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International Journal of Otorhinolaryngology and Head and Neck Surgery | February 2021 | Vol 7 | Issue 2 Page 403
International Journal of Otorhinolaryngology and Head and Neck Surgery
Munjal M et al. Int J Otorhinolaryngol Head Neck Surg. 2021 Feb;7(2):403-408
http://www.ijorl.com
pISSN 2454-5929 | eISSN 2454-5937
Review Article
Anatomy of the lacrimal apparatus from a rhinologist’s perspective:
a review
Manish Munjal1*, Shubham Munjal2, Hitant Vohra2, Anu Prabhakar2, Ajay Kumar2,
Sonia Singh2, Anshu Soni2, Seema Gupta2, Meenakshi Agarwal2
INTRODUCTION
The lacrimal apparatus
The lacrimal apparatus comprises the lacrimal gland,
which secretes a complex fluid (tears), and their excretory
ducts convey fluid to the surface of the eye, the punctae,
canaliculi, lacrimal sac and nasolacrimal duct, by which
the fluid is collected and conveyed into the nasal cavity.1
The epithelium of the cornea and conjunctiva is of
ectodermal origin, as are also the eyelashes and the lining
cells of the tarsal, ciliary and other glands, which open on
the margins of the eyelids.2
REVIEW OF LITERATURE
Embryology of the lacrimal gland
The epithelium of the alveoli and ducts of the lacrimal
gland arise as a series of tubular buds (usually 8 in
number) from the ectoderm of the superior conjunctiva)
These buds are arranged in two groups; one forming the
gland proper, and the other its palpebral process. The
lacrimal sac and nasolacrimal duct are considered to be
derived from the ectoderm in the nasomaxillary groove
between the lateral nasal prominence and the maxillary
prominence. This thickens to form a solid cord of cells,
which sinks into the mesenchyme. During the third
month the central cells of the cord break down and a
lumen is acquired. In this way the nasolacrimal duct is
established. The lacrimal canaliculi arise as buds from the
upper part of the cord of cells and secondarily establish
openings (punctua lacrimalia) on the margins of the lids.
The inferior canaliculus cuts off a small part of the lower
eyelid to form the lacrimal caruncle and plica
semilunaris. The epithelium of the cornea and
conjunctiva is of ectodermal origin, as are also the
eyelashes and the lining cells of the tarsal, ciliary and
other glands, which open on the margins of the eyelids.
The accessory lacrimal glands (Krause, Wolfring)
probably, develop from an epithelial invagination of the
conjunctiva. Tears are not produced until the second or
third month after birth.1,2
The lacrimal gland is derived phylogenetically from
serous secreting glands and those producing oily
ABSTRACT
The postero-superioly situated lacrimal glands secreate tears to lubricate the exposed sclera, limbus and the cornea.
The tears are ultimately are channeled into the antero-inferior sited lacrimal sac and thereby into the nasal inferior
meatus. Epiphora may be secondary to irritative or obstructive pathology in the naso-lacrimal system. Individual
with epiphora necessitates intervention, medical or surgical. The naso-lacrimal system with its unique anatomy has
been elaborated upon to assist in detecting the precise site of pathology and plan management likewise.
Keywords: Lacrimal galand, Lacrimal sac, Nasolacrimal duct
1Department of Otorhinolaryngolgy, 2Department of Anatomy, Dayanand Medical College, Ludhiana, Punjab, India
Received: 02 December 2020
Revised: 11 January 2021
Accepted: 12 January 2021
*Correspondence:
Dr. Manish Munjal,
E-mail: manishmunjaldr@yahoo.com
Copyright: © the author(s), publisher and licensee Medip Academy. This is an open-access article distributed under
the terms of the Creative Commons Attribution Non-Commercial License, which permits unrestricted non-commercial
use, distribution, and reproduction in any medium, provided the original work is properly cited.
