OCULAR APPENDAGES.ocular anatomy in very easy way

OCULAR APPENDAGES /ADNEXA
by Azmat jehan

 Ocular; from oculars (Latin) meaning eye.
 Adnexa: Pertaining or relating structure
 Accessory parts or parts related to the
eye.
 Eyelids and eyebrows.
 Lacrimal apparatus. etc

Eyebrow
 Eyebrows are hair bearing areas of skin
that lie at the junction of forehead and
upper eyelid.
 The hair of the eyebrow is darker than
scalp hair and are thick and short.

 The eyebrows can be raised, lowered or
drawn towards each other, by the action of
different muscles.
 The nerve that makes these muscles move
is the facial nerve.
 In the paralysis of this nerve the affected
eyebrow is set lower than their normal one.

Eyelids
Eyelids are a pair of thin fleshy curtains
that cover the orbit and its contents on
each side.
There are two eyelids on each side, an
upper eyelid and lower eyelid. The upper
eyelid is large than the lower and is more
mobile.

 A skin crease or furrow marks both
the eyelids called superior and the
inferior palpebral sulcus.
 These skin creases divide the eyelid
into two parts the:

 Orbital part &
 Tarsal part
 The upper skin crease is more pronounced.

 The upper and the lower eyelids meet at
their inner and outer ends forming angles
called canthi ;
 medial canthus for the inner one &
 lateral canthus for the outer one.

Palpebral fissure/ aperture.
Palpebra - Latin eyelid
 When open the eyelids margin form an
elliptical opening called the Palpebral fissure
or Palpebral aperture.
 From the medial to the lateral canthus it
measures about 30 mm.

 The vertical height of the fissure is 7 – 10 mm
in males, and 8 –12 mm in females.
 Size of the fissure varies from person to
person and from race to race.

Blood supply to eyelid
 Arterial blood supply
 Medial palpebral branch of ophtalmic
 Lateral palpebral branch of lacrimal
 Branches of facial
 Veinus supply
 Pretarsal plexus-------facial and temporal vein
 Post tarsal plexus----ophtalmic vein

Nerve supply to eyelid
 Sensory =supra orbital (v1)
 supra trochlea(v1)
 Uper lid =infra trochlea
 palpebral branch of lacrimal (v1)
 Lower lid=infra orbital (v2)

Motor supply
 Orbicularis -----------facial nerve
 Levator----------------occulu0motor nerve
 Muller -----------------sympathetic nerve

Epicanthus or Pesudo strabismus
 A fold of skin overlaps the medial canthus in
some races like the Chinese race.
 It gives a false impression of an inwardly
deviated eye (squint)

Lacrimal caruncle
 Caruncle (Latin-meaning a piece of flesh)
 At the medial canthus between the eyelid
margins there is a triangular area called the
Lacrimal caruncle.
 Lateral to the caruncle is a vertical curved
fold of conjunctiva ,called the semilunar fold
(plica semilunaris)

Eyelid margin
 The eyelids have got free edges called the
eyelid margins.
 Which meet at the canthi.
 The inner canthus is somewhat rounded
while the outer canthus makes an angle of
60.

 Length of the lid margins is about 30 mm.
 Thickness of lid margins is 2mm.
 Lid margin is divided into outer 5/6 and inner
1/6

 The inner 1/6 is called the Lacrimal margin
and it is rounded. It does not have
eyelashes.
 The outer 5/6 is called the ciliary margin
(cilia – hair). It bears the eyelashes.
 Gland of the eyelids open onto the lid
margin and these opening can be seen.

Eyelashes
 Arise from the ciliary margin in front of the
opening of the glands.
 more on the upper lid, about 175 in the
upper lid and 75 in the lower.
 They are arranged in two rows.

 Darker than scalp hair and usually do not
get gray with aging.
 are replaced every 100-150 days i.e. 3-5
months.
 The eyelashes of the upper lid are curved
upwards and those of the lower lid are
curved downwards, to avoid rubbing
against the eyeball and scratching the
cornea.

