2. Bony Orbit
Seven bones make up
the bony orbit:
Frontal
Zygomatic
Maxillary
Ethmoidal
Sphenoid
Lacrimal
Palatine
3. Bony Orbit
ROOF:
FLOOR:
The orbital roof formed
The floor of the orbit
from both the orbital
plate of the frontal
bone and the lesser
wing of the sphenoid
bone. Above the roof is
cranial cavity.
Contains: Lacrimal
fossa for lacrimal gland
is formed from three
bones and related to
maxillary sinus:
Maxillary
Palatine
Orbital plate of the
zygomatic
It contains:
Infraorbital groove
Attachment of Inferior
oblique muscle
4. Bony Orbit
MEDIAL WALL of the
orbit is formed from four
bones and related to lateral
wall of nose:
Frontal process of the
maxillary
Lacrimal
Orbital plate of the ethmoidal
Lesser wing of the sphenoid
Lacrimal fossa for lacrimal
sac.
LATERAL WALL:
Formed from two bones:
Zygomatic
Greater wing of the sphenoid
Thickest and strongest
Lateral orbital tubercle
(Whitnall’s tubercle) for
attachment of lateral
check ligament
5. Orbital Foramina
The optic foramen: Transmit
Optic nerve and Ophthalmic
artery
The supraorbital foramen,
or notch: transmit supraorbital
nerve and vessels
The zygomatic foramen:
Transmit Zygomatic nerve
Infraorbital canal: Transmit
Infraorbital nerve and vessels
Superior orbital fissure:
Transmit occulomotor nerve,
trochlear nerve, abducent
nerve, Branches of Ophthalmic
nerve, Ophthalmic veins
Inferior orbital fissure:
Maxillary nerve
8. Extraocular Muscles
The four recti and
two oblique muscles
All are supplied by
oculomotor nerve III
except superior
oblique (Trochlear
N) and lateral rectus
(Abducent N)
9. Extra ocular Muscles in the Orbit
Voluntary Muscles:
1. Four Recti – Superior, inferior, medial and lateral.
2. Two Oblique – Superior & inferior.
3. Elevator of upper eyelid – Levator palpebrae
superioris.
Involuntary Muscles:
1. Superior tarsal muscle – Deeper part of levator
palpebrae superioris
2. Inferior tarsal muscle
3. Orbitalis muscle
12. Extra ocular Muscles:Origin
Levator palpebrae superioris
Superior Oblique
Superior Rectus
Lateral Rectus
Medial Rectus
Inferior Rectus
Inferior Oblique
13. Levator Palpebrae Superioris
Origin: Orbital surface of lesser wing of
sphenoid bone, anterosuperior to optic
canal.
Insertion: Splits in two lamina
Superior lamina (voluntary) to Skin of
upper eyelid & anterior surface of
superior tarsal plate
Inferior lamina (Muller’s muscle)
(involuntary) to upper margin of superior
tarsus (superior tarsal or muller’s muscle)
& superior conjunctival fornix
Nerve Supply : Oculomotor nerve
(voluntary part); Sympathetic (involuntary
part)
Action: Elevation of upper eyelid.
Damage to oculomotor nerve lead to
paralysis of this muscle and leads to
ptosis.
Even damage to sympathetic fibers in
Horner’s syndrome leads to partial ptosis
due to paralysis of Muller’s muscle.
14. Extra ocular Muscles
Insertion: on the sclera
Recti – on sclera in front of equator ; distance from cornea –
SR = 7.7mm, LR = 6.9mm. IR = 6.5mm; MR = 5.5mm.
Superior Oblique – Behind the equator on sclera in superolateral
posterior quadrant, between the recti superior and lateralis.
Inferior Oblique : - Behind the equator on sclera in inferolateral
posterior quadrant, between the recti superior and lateralis.
26. Applied Anatomy
Abnormal deviation of eyeball is known as
Squint (Strabismus).
Paralysis of Lateral rectus due to damage to
Abducent nerve leads to Medial Squint.
Medial Squint
Damage to Occulomotor nerve leads to
paralysis of all muscles of eye except Superior
oblique and lateral rectus leading to Lateral
Squint and Ptosis-Dropping of Eyelid.
Damage to Trochlear nerve cause
paralysis of superior oblique muscle causing
diplopia while looking downwards.
Lateral Squint and
Ptosis -Dropping of
Eyelid.
28. Horner’s syndrome
• Causes: interruption of sympathetic pathway like multiple sclerosis,
syringomyelia, traction of stellate ganglion by cervical rib, ganglion
metastatic lesion.
• Signs:
•
Constriction of pupil (miosis) due to paralysis of dilator pupillae
•
Slight drooping of eyelid (ptosis) due to paralysis of Muller’s muscle
(Part of Levator palpebrae superioris)
•
Enophthalmos (Retraction of eyeball) due to paralysis of Orbitalis
muscle which support the eyeball
•
Loss of sweating (anhydrosis) damage to sympathetic fibers to
sweat glands
•
Loss of ciliospinal reflex