1. Old question papers discussion
1.Anatomy of Orbital walls
Associated clinical applications
Presenter: Dr S Rajani (PG)
Disscussant:Dr Geethanjali Asst.Prof
Chairperson:Dr Padmaprabha Asst.Prof
2. An Outline statement
The clinician must have a detailed
knowledge of orbital anatomy to
understand the structural disarrangements
in orbital disease and to employ
appropriate medical and surgical
procedures
3. Bony orbit
Quadrangular truncated pyramid with optical
canal situated between anterior cranial fossa
above and maxillary sinus below.
Pear shaped space, with 25-30cc volume
Each globe is tonically adducted by extra
ocular muscles in order to maintain ocular
alignment and occupies 6-7cc of space in
orbit
Ratio between the volume of the orbit &
eye ball is 4.5:1
4. Anatomic relations of the bony orbit
Roof: Anterior cranial fossa, frontal sinus.
Medial: Ethmoid air cells, sphenoid sinus.
Floor: Maxillary antrum.
Lateral: Temporal fossa, middle cranial
fossa.
5. Orbital contents
With in the orbit have Globe with optic nerve,
occupies 1/5th of the orbital volume
Nerves-2,3,4,6 cranial nerve, V1
(lacrimal,frontal,nasocilliary), V2 (infraorbital,
zygomatic) ,some sympathetic fibres.
Ocular muscles & Orbital fat & fascia
Lacrimal gland and sac
Vessels-Ophthalmic artery its branches,
Infraorbital vessels,
Orbital branch of middle meningeal artery
Superior & inferior ophthalmic vein
11. ORBITAL
MARGINS
• Superior margin formed by the
frontal lobe.
• Medial margin formed by the
frontal bone, Anterior lacrimal
crest and posterior lacrimal crest
of the lacrimal bone.
• Inferior margin is formed by the
Maxillary and zygomatic bones.
• Lateral margin is formed by the
Zygomatic and Frontal bones
12. Orbital rim
Superior orbital margin:
Sharp in Newborn and females
Rounded in Males
Junction of medial1/3- supraorbital notch
(SON,SOA innervate the forehead and frontal
sinus)
25% of skulls, the frontal bone turns it to a foramen.
13. Lateral orbital margin:
Orbital protector or “facial buttress”
Withstand significant trauma without fracturing.
When fractured, steps may be palpable inferiorly at
the zygomaticomaxillary suture and superolaterally
at the zygomaticofrontal suture
The lateral orbital rim is approximately at the level
of the equator of the globe
14.
15. Orbital rim
Medial orbital rim: The lacrimal sac fossa
complicates the medial rim by indenting the
bone and forming anterior (maxillary bone)
and posterior (lacrimal bone)crests.
(ALC/PLC)
Inferior orbital rim: Inferior to the rim exits the
infraorbital nerve and artery
Whitnall defined orbital rim to a single coil of an
undulating spiral
18. Orbital dimensions (Adult)
Horizontal entrance width 40 mm The maximum width is about
1cm behind the anterior orbital margin
Vertical entrance height 35 mm
Volume 30 cc
Orbital depth (measured from rim to the
optic strut)
45–55 mm, both race and sex affect
these measurements
Distance from back of globe to optic
foramen
18 mm
Orbital segment of optic nerve 25 mm
7 mm of slack in the optic nerve results
in a gentle curve with a convexity
directed inferotemporally in the orbit.
This degree of play in the nerve allows
free eye movement and affords a
margin of safety in proptotic states
without excessive stretching of the ON
20. Orbital dimensions (Adult)
Medial orbital walls: Both separated by 25mm
Roughly parallel to each other
Length is 45 to 50mm(ALC)
Lateral orbital walls:
Angled 90 degrees from each other
45 degrees in the AP direction.
Divergent axis of each orbit 22.5 degrees
Length is 40-45mm (rim to the SOF)
Long axes pass backwards and medially
.
21.
22.
23.