Gray Line
 At the lid margin between the openings of
the lid glands and the eyelashes there is a
shallow groove called the intermarginal
sulcus or the gray line.
 If the lid is cut at the line it can be easily
split into two layers.

Lacrimal Papilla, Punctum, &
Canaliculi
 Close to the medial canthus on both the
upper & the lower lid, there is an elevation
called the “Lacrimal papilla”
 On top of this elevation is an opening
called the Lacrimal punctum
 (punctum; Latin; point)

 this is a small hole which opens into a
small tube called the Lacrimal canaliculus
(meaning small canal)
These small tubes open into a sac like
structure on either side of the nose
called the lacrimal sac.
All these structures belong to the
tear drainage system.

STRUCTURE OF EYELIDS
Eyelids are basically composed of four
structures:
 Skin
 Fibrous tissue
 Muscle
 Mucous membrane

 If the eyelid is split at the gray line you
get two layers called the laminae.
 The front layer makes
 the anterior lamina &
 the back layer is called the posterior
lamina.

ANTERIOR LAMINA
Consists of:
SKIN
 Skin of the eyelids is very thin.
 It does not have the fat layer underneath
it like the rest of the body.
 Therefore there is lot of loose space
beneath the skin.

 Eyelids have an enormous capacity of
swelling up because of loose tissue.
MUSCLE
 The muscle beneath the skin is called
oricularis oculi.

ORBICULARIS OCULI:
 This muscle belongs to the variety of
skeletal muscles.
 Its fibers encircles the eye in the form of a
ring hence the name orbicularis.
 It is supplied by facial nerve.
 When it contracts it makes the eyelids
close.

 The action of the muscle helps in pumping
the tears in to the drainage system.
 In paralysis of this muscle the eyes remain
partly open and this dries up the tears
causing damage to the cornea.

POSTERIOR LAMINA
Consists of
 Muscles
 Fibrous tissue the tarsal plates
 Mucous membrane conjunctiva

FIBROUS TISSUE TARSAL PLATES
 Fibrous tissue forms the skeleton of the
lids.
 It is in the form of tough small plates that
give firmness and shape to eyelids.
 These plates with their attached ligaments
keep the lids in apposition with the eyeball.

 Tarsal plate of the upper eye lid is larger than the
lower eye lid.
 The upper tarsal plate is 10mm.
 &the lower tarsal plate is 5mm.
 Within the substance of the tarsal plate are glands
called the tarsal glands (Meibomian glands).which
are arrange in a single row and the duct discharge
their secreation on to the eye lid margin.when the
eyelid is everted,they can be seen as long yellow
structure beneath the conjuctiva.
 These gland secrete an oily secretion, which
become part of the tears.

 Their openings are situated at the lid
margins.
 There are number about 30-40 in the upper
lid and 20-30 in the lower lid.
 A thin sheet of fibrous tissue extends from
the tarsal plates to the orbital margins.
 The sheet is called ORBITAL SEPTUM
(partition).

 This serves as a partition to separate the lids
from the other orbital contents.
 It's the main barrier against transfer of
infection from the lids to the eyeball & its
related structures

Muscles
Muscles of the posterior lamina are
 Levator Palpebral Superioris
 The levator palpebral superiores originates from
the inferior surface of the lesser wing of sphenoid
above and anterior to the optic canal.The levator
palpebral superiores raises the upper lid .
 Fear or excitement cause contration of the smooth
muscle (superior tarsal muscle)resulting in further
elevation of the lid .
 Superior & Inferior Tarsal Muscles

Levator palpebrae Superioris
 It is a skeletal muscle.
 Capable of voluntary action.
 present in the upper lids.
 supplied by the 3rd cranial nerve.

 It opposes the action of orbicularis oculi i.e. it
opens up the eyelids.
 If damaged the upper-lid droops down will
causes ptosis.

Superior & Inferior tarsal muscles
 Small muscles present in both the upper
and lower lids.
 They belong to the variety of involuntary
muscles called the smooth muscles.

