Review of anatomy & physiology of the orbit & categories of ...

REVIEW OF CLINICAL ANATOMY & PHYSIOLOGY OF THE ORBIT Dr. Ayesha Abdullah 17.08.2016 LEARNING OUTCOME By the end of this lecture the

students would be able to; correlate the structural organization of the orbit with its functions and clinical significance ANATOMY OF THE ORBIT

The orbital cavities are Adult orbital dimensions Entrance height 35 mm

Entrance width 40 mm Medial wall

length / depth 45 mm Volume

30 cc Distance from 18 the back of the mm

globe to the optic foramen 35mm 45mm 45mm

SALIENT ANATOMICAL FEATURES

7 6 5 4

4 4 bones 7-6-5-4 contents important relationships walls

margins important openings v Bones & walls

MZSF ELP Which orbit ? IMPORTANT OPENINGS OF THE ORBIT

Optic Foramen Where? size? what passes through?

Clinical significance? Superior orbital fissure Where? What passes through?

What is annulus of Zinn? Clinical significance? Inferior orbital fissure: Where?

What passes through? Clinical significance? Openings of the orbit Nasolacrimal canal

Where? What passes through? Clinical significance Inferior orbital foramen Where? What passes through

Clinical significance? Sensory Nerve Supply of the Face Orbital walls Roof

Frontal bone and sphenoid lesser wing Lacrimal gland, trochlea Superior orbital notch

Brain Floor Zygomatic, maxilla and palatine bones. weak part Infraorbital groove & canal for the

infraorbital nerve Maxillary sinus. Medial Wall lacrimal, maxillary, ethmoid & sphenoid Thinnest wall

Lamina papyrecea It separates the orbit from the nasal cavity, the ethmoidal and the sphenoidal sinuses Lateral Wall Zygomatic & Sphenoid (greater wing) Stronger wall

It separates the orbit from the (temporal fossa) and the brain Roof Medial wall

Floor IMPORTANT RELATIONS OF THE ORBIT 1. 2. 3.

4. 5. Brain Para nasal sinuses Nasal cavity Cavernous sinus

Pterygopalatine fossa Orbit as seen from above Relations of the orbit to the paranasal sinuses :FS, frontal sinus; ES, ethmoidal sinus; MS , maxillary sinus; SS, sphenoid sinus- American Academy of Ophthalmology

CONTENTS OF THE ORBIT 1. Eyeball & the optic nerve 2. Muscles To move the eyeball. 3. Nerves

To move the muscles ( III, IV, VI). To carry different sensations ( V) parasympathetic innervation ( accommodation, pupillary constriction & lacrimal gland stimulation

Sympathetic innervation ( pupillary dilatation, vasoconstriction, smooth muscles of the eye lids & hidrosis) CONTENTS OF THE ORBIT 4. Blood vessels ( branches of ophthalmic artery, superior & inferior ophthalmic

veins) 5. Fat & orbital fascia For padding purposes & for smooth movements 6. Most of the Lacrimal Apparatus (lacrimal gland & part of the tear drainage system) Lacrimal gland and the

view of the orbit from the roof Orbital fascia

Periorbita Orbital septum Tenons capsule Fascial spaces intraconal

extraconal subtenon subperiosteal Subperiosteal space Extraconal

space Intraconal space Structure of the lids-AAO RADIOGRAPHIC ANATOMY OF THE

ORBIT VIEWS : AXIAL VIEWS CORONAL VIEW SAGITTAL VIEW

AXIAL CT SCAN Summary Orbit is the protective casing for the delicate visual apparatus - the eyeball It is made up of 7 bones, has 4 margins,

4 walls/ boundaries, 4 important openings , 5 important relations & 6 contents Infection can spread to the brain from the orbit directly or through the haematogenous spread- Orbital septum is a barrier to infection Trauma mostly damages the medial wall

& the floor (the weakest parts give way) The symptomotology of orbital diseases is reflective of its clinical anatomy

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