DOI: https://dx.doi.org/10.18203/issn.2454-5929.ijohns20210182
Munjal M et al. Int J Otorhinolaryngol Head Neck Surg. 2021 Feb;7(2):403-408
International Journal of Otorhinolaryngology and Head and Neck Surgery | February 2021 | Vol 7 | Issue 2 Page 404
secretions. In primates the lacrimal (serous) element has
migrated from its original position in the lower lid to the
upper. The human lacrimal gland is superolateral in the
orbit and has a large, upper orbital and smaller, lower
palpebral part, the two being continuous posterolateral
around the concave lateral edge of the levator
aponeurosis. The continuity of the two parts is through an
opening in the fascial support called the lacrimal
foramen.
The orbital part, about the size and shape of an almond,
lodges in the lacrimal fossa on the medial aspect of the
zygomatic process of the frontal bone, just within the
orbital margin. It lies above the levator palpebrae
superioris and. laterally, above the lateral rectus. It's
inferior aspect is connected to the levator’s sheath, its
upper to the orbital periosteum; its anterior aspect adjoins
the orbital septum and its posterior is attached to the
orbital fat. The orbital part of the gland measures about
20×l2×5 mm in the adult and weighs around 0.78 gm,
two to three times the size of the palpebral portion. The
greyish-pink colour of the gland can readily be
distinguished from the yellow orbital fat.3
The palpebral part, about one-third the size of the orbital,
has two or three lobules extending inferior to the levator
aponeurosis into the lateral part of the upper lid, where it
is attached to the superior conjunctival fornix. It is visible
through the conjunctiva when the lid is everted. Its ducts,
about 12 in number, open into the superior fornix, those
from the orbital part (four or five) passing through the
palpebral part to join some of its ducts and the rest (six to
eight) opening separately. The ducts then pass through
the Muller’s muscle and the conjunctiva, and enter the
superolateral conjunctival fornix, approximately 4 to
5mm above the convex lateral margin of the upper eyelid
tarsus. Thus all ducts traverse the palpebral part so that
excision of this part is functionally equivalent to the total
removal of the gland.1,2
Many small accessory lacrimal glands occur in or near
the fornices. They are more numerous in the upper lid
than in the lower. This may explain why the conjunctiva
does not dry up after extirpation of the main lacrimal
gland.
The accessory lacrimal glands consist of the glands of
Wolfring and Krause, and appear as small lobules within
the conjunctival connective tissue (substantia propria)
There are some 30 glands of Krause in the upper fornix,
and six to eight in the lower fornix.4 The accessory glands
of Wolfring are less numerous, with just three glands at
the superior border of upper tarsus and one at the inferior
border of lower tarsus. 4
The lacrimal gland has no definite capsule but possesses
a thin, connective tissue pseudo capsule that is
continuous with the tissue between the glandular lobules.
This thin pseudo capsule is clinically distinct and
provides an important anatomic landmark in the
management of lacrimal tumors. Many fascial strands
(inappropriately called ligaments) attach to the lacrimal
gland to provide support. The superior transverse
ligament of the orbit (Whitnall’s ligament) probably
provides most of the support to the orbital lobe, along
with help of the lateral edge and the horn of the levator
aponeurosis. Whitnall’s ligament inserts on the supero-
lateral orbital wall and intermingles with the connective
tissue of the gland, and connects via a small attachment
to the lateral orbital wall. Whitnall ligament is a sleeve of
fibrous tissue with both a superior and inferior
component which join medially and laterally before
inserting onto the bony orbit.5
Electron microscopy characterizes the truncated-conical
shape of the epithelial secretory cells of the acini
surrounded by a discontinuous layer of myoepithelial
cells.6
Microvilli are present on the luminar apical surface.
