Transcript IN THE NAME OF GOD ANATOMY OF THE EXTRAOCULAR MUSCLES MOHAMMAD REZA AKHLAGHI.
Slide 1
IN THE NAME OF GOD
Slide 2
ANATOMY OF THE EXTRAOCULAR
MUSCLES
MOHAMMAD REZA AKHLAGHI
Slide 3
EXTRAOCULAR MUSCLES
There are 7 extraocular muscles:
4 rectus muscles,
2 oblique muscles
levator palpebrae superioris muscle.
Slide 4
EXTRAOCULAR MUSCLES
Slide 5
INNERVATION
Cranial nerve VI (abducens) innervates the
lateral rectus muscle
cranial nerve IV (trochlear) innervates the
superior oblique muscle
cranial nerve III has an upper and a lower
division: innervates the levator palpebrae,
superior rectus, medial rectus, inferior rectus,
and inferior oblique muscles.
Slide 6
EYE POSITION & MUSCLE ACTIONS
primary position
The primary action is the major effect of a
muscle, when the muscle contracts while the
eye is in primary position.
The secondary and tertiary actions: of a muscle
are the additional effects on the position of the
eye in primary position
Slide 7
RANGE OF ACTION
The globe usually can be moved about 50° in
each direction from primary position.
Under normal viewing circumstances, the eyes
move only about 15°-20° from primary
position before head movement
Slide 8
ANNULUS OF ZINN
A cone-shaped structure, behind the eyeball,
composed of five extraocular muscles (medial
rectus, lateral rectus, superior rectus, inferior
rectus, and superior oblique), within which runs
the optic nerve (cranial nerve II), the
ophthalmic artery, and the ophthalmic vein
Slide 9
Slide 10
EXTRAOCULAR MUSCLES
Slide 11
MEDIAL RECTUS
Origin: annulus of zinn
Insertion: medially, in hori meri, 5.5 mm from
limbus
Length: 40mm L, 10mm W, 4mm T
Direction: 90o
Innervation: lower CN III
Blood supply: Inf. Mus. Branch Of Oph. A.
Action: addu
Slide 12
MEDIAL RECTUS
Slide 13
LATERAL RECTUS
Origin: annulus of zinn
Insertion: laterally, in horizontal meridian, 6.9mm
from limbus
Length: 40 mm L, 9 mm W, 8 mm T
Direction: 90o
Innervation: CN VI
Blood supply: Inf. Mus. Branch Of Oph. A.
Action: abd
Slide 14
LATERAL RECTUS
Slide 15
INFERIOR RECTUS
Origin: annulus of zinn
Insertion: inferiorly, in ver. Mer. 6.5 mm from
limbus
Length: 40 mm L, 10 mm W, 5.5 mm T
Direction:23o
Innervation: lower CN III
Action: Dep. Ext, Add,
Slide 16
INFERIOR RECTUS
Slide 17
SUPERIOR RECTUS
Origin: annulus of zinn
Insertion: superiorly, in ver. Mer. 7.7 mm from
limbus
Length: 40 mm L, 10 mm W, 5.5 mm T
Direction:23o
Innervation: upper CN III
Action: Dep. Ext, Add,
Slide 18
SUPERIOR RECTUS
Slide 19
SUPERIOR OBLIQUE
Origin: superior of annulus of zinn (func. At
trochlea
Insertion: post. to equator in suprotemp.
Length: 32 mm L, 6 mm W, 25 mm T
Direction:51o
Innervation: CN IV
Action: Int, Dep, Abd,
Slide 20
SUPERIOR OBLIQUE
Slide 21
INFERIOR OBLIQUE
Origin: behind of lacrimal fossa
Insertion: post. to equator in macular area.
Length: 37 mm L, 10 mm W, 1 mm T
Direction:51o
Innervation: lower CN III
Action: Ext, Elev, Abd,
Slide 22
INFERIOR OBLIQUE
Slide 23
LEVATOR PALPEBRAE SUPERIORIS
Origin: above of annulus of zinn
Insertion: above and anterior surface of tarsus.
