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REVIEW OF CLINICAL ANATOMY & PHYSIOLOGY OF
THE ORBIT
Dr. Ayesha Abdullah 19.08.2015
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 the back of the globe to the optic foramen
18 mm
45mm
45mm
35mm
SALIENT ANATOMICAL FEATURES
• 7 bones• 6 contents• 5 important relationships • 4 walls• 4 margins• 4 important openings
7-6-5-4
v
MZSFELP
Bones &
walls
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 • BrainFloor• 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. Brain : Orbit is closely related to the brain in relation to its roof and lateral wall.
2. Para nasal sinuses: Orbit is intimately connected to the paranasal sinuses.
– Maxillaly sinus via the floor. – Ethmoidal and sphenoidal sinus via the medial
wall. – Frontal sinus at the roof. – Any infection can easily spread to the orbit from
the sinuses. 3. Nasal cavity: Nasal cavity is related to the
orbit at its medial or inner wall & through the nasolacrimal duct
4. Cavernous sinus via the veins of the orbit5. Pterygopalatine fossa via the inferior
orbital fissure
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 nerve2. 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• Tenon’s capsule• Fascial spaces
intraconal extraconalsubtenon
subperiosteal
Extraconal space
Intraconal space
Subperiosteal space
Structure of the lids-AAO
VIEWS : AXIAL VIEWS
RADIOGRAPHIC ANATOMY OF THE ORBIT
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
• Trauma mostly damages the medial wall & the floor (the weakest parts give way)
• The symptomotology of orbital diseases is reflective of its clinical anatomy