ANATOMY OF EXTRAOCULAR

MUSCLES

Presenter :- Dr.PushkarModerated By :- Dr.Varshini

ORBITAL MUSCLES

INTRA-OCULAR

CILIARY MUSCLES

EXTRA- OCULAR

VOLUNTARY

INVOLUNTAR

Y

1.Superior tarsal muscle.2.Inferior tarsal muscle.3.Orbitalis

1.Levator Palpebrae Superioris2.Superior rectus3.Inferior rectus4.Medial rectus5.Lateral rectus6.Superior oblique7.Inferior oblique

LEVATOR PALPEBRAE SUPERIORIS

• Origin-

Inferior surface of lesser wing of sphenoid.

• Insertion- Upper lamina - Anterior

surface of superior tarsus & skin of upper eyelid.

Middle lamina-superior margin of superior tarsus.

(Superior Tarsus Muscle /Muller muscle)

Lower lamina- Superior

conjunctival fornix

• N/S - Upper division of occulomotor nerve

Whitnalls ligament

• Thickened band of orbital fascia which extends from trochlear pulley to lacrimal gland and its fossa.

• Formed by condensation of superior sheath of levator muscle joined medially by sheath of reflected tendon of superior oblique muscle.

• It forms a true check ligament of levator muscles.

• C/S :- Damage to Trochlea can lead to partial ptosis due to damage to whitnalls ligament.

• ACTION :- Elevation of upper eye lid• C/S :- Drooping of upper eyelid. > Complete ptosis-injury to occulomotor nerve. > Partial ptosis-disruption of postganglionic sympathetic fibres from superior cervical sympathetic ganglion. Or due to damage of whitnalls ligament.

• 4 rectus muscles - origin is in the common tendous ring (annulus of Zinn)– Oval ring of connective tissue– Continuous with periorbita– Anterior to optic foramen.

• Muscles traveling from the this tendon ring to the insertions create muscle cone

• Origin of SUPERIOR AND MEDIAL RECTUS are closely attached to the dural sheath of the optic nerve, which accounts for the characteristic pain in a case of Retrobulbar neuritis, felt during upward & inward movements of the globe.

• Thyroid orbitopathy -> Medial & Inf.rectus thicken. especially near the orbital apex -> compression of the optic nerve as it enters the optic canal adjacent to the body of the sphenoid bone.

• In ophthalmoplegia proptosis occur due to muscle laxity.

C/S:_

Superior RectusOrigin :- Superior limb of the tendonous ring, and optic nerve sheath.Insertion:- Sclera 7.7 mm away from limbus obliquely making an angle of 23 d with saggital axis.(Expansion of the SR is attached to the LPS. Thus when the SR makes the eye look up ,the upper lid is also raised.)

B/S:- Lateral Muscular Art. Branch of cerebral part of ICN/S:- 3rd CN Nrv.*Separated from roof by LPS

Medial Rectus

Origin :- Annulus of Zinn (upper & Lowe limb of common tendinous sheath)

Insertion:- Sclera , 5.5 mm away from limbus( The horizontal plane of eye bisects the insertion.)

Fascial expansion from muscle sheath forms the medial check ligament and attach to medial wall of orbit

B/S:-Medial Muscular Art. Branch of cerebral part of IC + lacrimal art.N/S:- 3rd CN Nrv.

Inferior Rectus

Origin :- Annulus of ZinnInsertion:- Sclera ,6.5 mm away from limbusB/S:- Medial Muscular Art. Branch of cerebral part of ICN/S:- 3rd CN Nrv.

Lateral Rectus

Origin :- Upper and lower limb of Annulus of Zinn, AND a process of the greater wing of the sphenoid bone. Insertion:- Sclera , 6.9 mm away from limbus.

Fascial expansion from muscle sheath forms the lateral check ligament and attach to lateral wall of orbit at Whitnalls tubercle

B/S:- Muscular Art. Branch of cerebral part of IC

N/S:- 6th CN Nrv.

SPIRAL OF TILLAUX

5.5 6.9

7.7

6.5

Medial rectus inserts closest to the limbus and is therefore susceptible to injury during ant. segment surgery.

Inadvertent removal of the MR is a well known complication of pterygium removalThe Scleral thickness behind the rectus insertion is the thinnest, being only 0.3 mm thick -> chances of scleral perforation while suturing

CLINICAL ASPECT

Length of EOMSR 42mmIR 40mmLR 48mmMR 40mmSO 60mm IO 37mm

R EOM dat LONG!!!!!

SR IR MR

LR SO IO 60 mm48 mm

42 mm 40 mm 40 mm

37 mm

PULLEYS OF EOM• Discrete rings of dense collagen

tisue encircling EOM & are about 2mm length COAXIAL .

• Each EOM consist of 2 layers -Global layer & orbital layer.

• Fibres of Global layer become contiguous with tendon to insert on the globe ; orbital layer contains remaining half of EOM fibres which insert on pulley.

Pulley function as the mechanical origins of EOM & play a vital role in ocular kinematics especially the rotational properties.

• Clinical Significance:-1. A-V pattern of squint.2. Brown syndrome -

difficulty in moving eye up, particularly during adduction

Listing Law

• All achieved eye orientations can be reached by starting from one specific "primary" reference orientation and then rotating about an axis that lies within the plane orthogonal to the primary orientation's gaze direction (line of sight / visual axis).

• This plane is called Listing's plane.

