Anatomy & Physiology of Lacrimal System

1. ANATOMY AND
PHYSIOLOGY OF LACRIMAL SYSTEM
Dr. Dev Raj Bharati
1st
YEAR RESIDENT
NEH,NAMS
8th Nov,2009

2. LACRIMAL SYSTEM
 SECRETORY APPARATUS:
∙Lacrimal gland & Ducts
∙Accessory glands of Krause
and Wolfring
 EXCRETORY APPARATUS:
∙Puncta
∙Lacrimal canaliculi
∙ Lacrimal sac
∙ Nasolacrimal duct

3. DEVELOPMENT:
Secretory Apparatus
 Lacrimal gland begins to develop between 6-7th
wks. of
gestation
 Forms as a series of ectodermal buds that grow
superolaterally from the superior fornix of the conjunctiva
into the underlying mesenchyme
 Buds branch & canalize to form ducts of glands
 Gland becomes divided into orbital & palpebral parts with
development of LPS
 Lacrimal gland do not function fully until 6wks. after birth
which explains why new born infants do not produce tears
when crying

4. DEVELOPMENT: EXCRETORY SYSTEM
 By the end of 5th
wk., the nasolacrimal groove forms as
a furrow between the nasal & maxillary prominence
 In the floor of the groove, NLD develops from the linear
thickening of ectoderm
 Solid cord separates from adjacent ectoderm into
mesenchyme forming NLD whose superior end
becomes dilated to form the lacrimal sac
 Canaliculi are formed from invaginated ectoderm
 canalization is usually complete around the time of
birth but failure of caudal end to completely canalize
results in congenital NLD obstruction

5. MAIN LACRIMAL GLAND
o Position: above and anterolateral to eyeball
o Parts:
∙Lateral horn of Levator aponeurosis indents the gland into:
 Large orbital or superior part
 Small palpebral or inferior part

6. Lo- Orbital Part
Lp- Palpebral Part
LA- Levator Aponeurosis

7. THE ORBITAL PART:
 Location: lacrimal fossa at anterolateral
area of orbital roof
 Almond shaped
 Superior surface :convex ,lies in the fossa of
frontal bone
 Inferior surface:concave, lies above aponeurosis of
LPS,more laterally above the upper margin of
lateral rectus muscle

8. CONT…
 Anterior Border: Orbital septum
 Posterior Border: Orbital fat, rounded & levels
with posterior pole of eye
 Medial extremity: rests on Levator
 Lateral extremity: rests on Lateral rectus

9. THE PALPEBRAL PART:
SIZE: about 1/3rd
the size of orbital part, consists
of only 1or 2 lobules
LOCATION: below the aponeurosis of LPS and
extend into the upper eyelid, lies mainly on the
superior fornix, palpebral conjunctiva & superior
palpebral muscles
RELATIONS:
Superior surface: related to Aponeurosis of LPS
Inferior surface: lateral part of superior fornix of
conjunctiva

10. LACRIMAL DUCTS:
8 – 12 in no.
Empty into the superior cul-de-sac
approx. 5mm above the lateral tarsal
border after passing posterior to the
aponeurosis
Ducts from orbital portion run through &
join the ducts of palpebral lobe

11. ACCESSORY LACRIMAL GLANDS:
Gland of Krause
 POSITION: between the superior fornix and tarsus as a
downward continuation of palpebral part.
 NUMBER: 42 in upper and 6-8 in lower fornix
Gland of Wolfring: present near upper border of
superior tarsal plate & along the lower border of
inferior tarsus
FUNCTION:Keep Cornea moist in conditions even if main
lacrimal glands become non functional

12. STRUCTURE
Light Microscope:
 Lobulated tubulo-acinar gland
with short branched tubules
 lobules are size of pin head
 Lobules are separated from
one another by loose connective
tissue
 Acini are seen as round or tube
shaped masses of columnar cells with central lumen
 Smallest intralobular ducts are lined with a layer of columnar or
cuboidal cells and have myoepithelial cells at the periphery
 Larger intralobular ducts have a two layered epithelial lining

