractures
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fractures at the suture
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Blowout fractures
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medial and inferior walls are thin and may fracture while the margin remains intact
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Superior wall is ________ but still thin and can be penetrated by sharp objects. Problematic because it is directly related to the _______.
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stronger; frontal lobe
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Openings into the Orbit
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Superior orbital fissure
Inferior orbital fissure Optic Canal |
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Optic Canal
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- transmits optic nerve (CN II), ophthalmic artery
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Superior Orbital Fissure
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- transmits oculomotor nerve (CN III), trochlear nerve (CN IV), ophthalmic division of trigeminal nerve (CN V1), abducens nerve (CN VI) and superior ophthalmic vein
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Inferior orbital fissure
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- transmits maxillary division of the trigeminal nerve (CN V2) and the infraorbital artery and vein
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Soft tissues of the orbit are called
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the eyelids
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Soft tissues of the orbit include
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Skin
Tela subcutanea Orbicularis oculi muscle Fibrous layer (for upper lid) Conjunctiva Muscles responsible for opening and closing palpebral fissure |
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SKin of the orbit
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thin, delicate and transparent
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Tela Subcutanea of the orbit
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loose, allows accumulation of fluid (edema or “black eye”)
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Orbicularis oculi muscle
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1. Closes palpebral fissure
2. Muscle of facial expression |
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Muscle of facial expression of the orbit
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a. Palpebral part
b. Orbital part c. Lacrimal part |
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Fibrous Layer (described for upper lid) of the orbit
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1. Orbital septum
2. Aponeurosis of levator palpebrae superioris muscle 3. Superior tarsal muscle 4. Tarsal plate |
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Orbital septum
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continuous with the periorbita inside the orbit and the periosteum covering frontal bone
Part of the fibrous layer of the orbit |
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Aponeurosis of levator palpebrae superioris muscle
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part of the fibrous layer of the orbit
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Superior tarsal muscle
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smooth muscle innervated by sympathetic n.s.
part of the fibrous layer of the orbit |
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What is the major support for the eyelid?
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Tarsal plate
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Tarsal plate
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a. major support for the eyelid
b. plate of dense connective tissue anchored to the anterior lacrimal crest medially and the orbital tubercle of zygomatic bone laterally c. embedded within it is the tarsal gland (responsible for increasing the viscosity of tears and decreasing their evaporation Part of the fibrous part of the orbit |
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Conjunctiva of the eye
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1. Palpebral conjunctiva- continuous with bulbar conjunctiva at superior and inferior conjunctival fornices)
2. Orbital (bulbar) conjunctiva 3. Conjunctival fornix - junction of palpebral and orbital (bulbar) conjunctivae |
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Palpebral conjunctiva
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continuous with bulbar conjunctiva at superior and inferior conjunctival fornices)
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Conjunctival fornix
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junction of palpebral and orbital (bulbar) conjunctivae
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Conjunctivitis
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conjunctiva is colorless except when vessels are dialated/congested; conjunctivitis results from bacterial or viral infections or severe allergies
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Subconjunctival hemorrhage
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can occur due to injury/inflammation
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Muscles responsible for opening palpebral fissure.
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a. Levator palpebrae superioris - comprised of skeletal muscle; innervated by Cranial Nerve III
b. Superior tarsal muscle - comprised of smooth muscle; innervated by sympathetic nervous system; see section VIII - Smooth Muscle of the Orbit |
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Levator palpebrae superioris
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comprised of skeletal muscle; innervated by Cranial Nerve III
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Superior tarsal muscle
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comprised of smooth muscle; innervated by sympathetic nervous system; see section VIII - Smooth Muscle of the Orbit
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Closure of the eyelid is done by _____ ____.
