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Duke Elder Exam Prep > Lacrimal System & Dry Eyes Anatomy > Flashcards

Lacrimal System & Dry Eyes Anatomy Flashcards

1
Q

What are the three layers of the tear film?

A

Lipid (superficial)
Aqueous
Mucous (deep)

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2
Q

What is the lacrimal gland?

A

A tubule-alveolar gland consisting of acini and ducts.. It consists of two parts, the orbital and the palpebral part.

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3
Q

What is the pathway of the lacrimal system?

A

Lacrimal gland -> puncta -> canaliculi -> lacrimal sac -> nasolacrimal duct -> inferior nasal meatus

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4
Q

What is the function of the lacrimal duct?

A

Forms the aqueous layer of the tear film

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5
Q

Where is the palpebral part of the lacrimal gland located?

A

Superolateral in the eyelids inferior to the Levator palpebrae muscle.

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6
Q

Where is the orbital part of the lacrimal gland located?

A

Lies in the frontal bone

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7
Q

What is the function of the lipid layer of the tear film and where is it produced?

A

Prevents the aqueous layer from evaporating, produced in the Meibomian gland.

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8
Q

What is the function of the aqueous layer of tear film and where is it produced?

A

Antibacterial activity, washing out the debris and then supplying the cornea with nutrients. Produced in the lacrimal gland and accessory lacrimal gland.

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9
Q

What is the function of the mucous layer and where is it produced?

A

Aids in spreading the tears and stabilising the tear film. Produced in the conjunctival gland cells.

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10
Q

What is the blood supply to the lacrimal gland?

A

The lacrimal branch of the ophthalmic artery.

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11
Q

What is the sensory supply to the lacrimal gland?

A

Lacrimal nerve (CNV1)

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12
Q

What nerve supplies the parasympathetic innervation to the lacrimal gland?

A

CNVII

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13
Q

Where does the preganglionic parasympathetic nerve for the lacrimal gland originate?

A

The superior salivatory nucleus in the pons

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14
Q

Where does the preganglionic parasympathetic nerve of the lacrimal gland travel and synapse?

A

It leaves the pons and travels with the greater petrosal nerve to synapse at the pterygopalatine ganglion.

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15
Q

What do the postganglionic parasympathetic nerves join with to reach the lacrimal gland/

A

The CNV1 lacrimal branch

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16
Q

What nerves are involved in the lacrimal reflex?

A

Afferent - CNV1

Efferent - CNVII

17
Q

What is the function of the accessory lacrimal glands?

A

These glands are histologically similar to the lacrimal glands. Their role is to maintain a basal secretory level of aqueous layer.
They are called the Krause and Wolfring glands

18
Q

What is the puncta?

A

This is a small round opening located in the medial posterior edge of the upper and lower lid margins, at the junction of the ciliated and non ciliated parts.

19
Q

What are the superior and inferior canaliculi composed of?

A

A vertical part, the ampulla, 2mm long

A second horizontal part, 8mm long, after the vertical part.

20
Q

What forms the canaliculus?

A

The superior and inferior canaliculi join to form this.

21
Q

What is the role of the Rosenmuller valve and where is it located?

A

It prevents tear reflux and is located in the junction between the lacrimal sac and the canaliculus.

22
Q

Where is the lacrimal sac located?

A

In the lacrimal fossa, which is formed y the lacrimal bone and the frontal process of the maxilla.

23
Q

Where is the nasolacrimal duct?

A

This is a continuation of the lacrimal sac which opens into the inferior meatus of the nose.

24
Q

What is found in the opening of the nasolacrimal duct and what is its purpose?

A

A fold of mucous called the valve of Hasner, which prevents air entering the nasolacrimal system during nose blowing.

25
Q

Define epiphora:

A

Excessive watering of the eye.

26
Q

Give some causes of acquired obstruction of the nasolacrimal duct:

A

Punctal stenosis
Nasolacrimal obstruction
Congenita

27
Q

What can cause Punctal stenosis?

A

Idiopathic causes

chronic blepharitis

28
Q

How do you treat Punctal stenosis?

A

Punctoplasty

29
Q

What can cause nasolacrimal obstructions?

A

Idiopathic
Trauma
Surgery
Tumours

30
Q

How do you manage nasolacrimal obstructions ?

A

Anastomosis of the lacrimal sac with the mucosa of the middle meatus - this is called dacryocystorhinostomy

31
Q

In congenital obstruction, where do most cases occur and how many resolve?

A

Obstruction typically occurs at the valve of Hasner and 90% will resolve within the first year of life.

32
Q

What are the management options for congenital obstruction?

A

1st line: observe and massage lacrimal sac
2nd Line: nasolacrimal duct probing
3rd line: nasolacrimal duct stent insertion, balloon dilatation or dacryocystorhinostomy

Duke Elder Exam Prep (18 decks)

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