The document discusses the lacrimal system, including its embryology, anatomy, secretory and excretory systems, and physiology. It describes how the lacrimal system forms during embryonic development and can have congenital abnormalities. The key structures include the lacrimal gland, puncta, canaliculi, lacrimal sac, nasolacrimal duct, and associated valves. Tears are secreted and drained through coordinated contractions of the orbicularis oculi muscle and lacrimal pump mechanism to flush the eye surface and drain tears into the nasal cavity.

1. The lacrimal system
Dr. Samten Dorji

2. Outline
• Introduction
• Embryology
• Osteology
• Secretory system
• Excretory system
• Physiology of lacrimal pump

5. Introduction

6. Introduction
• Tear formation and transport
• Secretory system
• Excretory system

7. Embryology

9. 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 at
3 to 4 months. D. At 7 months, canalization is nearly complete, with only the puncta and valve of
hasner remaining imperforate.

10. • Punctal membranes open at full term
• The membrane of Hasner remains
imperforate in up to 70% newborns.
This usually opens within the first
month but may remain imperforate for
a longer time, resulting in epiphora
and/or mucopurulent discharge.

11. Congenital nasolacrimal duct
obstruction
Lacrimal duct anlage
Congenital atresia of punctum
Absence of valves
Anomalies of canaliculi

12. Osteology
• The lacrimal sac fossa is a depression in
inferior medial orbital rim
• Bordered by anterior lacrimal
crest(maxillary bone) and posterior
lacrimal crest(lacrimal bone).

13. Osteology
Frontoethmoidal suture
16mm high*4-9mm
wide*2mm deep
• marks the roof of ethmoid
sinus
• Bony dissection superior to it
may expose dura.

14. The secretory system
1. Lacrimal gland
2. Accessory glands

15. Lacrimal gland
orbital lobe (black arrow) and the palpebral lobe (white arrow) separated
by the lateral horn of the levator aponeurosis (pointer).

16. The orbital part
• Almond shape
• 65% to 75% of gland
• 20 mm long × 5 mm thick × 12
mm wide
The sharp anterior border of the left lacrimal gland
(black arrow) rests behind the orbital septum
(pointer)
The temporal portion of the central
preaponeurotic fat pad (pointer) rests near the
anterior border of the orbital portion of the
lacrimal gland

17. The palpebral part
• 25% to 35% of the gland
• extends anteriorly beyond the orbital
margin to lie in the lateral portion of
the superior fornix

18. Secretory ducts
• 12 ducts(2-5 orbital and 6-8 palpebral)
• 0.66 mm in diameter and 2.31 mm in length
• Exit at conjunctival fornix 4 or 5 mm above the upper border of the
tarsus
Secretory ducts (arrow 1) of the right lacrimal
gland (arrow 2) are seen passing to the palpebral
conjunctiva (arrow 3).

19. Accessory glands
• exocrine glands of Wolfring and Krause

20. Blood supply and drainage
• Lacrimal branch of the ophthalmic artery
• Lacrimal vein
• Preauricular lymphnodes

22. Nerve supply
• lacrimal nerve (sensory)
• The facial nerve (parasympathetic)
• The sympathetic nervous system

24. Histology
Lobe
Lobules
Acinar unit Ductal system
• central lumen,
• a continuous inner layer
of columnar secretory
epithelial cells
• myoepithelial (basket)
cells
• central lumen,
• luminal cell layer
• basal cell layer.
1. Intralobular ducts
2. Interlobular ducts
3. main excretory
ducts

25. Lacrimal gland architecture
The acinar unit is composed of a central lumen, a
continuous inner epithelial layer of secretory cells,
and an interrupted outer layer of myoepithelial cells.
A larger interlobular duct is seen (middle right). A smaller intralobular duct is
seen among the acini.

26. Excretory system

27. Punctum
• Surrounded by lacrimal papilla
• average diameter of 0.2 to 0.3 mm
• nasal aspect of the eyelid margin
• Upper punctum opens inferoposteriorly
and lower opens superoposteriorly

29. Canaliculi
• First vertical and then
horizontal
• Vertical=2mm, horizontal 8mm
• Angle has 1mm dilatation
called ampulla
• traverse the lacrimal fascia
individually before they join to
form the common canaliculus
• Stratified squamous epithelium
supported by elastic tissue

30. Lacrimal sac
• lies within the bony
lacrimal sac fossa
• The layer of periorbita
that covers the lacrimal
fossa is termed the
lacrimal fascia
• 12 mm in height, 4 to 6
mm in depth, and 2 mm
wide.

