optha review
DESCRIPTION
Optha review . Anatomy . Number of bones in bone orbit = 7 bones Bones making up the Rim = Frontal, Maxillary, Zygomatic Close relation to cranial cavity = orbital roof Nasolacrimal fossa = Roof Weakest point of bony orbit = Ethmoidal bone , even infection can break it - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Optha review](https://reader035.vdocuments.us/reader035/viewer/2022062302/56816384550346895dd46aa3/html5/thumbnails/1.jpg)
OPTHA REVIEW
![Page 2: Optha review](https://reader035.vdocuments.us/reader035/viewer/2022062302/56816384550346895dd46aa3/html5/thumbnails/2.jpg)
Anatomy Number of bones in bone orbit = 7 bones Bones making up the Rim = Frontal,
Maxillary, Zygomatic Close relation to cranial cavity = orbital
roof Nasolacrimal fossa = Roof Weakest point of bony orbit = Ethmoidal
bone , even infection can break it Sinusitis (Mucocele) can cause = orbital
cellulitis
![Page 3: Optha review](https://reader035.vdocuments.us/reader035/viewer/2022062302/56816384550346895dd46aa3/html5/thumbnails/3.jpg)
Strongest wall of orbit = lateral wall usually fractured in RTA
Floor is strong but fractures are common
If we have muscle entrapment >> fixed eye + Diplopia maybe
Smallest = palatine , can’t be seen
![Page 4: Optha review](https://reader035.vdocuments.us/reader035/viewer/2022062302/56816384550346895dd46aa3/html5/thumbnails/4.jpg)
Optic foramen and superior ophthalmic fissure Optic foramen: within lesser wing of
sphenoid. Contents:1. Optic nerve 2. Opthalmic artery (internal carotid)3. Sympathetic plexus
![Page 5: Optha review](https://reader035.vdocuments.us/reader035/viewer/2022062302/56816384550346895dd46aa3/html5/thumbnails/5.jpg)
Superior orbital fissure : Annulus of zinn
Most of rectus muscle. Inside the Annulus:1. Optic foramen (canal)2. Abducent nerve3. Oculomotor (Sup. & Inf. Division)4. Nasociliary nerve
![Page 6: Optha review](https://reader035.vdocuments.us/reader035/viewer/2022062302/56816384550346895dd46aa3/html5/thumbnails/6.jpg)
Superior orbital fissure : Annulus of zinn Outside the Annulus:1. Trochlear nerve 2. Lacrimal nerve 3. Frontal nerve4. Opthalmic veins5. Recurrent meningeal branch of
opthalmic artery
![Page 7: Optha review](https://reader035.vdocuments.us/reader035/viewer/2022062302/56816384550346895dd46aa3/html5/thumbnails/7.jpg)
Extraocular muscles
All by 3rd CN (Oculomotor) Exception is :1. SO 4 : superior oblique by 4th
Trochlear 2. LR 6 : lateral rectus by 6th Abducent
Must know the function of each Superior oblique = depression,
intortion Inferior oblique = elevation ,
extortion
![Page 8: Optha review](https://reader035.vdocuments.us/reader035/viewer/2022062302/56816384550346895dd46aa3/html5/thumbnails/8.jpg)
Levator palpebra superioris Can raise upper eye lid by 15 mm Palsy >> Ptosis (CN 3)
Muscle that give you the eye Crease
Inserts little anterior to Tarsal plate Inside it >> Mebomian gland
(sebum) Sebum >> part of the tear film
![Page 9: Optha review](https://reader035.vdocuments.us/reader035/viewer/2022062302/56816384550346895dd46aa3/html5/thumbnails/9.jpg)
Conjunctiva Mucus membrane , Goblet cells (produce mucin) non keratinized epithelium lubrication, tears (mucin) , immunity
Palpebral conjunctiva Lines the eyelids.
Bulbar or ocular conjunctiva Covers the eyeball.
Fornix conjunctivaForms the junction between the bulbar and palpebral conjunctivas.
Terminates at the Limbus
![Page 10: Optha review](https://reader035.vdocuments.us/reader035/viewer/2022062302/56816384550346895dd46aa3/html5/thumbnails/10.jpg)
Arterial blood supply of EYE LID Superficial:1. Facial ( external carotid)
Deep:1. Opthalmic ( internal carotid)
![Page 11: Optha review](https://reader035.vdocuments.us/reader035/viewer/2022062302/56816384550346895dd46aa3/html5/thumbnails/11.jpg)
Venous drainage of EYE LID Superficial:1. drains into the internal and external
jugular veins. Deep:1. Vortex >> which flows into the
cavernous sinus.
![Page 12: Optha review](https://reader035.vdocuments.us/reader035/viewer/2022062302/56816384550346895dd46aa3/html5/thumbnails/12.jpg)
LYMPHATICS
Only found in eye lid & conjunctiva
Spread of systemic infection to the eye is not easy because of this.
