Special Senses: Ocular Flashcards
Lines the linear aspect of the eyelids
Palpebral conjunctiva
Thin, transparent vascular tissue that extends from the limbus to the mucocutaneous junction of the eyelid.
Conjunctiva
Covers the sclera
Bulbar conjunctiva
Vascular supply of the conjunctiva
Anterior ciliary artery
Conjunctiva is innervated by the 1st division of
CN V (Ophthalmic division)
Fine, thin, elastic layer which covers the sclera. Underneath the conjunctiva. Contains numerous blood vessels which provides nourishment for the sclera.
Episclera
Thick outer coat of the eye. Normally white and opaque. Avascular & fibrous (collagen). Continuous with the cornea anteriorly and with the dural sheath at the optic nerve posteriorly. _____ mm thick where the EOMs insert and about 1mm thick.
Sclera. 0.3.
Transparent front window of the eye. Refracts light.
Cornea
Layers of Cornea: nonkeratinized stratified squamous epithelium. Regenerative ability.
Corneal epithelium
Layers of Cornea: collagen fibers
Bowman’s layer
Layers of Cornea: thick layer (90%) of regularly arranged collagen fibers (type1), keratinocytes.
Corneal stroma
Layers of Cornea: thin, strong layer.
Dual’s layer
Layers of Cornea: thin acellular layer that serves as the modified basement membrane of the endothelium, collagen type IV.
Descemet’s membrane
Layers of Cornea: monolayer of cuboidal cells, not able to regenerate, responsible for the corne’s deturgescence.
Endothelium
The junction between sclera and cornea. May develop whitening as part of old age _______.
Limbus. Arcus senilis.
The space between the cornea and iris. Contains a watery fluid called __________. Normally acellular. Cells seen in inflammatory and infectious decision.
Anterior chamber. Aqueous humor.
Angle formed by the inner cornea and iris roots. Comprised several structure that make up the eye’s drainage system, _________ and ________.
Anterior chamber angle. Trabecular meshwork & Schlemm’s canal.
Middle avascular layer of the eye. Composed of
Uveal tract. Ciliary body, Iris & Choroid.
Contributes to the blood supply of the retina
Choroid
Colored part of the eye that controls the amount of light that enters the eye.
Iris
Hole at the center of the iris that, size is controlled by the iris muscle.
Pupil
Accounts for the variety of colors seen. Dependent on the amount of pigment in the iris. Composed of BV,CT,Melanocyte & pigment cells.
Pigmented posterior surface
Contains both dilator and sphincter muscles
Iris stroma
Contraction of the sphincter muscle leads to
Pupil constriction
Contraction of dilator muscle leads to
Pupil dilation
Blood supply of the iris
Major circle of the iris
Sensory innervation of the iris
Ciliary nerves
Circular opening at the center of the iris. Adjusts the amount of loght entering the eye.
Pupil
Parasympathetic activity of CN III will lead to
Pupillary constriction
Sympathetic activity of the pupil leads to
Dilation
Structure of the eye that produces aqueous humor
Ciliary body
Contraction of the ciliary body changes the tension of the ________ suspending the lens.
Zonular fibers
Change in tension leads to increased thickness of the lens which allows eye to focus at ______ objects ( _______ )
Near. Accomodation.
Vascular, pigmented layer between the sclera (externally) and retina (internally). Provides blood supply to the outer retinal layers.
Choroid
Biconvex structure. Refracts and focuses light on the retina. Suspended in place by zonule fibers. Anteroposterior _______ & Equatorial diameter _______.
Crystalline lens. 4-5mm. 9-10mm.
Narrow space behind the iris and in front of the zonule fibers. Space anterior to the crystalline lens. Filled with aqueous humor. Normally acellular.
Posterior chamber
Large space behind the lens. Extends up to the retina. Approximately ____ cc in volume. Filled with a transparent gel like material called ________.
Vitreous cavity. 4.5. Vitreous humor.
Thin, semitransparent, multilayer sheet of neural tissue lining the vitreous cavity.