Innervation: upper CN III
Action: eyelid elevation
Slide 24
ADDUCTOR MUSCLES
Slide 25
ABDUCTORS
Slide 26
ELEVATORS
Slide 27
DEPRESORS
Slide 28
INTERNAL ROTATORS
Slide 29
EXTERNAL ROTATORS
Slide 30
INSERTION RELATIONSHIPS OF THE RECTUS MUSCLES
Spiral of Tillaux
Slide 31
MUSCLE CONE
The muscle cone lies posterior to the equator. It
consists of the extraocular muscles, the
extraocular muscle sheaths, and the
intermuscular membrane. The muscle cone
extends posteriorly to the annulus of Zinn at
the orbital apex
Slide 32
TENON'S CAPSULE
Is the bulk of the orbital fascial system
Forms the envelope within which the eyeball
moves
Fuses posteriorly with the optic nerve sheath
and anteriorly with the intermuscular septum
Posterior portion is thin and flexible
Posterior to the equator, it is thick and tough,
suspending the globe to the periorbital tissues
Slide 33
Slide 34
Slide 35
INTERMUSCULAR SEPTUM
a membrane that spans between rectus
muscles and fuses with the conjunctiva 3 mm
posterior to the limbus.
Posterior to the globe, it separates the
intraconal fat pads from the extraconal fat
pads.
Numerous extensions from all the extraocular
muscle sheaths attach to the orbit and help
support the globe.
Slide 36
ANATOMICAL CONSIDERATIONS DURING
SURGERY
Damaging of nerves during anterior surgery
An
instrument thrust more than 26 mm posterior to the rectus
muscle's insertion may cause injury to the nerve.
The nerve supplying the inferior oblique muscle
enters the lateral portion of the muscle, where
it crosses the inferior rectus muscle; the nerve
can be damaged by surgery in this area.
Cranial nerve IV would not be affected by a
retrobulbar block.
Slide 37
CONT.
The intermuscular septum connections,
especially between rectus muscles and oblique
muscles, can help locate a lost muscle during
surgery.
Extensive intermuscular septum dissections
are not necessary for rectus recession surgery.
During resection surgery, the intermuscular
septum connections should be severed
Slide 38
The blood supply to the extraocular muscles
provides almost all of the temporal half of the
anterior segment circulation and the majority of
the nasal half of the anterior segment
circulation. Therefore, simultaneous surgery on
3 rectus muscles may induce anterior segment
ischemia, particularly in older patients.
Slide 39
The inferior rectus muscle is distinctly bound to
the lower eyelid by the fascial extension from its
sheath
Slide 40
Slide 41
The sclera is thinnest just posterior to the 4
rectus muscle insertions. This area is the site
for most muscle surgery, especially for
recession procedures. Therefore, scleral
perforation is always a risk during eye muscle
surgery.
Slide 42
Slide 43
IN THE NAME OF GOD
Slide 2
ANATOMY OF THE EXTRAOCULAR
MUSCLES
MOHAMMAD REZA AKHLAGHI
Slide 3
EXTRAOCULAR MUSCLES
There are 7 extraocular muscles:
4 rectus muscles,
2 oblique muscles
levator palpebrae superioris muscle.
Slide 4
EXTRAOCULAR MUSCLES
Slide 5
INNERVATION
Cranial nerve VI (abducens) innervates the
lateral rectus muscle
cranial nerve IV (trochlear) innervates the
superior oblique muscle
cranial nerve III has an upper and a lower
division: innervates the levator palpebrae,
superior rectus, medial rectus, inferior rectus,
and inferior oblique muscles.
Slide 6
EYE POSITION & MUSCLE ACTIONS
primary position
The primary action is the major effect of a
muscle, when the muscle contracts while the
eye is in primary position.
The secondary and tertiary actions: of a muscle
are the additional effects on the position of the
eye in primary position
Slide 7
RANGE OF ACTION
The globe usually can be moved about 50° in
each direction from primary position.
Under normal viewing circumstances, the eyes
move only about 15°-20° from primary
position before head movement
Slide 8
ANNULUS OF ZINN
A cone-shaped structure, behind the eyeball,
composed of five extraocular muscles (medial
rectus, lateral rectus, superior rectus, inferior
rectus, and superior oblique), within which runs
the optic nerve (cranial nerve II), the
ophthalmic artery, and the ophthalmic vein
Slide 9
Slide 10
EXTRAOCULAR MUSCLES
Slide 11
MEDIAL RECTUS
Origin: annulus of zinn
Insertion: medially, in hori meri, 5.5 mm from
limbus
Length: 40mm L, 10mm W, 4mm T
Direction: 90o
Innervation: lower CN III
Blood supply: Inf. Mus. Branch Of Oph. A.
Action: addu
Slide 12
MEDIAL RECTUS
Slide 13
LATERAL RECTUS
Origin: annulus of zinn
Insertion: laterally, in horizontal meridian, 6.9mm
from limbus
Length: 40 mm L, 9 mm W, 8 mm T
Direction: 90o
Innervation: CN VI
Blood supply: Inf. Mus. Branch Of Oph. A.