Narrow extensions known as canaliculi are found
between adjacent cells. The apical cytoplasm contains a
well-developed, rough endoplasmic reticulum and golgi
apparatus, as well as a moderate number of mitochondria,
free ribosomes, and lipid droplets and vacuoles. A large
number of secretory granules dominate the apical and
middle regions. These round-to-ovoid, membrane-bound
granules may be homogeneous or finely granular and
may represent different stages in one or two distinct cell
types. The dense granules are mainly serous, but staining
for acid mucopolysaccharides shows that mucus is also
produced. A small amount of the mucoid layer of the
precorneal tear film is of lacrimal gland origin. Plasma
cells represent the predominant mononuclear cell
population of the normal lacrimal gland. Most of these
plasma cells contain gamma A immunoglobulin.
Suppressor-cytotoxic T cells, followed by helper T cells,
represent the next common cell types found. These
findings help support a concept that the lamcrial gland-
associated lymphoid belongs to the mucosa system.1,2,7,8
Muscles at the lateral canthus
The muscles within the eyelid in front of the tarsus
(pretarsal orbicularis), the protractor muscles, are
anchored at the lateral canthal tendon and the lateral
palpebral raphe. They travel horizontally across the
surface of the upper and lower tarsus, and as they reach
the medial canthal area they split into a superficial and
deep portion or the head. The deep head of the pretarsal
orbicularis muscle from the upper and lower lid inserts on
the lacrimal bone at the posterior lacrimal crest behind
the sac and in some cases has been referred to
as Horner’s muscle. An additional strand of orbicularis
muscle from the preseptal area in the lower lid inserts on
the periosteum, which covers the lacrimal sac and its
fossae, it extends from the posterior to the anterior
lacrimal crest as described by Jones.4 The superficial
Munjal M et al. Int J Otorhinolaryngol Head Neck Surg. 2021 Feb;7(2):403-408
International Journal of Otorhinolaryngology and Head and Neck Surgery | February 2021 | Vol 7 | Issue 2 Page 405
head of the pretarsal orbicularis and preseptal orbicularis
fibers insert in a dense conjoined medial canthal tendon
anterior to the fundus of the lacrimal sac (Figure 1).
Figure 1: Schematic relations of the lacrimal gland.
Vascularity and lymphatics of the lacrimal gland
The main blood supply to the gland is through the
“lacrimal artery”, a branch of the ophthalmic artery and
therefore a branch of the internal carotid artery. The
lacrimal artery penetrates the gland posteriorly.
Branches of the transverse facial or infraorbital arteries
may supply the gland in some patients. Thus connecting
the external and internal carotid branches. The lacrimal
artery often anastomoses with the anterior division of the
middle meningeal artery (external carotid) through the
distal tip of the superior orbital fissure. Terminal
branches of the lacrimal artery also anastomoses in the
eyelid with the anterior deep temporal artery (external
carotid).2,10
The venous drainage of the gland is usually into the
superior ophthalmic vein. The lymphatic drainage of the
gland passes to the preauricular (superficial parotid)
lymph nodes.
The naso-lacrimal duct system
The lacrimal duct system is constituted by the superior
and the inferior units. Tears first enter the superior unit at
the lacrimal punctum. The punctum is a 0.2 to 0.3 mm
opening at the mucocutaneous junction on both the upper
and lower eyelids. The punctae of the upper and lower lid
are 5 mm and 6 mm, respectively, lateral to the edge of
the medial canthus. The punctae ideally approximate each
other on closure of the eyelids .Tears on entering the
punctae, flow through the canaliicular system. The 2 mm
long vertical canaliculus extends perpendicular to the
eyelid margin and dilates to form the ampulla. At the
ampulla, the canaliculus makes a 90-degree turn
medially.11 The canaliculi then proceed 8 mm
horizontally, following the arc of the eyelid. In 90% of
individuals, the lower and upper canaliculi join proximal
to the lacrimal sac, forming a single 3 to 5 mm long
common canaliculus. In 10%, the canaliculi enter the
lacrimal sac directly and independently. Proximal to the
lacrimal sac, the common canaliculus dilates to form the
sinus of Maier. Tissue in-foldings form the valve of
Rosenmuller, to partition the common canaliculus from
the lacrimal sac.12 Thereby prevents reflux through the
lacrimal system.
