Coats of the eyeball

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Coats of the eyeball

• Outer fibrous coat
  1-.cornea anterior transparent part
• 2-sclera--- posterior dense white part
• Middle vascular coat
  1- choroid (posteriorly) black vascular
  membrane deep to sclera.
  
  2-ciliary body (middle),contains the ciliary
  muscle (accomodation). 3-Iris
  (anteriorly) it has opening in its center
  called the pupil contains circular muscle
  fibres called sphincter pupillae radial muscle
  fibres called dilator pupillae.
• Inner nervous coat the retina

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The
Conjunctiva

• It is a thin mucous membrane that lines the inner
  surface of eyelids and reflected superiorly
  inferiorly onto anterior surface of eyeball to
  form superior inferior fornices.
• Its epithelium is continuous with that of cornea.
  
• The upper lateral part of superior fornix is
  pierced by ducts of lacrimal gland.

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Levator palpebrae superioris

• Origin roof of orbit above optic canal ,
• Insertion
  1-by superior lamella (striated
  muscle) ---anterior surface of sup. tarsal plate
  skin of upper lid.
  2-by
  inferior lamella (smooth m.F)....
  Upper margin of sup.tarsal plate.
• Nerve 1-striated ms. by oculomotor N. 2-smooth
  ms. by superior cervical sympathetic F.
• Action elevation of upper eyelid.
• Lesion of occulomotor or cervical symp.trunk
  leads to dropping of upper lid (Ptosis).

Sagittal section of eyeball

• Tarsal plates Dense fibrous tissue, lying in the
  eyelids and containing tarsal glands.

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The eyelids

• The aponeurosis of insertion of levator palpebrae
  superioris pierces the orbital septum to reach
  superior tarsal plate skin of upper eyelid.
• The superficial surface of tarsal plates
  orbital septum are covered by palpebral part of
  orbicularis oculi muscle.
• Action
  1-closed by orbicularis oculi.
  2-opened by levator
  P.S.

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The lacrimal apparatus

• Lacrimal gland 1-main
  part (orbital part) lies in lacrimal fossa in
  anterolateral part of roof of orbit.
  2-palpebral part lies in
  the lateral part of upper eyelid.
• It gives 12 ducts open into superior fornix of
  conjunctiva carrying tears to conj.sac. lacrimal
  pucti - 2 canaliculi lacrimal sac (lies in
  lacrimal groove behind medial palpebral
  ligament) nasolacrimal duct inferior meatus.

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The Lacrimal gland

• N.supply Parasymp.secretomotor fibers via
  lacrimal N.
• Preganglionic fibers pass via N. of pterygoid
  canal to the pterygopalatine ganglion.
• Postganglionic fibers leave ganglion via
  lacrimal N. into lacrimal gland.

N.of pterygoid canal
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Fascial sheath of the eyeball

• It surrounds the eyeball posteriorly from the
  optic nerve to the corneoscleral junction.
• It separates the eyeball from the orbital fat and
  provides the eyeball with a socket for free
  movement.
• Posteriorly, it fuses with the dural sheath of
  the optic nerve.
• It is pierced by
  1-ciliary nerves vessels.
  2-tendons of orbital muscles , fascial sheath is
  reflected onto each ms. as a tubular sheaths.

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The check suspensory ligaments of the
eyeball.

• The fascial sheaths for the tendons of the medial
  lateral recti are attached to the med. lat.
  walls of the orbit by medial lateral check
  ligaments.
• The lower part of fascial sheath below the
  eyeball is thickened to form suspensory ligament
  of eye, and connects the check ligaments, so it
  serves to suspend the eyeball.

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The Orbit

• What is the common tendinous ring ?
• What are the structures passing through the
  openings in the orbit ?
• Muscles of the orbit
  1-muscles of
  eyelids
  (levator palpebrae superioris).
  2-extrinsic
  muscles of eyeball.
• 3-intrinsic muscles of eyeball
• 
  

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The Common tendinous ring

• It is a fibrous ring of thickening of the
  periosteum.
• It surrounds the optic canal and bridges the
  superior orbital fissure.
• It gives origin to the 4 recti muscles.
• The sup.R .arises from the upper part of the ring
  , The inf. R. arises from the lower part of the
  ring , The med.R. arises from the med.part of the
  ring. The lat.R. arises by 2-heads from the
  lateral part of the ring.

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What are the structures passing through the
openings in the orbit ?
Maxillary N. inf. ophthalmic V..
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The 4-Recti muscles

• Origin common tendinous ring.
• Insertion they form a muscular cone that
  encloses the optic nerve and post.part of
  eyeball,/ each tendon of the muscles pierces the
  fascial sheath of the eyeball and inserted into
  sclera, 6 mm behind margin of cornea (posterior
  to corneoscleral junction)
• N.supply sup.,inf., medial recti --- oculomotor
  N./ lateral rectus--- abducent N.
• Action each ms.directs the cornea
  
  1-Superior R.--- upward medially.
  2-Inferior R.---
  downward medially.
• 3-Medial R. directs cornea medially
  
  4-lateral R.---laterally.

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The 2 oblique Muscles

• Superior O. origin post.wall of orbital cavity
  (body of sphenoid). Insertion--- its
  tendon passes through trochlea (it is a
  fibro-cartilagenous pully attached to frontal
  bone), then inserted into sup. surface of eyeball
  (sclera) beneath sup.rectus. N.supply---
  trochlear N.
  Action rotates eyeball,so that cornea looks
  downward and laterally.
• Inferior O.
  origin floor of orbital cavity.
  Insertion
  lateral surface of eyeball (sclera) ,deep to
  lateral rectus. N.supply--- N.to inferior
  oblique from oculomotor N.
• Action--- rotates eyeball so that cornea
  looks upwards laterally.