13. CONT..
Electron microscope:
 The epithelial secretory cells of acini are surrounded by a discontinuous
layer of myoepithelial cells and rest on basal lamina
 The secretory cells are truncated-conical in shape,have microvilli on their
apical or luminal surface
 Narrow extension of acinar lumen can be seen between secretory cells
known as canaliculi

14. CONT..
 The secretory cell - basally located nucleus, rough
surface endoplasmic reticulum, golgi complex,
mitochondria,free ribosomes, lipid droplets & vacuoles
Secretory granules - In apical & middle regions of
cytoplasm round or ovoid either homogenous or finely
granular vary in their electron density.
 Secretory cells –mostly serous type but also of mucus
type
 Plasma cells of interstitial space – imp. Source of
immunoglobulins secreted into tears.

15. ARTERIAL SUPPLY:
 Lacrimal artery ,a branch of Ophthalmic artery which enters
its posterior border
 The infraorbital artery ,a branch of maxillary artery
 Sometimes a branch of transverse facial artery

16. VENOUS & LYMPHATIC DRAINAGE
 VENOUS DRAINAGE: into Superior ophthalmic vein via
the lacrimal vein
 LYMPHATIC DRAINAGE: joins that of conjunctiva & into
preauricular nodes

17. NERVE SUPPLY
 Lacrimal
gland
receives
both
autonomic
& sensory
nerve fibres

18. THE AUTONOMIC INNERVATION
 The parasympathetic secretomotor nerve supply is
derived from superior salivatory nucleus of facial nerve
 The pre-ganglionic fibres reach pterygopalatine
ganglion through facial nerve & its greater petrosal
branch & through nerve of pterygoid canal
 The post-ganglionic fibres then join the maxillary nerve,
then into its zygomatic branch & zygomaticotemporal
nerve.They reach the lacrimal gland within lacrimal
nerve

19. CONT…….
 The sympathetic postganglionic fibres arise from
superior cervical sympathetic ganglion then travel in
plexus of nerves around the internal carotid artery
 They join deep petrosal nerve,nerve of pterygoid
canal ,maxillary nerve, zygomatic nerve,
zygomaticotemporal nerve and finally lacrimal nerve
 The sensory fibres reach the lacrimal gland in the
lacrimal nerve,a branch of ophthalmic division of
trigeminal nerve

20.  Ruskell describes a parasympathetic pathway through orbital
branches of pterygopalatine ganglion which joins a retro-
orbital plexus whose rami lacrimalis carry postganglionic
fibres, both sympathetic & parasympathetic .
 Postganglionic sympathetic fibres may reach the gland by
several routes: along lacrimal artery, through deep petrosal
nerve & through lacrimal nerve.
 Has identified Sympathetic fibres in the adventitia of lacrimal
artery &lacrimal nerve.

21. HIGHER NERVOUS CONTROL
REFLEX CONTROL OF LACRIMAL SECRETION
 Excessive production of tears in emotional conditions
Parasymapthetic lacrimatory nucleus of facial nerve
receive afferent fibres from hypothalamus through
descending autonomic pathway in reticular formation
 Excessive tear production in response to Olfactory
stimuli Similar pathway connect olfactory system with
lacrimatory nucleus
 Reflex Lacrimation secondary to cornea or conjunctival
irritation sensory nuclei of ophthalmic & maxillary
division of trigeminal nerve are connected to
lacrimatory nucleus by internuncial neurons

22. APPLIED ANATOMY
Lacrimal gland:
 Lacrimal ducts originate in orbital part of
gland then traverses the palpebral part of
gland to open into superior fornix of
conjunctival sac. So surgical removal of
palpebral part destroy the drainage of
whole gland
 Surgical damage to palpebral part of lacrimal
gland may occur during surgery as it lies within
the upper lid