24. Walls of the orbit
Roof
Medial wall
Inferior wall
Lateral wall
25. Orbital roof
Triangular in shape
Greater thickness than medial and floor, resistant to fracture.
Bones involved- Orbital plate of frontal bone
Lesser wing of sphenoid(posteriorly)
(Optic foramen with ON)
Located adjacent to Anterior cranial fossa and the frontal
sinus.
Relations Above-Frontal lobe cerebrum with meninges.
Below- Periorbita,Frontal nerve,LPS,SR,SO
Trochlear nerve, Lacrimal gland
26. Roof fossae The anterolateral part of the
roof has a depression-
Lacrimal fossa lodges
Lacrimal gland.
At the junction of the roof
and medial wall ,the
Trochlear fossa is situated,
U-shaped trochlea pulley like
structure attached 2mm
behind the superior orbital
margin through which
tendon of SO passes.
27. Supra orbital notch with foramen located at
medial 1/3 Jn, superolateral to the trochlear
fossa, through which supraorbital artery ,nerve
vein pass.
Above Frontoshenoid suture –Meningeal
foramen –Recurrent meningeal artery passes
and anastomoses with Lacrimal
artery(ICA),provides collateral blood flow to orbit,
if this foramen is absent MMA courses directly
via SOF.
28. Clinical
Applications
1.As the roof is perforated neither
by major nerves nor blood
vessels, it can be easily nibbled
away in Transfrontal Orbitotomy.
2.A defect in the roof may cause
pulsatile proptosis as a result of
transmission of CSF pulsation to
the orbit and the risk of brain
herniation into the orbit.
3.The roof is reinforced laterally
by the greater wing of sphenoid &
anteriorly by superior orbital
margin so the fractures which
involve frontal bone tend to pass
towards the medial side
29. Medial wall
Medial wall formed from 4 bones:
-Frontal process of the Maxillary bone
-Lacrimal bone(anterior aspect of medial wall)
-Orbital plate of ethmoidal bone
-Lesser wing of sphenoid
Lacrimal sac fossa formed by frontal process of maxillary
bone-anterior lacrimal crest, lacrimal bone – posterior
lacrimal crest, provides insertion for the anterior and
posterior limbs of MCT.
30. With in the frontoethmoid suture(FES), 2 apertures namely
Anterior and Posterior ethmoidal foramen(AEF/PEF) through
which exits their respective artery and nerve.
AEF is typically located 24 mm posterior to the orbital rim and
the PEF lies 36 mm posterior to the rim,while optic foramen is
located 6 mm posterior to the PEF, help the surgeon to
delineate the FES which is an important surgical landmark for
the roof of the ethmoid sinus/ foveaethmoidalis.
The orbital roof slopes downward as it travels medially.
Medial to the orbital space, just beyond the frontoethmoidal
suture line, the foveaethmoidalis continues in a downward
plane and ends sagittally just above the nasal cavity and
below the anterior cranial fossa at the cribriform plate.
Bony dissection of the medial wall above the suture line
exposes the dura of the frontal lobe.
31.
32. Ethmoid portion of the medial wall, the lamina papyracea,
- extremely thin, thus prone to fracture with trauma
-easily transmit infection from the ethmoid air cells
into orbit as subperiosteal abscesses.
The thickening of medial wall at the inferior suture between
the ethmoid and maxillary bones, the Maxilloethmoid strut -
provides support to the inferomedial orbital wall and often
survives trauma.
Relations:
Medially - middle meatus of nose, sphenoidal air sinuses
- anterior/middle/posterior ethmoidal air cells
Laterally - SO & MR muscles and in between them anterior and
posterior ethmoidal and infratrochlear nerves and terminal
branch of ophthalmic artery traverse.
33. Clinical
Applications
It is the thinnest wall of the
orbit, hence frequently
fragmented d/t indirect blow
out fractures.
This accounts for ethmoiditis
being the most common
cause of orbital cellulites,
especially in children.