Action: abd
Slide 14
LATERAL RECTUS
Slide 15
INFERIOR RECTUS
Origin: annulus of zinn
Insertion: inferiorly, in ver. Mer. 6.5 mm from
limbus
Length: 40 mm L, 10 mm W, 5.5 mm T
Direction:23o
Innervation: lower CN III
Action: Dep. Ext, Add,
Slide 16
INFERIOR RECTUS
Slide 17
SUPERIOR RECTUS
Origin: annulus of zinn
Insertion: superiorly, in ver. Mer. 7.7 mm from
limbus
Length: 40 mm L, 10 mm W, 5.5 mm T
Direction:23o
Innervation: upper CN III
Action: Dep. Ext, Add,
Slide 18
SUPERIOR RECTUS
Slide 19
SUPERIOR OBLIQUE
Origin: superior of annulus of zinn (func. At
trochlea
Insertion: post. to equator in suprotemp.
Length: 32 mm L, 6 mm W, 25 mm T
Direction:51o
Innervation: CN IV
Action: Int, Dep, Abd,
Slide 20
SUPERIOR OBLIQUE
Slide 21
INFERIOR OBLIQUE
Origin: behind of lacrimal fossa
Insertion: post. to equator in macular area.
Length: 37 mm L, 10 mm W, 1 mm T
Direction:51o
Innervation: lower CN III
Action: Ext, Elev, Abd,
Slide 22
INFERIOR OBLIQUE
Slide 23
LEVATOR PALPEBRAE SUPERIORIS
Origin: above of annulus of zinn
Insertion: above and anterior surface of tarsus.
Innervation: upper CN III
Action: eyelid elevation
Slide 24
ADDUCTOR MUSCLES
Slide 25
ABDUCTORS
Slide 26
ELEVATORS
Slide 27
DEPRESORS
Slide 28
INTERNAL ROTATORS
Slide 29
EXTERNAL ROTATORS
Slide 30
INSERTION RELATIONSHIPS OF THE RECTUS MUSCLES
Spiral of Tillaux
Slide 31
MUSCLE CONE
The muscle cone lies posterior to the equator. It
consists of the extraocular muscles, the
extraocular muscle sheaths, and the
intermuscular membrane. The muscle cone
extends posteriorly to the annulus of Zinn at
the orbital apex
Slide 32
TENON'S CAPSULE
Is the bulk of the orbital fascial system
Forms the envelope within which the eyeball
moves
Fuses posteriorly with the optic nerve sheath
and anteriorly with the intermuscular septum
Posterior portion is thin and flexible
Posterior to the equator, it is thick and tough,
suspending the globe to the periorbital tissues
Slide 33
Slide 34
Slide 35
INTERMUSCULAR SEPTUM
a membrane that spans between rectus
muscles and fuses with the conjunctiva 3 mm
posterior to the limbus.
Posterior to the globe, it separates the
intraconal fat pads from the extraconal fat
pads.
Numerous extensions from all the extraocular
muscle sheaths attach to the orbit and help
support the globe.
Slide 36
ANATOMICAL CONSIDERATIONS DURING
SURGERY
Damaging of nerves during anterior surgery
An
instrument thrust more than 26 mm posterior to the rectus
muscle's insertion may cause injury to the nerve.
The nerve supplying the inferior oblique muscle
enters the lateral portion of the muscle, where
it crosses the inferior rectus muscle; the nerve
can be damaged by surgery in this area.
Cranial nerve IV would not be affected by a
retrobulbar block.
Slide 37
CONT.
The intermuscular septum connections,
especially between rectus muscles and oblique
muscles, can help locate a lost muscle during
surgery.
Extensive intermuscular septum dissections
are not necessary for rectus recession surgery.
During resection surgery, the intermuscular
septum connections should be severed
Slide 38
The blood supply to the extraocular muscles
provides almost all of the temporal half of the
anterior segment circulation and the majority of
the nasal half of the anterior segment
circulation. Therefore, simultaneous surgery on
3 rectus muscles may induce anterior segment
ischemia, particularly in older patients.
Slide 39
The inferior rectus muscle is distinctly bound to
the lower eyelid by the fascial extension from its
sheath
Slide 40
Slide 41
The sclera is thinnest just posterior to the 4
rectus muscle insertions. This area is the site
for most muscle surgery, especially for
recession procedures. Therefore, scleral
perforation is always a risk during eye muscle
surgery.
Slide 42
Slide 43