23. APPLIED ANATOMY
 Obstruction to secretion: openings of ducts
into conjunctival sac may be obstructed by
scarring of conjunctiva like erythema multiforme,
trachoma,chemical burns, ocular cicatricial
pemphigoid (Causes of Dry eye)
 Tumors of lacrimal gland:
●Benign(common)--mixed cell tumor
(pleomorphic adenoma),benign lymphoid
hyperplasia.
●Malignant(less common)—maligant
lymphoma, adenocarcinoma

24. APPLIED ANATOMY
 Dacryoadenitis: Inflammation of lacrimal gland
 Dacryops : cystic swelling in upper fornix due to
retention of secretion following blockade of one of the
lacrimal ducts
 Mikulicz Syndrome: symmetrical enlargement of
lacrimal & salivary glands

25. LACRIMAL SECRETION
 The secretion are produced by acinar
cells----passes into the duct----the lining
cells of duct modify its composition.
 Final lacrimal secretion:
Lysozyme
IgA
B-lysin

26. FUNCTIONS OF LACRIMAL SECRETION
 Keep corneal epithelium moist so that the surface epithelial
cells have a medium to live
 First and major refractive surface of eye
 Lubricate apposed surface of lids and eyeball so that it
moves freely beneath the lids
 Lysozyme(antibacterial enzyme)
IgA(Immunoglobin)
B-lysin(bactericidal protein)
 secretes substance which affects ocular surface by
regulating epithelial cell turnover

27. LACRIMAL PUNCTA
 Entrance to the lacrimal drainage system
 0.3 mm in diameter
 2 small round or oval orifice situated on the papillae
lacrimalis at the medial end of lid margin at the junction of
its ciliated and non ciliated part
 slightly inverted & lying against the globe
 The punctum is in line with openings of tarsal glands
 The conjunctiva surrounding the puncta is relatively
avascular & thus paler than surrounding area
 The upper punctum is slightly medial to lower punctum,
they are 6 and 6.5mm medial to medial canthus
respectively

28. CONT….
 Puncta are visible only on everting eyelids
 upper punctum opens inferoposteriorly & lower punctum
opens superoposteriorly
 Patency maintainance by surrounding dense tissue
continued with adjacent tarsal plate
 The fibres of orbicularis oculi press the puncta backward
towards the lacus lacrimalis. In old age there will be
muscle atropy, so there will be prominence of papilla

29. APPLIED ANATOMY
 Pallor of puncta is accentuated on applying
lateral tension to lower lid – aids in finding a
stenosed puncta
 In the elderly the puncta become more
prominent due to the atrophy of orbicularis

30. LACRIMAL CANALICULI
 Length: 10mm
 Parts: Vertical--2mm
Horizontal—8mm
 Diameter : 0.5 mm
 vertical part turns medially at a right angle to become
horizontal part
 Upper canaliculi runs medially & downward,the lower
runs medially and upward, upper is shorter
 At the junction of vertical &horizontal portions the
canaliculi slightly dilate & form ampulla

31. CONT….
 The canaliculi pierce the periorbita covering the lacrimal
sac then they enter the posterolateral surface of sac
about 2.5mm below its apex either separately or united
to form a common stem
 In 90% of patients,upper & lower canaliculi combine to
form a single common canaliculus that enters the lateral
wall of sac
 A small diverticulum of the sac (the sinus of Maier) is
situated at the site of entry.