The medial wall is frequently
eroded by inflammatory
lesions, cysts and
neoplasms
34. Floor of the orbit
The floor of the orbit formed from 3 bones:
- Maxillary(bulk of the floor)
-Zygomatic orbital part(anterolateral floor)
-Palatine(posterior floor)
Infra orbital groove(major landmark)
-25-30 mm posterior to the orbital rim
- deepens to an enclosed canal, travels anteriorly
-opens into the infraorbital foramen on the maxillary
face(4-6mm from the rim in adults).contains the infraorbital
neurovascular bundle (easily injured by floor fractures or
inadvertent surgical dissection).
35. Floor contd…
Thinnest portion of Maxillary bone (medial to IOG)
- susceptible to blowout fractures,
- area for inferior orbital decompression
(bone can be removed with relative ease)
Relations:
Above-Inferior rectus muscle
Inferior oblique muscle
Nerve to IO muscle
Below-Maxillary air sinus
36. Clinical
Applications
The orbital floor being quite
thin is commonly involved in
‘blow –out fractures’ d/t
unsupported dome of
maxillary sinus + IOG and
IOC further weaken the
already thin floor
It is easily invaded by
tumors of the maxillary
antrum
37. Lateral orbital wall
It is the Thickest and strongest Orbital wall.
Formed from 2 bones-
Anterior part –Zygoma,has Whitnalls tubercle/Lateral orbital tubercle
located 4-5mm behind the orbital rim,1cm below FZ suture,
with insertions of posterior head of lateral canthal ligament
Lateral horn of levator aponeurosis
Check ligament of lateral rectus muscle
Lockwood’s ligament(orbital septum/L.gl fascia)
Superoanterior zygoma has zygomaticotemporal canal(ZT nerve)
Zygomaticofacial canal(ZF nerve,Lacrimal vessels and nerve)
Posterior part –Zygomatic bone and Greater wing of sphenoid,
separates posterolateral orbit from Middle cranial fossa.
Frontosphenoid suture forms boundary between lateral/roof.
Posterior border defined by SOF and IOF.
The anterior half of the globe is vulnerable to lateral trauma since it protrudes
beyond the lateral orbital margin.
38. Relations
It separates the orbit from Temporal fossa
Middle cranial fossa.
Medially -lateral rectus,
lacrimal nerve and vessels
zygomatic nerve.
39. Clinical Applications
The anterior half of globe is not covered by bone on
lateral side,so palpation of retrobulbar tumors is
easier from the lateral side.
It is the strongest portion of the orbit and needs to
be sawed open in lateral orbitotomy.
The zygomatico-sphenoid suture is an important
landmark during surgery.
Whitnall Tubercle is spared in Maxillary resection in
CA ,as it gives attachment to Lockwood ligament
etc, can lead to diplopia if resected.
40. Apertures in orbital wall
Superior orbital fissure-III, IV, VI, V1
•Inferior orbital fissure-V2, infraorbital
vessels
•Optic canal-II, Ophthalmic artery
Anterior and posterior ethmoidal
foramen (in medial wall b/w frontal &
ethmoidal bone)- transmit Anterior and
posterior ethmoidal nerve & vessels
41. Superior orbital fissure -slit linking the cranium and orbit,
between the greater and lesser wings of sphenoid bone,
through which pass the following important structures.
superior portion -lacrimal, frontal and trochlear nerves
superior ophthalmic vein.
Inferior portion -superior and inferior divisions
occulomotar nerve, abducens and nasociliary nerves
and sympathetic fibres from cavernous plexus.
Clinical application:Inflammation of the superior orbital fissure
and apex [Tolosa-Hunt syndrome] result in a multitude of sign
including ophthalmoplegia and venous outflow obstruction
42. Inferior orbital fissure-Between the greater wing of
sphenoid bone and maxilla,
connects the orbit to the pterygopalatine and
infratemporal fossae.
Through it run the maxillary nerve,
the zygomatic nerve,
branches of the pterygopalatine,
inferior ophthalmic vein
47. Ciliary ganglion –
Temporal to the ophthalmic artery,
In between the lateral rectus and optic nerve
1.5-2.0 cm (15-20 mm) posterior to the globe
1.0 cm (10 mm) anterior to the Annulus of Zinn
& SOF
The ciliary ganglion serves as the site of synapse
for the parasympathetic nerves innervating the
eye
48.
