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134 Cards in this Set
- Front
- Back
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General contents of the orbit
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eyeball, muscles, neurovascular and lacrimal apparatus structures, orbital fat, ciliary ganglion, optic nerve
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Which bones is the orbit of the eye comprised of?
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frontal, sphenoid, ethmoid, lacrimal, maxilla, palatine, zygomatic bones
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Osteology: what is the name of the part of the maxilla which extends superiorly by the nasal and frontal bone?
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frontal process of the maxilla
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Osteology: what is the name of the part of the maxilla which extends deep toward the superior orbital fissure?
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orbital process of the maxilla
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Which wing of the sphenoid bone is found in the orbit of the eye?
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greater wing
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What are the apertures of the orbit?
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base (outer), superior orbital fissure, inferior orbital fissure, optic canal (apex)
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In the orbit, what is the name of the indentation on the lacrimal bone?
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lacrimal fossa
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What is the name of the groove in the orbit?
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Infraorbital groove
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What aperture of the orbit is the apex?
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the optic canal
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What are the functions of the eyelids?
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cover the eyeball anteriorly
-protect it from excessive light and foreign objects -help spread lacrimal fluid to keep cornea moist |
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Eyelids are covered externally by what and internally by what
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externally--skin
internally-palpebral conjunctiva |
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The lacrimal apparatus consists of what?
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lacrimal glands,
ducts, papilla/punctum, canaliculi, sac, nasolacrimal duct |
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What stimulates lacrimal fluid?
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parasympathetic from CN VII
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What fluid is responsible for keeping the eyeball moist?
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lacrimal fluid
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The palpebral conjunctiva is continuous with what which covers the sclera and cornea?
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bulbar conjunctiva
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palpebral conjunctiva and bulbar conjunctiva meet where?
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At the superior and inferior fornices (singular: fornix)
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What is the name of the medial fold of conjunctiva near the lacrimal lake?
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plica semilunaris
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Describe the iris
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lies on anterior surface of lens
is a thin, contractile diaphragm with a central aperature (pupil) |
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The diameter of the pupil (controlling transmission of light) is controlled by what?
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sphincter pupillae and dilator pupillae
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eyelids are strengthened by dense bands of connective tissue known as:
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tarsal plates
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tarsal plates connected to the medial and lateral angles of the eye by what?
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the medial and lateral palpebral ligaments
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What is the name of the weak membrane that spans from the tarsal plates to the margins of the orbit where it eventually becomes continuous with the periosteum
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orbital septum
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Eyelids have 5 layers. What are they?
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outer skin layer
subcutaneous layer muscular layer tarsofacial layer conjunctival layer |
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What are the muscles found in the eyelid
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palpebral part of the orbicularis oculi
levator palpebrae superioris |
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What is contains within the tarsofacial layer?
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tarsal glands and plate
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What is the conjunctival layer of the eyelid?
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palpebral conjunctiva
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lacrimal gland split into two parts by what?
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a lateral expansion of the levator palpebrae superioris m.
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Describe course of drainage of tears.
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lacrimal gland--> lacrimal ducts--> superior and inferior fornices-->lacrimal lake --> lacrimal punctum on the lacrimal papilla-->lacrimal canaliculi--> lacrimal sac--> nasolacrimal duct--> inferior nasal meatus of nasal cavity
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mound of modified skin tissue found in the lacrimal lake is called what?
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lacrimal caruncle
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Bones forming the orbit are lined with what (name the periosteum)
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periorbita
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What forms the fascial sheath of the eyeball
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periorbita
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The fascial sheath of the eyeball is also known as
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bulbar sheath or Tenon's capsule
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Expansions of the fascial sheath at the medial and lateral rectus muscles are called what?
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medial and lateral check ligaments
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The blending of the check ligaments with the fascia of the inferior rectus and inferior oblique muscles is called what?
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suspensory ligament
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the fascial sheath is pierced by the tendons of extraocular muscles and is reflected onto each of them as what?
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tubular (muscle) sheath
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What is the function of medial and lateral check ligaments?
