Anatomy of the Lacrimal Apparatus

8/12/2019 Anatomy of the Lacrimal Apparatus

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SIVATEJA

CHALLA

ANATOMY OF THE LACRIMAL

APPARATUS


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LACRIMAL APPARATUS consists of

1.Lacrimal gland

2.Lacrimal ducts3.Conjunctival sac

4.Lacrimal puncta

5.Lacrimal canaliculi

6.Lacrimal sac and

7.Naso lacrimal duct


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LACRIMAL GLAND

DEVELOPMENT

Develops from surface ectoderm

Develops as epithelial bud evaginating from basal

cells of conjunctiva in supratemporal portion of

embryonic fornix Initially solid cords formed,but by 3months central cells

vacuolte and lumina appear

Full differentiation by 3-4 yrs postnatally

Composed of ectodermal glandular units and

mesodermal myoepidermal cells and fibrous

tissue.

Functions 6wks after birth.so no tears in new born

when crying.


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ANATOMY

Located in anterolateralpart of the roof of orbit

in fossa for lacrimal

gland

Divided in to largesuperficial orbital part

and small deep

palpebral part which

are continuous witheach other around

aponeurosis of LPS


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ORBITAL PART

Almond shaped

Two surfaces (superior and inferior) two borders

(anterior and posterior and two extremities (medial

and lateral)

superior surface convex and related to orbit roof

Inferior surface concave and related to LPS

Anterior borderlimited by orbital septum

Posterior border related to orbital pad of fat

Medial extremity related to LPS

Lateral extremity rests on lateral rectus


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PALPEBRAL PART

1/3RD

size of orbital partSuperiorly related to

LPS and inferiorly to

superior fornix

When lid is everted thegland can be seen in

superior fornix of

conjunctiva


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ANCHORS

1.Above by suspensory ligament

2.Below by fibrous attachment to the zygomatic bone

3.Behind by fascial condensation around lacrimal

nerves and vessels4.Internally by fascial expansion of ocular muscles


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LACRIMAL DUCTS

10-12 ductsDucts arising from the orbital part passes through

palpebral part and opens in to superior fornix of

conjunctiva

Additional ducts from palpebral part open directly into conjunctiva

Removal or damage to palpebral part of the gland

will stop secrections reaching the fornix

So biopsy of gland always done in orbital part of

lobe


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STRUCTURE OF LACRIMAL GLAND

Lobulated tubulo acinar gland

Microscopically has Glandular tissue,Stroma andSepta-Glandular tissue consists of

acini and ducts arranged in

lobes and lobules seperated by

Septa

-acini has pyramidal cells which

secrete the tears expelled by the

contraction of myofibrils

-Stromaformed by mesodermal

tissue which has connective

tissue,lymphoid cells,plasma

cells,rich nerve terminals and


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BLOOD SUPPLY-

Internal carotid artery Angular vein

Ophthalmic artery Superior

ophthalmic vein

Lacrimal artery Lacrimal vein

Some times by infraorbital artery(Br of maxillary artery)

LYMPHATIC DRAINAGE-

Pre auricular group


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NERVE SUPPLY

Parasympathetic secretomotor fibres(efferent) from

superior salivatory nucleus

Sympathetic nerve supply from carotid plexus

Sensory supply(afferent) from lacrimal nerve Br of

ophthalmic division of fifth nerve


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CONJUNCTIVAL SAC

Conjunctiva stretches from lid margin to limbusand encloses a potential space conjunctival sac

which opens at palpebral fissure

Sac is closed only when lids are approximated


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LACRIMAL PUNCTA

Two puncta situated ineach lid margin at the

junction of ciliary and

lacrimal parts on

elevtion called lacrimalpapilla

Upper punctum 6mm

and lower 6.5 mm from

medium canthus

Surrounded by fibroustissue which keeps them

patent


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LACRIMAL CANALICULI

2 in number,Joins puncta to lacrimal sac

Two parts vertical(2mm) and horizontal(8mm) at

junction dilated to form ampulla

Pierce lacrimal fascia and unite to form common

canaliculi opens in to lacrimal sinus of maier

At opening in to sac protected by valve of

rosenmuller

Surrounded by fibres of pars lacrimalis of orbicularisoculi muscle

During blink canaliculi pulled medially,shortened and

compressed by pars lacrimalis.also helps in dilatation

of lacrimal sac


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DUCT

DEVELOPMENT

At junction of maxillary process and lateral nasal processamass of ectodermal cells submerge gets canalised to form

lacrimal sac and NLD.

The lacrimal canaliculi

are extensions from the

lacrimal sac in to the

eyelid

Non fusion of maxillary

and lateral processes

resuts in oblique facialcleft and in such cases

NLD not formed


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Fig. 6. Lacrimal drainage system embryology. A. At 5.5 weeks' gestation, an

ectodermal invagination forms between the lateral nasal process and

maxillary process,which becomes pinched off from the surface. B. At 6 weeks' gestation, a solid

cord of ectoderm is located between the primitive medial canthus and nose.

C. At 12 weeks' gestation, proliferation of the cord occurs laterally toward the

eyelid and inferiorly toward the

inferior turbinate. The isolated cavities shown appear at3 to 4 months. D. At 7

months, canalization is nearly complete, with only the puncta and valve of


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LACRIMAL SAC

Upper expanded portion of

NLD

Lodged in lacrimal fossa(medial

wall is lamina

papyracea,formed by lacrimal

bone and frontal process ofmaxilla)

Surrounded by lacrimal fascia

which results from splitting of

periorbita Between sac and fascia are

venous plexus

Part of sac above MPL is

fundus.At junction of fundus


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RELATIONS

Anter ior ly to medial palpebral ligament

Poster ior lyto posterior lacrimal crest and orbicularis

oculi

Mediallyto middle meatus and ant ethmoidal sinus

Laterallyto skin,fascia and orbicularis oculi(lacrimalpart)

ANGULAR VEIN and ANGULAR ARETRY crosses

MPL about 8mm from the medial canthus.many timesa tributary runs 3mm from medial canthus.so to avoid

profuse bleeding during sac surgery incison should

be made within 3mm medial to medial canthus


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Extends from lacrimalsac to inferior meatus ofnose

18 mm in length and

3mm diameter Upper end is the

narrowest

Runs

downward,backwardand laterally

Lined by two layers ofcoloumnar epithelium

Has intraosseus and

intra mural part

NASO LACRIMAL DUCT


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Intraosseus part lodged in naso lacrimal Canal

formed by maxilla anterolaterally,lacrimal bone

and inferior nasal concha postero medially Intramural part variable in length and lies in inferior

meatus.

NLD opens below in to anterior part of inferior

meatus. opening guarded by a fold of mucosa-valve of

hasner.prevents air from entering the sac when air

blown out of closed nose

In infants some times canalisation is delayed or do

not occur causing epiphora and cong dacrocystitis

Duct is surrounded by rich plexus of veins,forming a

erectile tissue .engorgement leads to obstruction of

NLD and epiphora


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BLOOD SUPPLY

ARTERIAL SUPPLY

Superior and inferior palpebral

A.Angular A.

Infraorbital A.

Nasal br. Of sphenopalatine A.

VENOUS DRIANAGE

Angular vein

Infraorbital vein

Nasal vein

LYMPHATICS

Sub mandibular group

Deep cervical group

NERVE SUPPLY

Infra trochlear nerve

Anterior superior alveolar N.


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THANK YOU

Anatomy of the Lacrimal Apparatus

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