49. Ciliary ganglion
Small, 2 mm horizontally
1 mm vertically.
Blood supply from the posterior
lateral ciliary artery (supplying the anterior
half of the ganglion) and from the lateral
muscular arterial trunk (entering the
ganglion from its lateral side).
50. There are essentially 3 groups of nerves that course
through the ciliary ganglion :
sensory, parasympathetic, sympathetic
Only 1 group of nerves synapses in the ganglion
(parasympathetic).
The postganglionic parasympathetic nerves have a
short distance to go to the eye and travel along the
short ciliary nerves.
51.
52. The postganglionic sympathetic nerves travel a
long distance from the superior cervical ganglion
to get to the eye and travel along the long
ciliary nerves. .
The sensory nerves travel along both short and
long ciliary nerves. They eventually merge with
the nasociliary nerve (V1), which travels
through the annulus of Zinn.
53.
54. Afferent nerves
The sensory nerves that travel from the eye
are actually fibers of the nasociliary nerve, a
branch of the trigeminal nerve (V1). These
fibers travel along the short and long ciliary
nerves through the ciliary ganglion without
synapsing and forms a sensory root exiting
the ciliary ganglion posteriorly before merging
with the nasociliary nerve, which course along
V1 and ultimately synapse at the trigeminal
ganglion.1
55. Efferent nerves
Preganglionic (presynaptic)parasympathetic
nerves arising from the Edinger-Westphal
nucleus in the CN3 complex synapse in the
ciliary ganglion, mediate the pupil constriction
(light) and accommodative responses.
These fibers course along CN3, follow along
the inferior division of CN3 when it splits at the
level of the annulus of Zinn, and forms the
motor root entering the ciliary ganglion, where
they synapse.
57. There are also postganglionic sympathetic fibers
that course through the ciliary ganglion. These are
NOT myelinated, and arise from the superior
cervical ganglion,located near the angle of the jaw
and the bifurcation of the common carotid artery.
These sympathetic fibers do NOT synapse in the
ciliary ganglion, and follow the long posterior
ciliary nerves and short ciliary nerves to innervate
the pupillary dilator muscle.
58. Clinical correlations
Adie’s Tonic Pupil and Holmes-Adie
Syndrome
Adie’s tonic pupil is caused by postganglionic
parasympathetic pupillomotor damage, characterized
by an idiopathic, sudden-onset denervation of the
ciliary body and iris sphincter, followed by a slow
abnormal reinnervation.
This results in a sudden fixed, dilated pupil and loss
of accommodation in that eye and photophobia.
sluggish, segmental pupillary responses to light and
better response to near effort followed by slow
redilation.
Typically initially unilateral (80%), Females 70%
59. The denervation occurs at the level of the ciliary
ganglion, with aberrant regeneration of
accommodation occurring over the course of the
next 1-2 years.
Other clinical features include:
Segmental iris sphincter palsy,
light-near dissociation, and
cholinergic hypersensitivity.
• When in association with a loss of deep tendon
reflexes (hyporeflexia or areflexia)and orthostatic
hypotension it is called Holmes-Adie syndrome
60. Ciliary Ganglion Injury
The ciliary ganglion can be injured directly or
iatrogenically. Ocular and orbital surgeries
that have been associated with ciliary ganglion
injury include the following:
Retinal attachment surgery
Inferior oblique muscle surgery
Orbital surgery
Optic nerve sheath fenestration (especially
lateral orbitotomy approach)
62. Ciliary Ganglion Injury Associated With
Systemic Illness
There are some systemic infections and
inflammations that have been reported to cause a
tonic pupil, which includes the following:
Herpes zoster
Chickenpox
Measles
Diphtheria
Syphilis (congenital and acquired)
Lyme disease
Sarcoidosis
Scarlet fever
