The document discusses the anatomy and functions of the extrinsic and intrinsic muscles of the eye, detailing their origins, insertions, blood supply, and innervation. It describes various muscles, including the sphincter pupillae, dilator pupillae, ciliary muscle, and several extraocular muscles, outlining their roles in eye movement and pupil size regulation. Additionally, it notes the developmental origins of these muscles from neuroectoderm and mesodermal mesenchymal tissue.

1.  Extrinsic and intrinsic muscles of the eye
• Learning objectives
a. Definition
b. Origin and insertion
c. Blood supply
d. Innervation
e. Embryologically
f. Some related

2.  Introduction
Orbital muscles
 Extraocular muscles of the eyeball
 involved in movement of the eyeball
 Intraocular muscles
 Controls shape of lense and size of pupil

3. Intraocular muscles
 Types of intraocular muscles
1. Sphincter pupillae muscle
2. Dilator pupillae muscle.
3. Ciliary muscle

4. 1. Sphincter pupillae
 Sphincter pupillae is a circular muscle, about 1
millimeter wide. It is located at the pupillary margin of
iris.
 The sphincter muscle contracts the pupil in a circular
motion while the dilator muscles enlarge the pupil by
pulling the iris radially.(diverging from the center)
 An area called the iris collarette is the thickest portion
of the iris where the sphincter muscle and dilator
muscle overlap.

5. Cont................
 Origin and insertion.
 Pupillary margin of iris.
 Action
 Constriction of pupil (miosis)
 Innervation
 Parasympathetic fibers of oculomotor nerve (CN III) via short ciliary nerves.
 Blood supply
 Long posterior ciliary arteries, anterior ciliary arteries (via minor arterial circle)

6. 2=Dilator pupillae muscle
 The dilator pupillae muscles is a ring of contractile cells within
the iris. The pupillary dilator consists of a spokelike
arrangement of modified contractile cells called myoepithelial
cells. These cells are stimulated by the sympathetic nervous
system. When stimulated, the cells contract, widening the pupil
and allowing more light to enter the eye.

7. Dilator pupillae muscle
 Origin and insertion
 outer margins of iris
 Action
 Dilates the pupil
 Innervation
 Long Ciliary nerves(sympathetic)
 Blood supply
 Not found
 Embryologically
 Both sphincter and dilator muscles originate from
NEUROECTODERM

8. 3=Ciliary muscle
 The ciliary muscle occupies the biggest portion
of the ciliary body, which lies between the
anterior border of the choroid and iris.
 The contraction of the ciliary muscle loosens
the zonular fibers increasing the convexity of
the lens, which induces accommodation for
near vision.
 The ciliary processes are attached to the lens
via zonular fibers. Through this indirect
attachment, the ciliary muscle acts on the lens
facilitating the accommodation.

9.  Layers of Ciliary muscle
 The Ciliary muscle consists three main layers :-
 longitudinal layer is the outermost muscle layer situated
adjacent to the loose connective tissue of the ciliary body.
 The middle layer is the radial layer of muscle. It
represents the transition from the longitudinal to the
circular muscle layer.
 The annular or circular layer (Müller’s muscle) is the
innermost muscle layer that functions as a sphincter of the
eye.

10. Cont..............
 Origin
 originates from a protrusion of the sclera (scleral spur)
Insertion
 The llongitudinal part inserts onto the anterior one-third of the choroid
 The Radial part: inserts connective tissue near the base of the ciliary processe
 Action
 Accommodation; and regulation of trabecular meshwork pore size
 Innervation
 Parasympathetic component of oculomotor nerve (CN III)
 Blood supply
 Long posterior ciliary arteries;(branch of ophthalmic artery)
 And drained by vorticose veins

11.  Embrylogical of the ciliary muscle
 The ciliary muscle developed from the vascular layer of
the mesenchyme Surrounding the optic cup.

12. Extraocular muscles
Has two types :
Voluntary
1. Levator pulpebrae superioris
2. Superior rectus
3. Inferior rectus
4. Medial rectus
5. Lateral rectus
6. Superior oblique
7. IInferior oblique
Involuntary
1. Superior tarsal muscle
2. Inferior tarsal muscle
3. Orbitalis

13.  Voluntary extraocular
muscles

14. 1=Levator pulpebrae superioris
1=The levator pulpebrae superioris, Does not act on eyeball but iit's Responsible
for elevating the upper eyelid
 Length 60mm long
 Muscle 40mm
 Tendon 14-20mm

15. Cont.......
 Origin
 Lesser wing of sphenoid bone
 Action
Elevation of the upper muscle
 Innervation
a) Voluntary part :superior division of oculomotor nerve
b) Involuntary part:sympathetic innervation from the carotid plexus whose
fibers join the oculomotor nerve
 Blood supply
 Receives from ophthalmic artery and it's branch via supraorbital branch

16.  Insertion (aponeurosis of the muscle splits into 3 lamina)
Upper lamina (voluntary) is inserted iinto the skin of upper lid
Middle lamina.(involuntary) atached to upper margin of superior
Lower lamina (involuntary)is attached to Superior conjunctival fornix
 Embrylogical
At 2.5 months' gestation, the levator
palpebrae superioris develops. It
separates from the superior rectus
muscle at the fourth month of
gestation. Clinically, failure of
separation of these muscles would
result in congenital ptosis.

