Occular Anatomy 2 Lacrimal System

Question 1

Describe the lacrimal gland

Answer 1

Bilobed gland -
Larger orbital lobe and smaller palpbral lobe
Lobes are continuous around the lateral border of levator palpebrae aponeurosis

Question 2

Where is the lacrimal gland located

Answer 2

Superotemporally in the orbit behind the orbital septum

Question 3

Where to lacrimal ducts arise and insert

Answer 3

arise in the orbital lobe, pass through the palpebral lobe and into the superior fornix of the conjiunctiva.

Question 4

Where does the parasympathetic supply to the lacrimal gland arise?

Answer 4

Superior salivatory nucleus

Question 5

Describe the path of parasympathetic supply to the lacrimal gland

Answer 5

Superior salivatory nucleus
Nervus intermedius
GReater petrosal nerve to middle cranial fossa
Greater petrosal nerve and deep petrosal nerves combine in pterygoid canal to pterygopalatine fossa
Preganglionic fibres synapse in the pterygopalatine ganglion nad postganglionic fibres travel along infraorbital, zygomaticotemporal and lacrimal nerves to lacrimal gland

Question 6

What type of gland is the lacrimal gland

Answer 6

Lobulated tubuloacinar gland

Question 7

Where are the nuclei in acinalr cells

Answer 7

Basally located

Question 8

What type of secretion to acinar cells secrete?

Answer 8

predominanlty serous secretion

Question 9

Describe the lining of intralobular ducts

Answer 9

Larger - two layered epithelial lining
Smaller - single layer of cuboidal cells
Both ringed by contractile myoepithelial cells (spearated by basement membrane)

Question 10

Describe the lacrimal cannaliculus

Answer 10

L shaped - short 2mm vertical portion and 10mm horizontal potion.
Unite to form common canaliculus

Question 11

Where does the common canaliculus lie?

Answer 11

Behind the medial palpebral ligament
Pierces the lacrimal sac 2.5mm below its apex
May enter sac seprarately

Question 12

What surrounds the lacrimal cannaliculi?

Answer 12

Fibres continuous with the palpebral component of orbicularis oculi
Contraction aids pumping action of tears from the lacrimal canaliculi into the lacrimal sac

Question 13

Where is the lacrimal sac located? What bones form this?

Answer 13

Lacrimal fossa formed by the lacrimal bone , the frontal process of the maxilla and the lacrimal fascia

Question 14

What surrounds the lacrimal sac?

Answer 14

Fascial sheath separated from the sac by a venous plexus

Question 15

What cells line the lacrimal sac?

Answer 15

Columnar cells

Question 16

Describe the nasolacrimal duct and the direction it passes? Where does it drain

Answer 16

Membranous structure
Passes down, back and laterally in an osseous canal
Enters inferior meatus of nose

Question 17

What structure should you be aware of in dacryocystorhinostomy

Answer 17

ANTERIOR TO SAC
Medial canthal tendon (medial palpebral ligament) - anterior to the sac
Angular vein - anterior to sac 8mm medial to medial canthus

Question 18

Where do the ethmoidal air cells lie in realation to the sac

Answer 18

Medially - may be entered inadvertently if lamina papyracea is breached during surgery

Question 19

What forms the osseous canal for the nasolacrimal duct?

Answer 19

MAxilla, lacrimal bone, inferior nasal concha

Question 20

Where does the nasolacrimal duct drain through?

Answer 20

Valve of Hasner ostium covered by mucosal fold

Question 21

What is the valve of Rosenmuller

Answer 21

Superior and inferior canalliculi join to form the common canaliculus