32. STRUCTURE
 The canalicular lining - non keratinised stratified
squamous epithelium, supported by elastic tissue
 Very thin wall & elastic

33. CONT…..
 Also surrounded by fibres of pars lacrimalis of
orbicularis muscle which invert the punctum inwards
the lower lid
 The medial third are covered in front by two bands
which connect the medial palpebral ligaments to tarsi,
while behind is the lacrimal part of orbicularis oculi
(horner’s muscle)
 common canaliculus bends from posterior to an anterior
direction behind the medial canthal tendon at an acute
angle before entering sac, thus playing a role in blocking
reflux

34. APPLIED ANATOMY
 Wall is so thin & elastic that it can be dilated to 3 times
normal diameter which is 0.5mm
 Lateral traction on the lids easily straightens them to
facilitate probing
 Should remember the direction & length of canaliculi
while passing probe
 Coloured fluid injected into a canaliculi can be seen
through the transluscent tissue of lid margins

35. LACRIMAL SAC
 Position: lacrimal fossa, formed by lacrimal
bone & frontal process of maxilla near the
anterior border of medial orbital wall
Length:12mm,when distended 15 mm long & 5-
6mm wide
 sac closed above & open below &continuous
with nasolacrimal duct below
It is enclosed by periorbita
splits at posterior lacrimal crest – encloses the
sac – reunites at the anterior lacrimal crest- thus
forms lacrimal fascia

36. CONT..
 RELATIONS:
Anteriorly: Medial palebral ligament●
● Angular vein
Posteriorly: Lacrimal part of●
orbicularis oculi
● Orbital septum
● Check ligament of
medial rectus
Medially: Upper half of sac –Anterior●
ethmoidal air sinus
● Lower half of sac—Anterior
part of middle meatus
Laterally: Skin, Part of Orbicularis●
oculi
● Lacrimal fascia
● Few fibres of inferior oblique

37. STRUCTURE OF SAC
 Wall consists of fibroelastic tissue & is lined by 2
layers of columnar cells, goblet cells are present.
 is lined by Pseudostratified columnar epithelium
& wall contains elastic & lymphoid tissue

38. APPLIED ANATOMY
 Dacryocystitis: An Inflammation of the lacrimal sac
 Anterior to medial palpebral ligament & lateral to facial
artery, angular vein crosses7- 8mm from the medial
canthus. Incision for removal of sac should not be more
than 2-3mm medial to medial canthus.
 upper part of sac is covered anteriorly by medial palpebral
ligament & covered below only by fibres of orbicularis so
distension of sac with inflammatory exudate or pus will
cause swelling below the lower border of ligament,
abscess or fistula will point or open in this region
 sudden strain on the ligament may tear the sac

39. CONT.
 A sheet of areolar tissue ascends laterally from inferior
edge of medial palpaebral ligament to blend with the
Lacrimal facsia covering the fundus of sac,thus even
relatively slight blows to the eyes may lead to swelling
of the lids on blowing the nose.

40. NASOLACRIMAL DUCT
 Continuation of lacrimal sac neck to the
inferior meatus in the nose
 Length:15-18mm, 3mm in diameter
 Direction: downward, backward & laterally
at 15-25◦◦
 Surface anatomy: a line from medial canthus to first
upper molar tooth
 Position: lies in the canal formed by
maxilla,lacrimal bone & lacrimal process of inferior
concha

41.  The wall of NLD is attached to periosteum
lining the canal. Within the wall is a venous
plexus which continues above with that of
lacrimal sac & below with veins of nasal
mucosa
 opening of inferior orifice varies
 Structure: 2 layers of epithelium, superficial
layer composed of columnar cells & deeper
cells being flatter

42. CONTD.
 It connects the lower end of sac with inferior
meatus of nose
 opening of inferior orifice varies greatly
i.e. rounded or slit like

43. THE VALVES
 Definition: folds of mucous
membrane with no valvular
function.
 Types
valve of Rosenmuller
valve of Huschke
valve of Bochdalek
valve of Foltz
valve of medial palpebral ligament
valve of Beraud or of Krause
valve of taillefer
valve of Hansner

44. CONT….
 The duct opens below into ant part outer wall of
inferior meatus of nose,the opening is guarded by a
flap of mucus membrane called the valve of Hasner
 The most constant is valve of Hasner(plica lacrimalis)
at the lower end,a relic of fetal septum.
 Well developed plica prevent a sudden blast of air
entering the lacrimal sac while blowing the nose.
 A fold of mucosa at the junction between common
canaliculi & lacrimal sac is Valve of Rosenmuller,
which prevent reflux of tear from sac back into the
canaliculi,acts as one way valve

