Ocular Anatomy Lecture Notes

These flashcards cover essential vocabulary and concepts from the ocular anatomy lecture notes.

Orbit

The orbit is made up of 7 bones: frontal, zygomatic, maxillary, ethmoid, lacrimal, sphenoid, palatine.

Clinical Note on Orbital Floor

The floor is the weakest wall, prone to blowout fractures leading to herniation of orbital fat/IO muscle into maxillary sinus.

Inferior Orbital Fissure (IOF)

Boundaries formed by maxillary, sphenoid, palatine, and zygomatic bones; connects orbit with pterygopalatine and infratemporal fossae.

Medial Canthus Ligament

Anterior limb of medial canthal tendon is positioned anterior to lacrimal sac.

Optic Foramen

Contains the optic nerve (CN II) and ophthalmic artery.

Roof of the Orbit

Formed by the frontal bone (anterior) and lesser wing of sphenoid (posterior).

Components of the Orbital Septum

Dense fibrous tissue sheet arising from orbital rim periosteum; functions as a barrier to orbital infection.

Frontal Sinuses

Variable in number (often 2), they are the most variable paranasal sinuses in size and symmetry.

Superior Orbital Fissure (SOF) Contents

Inside annulus: CN III, nasociliary nerve, CN VI, optic nerve; outside: CN IV, frontal nerve, lacrimal nerve, superior ophthalmic vein.

Bell's Palsy Signs

Ipsilateral facial muscle paralysis including inability to close eyelids, drooping mouth.

Bell's Phenomenon

Protective reflex where the eye rolls upward on attempted eyelid closure.

Normal Blink Rate

Approximately 15 blinks per minute.

Afferent Pathway of Reflex Blink

Involves CN V (ophthalmic branch, V1).

Orbital Portion of Orbicularis Oculi

Muscle involved in forceful eyelid closure.

Hordeolum (Stye) Types

Superficial originates from Zeis or Moll glands; deep from Meibomian glands.

Layers of the Eyelid

1. Skin 2. Subcutaneous areolar tissue 3. Orbicularis oculi muscle 4. Submuscular areolar tissue 5. Fibrous layer 6. Smooth muscle 7. Conjunctiva.

Innervation of Lower Eyelids

Infraorbital nerve (V2), zygomaticofacial nerve (V2), infra-trochlear nerve (V1).

Muscles for Eyelid Opening

Levator palpebrae superioris (CN III) and Müller’s muscle.

Gentle vs Forceful Eyelid Closure

Gentle closure uses the palpebral portion; forceful closure uses the orbital portion of orbicularis.

Fornix in Conjunctiva

The medial side does not have a true fornix, containing instead the plica semilunaris and caruncle.

Goblet Cells Location

Found mainly in the fornix and palpebral conjunctiva.

Lymphatic Drainage of Conjunctiva

Medial conjunctiva drains to submandibular lymph nodes; lateral drains to preauricular lymph nodes.

Papillae vs Follicles in Conjunctivitis

Papillae are larger with central blood vessels, follicles are dome-shaped without vessels.

Trapping System for Foreign Bodies

The subtarsal groove catches debris which is moved medially by blinking.

Blood Vessel Injection Patterns

Conjunctival injection is prominent away from limbus; ciliary injection is prominent at limbus.

Lacrimal Drainage Pathway

Tears drain via superior & inferior puncta → canaliculi → common canaliculus → lacrimal sac → nasolacrimal duct → inferior meatus.

Lacrimal Gland Duct System Levels

1. Intralobular ducts 2. Interlobular ducts 3. Main excretory ducts.

Nerve Innervation of Lacrimal Gland

Parasympathetic (CN VII) promotes tear production; sympathetic assists in baseline secretion.

Layer of Tear Film - Glycocalyx

Increases adhesion & friction; essential for tear stability on cornea.

Jones I & II Tests

Jones I tests for obstruction after fluorescein instillation; Jones II tests after irrigation with saline.

Meibomian Gland Secretion Function

Secretes oil to slow evaporation and stabilize tear film.

Tear Film Composition

Antibacterial defense includes lysozyme, lactoferrin, IgA, IgG.

Turning Over Rate of Tears

Tear turnover is approximately 16% per minute.