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orbicularis oculi - comprised of skeletal muscle; innervated by Cranial Nerve VII
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Orbicularis oculi is innervted by
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Cranial nerve VII
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Lacrimal Apparatus includes
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A. Lacrimal gland
B. Lacrimal Puncta C. Lacrimal Canaliculi D. Lacrimal Sac E. Nasolacrimal Duct F. Lacrimal Gland Secretion |
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Lacrimal Gland
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1. Located in lateral aspect of the orbit posterior to the orbital septum
2. Curves around lateral edge of aponeurosis of levator palpebrae superioris muscle 3. Tears are secreted into the superior fornix of conjunctival sac and washed across the eyeball to the lacrimal lake to then enter: B. Lacrimal Puncta C. Lacrimal Canaliculi D. Lacrimal Sac E. Nasolacrimal duct |
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Tears are secreted into the ________ of conjunctival sac and washed across the eyeball to the lacrimal lake to then enter:
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superior fornix
B. Lacrimal Puncta C. Lacrimal Canaliculi D. Lacrimal Sac E. Nasolacrimal duct |
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Nasolacrimal duct
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Connects lacrimal sac to the inferior meatus
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Lacrimal Gland Secretion is a result of stimulation of _______.
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postganglionic parasympathetic fibers in lacrimal n.
Cell bodies: pterygopalatine ganglion Preganglionic parasympathetic fibers have their cell bodies in the superior salivatory nucleus and leave the brainstem in the facial nerve (CN VII). |
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Cell bodies of Lacrimal gland secretion are located in
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pterygopalatine ganglion
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Preganglionic parasympathetic fibers have their cell bodies in the________ and leave the brainstem in the ______.
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superior salivatory nucleus; facial nerve (CN VII
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Superior Oblique muscle is innervated by the ______ and the cell bodies are in the ____
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the Trochlear N; Trochlear nucleus
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The origin of the superior oblique muscle is
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the body of the sphenoid
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The Lateral Rectus muscle is innervated by the ___ and the cell bodies are in the ____
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Abducens N; Abducens nuclues
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The levator palpebrae superioris is innervated by the _____ and the cell bodies are located in the _____.
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Oculomotor N; oculomotor nucleus
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The inferior rectus, medial rectus, superior rectus, levator palpebrae superioris, and inferior oblique muscles are all innervated by the _____ and the cell bodies are in the _____
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Oculomotor N; oculomotor nucleus
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The origin of the levator palpebrae superioris muscle is the
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lesser wing of sphenoid
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The origin of the inferior rectus muscle, medial rectus muscle, and superior rectus muscle is the
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common tendinous ring
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The origin of the inferior oblique muscle is the
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anterior floor of orbit
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Medial rectus muscle functions only in
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adduction
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Lateral rectus muscle functions only in
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abduction
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Primary and secondary action of superior rectus m.
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P-elevation
S-adduction |
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Primary and secondary action of the inferior rectus
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p-depression
s-adduction |
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Inferior oblique primary and secondary action
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p-elevation
s-abduction |
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Superior oblique muscle primary and secondary action
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p-depression
s-abduction |
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Testing of Extraocular Muscles
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1. Each muscle is examined at its position of greatest efficiency
2. The medial and lateral recti can be tested easily for their single actions 3. The other four muscles must be specially positioned so that the muscle being tested is the only muscle capable of performing the required primary action. a. Eye abducted - superior rectus elevates, inferior rectus depresses b. Eye adducted - inferior oblique elevates, superior oblique depresses |
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Eye abducted (what muscles)?
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superior rectus elevates, inferior rectus depresses
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Eye adducted (what muscles)?
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inferior oblique elevates, superior oblique depresses
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Arterial supply to the orbit and eyeball includes
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branch of internal carotid
branches of ophthalmic artery 1. Posterior ethmoidal 2. Anterior ethmoidal 3. Dorsal nasal 4. Supratrochlear 5. Supraorbital 6. Central artery of the retina - an end artery 7. Ciliary arteries - long and short posterior ciliary arteries 8. Lacrimal 9. Palpebral arteries infraorbital A. |
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branches of Ophthalmic A that supply orbit and eyeball
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1. Posterior ethmoidal
2. Anterior ethmoidal 3. Dorsal nasal 4. Supratrochlear 5. Supraorbital 6. Central artery of the retina - an end artery 7. Ciliary arteries - long and short posterior ciliary arteries 8. Lacrimal 9. Palpebral arteries-to supply the upper and lower lids |
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Veins of the orbit communicate with the dural venous sinuses (via the cavernous sinus), with the _____, and with the veins of the face via the _____
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pterygoid plexus; angular vein
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Veins of the orbit
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1. Supraorbital vein
2. Infraorbital vein 3. Superior ophthalmic vein 4. Inferior ophthalmic vein |
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Nerves of the orbit
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A. Optic (CN II)
B. Oculomotor (CN III) 1. Superior Division: levator palpebrae superioris, superior rectus 2. Inferior Division: medial rectus, inferior oblique and inferior rectus C. Trochlear (CN IV) D. Ophthalmic - V1 (sensory) 1. Frontal nerve a. supraorbital b. supratrochlear 2. Nasociliary nerve 3. Anterior ethmoid 4. Infratrochlear 5. Long ciliary 6. Short ciliary E. Abducens (CN VI) |
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What muscles does the superior division of the oculomotor N innervate?
