Transcript orbit-ana-phy

REVIEW OF CLINICAL ANATOMY
& PHYSIOLOGY OF THE ORBIT
Dr. Ayesha Abdullah
12.09.2012
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
•4
•4
•4
•6
•5
bones
walls
margins
important openings
contents
important relationships
v
Bones
& walls
MZSF
ELP
IMPORTANT OPENINGS OF THE ORBIT
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?
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
CONTENTS OF THE ORBIT
1.
2.
3.
–
–
–
–
4.
5.
6.
Eyeball & the optic nerve
Muscles – To move the eyeball.
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)
Blood vessels ( branches of ophthalmic artery, superior & inferior
ophthalmic veins)
Fat & orbital fascia – For padding purposes &for smooth
movements
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
extraconal
Intraconal
subtenon
subperiosteal
Subperiosteal
space
Extraconal
space
Intraconal
space
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 venous drainage
• Trauma mostly damages the medial wall &
the floor ( the weakest parts give way)
• The symptomotology of orbital diseases is
reflective of its clinical anatomy
References
• American Academy of Ophthalmology.Orbit,
eyelids & lacrimal system. American Academy
of Ophthalmology; 1997-98
• Jack J Kanski. Clinical ophthalmology a
systematic approach. 5th ed;2003:557-89
• Parsons’ diseases of the eye. Diseases of the
adnexa-diseases of the orbit. 19th ed. 2004;
505-524
• Remington LA. Clinical Anatomy of the visual
system. Bones of the skull & orbit. 1998; 12335