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LACRIMAL APPARATUS

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  • The lacrimal apparatus consist of:
  • Secretory Portion
  • Lacrimal glands
  • Accessory lacrimal glands
  • Krause and wolfring

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2. Drainage portion:

  • Canalicali (puncta)
  • Lacrimal sac
  • Lacrimal duct (with opening in the inferior nasal meatus.)

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SECRETARY PORTION

  • 1o made up of lacrimal gland located in the anterior lateral portion of the roof of the orbit in the lacrimal fossa.
  • It is divided:
  • A large orbital portion
  • A small palpebral portion by the lateral part of the aponeurosis of the LPSM.
  • The lacrimal gland is of the tubulo alveolar type has numerous acini composed of a double layer of cell surrounding a central canal which open into the secretory.

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  • 3 – 5 ducts drain the orbital portion while 5 – 7 ducts drain the palpebral portion.
  • The ducts of the orbital portion pass through the palpebral tube and each of the ducts opens separately into the superior temporal fornix.

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  • Secretory innervation begin in the lacrimal (salivatory nucleus of the facial nerve (CNVII)). In the floor of the 4th ventricle and run through the facial nerve to the geniculate ganglion.
  • The lacrimal gland is drained by:
  • Lymphatic vessels ending in the pre–auricular lymph nodes

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COMPOSITION OF THE LACRIMAL GLAND

  • Puncta
  • Ampullae/Vertical Canaliculi
  • Horizontal canaliculi
  • Lacrimal sac
  • Nasolacrimal duct

PUNCTA

  • Location:

Near the medical end of each eyelid

Normally the face in the slightly posterior direction and can be inspected by everting the medical aspect of the eyelids

NB: Treatment of excessive watering caused by punctual stenosis or malposition is relatively straight forward

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AMPULLAE/VERTICAL CANALICULI

  • Length: 2mm long and
  • Forms the most proximal part of the lacrimal drainage system
  • In a one snip procedure the ampullae is slit vertically.

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HORINZOTAL CANALICULI

  • Length: 8mm long
  • Upper and lower canaliculi form the common canaliculus which opens into the lateral wall of the of the lacrimal sac in about 90% of individual
  • In the remainder each canaliculi open separately.

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  • A small flap of mucosa (valve of Rosen Muller) over hangs the entrance of the common canaliculi and:
  • Prevents reflux of tears from the sac into the canaliculus
  • Treatment of canaliculi Obstruction is frequently complicated.

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LACRIMAL SAC

  • Length: 10mm long
  • Location: lie in the lacrimal fossa between
  • Anterior and
  • Posterior lacrimal crest

NB: the lacrimal bone and frontal process of the maxillary separates the lacrimal sac from the middle meatus of nasal cavity.

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NASOLACRIMAL DUCT

  • Length: 12mm long
  • Location: Passes downward and angles slightly
  • Medial
  • Posterior to open into the inferior nasal meatus, lateral and below the inferior turbinate
  • The opening of the duct is particularly covered by a mucosal fold (valve of Hasner).

BLOOD SUPPLY

  • Obstruction of the duct may cause a 2o distension of the sac.
  • NB: The eye and the orbital content receive their main blood supply from the ophthalmic artery.