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Anatomy of the lacrimal apparatus sivateja

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2. 1.Lacrimal gland 2.Lacrimal ducts 3.Conjunctival sac 4.Lacrimal puncta 5.Lacrimal canaliculi 6.Lacrimal sac and 7.Naso lacrimal duct 3. Embryology Osteology Secretory system Excretory system 4. EMBRYOLOGY DEVELOPMENT-LACRIMAL GLAND surface ectoderm Initially solid cords formed from supero lateral conjunctiva,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 no tears in new born when crying. 5. DEVELOPMENT- LACRIMAL SAC & NASO LACRIMAL DUCT At junction of maxillary process and lateral nasal process a mass 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 facial cleft and in such cases NLD not formed 6. 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 7. OSTEOLOGY The lacrimal sac fossa is a depression in the inferomedial orbital rim, Maxillary and lacrimal bones. Bordered by the anterior lacrimal crest (maxillary bone) & posterior lacrimal crest (lacrimal bone). The fossa is approximately 16-mm high, 4- to 9- mm wide, and 2-mm deep. 8. The medial orbital wall : Frontal process of maxilla, lacrimal ,ethmoid , lesser wing of sphenoid bone. The frontoethmoidal suture is important in lacrimal surgery It marks the roof of the ethmoid sinus. Bony dissection superior to this suture may expose the dura of the cranial cavity. 9. The nasolacrimal canal originates at base of lacrimal fossa. Formed by the maxillary bone laterally and the lacrimal and inferior turbinate bones medially. The width of superior opening is 46 mm. The duct courses posteriorly and laterally in the bone for 12 mm to drain into the inferior meatus of the nasal cavity. 10. SECRETORY SYSTEM It includes lacrimal gland, accessory glands Lacrimal gland is above & anterolateral to globe. Secretes tears into superior fornix. Tears moisten & lubricates the : cornea , conjunctiva. 11. 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 no tears in new born when crying. 12. ANATOMY Located in anterolateral part of the roof of orbit in fossa for lacrimal gland Divided in to large superficial orbital part and small deep palpebral part which are continuous with each other around aponeurosis of LPS 13. 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 border limited by orbital septum Posterior border related to orbital pad of fat Medial extremity related to LPS Lateral extremity rests on lateral rectus 14. PALPEBRAL PART 1/3RD size of orbital part Superiorly related to LPS and inferiorly to superior fornix When lid is everted the gland can be seen in superior fornix of conjunctiva 15. ANCHORS 1.Above by suspensory ligament 2.Below by fibrous attachment to the zygomatic bone 3.Behind by fascial condensation around lacrimal nerves and vessels 4.Internally by fascial expansion of ocular muscles 16. LACRIMAL DUCTS 10-12 ducts Ducts arising from the orbital part passes through palpebral part and opens in to superior fornix of conjunctiva Additional ducts from palpebral part open directly in to 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 17. STRUCTURE OF LACRIMAL GLAND Lobulated tubulo acinar gland Microscopically has Glandular tissue,Stroma and Septa -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 -Stroma formed by mesodermal tissue which has connective tissue,lymphoid cells,plasma cells,rich nerve terminals and 18. 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 19. 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 20. EXCRETORY SYSTEM 21. CONJUNCTIVAL SAC Conjunctiva stretches from lid margin to limbus and encloses a potential space conjunctival sac which opens at palpebral fissure Sac is closed only when lids are approximated 22. LACRIMAL PUNCTA Two puncta situated in each lid margin at the junction of ciliary and lacrimal parts on elevtion called lacrimal papilla Upper punctum 6mm and lower 6.5 mm from medium canthus Surrounded by fibrous tissue which keeps them patent 23. 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 orbicularis oculi muscle During blink canaliculi pulled medially,shortened and compressed by pars lacrimalis.also helps in dilatation of lacrimal sac 24. LACRIMAL SAC Upper expanded portion of NLD Lodged in lacrimal fossa(medial wall is lamina papyracea,formed by lacrimal bone and frontal process of maxilla) 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 25. RELATIONS Anteriorly to medial palpebral ligament Posteriorly to posterior lacrimal crest and orbicularis oculi Medially to middle meatus and ant ethmoidal sinus Laterally to skin,fascia and orbicularis oculi(lacrimal part) ANGULAR VEIN and ANGULAR ARETRY crosses MPL about 8mm from the medial canthus.many times a tributary runs 3mm from medial to avoid profuse bleeding during sac surgery incison should be made within 3mm medial to medial canthus 26. Extends from lacrimal sac to inferior meatus of nose 18 mm in length and 3mm diameter Upper end is the narrowest Runs downward,backward and laterally Lined by two layers of coloumnar epithelium Has intraosseus and intra mural part NASO LACRIMAL DUCT 27. 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 28. 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. 29. ELIMINATION OF TEARS Lacrimal fluid over the preocular surfacemarginal tear stripLacus lacrimalisinner canthus lacrimal passages nasal cavity Lacrimal pump mechanism:- fibres of the pretarsal & preseptal portion of the Orbicularis which arise from the lacrimal fascia & posterior lacrimal crest. This LPM operates with the blinking movements of the eyelids as follows:- 30. DRAINAGE OF LACRIMAL FLUID FROM NLD INTO NASAL CAVITY Gravity helps downward flow. Air currents in nose induce negative pressure within NLD draw the fluid down the potential lumen of the duct into the nose. Hasners valve present at lower end of NLD, remains open as long as the pressure within nose is less than the NLD, allows the tears to flow from NLD to nose 31. THANK YOU