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Intrinsic muscles of eyeball
(smooth muscles)

• Smooth ,involuntary muscles of circular F
  (sphincter pupillae) radiating F.
  (dilator pupillae).... lying in the iris.
• Sphincter Pupillae N.supply by parasymp.F. from
  oculomotor N. via N.to inferior oblique after
  relay in ciliary ganglion, postganglionic fibres
  pass to eyeball via short ciliary nerves. Action
  constricts pupil in bright light during
  accommodation.
  
• Dilator Pupillae N.supply by symp.F, which
  pass to eyeball via long ciliary Ns.
  Action dilates pupil in low intensity light
  in excessive symp. activity as in fright.
  
• Ciliary muscle smooth muscle in the ciliary
  body. N.supply parasymp.F. of 3rd N. as
  sphincter pupillae muscle. Action accomodation
  by making lens more biconvex and increasing the
  refractive power of lens.

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The End

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Sensory Nerves
1-optic 2-(lacrimal)

3-frontal. 4-(nasociliary)

• Optic Nerve It is the sensory nerve of vision.
• Arise from the retina,and peirces the posterior
  surface of sclera.
• It passes through the optic canal ,accompanied by
  the ophthalmic artery (below lateral to N.)
  into the middle cranial fossa, where it joins the
  optic chiasma.
• It is surrounded by ciliary nerves vessels
  and 4 recti muscles. It is surrounded also by
  meninges, which fuse with the posterior part of
  sclera.

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Lacrimal N
parasymp.

• It arises from ophthalmic division of trigeminal
  N. in lateral wall of cavernous sinus.
• It enters orbit through S.O.F, outside tendinous
  ring.
• It passes forward above lateral rectus muscle to
  enter lacrimal gland (parasymp.secretomotor N.).
• It ends by supplying skin of lateral part of
  upper lid.

• Frontal N.
• As above in orgin and enters orbit through S.O.F,
  outside tendinous ring.
• It passes forward above L.P.S muscle and ends by
  dividing into supraorbital supratrochlear
  nerves to supply skin of forehead.

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Nasociliary Nerve

• Origin from ophthalmic N. of trigeminal N. in
  the lateral wall of cavernous sinus.
• It enters orbit through sup. Orbital fissure
  inside the tendinous ring.
• It passes medially, crossing above optic N. with
  ophthalmic artery to reach medial wall of
  orbit., along upper margin of medial rectus to
  end by dividing into 2 terminal branches.
• Branches
  1-sensory root to ciliary ganglion to
  supply eyeball through short ciliary Ns.
  2-2
  long ciliary Ns. contains sympathetic Fs. To
  dilator pupillae.
  3-posterior ethmoidal N. to supply ethmoid
  air sinuses.
  4-anterior ethmoidal N. one of the
  terminal branches.
  5- infratrochlear N. its 2nd
  terminal branch.

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Motor nerves 1-Oculomotor
2-Trochlear 3-Abducent

• Oculomotor N.
• Sup.division leaves lat.wall of cavernus sinus
  and enters the orbit through sup.orbital
  fissure,inside tendinous ring.It supplies
  sup.rectus levator P.S.
• Inf.division--- as above ,and supplies inf.rectus
  ,med.rectus ,and inf.oblique. The nerve to
  inf.oblique gives off preganglionic Fs. to
  ciliary ganglion and carries parasympathetic
  fibers to the sphincter pupillae ciliary
  muscles, via short ciliary nerves

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Trochlear abducent nerves

• Trochlear N. leaves lat.wall of cavernus S. To
  enter orbit through S.O.F, outside tendinous ring
  ---- to supply sup.oblique muscle.(SO4).
• Abducent N. leaves cavernus sinus to enter orbit
  through S.O.F, within tendinous ring---- to
  supply lateral rectus (LR6)

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The ciliary ganglion

• It is parasympathetic ganglion, situated in the
  posterior part of the orbit lateral to optic
  nerve.
• It receives preganglionic parasymp.f. from nerve
  to inf.oblique of oculomotor N.
• It sends postganglionic Fs. via short ciliary
  nerves to the eyeball to supply--- sphincter
  pupillae ciliary muscle.
• Few sympathetic Fs. pass from internal carotid
  plexus into orbit without relay in the ganglion.

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Ophthalmic artery

• It is a branch of the int.carotid artery after it
  emerges from the cavernous sinus.
• It passes through the optic canal below lateral
  to the optic nerve, then crosses above it to
  reach medial wall of orbit. It is now gives off
  numerous branches.
• Branches .

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Branches of Ophthalmic artery

• Centeral artery of retina it
  pierces meningeal sheaths of optic N. to enter
  inside substance of optic N. to reach eyeball
  (optic disc) and divides into terminal end
  arteries.
• Muscular branches.
• Ciliary arteries anterior group which enter eye
  at corneoscleral junction posterior group,
  which enters near optic N.
• Lacrimal artery to lac.gland.
• Supratrochlear supraorbital arteries to skin of
  forehead.

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Ophthalmic veins

• Sup.oph.V.communicates in front with the facial
  V.
• Inf.oph.V.communicates throuth the inf.orbital
  fissure with the pterygoid venous plexus.
• Both veins pass
• backward through
• sup.orbital fissure
• to drain into the
• cavernous sinus.
• No lymph vessels
  or
  nodes are present
  in orbital
  cavity.

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• Medial rectus.
• Lateral rectus.
• Superior rectus.
• Inferior rectus.
• Superior oblique.
• Inferior oblique.

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The optic disc

• It is the site where the optic N. leaves the
  retina.
• It is the site where it is pierced by the
  centeral artery of the retina ,and there is
  complete absence of rods cones, so that it is
  insensitive to light and is referred to as
  Blind Spot.