45. ARTERIAL SUPPLY TO LACRIMAL SAC AND NLD
 Medial palpebral branches of ophthalmic artery
 Angular artery from facial
 Infraorbital artery from maxillary
 Sphenopalatine artery of maxillary

46. VENOUS , LYMPHATIC DRAINAGE & NERVE
SUPPLY OF SAC AND NLD
Venous drainage
Above: drains into angular &infraorbital vessels
Below: into nasal veins
Lymphatics: pass to submandibular & deep
cervical nodes
Nerve supply: infratrochlear branch of
ophthalmic division of trigeminal nerve
Anterior superior alveolar nerve,a
branch of maxillary div of trigeminal nerve

47. APPLIED ANATOMY
 Nasolacrimal duct: direction of NLD is
downward,backward and laterally. while passing
probe ,it is inserted into punctum of upper lid directed
vertically and medially into lacrimal sac then downward
at right angle in NLD to inferior meatus. End of the
probe should be visible within the nose
 The distal portion of the duct bends medially in an
irregular J-shape in many neonates but it tends to
straighten out with growth
 NLD is easily separable from bone in upper part but
below it is closely adherent forming mucoperiosteum
which facilitates spread of infection

48. PHYSIOLOGY OF TEAR PUMP
 Physiology of tear pump: Rosengren-Doane mechanism
 70% of tear enter the lower canaliculus by capillarity
and 30% enter the upper and some evaporate.
 In young 10% & in elderly 20% or more ,tear eliminates
by evaporation
 Capacity of conjunctival sac :25-30 μl. When this volume
exceeds then tearing occurs

49. ROSENGREN-DOANE MECHANISM

50. CONT..
 Tear is produced by main & accessory lacrimal gland---
 During the act of blinking, closure of eyelids occurs from lateral to
medial
 Brings fluid in the conjunctival sac medially
 tear then enter the canaliculi by capillarity
 blinking causes contraction of lacrimal part of orbicularis muscles
which dilate the sac partly by pulling medial palpebral ligament
which is attached anteriorly & partly by contracting orbicularis
which is attached posteriorly
 this creates negative pressure so that fluid is passed into sac from
canaliculi

51. CONTD….
 on opening the eye the muscle relax and the sac
collapse & a positive pressure created which forces the
tear passes from sac into NLD then into nose as a result
of gravity
 evaporation of tear in nose occur during inspiration and
expiration of air.

52. TEAR FILM
 Layers:
1)Thin superficial oily layer or lipid layer: 0.9-0.2 μm
Produced by tarsal (meibomian)gland, sebaceous
gland(Zeis) & sweat gland(Moll)
2)Intermediate thick aqueous layer: 6.5-7.5 μm
Secreted by Main lacrimal gland & accessory gland(Gland
of Krause and Wolfring)
3)Inner thin mucin layer: 0.5 μm
Secreted by conjunctival goblet cells, glands of Manz &
Henle

53. FUNCTIONS
 Lipid layer: reduces the evaporation of underlying
aqueous layer
 aqueous layer: contains lysozyme, immunoglobulin, B-
lysin , is defence against invading organism
 Mucin layer: allows equal distribution of tear film over
the ocular surface

54. APPLIED ANATOMY
 Dry eye: Either due to Decreased tear
production or Increased tear evaporation
 Lacrimation: Excessive lacrimation occurs reflexly
as in photophobia, inflammations of
conjunctiva, cornea, ciliary body
 Epiphora: overflow of tears from the eye due to
obstruction ,stenosis, punctal malposition or
functional disorder of lacrimal passages

55. © dev
Juphal, Dolpa

56. Thawang, Rolpa