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levator palpebrae superioris, superior rectus
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What muscles does the inferior division of the oculomotor N innervate?
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medial rectus, inferior oblique and inferior rectus
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The three-layered sphere of the eyeball contain what three structures?
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Fibrous coat (sclera and cornea)
Vascular coat (choroid, ciliary body, and iris) Retina |
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The fibrous coat of the eyeball contains
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a. Sclera - opaque posterior 5/6; provides shape, resistance, attachment for extraocular muscles and intrinsic muscles of the eye; “white of the eye”
b. Cornea - transparent anterior 1/6 |
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Sclera is located in what part of the fibrous coat of the eyeball
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opaque posterior 5/6; provides shape, resistance, attachment for extraocular muscles and intrinsic muscles of the eye; “white of the eye”
Part of the fibrous coat of the eyeball |
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Cornea is located in what part of the fibrous coat of the eyeball
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transparent anterior 1/6
part of fibrous coat of eyeball |
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Vascular coat(uvea) contains
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a. Choroid-between the slera and retina; firmly attached to retina and engorged with blood
b. Ciliary body - suspensory mechanism for lens, ciliary muscle controls shape of lens and thus, focus; ciliary processes secrete aqueous humor c. Iris - muscular diaphragm to control light entrance; central aperature is the pupil |
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Choroid
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between the slera and retina; firmly attached to retina and engorged with blood
part of vascular coat |
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Ciliary body
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suspensory mechanism for lens, ciliary muscle controls shape of lens and thus, focus; ciliary processes secrete aqueous humor
vascular coat of eyeball |
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iris
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muscular diaphragm to control light entrance; central aperature is the pupil
part of vascular coat of eyeball |
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Retina
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a. inner layer
b. two parts: 1 optic: light sensitive; terminates along ora serrata 2. non-visual: fundus at posterior part of the eyeball; optic disc –sensory fibers and vessels conveyed by optic nerve enter ; insensitive to light |
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Refractive media of the eyeball includes
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cornea
aqueuous humor lens vitreous body |
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Cornea
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- transparent due to regular arrangement of collagen fibers and dehydrated state ; sensitive to touch; avascular, nourished by the aqueous humor and lacrimal fluid
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Aqueous humor
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made by ciliary processes; provides nutrients to the cornea and lens ; drains to the scleral venous sinus
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lens
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a. posterior to iris and anterior to vitreous humor/body
b. transparent, biconvex c. elastic capsule anchored by zonular fibers to ciliary body and encircled by ciliary processes; contraction of smooth muscle in the ciliary body reduces tension on lens and it rounds up for near vision (accommodation) |
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Vitreous body
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transmits light and holds retina in place; supports lens
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Corneal abrasions/lacerations
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foreign objects produce corneal abrasions
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Glaucoma
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a. drainage of aqueous humor thru sclera venous sinus is decreased; pressure builds in anterior and posterior chambers
b. can lead to blindness if pressure isn’t reduced. |
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Cataracts
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loss of transparency in lens; results in areas of opaqueness
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Hemmorhage into the anterior chamber
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result of blunt force trauma to eye
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Retinoblastoma
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a. rare childhood cancer
b. can be unilateral or bilateral c. most common sign: visible whiteness of normally black pupil in flash photography d. Prototype of cancer with a genetic component: RB1 gene on Chromosome 13q. |
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Ciliary muscle
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1. Action: narrows diameter of the ring formed by the ciliary body, releasing tension on the zonular fibers which, in turn, increases the curvature of the lens for near vision (accommodation).
