Anatomy of lacrimal apparatus

OPTHAL MBBS

1. Anatomy of Lacrimal Apparatus 12-10-2015 1

2. Contents Lacrimal apparatus Main gland Accessory glands Blood supply and Nerve supply Lacrimal Passages Puncta Canaliculi Sac Nasolacrimal duct Tear film Functions of tear film Lacrimal pump mechanism 12-10-2015 2

3. Lacrimal Apparatus The lacrimal apparatus comprises Main lacrimal gland Accessory lacrimal glands Lacrimal passages, which include : Puncta Canaliculi Lacrimal Sac Nasolacrimal Duct (NLD) 12-10-2015 3

4. Main Lacrimal Gland Orbital Part : About the size and shape of a small almond Situated in the lacrimal fossa on the frontal bone, at the outer part of the orbital plate The superior surface is convex and lies in contact with the bone The inferior surface is concave and lies on the levator palpebrae superioris (LPS )muscle 10-12 ducts pass downward from the gland and open into the lateral part if the superior fornix 12-10-2015 4

5. Main Lacrimal Gland Palpebral Part : It is s mall and consists only of 1-2 lobules It is situated in the course of the ducts of the orbital part Posteriorly it is continuous with the orbital part 12-10-2015 5

6. Accessory Lacrimal Glands Glands of Krause : They are microscopic groups of acini that lie beneath the palpebral conjunctiva between the fornix and the edge of the tarsus There are about 42 in the upper fornix and 6-8 in the lower fornix The ducts of numerous acini unite to form a larger duct that open into the fornix Glands of Wolfring : These are present near the upper border of the superior tarsal plate and along the lower border of the inferior tarsus 12-10-2015 6

7. Structure : All glands are made up of serous acini and ducts, connective tissue and puncta 12-10-2015 7

8. Blood Supply : Main gland is supplied by lacrimal artery, a branch of ophthalmic artery Nerve Supply : Sensory supply : Lacrimal nerve Sympathetic supply : Carotid plexus of cervical sympathetic chain Secretomotor fibres 12-10-2015 8

9. Lacrimal Passages 12-10-2015 9

10. Lacrimal Puncta Two small rounded or oval openings, on the upper and lower lids, about 6 and 6.5 mm respectively, temporal to the inner canthus Each punctum is situation on a slight elevation called lacrimal papilla Normally, puncta dip into lacus lacrimalis 12-10-2015 10

11. Lacrimal Canaliculi Each canaliculus has two parts : vertical (1-2mm) and horizontal (6-8mm) which lie at right angles to each other Horizontal canaliculi open either separately or join together and open into the lacrimal sac Fold of mucosa at this point forms the Valve of Rosenmuller which prevents reflux of tears 12-10-2015 11

12. Lacrimal Sac Lies in lacrimal fossa which is formed by lacrimal bone and frontal process of maxilla When sac is distended, it measures 12-15mm vertically and 5-6mm horizontally Fundus extends slightly beyond medial palpebral ligament and sac itself is surrounded by fibres of the orbicularis muscle 12-10-2015 12

13. Nasolacrimal Duct Extends from neck of sac to inferior meatus of the nose It is about 15-18mm long, and lies in a bony canal formed by maxilla and inferior turbinate Direction is downwards, backwards and laterally Surface marking : Line joining inner canthus to ala of nose Mucous lining forms an imperfect Valve of Hasner at the lower end of the duct and prevents reflux from the nose 12-10-2015 13

14. Tear Film Structure of fluid covering the cornea : Mucus Layer Aqueous layer Lipid or Oily Layer 12-10-2015 14

15. Functions of the Tear Film Keeps c ornea and conjunctiva moist Provides oxygen to conjunctival epithelium Washes away debris and noxious irritants Prevents infection due to presence of antibacterial substances Facilitates movement of lids over the globe 12-10-2015 15

16. Elimination of tears Lacrimal Pump Mechanism 12-10-2015 16

17. Applied Anatomy Dry eye or Keratoconjunctivitis Sicca (KCS) due to lacrimal gland deficiencies or obstructions Hyperlacrimation due to tumors or cysts of the lacrimal gland, or the effect of strong parasympathomimetic drugs Epiphora due to pump failure or obstructions Dacryocytitis due to blockage or infection In atonia of the sac tears aren’t drained through lacrimal passages, in spite of anatomical patency, leading to epiphora 12-10-2015 17

18. References Parsons’ Diseases of the Eye ; 21 st Edition; Editors : Ramanjit Sihota , Radhika Tandon ; Elsevier A K Khurana : Comprehensive Ophthalmology; Fifth Edition; New Age International Publishers 12-10-2015 18

19. Thank You 12-10-2015 19