The inferior unit is constituted by the lacrimal sac and the
naso-lacrimal duct. The lacrimal sac being superficial to
the orbital septum is enclosed by a separate fascia in the
lacrimal fosse. The anterior border of the lacrimal fossa is
formed by the lacrimal crest of the maxillary bone
and the posterior border by the lacrimal crest of the small
lacrimal bone. The suture line joining the lacrimal and
maxillary bones marks the medial border of the lacrimal
fossa.13
The site of insertion of the common canaliculus into the
lacrimal sac is the seaparating point between the upper
and lower units. The fundus of the lacrimal sac is situated
above the insertion, and the body below it. The lacrimal
sac is 12 to 15 mm long, 2 to 3 mm wide, 4 to 6 mm
deep, and is usually in a collapsed state.14
The tendinous insertions of the orbicularis muscle bind
the lacrimal sac anteriorly and posteriorly, aiding in the
movement of tears. Posterior to the sac, the deep heads of
the pre-tarsal and preseptal orbicular muscles insert.
Anterior to the sac, the superficial heads of the pre-tarsal
and preseptal orbicularis muscles insert onto the anterior
crest of the lacrimal fossae. Together, these insertions
help squeeze the lacrimal sac to move tears forward
through the system.15
Figure 2: The naso-lacrimal system (cadaveric
external dissection).
Infero-posteriorly as visualised in the coronal view, the
naso-lacrimal duct descends, from the sac at an angle
between 15 and 30 degrees. In the mid-sagittal plane, it
descends infero-laterally at an angle of about 5 degrees.
The duct is intra-osseous and traverses the maxillary
bone. Superiorly the ethmoid bone forms its medial
Munjal M et al. Int J Otorhinolaryngol Head Neck Surg. 2021 Feb;7(2):403-408
International Journal of Otorhinolaryngology and Head and Neck Surgery | February 2021 | Vol 7 | Issue 2 Page 406
border and inferiorly the inferior turbinate. It is about 12
mm long and 3 to 5 mm wide. It opens into the inferior
meatus at the valve of Hasner. The ostium’s location is
variable, but it is generally 25 to 35 mm posterior to the
external nares and 4 to 18 mm above the nasal floor
(Figure 2 and 3).
Figure 3: Schematic representation of the naso-
lacrimal system (punctae, lacrimal sac, nasolacrimal
duct). The valves are 1, valve of Rosenmüller; 2, valve
of Krause; 3, spiral valve of Hyrtl; 4, valve of
Taillefer; 5, valve of Hasner or plica lacrimalis.
Embryology of the naso-lacrimal system
The nasolacrimal duct forms from a cord of ectodermal
cells beginning at the seventh week of development. The
surface ectodermal cord joins with a growing cord of
epithelial cells extending from the nasal cavity. The cord
bifurcates in the canthal area, forming early canaliculi.
These projections reach the lid margins at 12 weeks.16 By
seven months’ gestation, the papilla and punctual
portions of the nasolacrimal duct system are fully formed
and patent. The nasal lacrimal duct system canalizes
along its extent simultaneously. The last portion to
canalize, and the most frequent site of obstruction, is the
opening to the inferior meatus of the nasal cavity. After
birth, the size of the nasolacrimal duct system continues
to increase relative to the surrounding facial structures.
The maximum growth occurs in the first six months after
birth. (Figure 4).17
Figure 4: The embryology of the naso-lacrimal
system.
Figure 5: Schematic orientation of the naso-lacrimal
duct on coronal view.
Vascularity and lymphatics of the naso-lacrimal system
The superior and inferior palpebral arteries supply the
canaliculi. These are terminal branches of the ophthalmic
artery. The angular vessels branching off of the facial
artery run superficially and supply the lacrimal sac.
