1 - Zill - Orbit Flashcards
Bones of the Orbit
- Roof - Frontal
- Floor - Maxillary
- Medial Wall - Maxillary, Lacrimal, Ethmoid, Frontal, Sphenoid Bones
- Lateral Wall - Zygomatic, Sphenoid
What does the orbit serve as a highways for?
Nerves and Vessels to Face, Scalp, and Nasal Cavity
Optic Canal
In base of Lesser Wing of Sphenoid
Contents:
Optic Nerve (CN II)
Opthalmic Artery
Superior Orbital Fissure
Between Greater and Lesser Wings of Sphenoid
Contents:
Cranial Nerves III, IV, V1, VI (3, 4, 5.1, 6)
Ophthalmic Veins
Supraorbital Notch (Foramen)
In frontal bone
Contents:
Supraorbital Nerve (From V1)
Supraorbital Artery (From Ophthalmic A.)
Supraorbital Vein (From Opthalmic V.)
Infraorbital Foramen
In maxillary bone
Contents:
Infraorbital Nerve (From V2)
Infraorbita Artery (From Maxillary Artery)
Infraorbita Vein
Anterior and Posterior Ethmoidal Foramina
Between Ethmoid and frontal bones (back of the eye)
Connect Orbit and Nasal Cavities
Contains:
Anterior and Posterior Ethmoidal Nerves (branch of V1)
Anterior and Posterior Ethmoidal Arteries (branch of Ophthalmic)
Anterior and Posterior Ethmoidal Veins (branch of Ophthalmic)
Opening of Nasolacrimal Duct
In Maxillary, Lacrimal, and Inf. Nasal Concha
Contains:
Membraneous Nasolacrimal Duct
Tears
Stye (Horde’olum)
Obstruction or Infection of Sebaceous Gland in subcutaneous layer
Eyelids (Palpebrae)
Layers
Layers:
Skin - Contains eyelashes, openings of sebaceous, sweat glands
Subcutaneous Layer - Connective tissue, contains sebaceous glands (Stye here)
Tarsal Plate - Fibrous CT skeleton of eyelid (Chalazion here)
Orbital Septum - CT layer continuous with periosteum of orbit
Conjuctiva - Clear membrane covering inside of lide, fuses to sclera (Conjuctiva or “Pinkeye”)
Muscles:
Orbicularis Oculi (palpebral part) - Closes eye, Cranial Nerve 7
What can occur if Orbicularis Oculi is paralyzed?
What nerve innervates this?
Cornea can become damaged, as the eyelid does not function
Cranial Nerve VII
Chalazion
Obstruction of Tarsal (meibomian) Gland in eyelid
Levator Palpebrae Superioris
Action?
Innervation?
Clinical?
Action: Lift upper eyelid
Innervation:
Skeletal muscle part - CN III
Smooth Muscle Part - Sympathetics
Clinical: Eyelid Droop, damage to CN III or Sympathetics
Conjuctivitis (Pinkeye)
Inflammation of Conjunctiva
Lacrimal Gland
Action?
**Innervation?**
Action: Superolateral orbit, opens by ducts through conjunctiva to superior fornix, constantly produces tears
**Innervation: Cranial Nerve VII**
Facial Nerve and Lacrimal Duct:
Block VII?
Pressure/Irritate VII?
Block - Decrease tears
Pressure/Irritate - Excessive Tears
Human Development - Obstructed Nasolacrimal Duct
Failure of duct to canalize, tears drain over lower eyelid to face
Opened surgically for tears to drain to nasal cavity