17. 2=Superior rectus muscle
Length=41.8mm long
 Tendon=5.8mm long
 Wide=10.6mm
Origin
 Annulus of zinn
Insertion
Superiorly about 7.7mm from
limbus
•Action
• Elevates, adducts, internally rotates
eyeball
•Blood supply
• muscular branch of ophthalmic artery
•Innervation
• Superior division of CN III
• Expansion of the SR is attached to the
LPS. Thus when the SR makes the eye
look up the upper lid is also raised.

19. 3=inferior rectus muscle
• Length=4omm long
• Tendon=5.5mm long
• Wide=9.8mm
•Origin
• Annulus of zinn
•Insertion
• inferiorly about 6.5mm from
limbus
• Action
• Depresses, adducts, externally
rotates eyeball
• Blood supply
• muscular branch of ophthalmic
artery and infraorbital artery
• Innervatio
• InfeInferior division of CN III
(oculomotor)

20. 4=medial rectus muscle
• Length=4o.8mm long
 Tendon=3.7mm long
• Wide=10.3mm
Origin
• Annulus of zinn
• Insertion
• Medially about 5.5mm from
limbus
•Action
• Adducts the eyeball
•Blood supply
• muscular branch of ophthalmic
artery
Innervation
• InfeInferior division of CN III
(oculomotor)

21. Facial expantion of the sheaths (muscular fascia)
of the medial rectus attached to the zygomatic
bone.

22. 5=lateral rectus muscle
Length=4o.6mm long
 Tendon=8mm long
 Wide=9.2mm
Origin
• Annulus of zinn
 Insertion
• laterally about 6.9 mm from
limbus from limbus
Action
• Abducts the eyeball
•Blood supply
• muscular branch of ophthalmic
artery and lacrimal artery
•Innervation
• CN VI (abducens)

23.  Facial expantion of the sheaths (muscular fascia)
of the lateral rectus attached to the zygomatic
bone.

24. 6=Superior oblique muscle
Length=4omm long
 Tendon=20mm long
 Wide=10.8mm
Origin
• Medial to optic foramen, between
annulus of zinn and periorbita
Insertion
• Through pulley(trochlea) ends
superolateral aspect of eyeball.
Action
 Abducts, depresses, internally
rotates eyeball
•Blood supply
muscular branch of ophthalmic
artery
Innervation
• CN IV (trochlear)

25. 7=inferior oblique muscle
• Length=37mm long
• Tendon=1mm long
• Wide=9.6mm
• Origin
• Orbital surface of maxilla.
• Insertion
• Inferolateral aspect of eyeball
(deep to lateral rectus muscle)
•Action
• Abducts, depresses, internally
rotates eyeball
•Blood supply
• muscular branch of ophthalmic
artery
•Innervation
• CN IV (trochlear)

26. Spiral Of Tillaux

27.  Involuntary extraocular
muscles(Miller's muscles)

28. 1=Superior tarsal muscle
Superior tarsal (Muller's muscle) is a small muscle found within
the superior eyelid. It is a smooth muscle, but it is considered as a
structural component of the larger skeletal muscle of the eyelid;
levator palpebrae superioris.

29. Cont........
 Origin
Deep surface of levator palpebrae superioris muscle
 Insertion
Superior tarsal plate of the eyelid
 Action
Elevates and retracts the upper eyelid
 Innervation
Sympathetic nervous system (via internal carotid plexus)
 Blood supply
Ophthalmic artery.

30. 2=Inferior tarsal muscle
 The inferior tarsal muscle :is commonly described as a part of the
capsulopalpebral fascia and the smooth muscle fibers under the
fornix adjacent to the capsulopalpebral fascia
.The inferior tarsal muscle of the lower eyelid is a homologous
organ with the Müller muscle of the upper eyelid.

32. Cont.....
 Origin
Capsulopalpebral fascia
 Insertion
Inferior tarsal plate
 Action
Lower lid retraction
 Innervation
sympathetic nervous system like the Müller muscle.
 Blood supply
Not found

33. 3=orbitalis muscle
• The orbitalis muscle is a vestigial or rudimentary nonstriated
muscle (smooth muscle) that crosses from the infraorbital
groove and sphenomaxillary fissure and is intimately united with
the periosteum of the orbit.

34. About orbitalis muscle
• Vestigial muscle
• Crosses inferior orbital fissure and sphenomaxiliary fissure
• Unites with periosteum of orbit
Action
Forward protrusion of orbit
Innervation
Sympathetic nervous system (via internal carotid plexus)

35. • Embreologically of EOM
All the extraocular muscles develope from mesodermal
mesenchymal tissue