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They limit adduction and abduction respectively
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What is the function of the suspensory ligament
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supports the eyeball and limits downward displacement
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How many extraocular muscles are there and what are their names
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7
levator palpebrae superioris superior rectus inferior rectus medial rectus lateral rectus superior oblique inferior oblique |
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All extraocular muscles, except superior oblique and lateral rectus, are innervated by which nerve
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CN III (oculomotor n.)
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Origin of levator palpebrae superioris
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lesser wing of sphenoid
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insertion of levator palpebrae superioris
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upper eyelid and superior tarsal plate
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innervation of levator palpebrae superioris
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CN III (superior division); superior tarsal muscle is innervated by VE- symp/post fibers
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function of levator palpebrae superioris
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elevates upper eyelid
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Origin of superior rectus
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common tendinous ring (annulus of Zinn)
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Insertion of superior rectus
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superior sclera
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innervation of superior rectus
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CN III (superior division)
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action of superior rectus
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elevate, adduct and medially rotate eyeball
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origin of inferior rectus
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common tendinous ring (annulus of Zinn)
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Insertion of inferior rectus
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inferior sclera
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innervation of inferior rectus
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CN III (inferior division)
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action of inferior rectus
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depress, adduct and laterally rotate eyeball
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origin of medial rectus
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common tendinous ring (annulus of Zinn)
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insertion of medial rectus
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medial sclera
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innervation of medial rectus
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CN III (inferior division)
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action of medial rectus
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adducts eyeball
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origin of lateral rectus
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common tendinous ring (annulus of Zinn)
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insertion of lateral rectus
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lateral sclera
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innervation of lateral rectus
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CN VI (abducens nerve)
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action of lateral rectus
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abduct eyeball
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origin of superior oblique
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body of sphenoid bone
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insertion of superior oblique
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superior sclera deep to superior rectus
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innervation of superior oblique
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CN IV trochlear nerve
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action of superior oblique
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abducts, depresses and medially rotates eyeball
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What is a trochlea?
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a fibrous ring that acts like a pulley
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origin of inferior oblique
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anteromedial floor of orbit
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insertion of inferior oblique
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sclera inferior to lateral rectus
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innervation of inferior oblique
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CN III (inferior division)
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action of inferior oblique
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abducts, elevates, and laterally rotates eyeball
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optical and orbital axis deviate by how many degrees?
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23 degrees
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Point of maximum visual acuity
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fovea centralis
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where is the fovea centralis in relation to the blind spot created by the optical disk?
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lateral to it.
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What are the two muscles responsible for elevating the eyeball?
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superior rectus and inferior oblique
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movemnet of the eyeball occurs at three different axes of rotation
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anteroposterior, horizontal and vertical axes
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elevation of the eyeball occurs at which axis?
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horizontal axis
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What are the two muscles responsible for depressing the eyeball?
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inferior rectus and superior oblique
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depression of the eyeball occurs at which axis?
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horizontal axis
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What are the three muscles responsible for abducting the eyeball?
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lateral rectus, inferior oblique, and superior oblique
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abduction movement occurs at which axis?
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vertical axis
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What are the three muscles responsible for adducting the eyeball?
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medial rectus
inferior rectus superior rectus |
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adduction movement occurs at which axis?
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vertical axis
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which two muscles are responsible for laterally rotating the eyeball?
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inferior oblique and inferior rectus
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movement of lateral rotation occurs at which axis?
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anteroposterior axis
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movement of medial rotation occurs at which axis?
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anteroposterior axis
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which two muscles are responsible for laterally rotating the eyeball?
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superior oblique and superior rectus
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What are the nerves of the orbit?
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CN II (optic)
CN III (oculomotor) CN IV (trochlear) CN VI (abducens) CN V1 (ophthalmic division) ...and their branches |
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CN V1 supplies has what fibers and innervates what?
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SA fibers...supplies face and ethmoidal air cell mucosa
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What goes through the optic canal?
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CN II (optic n.)
ophthalmic a. and v. |
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The Optic nerve is surrounded by what
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meninges (all 3)
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The optic nerve is pierced by what?
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the central artery of the retina
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Describe CN III's VE Para fibers' path from brain to target
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Edinger-Westphal nucleus in the midbrain--> cilliary ganglion-->short ciliary nerves--> ciliary body and sphincter pupillae muscles
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CN V1 or ophthalmic n. divides into 3 branches:
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frontal, lacrimal, and nasociliary ns.