Retina
Blood supply of Retina: branch of the ophthalmic artery. Supplies inner 1/3 of the retina.
Central Retinal Artery
Blood supply of Retina: supplied by the ophthalmic artery. Supplies outer 2/3 of the retina.
Choroid artery
Area of the retina responsible for fine & central vision.
Macula
Oval depression in the center of the macula. Approximately ___ disc diameters away from the optic disc.
Fovea. 2.
Not really a peripheral nerve, it is actually a direct extension of the CNS. 1.2 m axons. ___ mm long. Synapses at the lateral geniculate nucleus.
Optic nerve. 50.
Blood supply of the Optic nerve
Circle of zinn-haller
Optic nerve segment: 1mm long. 1.5 mmHg. Optic disc (visible by fundoscopy)
Intra ocular (optic nerve head)
Optic nerve segment: 25mm in length, 3 to 4.5 mm in diameter. Lined by dura, arachnoid and pia mater. Fuses at the apex of the orbit with periosteum and annulus of zinn.
Intra orbital
Optic nerve segment: 9mm in length. Firmly anchored to the bone (optic canal)
Intra canalicular
Optic nerve segment: 10mm long (3-16mm) just before it becomes the optic chiasm.
Intra cranial
Parietal and temporal lobes
Optic radiation
Occipital lobe
Visual cortex
X shaped structure wherein the medial fibers of both optic nerves decussate or cross to the other side. Suspended above the sella turcica.
Optic chiasm
Paired structures posterior to the optic chiasm. Composed of lateral fibers from the ipsilateral optic nerve and medial fibers from the contralateral optic nerve.
Optic tract
Sensory relay nucleus. Located in the thalamus.
Lateral geniculate body
Paired structure that carry visual information from the LGB to the visual cortex. Pass thru the parietal or temporal lobes.
Optic radiation
Inferior fibers that pass through the temporal lobe looping around the inferior horn of the lateral ventricle.
Meyer’s loop
Striate cortex or VI. Occipital lobe. Responsible for image processing.
Primary visual cortex (BA 17)
Bony cavity which contains the eye. Pear shaped with the optic nerve representing its stem. Medial walls are parallel to each other, separated by the ethmoidal and sphenoidal sinuses.
Orbit
Fluid volume of orbit
30cc
Contains the lacrimal gland fossa
Orbital plate of the frontal bone
Contains the optic canal
Lesser wing of the sphenoid
Depression located at __mm from orbital margin. Serves as the attach,ent of the cartilaginous pulley from the superior oblique muscle.
Trochlear fovea
Contains the nasolacrimal canal and lacrimal sac.
Medial orbital wall
Paper thin medial wall is known as
Lamina papyracea
Lateral wall of the orbit formed by
Zygomatic bone & Greater wing of sphenoid
Thickest and strongest wall
Lateral wall of the orbit
Site of attachment for check ligament of lateral rectus muscle, suspensory ligament of eyeball, lateral palpebral ligament and aponeurosis of the levator ligament.
Lateral orbital tubercle
Roof of the maxillary sinus. Contains the infraorbital groove. Made up of 3 bones. Maxillary, palatine and orbital plate of zygomatic bone.
Floor of the orbit
Arises from the orbital floor. Only Extraocular muscle that does not originate from the orbital apex.
Inferior Oblique muscle
Entry portal for all nerves and vessels to the orbit
Orbital apex
Ring of fibrous tissue comprised of the origins of the 4 rectii muscle, levator palpebrae. Divides the superior orbital fissure.
Annulus of Zin
Foramen in the skull between the greater and lesser wings of the sphenoid bone.
Superior orbital fissure
Outside the annulus of Zinn. Lacrimal and frontal branch of CN V. Trochlear nerve CN IV.
Lateral
Within the annulus of Zinn. Superior and inferior divisions of CN III. Nasociliary branch of CN V. Abducens nerve. Superior ophthalmic vein.
Medial
Consists of optic nerve and artery
Optic canal
Consists of maxillary and pterygoid parts of CN V. Inferior ophthalmic vein.