 They help the Levator in keeping the eyes open.
 They are supplied by the autonomic nervous system
 Therefore a weakness of the levator muscle or an elongation of its
tendon will result in a dropping of the upper lid that cannont be
counteracted by the action of mullers muscle.therefore complete
paralysisof the levator muscle result in complete closure of the
upper lid.sympathetic paralsis of the muller muscle ,on the other
hand ,will result in a relatively minor degree of ptosis,one of the
components of hornors syndrome of ocular –symphatic paralysis.

Mucus membrane
 A thin membrane lines the inner surface
(surface towards the eyeball) of the lids.
 This membrane is called the
CONJUNCTIVA.

Arterial supply of eyelids
 Branches of the ophthalmic artery supply
the eyelids ,including lateral palpebral
arteries are derived from the lacrimal artery
,the medial palpebral artey ,the superior and
inferior arises from the ophtalmic artery
below the trochlea of the superior oblique
muscles.

Veins
 Veins of eyelids drain into the ophthalmic
& Angular vein medially
 Superficial temporal vein (laterally)

Lymphatic drainage
 Lymphatic vessels of the eyelids &
eyebrow drain into the
 Lateral two third of then upper and lower
lids darin in to the superficial parotid nodes
(Preauricular lymph nodes).
 While medial part of the lid drain in to the
Submandibular lymph nodes

 These lymph nodes enlarge & become
palpable as small tender swellings in
infection of the eyelids.

Nerve supply of eyelids
Sensory:
 Ophthalmic and maxillary division of
trigeminal nerve.
Motor:
 orbicularis oculi –Facial nerve
 Levator palpebrae superioris oculomotor
nerve
 palpebral muscles of muller- sympathetic

Motor:
 orbicularis oculi –Facial nerve
 Levator palpebrae superioris oculomotor
nerve
 palpebral muscles of Muller- sympathetic

FUNCTIONS OF EYELIDS
PROTECTION OF THE EYEBALL
 Main function is to protect the eyeball
against different kinds of trauma.
 Keep the eye in its orignal position.
 They carry out this function by means of
BLINKING & forceful closure.

BLINKING
Blinking is mainly of two types:
Spontaneous Blinking
 occurs spontaneously
 is affected by visual tasks, emotions and
environment.
 is less in children (infants).

 is present in blind people as well.
 Average rate is 15 times per minute.

Reflex blinking
Blinking in response to:
 Something approaching the eyes.
 Something touching the cornea or
eyelashes.
 Strong noise is called reflex blinking
 The three primary sensory modalities activated in reflex blinking
includes tactile ,optic, and auditory sensations.
 The ophthalmic division of fifth cranial nerve is the afferent
pathway for the tactile corneal reflex, while the efferent pathway is
that of the seventh cranial nerve. the optic nerve is also the afferent
pathway for blink reflex of visual origin ,the menace and dazzle
reflex.

 Keeping the eyeball in its proper
position
Functions related to tear film:
Synthesis of the tear film
 Glands of the eyelashes & the tarsal
glands contribute to the oily part of
tear film, which keeps the cornea wet.
Accessary lacrimal glands are situated in the conective tissue of
conjuctiva,the accessary lacrimal gland are found scattered the
conjuctival sac.(conjuctival fornix).they may number as many as
50.they are similar to the lacrimal gland and their ducts open to
the free space of conjuctiva.

Spread of tears
 Spontaneous blinking helps spread the
tears across the surface of the
eyeball.
 This keeps the cornea & the surface of rest
of the eyeball wet & healthy.

Drainage of tears
 Spontaneous blinking generates pumping
machines, which help to pump tears from
the eye to the canaliculi & the lacrimal sac.
 From where they drain into the nose.

 Failure of this machine would cause tears
to accumulate in the conjunctival sac &
 overflow onto the cheeks a condition
called watering of the eyes.

Regulation of amount of light entering the
eye
 Eyelids can perform this function by
decreasing the palpebral fissure in bright
light & increasing it in dim light.
 The pupil mainly performs the function but
eyelids can also help.

OCULAR APPENDAGES.ocular anatomy in very easy way

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OCULAR APPENDAGES.ocular anatomy in very easy way