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V1's SA cell bodies are where?
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Trigeminal ganglion
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frontal branches of V1 divides into two nerves
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supraorbital and supratrochlear ns.
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nasociliary n. gives rise to:
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long ciliary, posterior and anterior ethmoidal ns and then changes names to become the infratrochlear n.
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relationships of ciliary ganglion
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lateral edge of optic nerve near the lateral rectus muscle
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What are the 3 roots of the ciliary ganglion?
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1. motor root para/pre (CN III inferior division)
2. sensory root: SA fibers from eyeball which join V1 3. sympathetic root (sym/post fibers from superior cervical ganglion via carotid plexus--courses with ophthalmic a. into orbit) |
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anterior ethmoidal n. of nasociliary branch give off what nerve?
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external nasal
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What is the main blood supply to the orbit?
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ophthalmic a.
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what are the sympathetic splanchnic nerves to the GIT?
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thoracic, lumbar
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Where does the ophthalmic a. enter the orbit?
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optic canal
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What are the branches of the orbit?
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central artery of the retina, lacrimal, long/short posterior ciliary, supraorbital, posterior and anterior ethmoidal, dorsal nasal, and supratrochlear.
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Veins corresponding to ophthalmic artery branches, along with inferior ophthalmic vein drain into what vein and then into what sinus?
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into the superior ophthalmic vein which leads to the cavernous sinus
the inferior ophthalmic vein also drains into the pterygoid venous plexus which drains into the cavernous sinus |
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Which artery pierces the optic nerve?
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The central artery of the retina
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eyeball consists of three layer or "tunics" which are?
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fibrous (outer) layer, vascular (pigmented) layer or uvea, and inner (retinal) layer
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what are the refractive media of the ey?
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cornea, aqueous humor, lens, and vitreous humor
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fibrous (outer) layer consists of what?
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cornea and sclera
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cornea covers how much of the eyeball?
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1/6
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cornea is responsbile for what
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refracts light entering eye
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sclera covers how much of eye and does what?
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posterior 5/6 of eyeball and provides shape and attachment sites for muscles
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vascular (pigmented) layer (or uvea) consists of what
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choroid, ciliary body, and iris
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choroid has 2 layers
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outer pigmented layer and inner highly vascularized layer
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function of choroid
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nourish the retina
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function of ciliary body
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muscular--controls thickness of lens
vascular connects choroid and iris attachment for lens ciliary processes secrete aqueous humor |
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ciliary muscle innervated by what fibers?
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VE para/post
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contration and relaxation of smooth muscle of ciliary muscle controls thickness of lens...result in?
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focus or accommodation
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what secretes aqueous humor?
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ciliary processes of the ciliary body
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aqueous humor fills what areas?
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anterior and posterior chambers
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which two muscles in the iris control the size of the pupil?
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sphincter (constrictor) pupillae and dilator pupillae
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Sphincter pupillae innervated by what fibers?
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VE para/post
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dilator pupillae innervated by what fibers
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VE symp/post
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retina has what layers?
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outer pigmented and inner neural layers
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Which retinal layer is the light receptor
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neural layer
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what are the 3 types of neurons in the neural layer of the retina
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rods and cones
bipolar neurons ganglion neurons--axons of these form the optic nerve |
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function of pigmented layer of the retina?
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reinforces the light absorbing property of the choroid by reducing light scattering
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circular area where teh optic nerve and central retina vessels are found
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optic disc--no photoreceptors and is insensitive to light
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yellow spot of retina
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macula lutea
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area of most acute vision in eye
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fovea centralis
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posterior part of eyeball
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fundus
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cornea
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function: refraction
transparent avascular sensitive to touch supplied by V1 fibers of the ciliary nerves |
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what attaches lens to ciliary bodies?
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zonular fibers
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which side of the lens changes the most to focus of accommodate?
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anterior surface
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What separates the anterior and posterior chambers of the eye
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iris
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posterior to the lens is what
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vitreous chamber
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function of vitreous humor
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holds retina in place, supports lens, transmits light
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