Transcript orbit-intro.for lig-in

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
Entrance width
35
mm
35mm
45mm
40
mm
Medial wall length / 45
depth
mm
Volume
30 cc
Distance from the
18
back of the globe to mm
the optic foramen
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 : Orbit is closely related to the brain in
relation to its roof and lateral wall.
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.
Nasal cavity: Nasal cavity is related to the orbit
at its medial or inner wall & through the
nasolacrimal duct
Cavernous sinus via the veins of the orbit
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 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
• Tenon’s 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
• Trauma mostly damages the medial wall &
the floor (the weakest parts give way)
• The symptomotology of orbital diseases is
reflective of its clinical anatomy