Eye And Orbit Flashcards
Borders of the orbit & their orientation
Base
- orbital margin surrounding the orbital opening
- anterolateral orientation
Apex
- At the optic canal in the lesser wing of the sphenoid, just medial to the superior orbital fissure
- Posteromedial
Walls of the orbit and structures that form them
For Sir, MOLS Many Parang Zoo ZS
Superior
- Frontal (orbital part)
- Sphenoid (Lesser wing)
Medial
- Maxillary (Frontal process)
- Orbital part of the ethmoid bone
- Lacrimal
- Sphenoid
Inferior
- Maxillary
- Palatine
- Zygomatic
Lateral
- Zygomatic (Frontal process)
- Sphenoid (Greater wing)
Demarcation of the inferior and lateral walls?
Inferior orbital fissure
Openings into the orbital cavity/Structures passing through
Opening
1. Optic canal - ophthalmic a., optic n.
- Superior orbital fissure
- lacrimal n., frontal n., trochlear n., oculomotor n., abducens n., nasociliary n., superior ophthalmic v. - Inferior orbital fissure
- Maxillary n. & its zygomatic branch
- Inferior ophthalmic v.
- Sympathetic n.
Orbital Fascia
Periorbita Periorbital Fascia
Bulbar Fascia
Muscular Fascia
Moveable folds of skin that cover the eyeball anteriorly when closed? Difference of the two? Elliptical opening between the two?
Eyelid!
Upper eyelid - larger and more mobile
Lower eyelid - limited movement
Elliptical opening in between the two eyelids: palpebral fissure
Layers of the eyelid
- Skin
-thin outermost layer/thinnest in the body
-contains hair follicles
-2 types of glands:
A. Sebaceous glands of Zeis/ciliary glands
B. Sweat glands of molls - Subcutaneous tissue
- next to the skin - Muscular Layer
-w/ palpebral portion of the orbicularis oculi ms.
-Superior Tarsal (Muller’s) Ms
>Smooth ms which helps elevate the Levator Palpebrae Superioris ms in the eyelid.
-supplied by sympathetic fibers - Tarsofacial Layer
- comprised of tarsus (dense fibroelastic plate) which support the eyelid
- surrounded by Tarsal gland (modified sebaceous gland) - Conjuctivae
- innermost layer
- Palpebral conjunctiva
- Bulbar conjunctiva
- Superior and inferior conjunctival fornices
- Conjunctival sac
Ptosis
Sty/Hordeolum
Conjunctivitis
-
Lacrimal apparatus portions
Secretory portion: lacrimal gland
Excretory portion:
>lacrimal canaliculi
>lacrimal sac
>lacrimal duct
What can you use to identify laterality of the eye?
Lacrimal gland
Nerve supply of the lacrimal gland
Presynaptic parasympathetic fibers: Facial n., greater petrosal n., nerve of pterygoid canal to the pterygopalatine ganglion
Synapse of pre- and postsynaptic fibers: occur at pterygopalatine ganglion
Postsynaptic: maxillary, infraorbital, zygomatic, lacrimal n.
Flow of tears?
Lacrimal puncta -> lacrimal canaliculi -> lacrimal sac -> nasolacrimal duct -> inferior nasal meatus
Movements of the Eyeball
AP axis - lat and med rotation
Vertical axis - abduction and adduction
Transverse axis - elevation and depression
Extraocular muscles
1. Innervation
- Innervation: CN III (Oculomotor n.) EXCEPT
>Lateral rectus: Abducens n (CN VI)
>Superior Oblique: Trochlear n. (CN IV)
Action
All RECTI muscles are adductors EXCEPT the lateral rectus which is an abductor.
All OBLIQUE muscles are ABductors
All superior muscles are intorters (MEDIAL rotators).
All inferior muscles are extorters (LATERAL rotators).
SO & IR are depressors.
IO & SR are elevators.
Levator Palpebrae Superioris
- Fxn
- Innervation? What happens if you disrupt its innervation?
- Elevates and depresses eyelids
2. CN III (Oculomotor n.); interruption produces constant ptosis