• According to Listing cycloversion was 0

• A critical aspect concerning Listing’s law is the half angle rule :-

States that in order to keep eye position within Listing’s plane, the angular velocity axes of eye rotation MUST TILT out of the Listing’s plane by half the angle of the gaze’s deviation from primary position.

To implement this concept of mechanical implementation came; which involves pulley mechanism for EOM.

Origin :- Anatomical origin :-lesser wing of the sphenoid bone.

Physiological origin is the trochlea, a cartilagenous “U” on the superior medial wall of the orbit

Longest thinnest EOM, the muscle ends before the trochlea.

Insertion:- The insertion line is curved with its concavity facing the trochlea.

Ant. end lies ~13.8 mm behind the limbus .Post. end lies ~18.8mm behind the limbus.

The tendon insertion fans out below the SR into parts: Anterior 1/3 responsible for intorsion Posterior 1/3 responsible for depression

and abduction

B/S:- Muscular Art. Branch of cerebral part of ICN/S:- 4th CN Nrv.

Superior Oblique

INFERIOR OBLIQUE

(Shortest EOM)

• Origin :- Maxillary bone inferior to the nasolacrimal fossa.

• The ONLY EOM originating in the anterior orbit.

• Insertion:- Posterior lateral aspect of globe mostly inferior, below the ant.-post. horizontal plane

• Near the insertion, the inf. vortex vein are in relation to its post. border.

• B/S:- Muscular Art. Branch of cerebral part of IC• N/S:- CNIII inferior division

Factors involved in mechanics of action of EOM

1.Cross sectional area of the muscle.

(Muscles exert force in proportion to their cross sectional area)

2.Length of the muscle.

3.Distance between the anatomic and physiologic insertion is called the arc of contact.

(The power of the muscle is proportionate to its length and arc of contact)

COMPILE UP

BLOOD SUPPLY

OPHTHALMIC ARTERY

Medial Muscular Artery

MR,IR,IO

Lateral Muscular Artery

LR,SR,SO,LPS

NERVE SUPPLY

• LR6 SO4• Rest muscles by CN3

Ocular Movements & Mechanism

MONOCULAR (DUCTIONS)

1. Ad-duction2. Ab-duction3. Supraduction/ Elevation4. Infraduction / Depression5. Incycloduction / Intorsion6. Excycloduction / Extorsion.

BINOCULAR

1. Versions2. vergence

MUSCLES CAUSING MONOCULAR MOVEMETS

• Extra-ocular muscles can have primary, secondary and tertiary actions. 

• Primary muscle action is the main and most powerful direction in which the eye moves when the muscle is contracted.

• Secondary muscle action is the second direction in which the eye moves when that muscle is contracted, but is not the main or most important action.

• Tertiary muscle action is the least powerful direction in which the eye moves as a result of contraction of the muscle.

MUSCLE PRIMARY ACTION

SECONDARY ACTION

TERTIARY ACTION

MR AD-DUCTION __________ ____________

LR AB-DUCTION __________ ____________

SR ELEVATION INTORSION ADDUCTION

IR DEPRESSION EXTORSION ADDUCTION

SO INTORSION DEPRESSION ABDUCTION

IO EXTORSION ELEVATION ABDUCTION

SIN

When Test Marks come

SIX CARDINAL

POSITIONS OF GAZE

• When the globe is abducted to 23°, the visual and orbital axis coincide. In this position it acts as a pure elevator.

• If the globe were adducted to 67° the angle between the visual and orbital axis would be 90° In this position it would act as a pure intorter.

• When the globe is adducted to 51 J, the visual axis coincides with the line of pull of the muscle, the SO acts as a depressor.

• When the globe is abducted to 39 J, the visual axis and the SO make an angle of 90 J, the SO causes only intorsion

Laws of ocular motility

• Synergists - Muscles of the same eye that move the eye in the same direction. Eg: right SR and right IO.

• Antagonists - A pair of muscles in the same eye that move the eye in opposite directions. Eg: right LR and right MR.

• Yoke muscles - Pair of muscles , one in each eye , that produce conjugate ocular movements. Eg: right LR and left MR in dextroversion

HERING’S LAW OF EQUAL INNERVATION States that during any conjugate eye movements, equal and

simultaneous innervation flows to yoke muscles, which is required for symmetrical binocular.

SHERRINGTON’S LAW OF RECIPROCAL INHIBITION

MOVEMENTS States that increased innervation to an EOM is accompanied by

reciprocal inhibition of its antagonist.

THANK YOU EVERYONE FOR PATIENTLY LISTENING TO THIS SEMINAR.

For feedbacks & brickbats plz mail atykush@yahoo.co.in./drdhir2014@gmail.com

NO MORE SEMI--NAR KYUNKI ABKI BAR ……..

• Myokemia is an involuntary, spontaneous, localised quivering of a few muscles, or bundles within a muscle, but which are insufficient to move a joint.

• Typically involves the lower eyelid or less often the upper eyelid. • It occurs in normal individuals and typically starts and disappears

spontaneously. • The condition typically resolves itself.

Dayi ankh ka fadakna - shubh hota hai ya ashubh? what medical reasons are behing this thing?

' ‘आं�खों� का� फड़काना� भी� कार जा�ता� है� बड़� सं�का� ता

!!!!!! Ever faced such question!!!!!

• WHY WE NEED 6 MUSCLES?• WHAT IS USE OF INTORSION N EXTORSION?• MODEL EXPLAINNING EVERYTHING• ORBITALIS N INF TARSAL DIAG• Why width of recti are important?• For listing ..bowl with markings.• Jajantaram• Ptosis pic