31. Nasolacrimal duct
• Inferiorly directed
continuation of the
nasolacrimal sac
• 3 to 4 mm in diameter in
adults and 2 mm in
infants
• 12.5 mm in vertical length
and usually terminates as
a 5-mm extension into the
inferior nasal meatus

32. Valves
• The mucosal lining of the nasolacrimal duct
contain crypts and folds that usually disappear by
adulthood.
• .The most significant fold is the one situated at the
meatal opening of the nasolacrimal duct called the
valve of Hasner.
• 30% of full-term neonates, there persists a
delicate membrane that, within 6 months after
birth, usually undergoes spontaneous perforation.
• Massage or lacrimal probing may be necessary to
permit patency

33. Diagram of the valves
and sinuses of the
nasolacrimal passages.
1 = Maier's sinus
2 = Rosenmüller's valve
3 = Arlt's sinus
4 = Kraus's or Béraud's
valve
5 = spiral valve of Hyrtl
6 = Taillefer's valve
7 = Hasner's valve
Prevents sudden blast of air from entering the lacrimal sac

34. Vascular supply
• The ophthalmic artery terminates as
the dorsal nasal artery, from which
emanates the superior medial
palpebral branches that supply the
lacrimal sac.
• The angular artery perforates the
superior orbital septum above the
medial canthal tendon to send
branches to the lacrimal sac as well
as to the duct.
• The infraorbital artery sends
branches to the lower lid that
eventually pierce the lateral margin
of the upper nasolacrimal canal to
supply the sac as well as the duct.

35. Venous drainage
• Superior aspect- see picture
• Inferior aspect-sphenophenopalatine
veins into the pterygoid plexus and
the internal maxillary vein
• The angular vein and artery are
important surgical landmarks in
dacryocystorhinostomy surgery.

36. Lymphatic drainage
• Sac- submaxillary nodes
• Lower aspect of nasolacrimal duct- deep
cervical nodes
Nerve supply
Sensory nerve supply
•sac-infratrochlear nerve
•The lower portion of the nasolacrimal
duct receives sensation from the
anterior superior alveolar branch of the
maxillary division of the fifth cranial
nerve

37. Histology
• mucous membrane
continuously from the
conjunctiva at the lacrimal
puncta, to the nasal
mucosa at the valve of
Hasner beneath the
inferior turbinate
• Lacrimal puncta and
canaliculi-nonkeratinizing
stratified squamous
epithelium
• Nasolacrimal sac-
columnar epithelium

38. Physiology of lacrimal pump
• Action of orbicularis oculi
Pump mechanism
• (1) the superficial and deep heads of the
pretarsal orbicularis muscle;
• (2) the deep heads of the preseptal
orbicularis muscle; and
• (3) the lacrimal fascia.

39. Passive phase
• Eyelids open
• The superficial and deep heads of the
pretarsal orbicularis muscle relax
• Canaliculus elongate and the puncta
opens to lie in contact with the lacrimal
lake.
• Aided by capillary attraction, tears collect
within the ampulla and canaliculus.

40. Passive phase
• The deep head of the preseptal orbicularis
muscle relaxes
• lacrimal sac collapse.
• The positive pressure assisted by gravity
forces fluid within the sac to move into the
nasolacrimal duct.

41. • The valve of Rosenmüller
prevents retrograde flow of
fluid from the lacrimal sac into
the canaliculus.

42. Active phase
• eyelid closure
• Contraction of the superficial and deep
head of the pretarsal orbicularis
• The canaliculi shorten and the puncta
close.

43. Active phase
• contraction of the deep heads of the
preseptal orbicularis muscle
• Fluid within the canaliculi is drawn into the
lacrimal sac by the negative pressure in
sac.

44. • As the lids reopen and the
passive phase returns
• The lacrimal fascia and sac
resume their relaxed, closed
position.
• The puncta reopen and the
canaliculi elongate, permitting the
drainage system to accept fluid
once again.

45. Outline
• Introduction
• Embryology
• Osteology
• Secretory system
• Excretory system
• Physiology of lacrimal pump

46. Thank you

47. References
• Duane’s Clinical ophthalmology Chapter
21
Orbital Anatomy and Its Clinical
Applications
Deborah D. Sherman, Cat N. Burkat and
Bradley N. Lemke
• American academy of ophthalmology
• Medscape
• internet