2. Innervation: parasympathetic 3. Preganglionic nerves: nucleus of Edinger-Westphal, travel with the oculomotor nerve (III) to the ciliary ganglion 4. Ganglion: ciliary ganglion (comprised of cell bodies of parasympathetic postganglionic neurons which innervate the ciliary muscle and sphincter pupillae muscle) 5. Postganglionic nerves: short ciliary nerves |
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Action of ciliary muscle
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narrows diameter of the ring formed by the ciliary body, releasing tension on the zonular fibers which, in turn, increases the curvature of the lens for near vision (accommodation).
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Innervation of ciliary muscle
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parasympathetic
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Ciliary muscle preganglionic nerves
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nucleus of Edinger-Westphal, travel with the oculomotor nerve (III) to the ciliary ganglion
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Ciliary muscle ganglion
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:ciliary ganglion (comprised of cell bodies of parasympathetic postganglionic neurons which innervate the ciliary muscle and sphincter pupillae muscle)
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Ciliary muscle postganglionic nerves
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short ciliary nerves
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Sphincter pupillae muscle
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1. Action: constricts the pupil
2. Innervation: parasympathetic 3. Preganglionic nerves: nucleus of Edinger-Westphal, travel with the oculomotor nerve (III) to the ciliary ganglion 4. Ganglion: ciliary ganglion (comprised of cell bodies of parasympathetic postganglionic neurons which innervate the ciliary muscle and sphincter pupillae muscle) 5. Postganglionic nerves: short ciliary nerves |
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Action of sphincter pupillae muscle
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constricts the pupil
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Innervation of sphincter pupillae muscle
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parasympathetic
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Preganglionic nerves of Sphincter pupillae m.
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nucleus of Edinger-Westphal, travel with the oculomotor nerve (III) to the ciliary ganglion
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Ganglion of sphincter pupillae m.
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ciliary ganglion (comprised of cell bodies of parasympathetic postganglionic neurons which innervate the ciliary muscle and sphincter pupillae muscle)
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Sphincter pupillae m. postganglionic nerves
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short ciliary nerves
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Dilator pupillae muscle
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1. Action: enlarges the pupil
2. Innervation: sympathetic 3. Preganglionic nerves: intermediolateral cell column of upper thoracic levels 4. Ganglion: superior cervical ganglion 5. Postganglionic nerves: pass through the ciliary ganglion (without synapsing) and travel to the eye via the short ciliary nerves Note: The superior tarsal muscle in the upper eyelid is also innervated by sympathetic nerves. |
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Action of dilator pupillae muscle
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enlarges the pupil
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Innervation of dilator pupillae muscle
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sympathetic
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Preganglionic nerves of dilator pupillae m.
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intermediolateral cell column of upper thoracic levels
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Ganglion of dilator pupillae m.
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superior cervical ganglion
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Postganglionic nerves of dilator pupillae m.
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pass through the ciliary ganglion (without synapsing) and travel to the eye via the short ciliary nerves
Note: The superior tarsal muscle in the upper eyelid is also innervated by sympathetic nerves. |
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The ciliary ganglion will have sensory fibers from nasociliary branches (V1), postganglionic sympathetic fibers from the ____, and preganglionic parasympathetic fibers from the ____. ONLY THE PREGANGLIONIC PARASYMPATHETIC FIBERS SYNAPSE IN THE CILIARY GANGLION.
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carotid plexus; oculomotor nerve
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Pupillary Light Reflex
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1. Light enters one eye and both pupils constrict because each retina sends fibers to the optic tract on both sides of the eye
2. One of the first signs of compression of the ophthalmic nerve is ipsilateral slowness of the papillary response to light |
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Horner Syndrome
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interruption of the cervical sympathetic trunk resulting in absence of sympathetic functions on the ipsilateral side of the head.
Signs include: -constriction of the pupil -ptosis -redness of skin and increased temperature of skin -absence of sweating |
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What part of the orbit allows accumulation of fluid (edema or 'black eye')
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tela subcutanea
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what is the major support for the eyelid?
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tarsal plate
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