Inferior orbital fissure
1st major branch of the intracranial ICA
Ophthalmic artery
Branches of the Ophthalmic artery: enters the optic nerve 8-15mm behind the globe. Supplies the inner retina.
Central retina artery
Branches of the Ophthalmic artery: supplies the lacrimal gland and upper eyelids
Lacrimal artery
Branches of the Ophthalmic artery: supplies the eyelid
Medial palpebral artery
Branches of the Ophthalmic artery: supplies the anterior segment of the eye
Long posterior ciliary artery
Branches of the Ophthalmic artery: supplies optic nerve, posterior segment of the eye.
Short posterior ciliary artery
Outer structure that protect the eyeball. Lubricates the eye surface. ______ within the tarsus.
Eyelids. Meibomian glands.
Come together at the medial and lateral canthi
Lids
Normally covers about 2 mm of the superior limbus
Upper lid
Is usually at the level of the inferior limbus
Lower lid
Exposed zone between the upper and lower eyelids. In adults: ___ mm long and _____ mm wide.
Interpalpebral fissure. 27. 8-11.
Upper eyelid is more ______ that the lower eyelid.
Mobile
Eyelid segment: thinnest in the body.
Skin
Due to insertion of levator aponeurosis near the upper border of the tarsus.
Eyelid fold
Eyelid segment: has no fat content
Subcutaneous connective tissue
Eyelid segment: punctum. Eyelashes arise from the anterior portion of the lid margin. Orifices at the meibomian gland are located along the posterior portion of the lid margin.
Lid margin
Eyelid segment: Arranged into a concentric band around the interpalpebral fissure
Orbicularis oculi muscle
Parts of OOM: inserts into the medial canthal tendon, orbital rim and corrugator supercili muscle. Sphincter like action, voluntarily controlled.
Orbital
Part of OOM: may be voluntary or involuntary z(for normal reflex blinking)
Palpebral
Eyelid segment: extension of the periosteum of the roof and floor of the orbit. Attaches to the anterior surface of the levator muscle. Provides a barrier to spread of blood or inflammation.
Orbital septum
Eyelid segment: originates from a tendon that blends with the superior rectus and superior oblique muscles at the apex of the orbit.
Levator muscle
Division of Levator muscle: produces the eyelid fold
Levator aponeurosis
Division of Levator muscle: elevates the eyelids. Innervated by superiro division of CN III.
Superior tarsal muscle (Mueller’s muscle)
Eyelid segment: consist if dense CT not cartilage. Attached the orbital margin by the media. And lateral palpebral ligaments.
Tarus
Modified holocrine gland. Oily layer of the tear film.
Meibomian glands
Narrow and highly vascularized crescent shape fold of conjunctiva tissue. Roch in goblet cells. Analogous to the nictating membrane in lower animals.
Plica semilunaris
Small, fleshy, ovoid structure. Contains sebaceous glabds and fine colorless hair.
Caruncle
Located in the frontal lobe
Lacrimal gland
Lacrimal gland is divided into 2 parts by the
Levator aponeurosis
Inner to the LA
Palpebral part
Outer to the LA
Orbital part
Blood supply of the lacrimal gland
Lacrimal artery
Consist of lacrimal punctum, upper & lower canaliculi, nasolacrimal sac & nasolacrimal duct.
Lacrimal excretory system
Flow of tears is mediated by pumping of this by the orbicularis oculi muscle
Nasolacrimal sac
Opens into the nasal cavity. Valve of Hasner.
Nasolacrimal duct
Ocular motility: adducts
Medial rectus
Ocular motility: abducts
Lateral Rectus
Ocular motility: elevates, adducts & intorts
Superior rectus
Ocular motility: depresses, adducts and extorts
Inferior rectus
Ocular motility: intorts, abducts and depresses
Superior oblique
Ocular motility: extorts, abducts and elevates
Inferior oblique
Blood supply of the EOM
Muscular branches of the ophthalmic artery
Innervate the superior, medial, inferior rectus muscles and inferior oblique
CN III
Innervates the superior oblique
CN IV
Innervates the lateral rectus
CN VI