Lymphadenopathy ? >> external eye infection
Adenovirus conjunctivitis >> lymphadenopathy in the neck
![Page 13: Optha review](https://reader035.vdocuments.us/reader035/viewer/2022062302/56816384550346895dd46aa3/html5/thumbnails/13.jpg)
Lacrimal gland
Located in nasolacrimal fossa (ROOF)
Divided into 2 parts: 1. Palpebral2. Orbital
Smaller, palpebral part can be seen in the superolateral conjunctival fornix, when you ever the eye lid.
![Page 14: Optha review](https://reader035.vdocuments.us/reader035/viewer/2022062302/56816384550346895dd46aa3/html5/thumbnails/14.jpg)
Eye globe
Vitreous >> Sodium hyaluronate
Anterior & posterior chambers >> aqueous fluid (ciliary body).
![Page 15: Optha review](https://reader035.vdocuments.us/reader035/viewer/2022062302/56816384550346895dd46aa3/html5/thumbnails/15.jpg)
Arterial blood Supply of the Orbit First you have to know : Uveal tract = Iris , Choroid , ciliary bodyvascular pigmented middle layer of the eye.
Posterior ciliary vessels >> uveal tract.
Cilioretinal arteries >> the sclera, cornea, conjunctiva.
The anterior ciliary arteries >> rectus muscles.
![Page 16: Optha review](https://reader035.vdocuments.us/reader035/viewer/2022062302/56816384550346895dd46aa3/html5/thumbnails/16.jpg)
Venous drainage
The vortex veins drain >> Uveal tract
Superior and inferior ophthalmic veins>> Orbit.
![Page 17: Optha review](https://reader035.vdocuments.us/reader035/viewer/2022062302/56816384550346895dd46aa3/html5/thumbnails/17.jpg)
Cornea
Layers :1. Tear film 2. Epithelium >> regrows in 7 days 3. Bowman’s membrane >> Scar if
injured4. Stroma >> keratocytes , collagen5. Decemet’s membrane 6. Endothelium >> single cells , if you
lose it its gone.
![Page 18: Optha review](https://reader035.vdocuments.us/reader035/viewer/2022062302/56816384550346895dd46aa3/html5/thumbnails/18.jpg)
Tear film
From outer most to inner :
1. Lipid >> mebomian gland2. Aqueous >> lacrimal gland 3. Mucus >> goblet cells in
conjunctiva
![Page 19: Optha review](https://reader035.vdocuments.us/reader035/viewer/2022062302/56816384550346895dd46aa3/html5/thumbnails/19.jpg)
Sclera
Opaque, fibrous, protective, containing collagen and elastic fiber.
![Page 20: Optha review](https://reader035.vdocuments.us/reader035/viewer/2022062302/56816384550346895dd46aa3/html5/thumbnails/20.jpg)
Retina
Neurosensory 10 layers Fovea >> sharpest image (all cons) Ganglion cells layer axons >> optic
nerve
![Page 21: Optha review](https://reader035.vdocuments.us/reader035/viewer/2022062302/56816384550346895dd46aa3/html5/thumbnails/21.jpg)
Lens
Outer most part >> capsule Epithelium keeps migrating Zonules >> for accomodation
![Page 22: Optha review](https://reader035.vdocuments.us/reader035/viewer/2022062302/56816384550346895dd46aa3/html5/thumbnails/22.jpg)
Optic nerve Formed by axons of ganglion cells
Optic nerve is surrounded by meninges.
The central retinal artery and vein enter the eye in the center of the optic nerve.
![Page 23: Optha review](https://reader035.vdocuments.us/reader035/viewer/2022062302/56816384550346895dd46aa3/html5/thumbnails/23.jpg)
Embryology
End of 4th week of pregnancy Forebrain Neuroectoderm : A pair of optic vesicles
evaginate ( gives optic stalk too) it is Invagination of optic vesicle >> optic cup
Invagination of Surface ectoderm >> lens placode >> lens pit >> lens vesicle.
Full development by 8 weeks.
![Page 24: Optha review](https://reader035.vdocuments.us/reader035/viewer/2022062302/56816384550346895dd46aa3/html5/thumbnails/24.jpg)
For reading
Neuroectoderm gives rise to the following compartments of the eye:
Retina Epithelial lining of Ciliary body and Iris Optic nerves Vitreous
Retina Develops from the walls of the optic cup
![Page 25: Optha review](https://reader035.vdocuments.us/reader035/viewer/2022062302/56816384550346895dd46aa3/html5/thumbnails/25.jpg)
Difference between Sclera & Cornea ??
Arrangement of the Stromal contents !
Choroid is very highly vascularised any problem like autoimmune or
infection is the job of choroid to deal with.