Figure 6: Schematic orientation of the naso-lacrimal
duct on saggittal view.
Figure 7: Variations in relationship of the lacrimal sac
fosse, the ethmoidal air cells, and the tip of the middle
turbinate (axial view).
Munjal M et al. Int J Otorhinolaryngol Head Neck Surg. 2021 Feb;7(2):403-408
International Journal of Otorhinolaryngology and Head and Neck Surgery | February 2021 | Vol 7 | Issue 2 Page 407
Innervation of the lacrimal gland and naso-lacrimal
system
Cranial nerve VII provides motor innervations to the
orbicularis muscle. This muscle helps pump tears through
the nasolacrimal duct system. The fifth cranial nerve
provides sensation superficial to the region of the
nasolacrimal duct system.
Figure 8: Variations in position and shape of the
opening of the end of the nasolacrimal duct under the
inferior turbinate (Saggital view).
Source: Adapted from Shaffer JP: Types of Ostia nasolacrimalia
in man and their genetic significance. Am J Anat 13:183, 1912.
Musculature of naso-lacrimal system
The superficial and deep heads of the pre-tarsal tendons
of the orbicularis muscle control the pumping action of
the lacrimal system. The tendon heads juxtaposed with
the cananiculi and the lacrimal sac. Therefore, when the
orbicularis muscle contracts, so do the tendon heads, and
in concert so does the lacrimal system. This contraction
facilitates the capillary action of the lacrimal puncta and
lacrimal system that directs the flow of tears to the nasal
cavity.
Physiologic variants
In East Asian descent, the lacrimal fossae or precisely the
medial wall of the lacrimal sac is formed predominantly
by the thicker maxillary bone instead of the lacrimal
bone. 18 A vital point during creation of a neo dacrostome
in dacryocystorhinostomy; the maxillary bone being
thicker with respect to the lacrimal bone.
In 10% to 15% of individuals, the ethmoid air cells may
extend anteriorly beyond the posterior lacrimal crest.
During a dacryo-cystorhinostomy, avoid aberrant
entrance into the air cells.
Figure 9: Orientation of the ductal system of the
lacrimal gland.
Applied anatomy
Nasolacrimal duct obstruction is a common problem,
especially in children. Up to 1 in 9 newborns have a
congenital nasolacrimal duct obstruction.19 It most often
leads to excessive tearing and epiphora. Probing of the
system and sometimes stenting are interventions that
open the system and permit tears to flow normally.
It is also a potential site of infection termed
dacryocystitis. This condition is more common in
children, and in the most severe sequelae can lead to
orbital cellulitis. Dacryocystitis can be acute or chronic. It
can also be congenital or acquired. When present, there is
medial canthal swelling of dacryocystitis, usually below
the medial canthal tendon.
Dacrocysto-rhinostomy, external and internal endoscopic
approaches are surgical interventions undertaken in
chronic dacrocystitis not resolving to medical therapy or
syringing.
CONCLUSION
The individual with excessive tearing can have an atretic,
inflammatory or post traumatic obstruction, beginning
from the punctae to its inferior meatal exit .The
conventional external trans-facial decaping of the
posterior wall of the lower naso-lacrimal unit, has given
way to the internal trans-nasal intervention. The latter
facilitated by the video endoscopic modality. Balloon
dilatation using dacro-endoscopy with stenting, though in
the trial period may be the future in the lacrimal surgery.
Funding: No funding sources
Conflict of interest: None declared
Ethical approval: Not required
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Cite this article as: Munjal M, Munjal S, Vohra H,
Prabhakar A, Kumar A, Singh S, et al. Anatomy of
the lacrimal apparatus from a rhinologist’s
perspective- a review. Int J Otorhinolaryngol Head
Neck Surg 2021;7:403-8.
