Conjunctiva

Question 1

Is the conjunctiva vascularized?

Answer 1

Highly

Question 2

Contains which type of epithelial cell that secretes mucus?

Answer 2

Goblet cells

Question 3

What is in the mucus secreted by goblet cells and what purpose does it have?

Answer 3

Contains mucin, water, epithelial cells, dead leukocytes, and inorganic salts.
Provides lubrication and protection of the ocular surface. Without it, there would be friction on the globe as the eye opens/shuts. Helps trap pathogens so they cannot enter deeper tissues.

Question 4

3 types of conjunctiva that together, form the conjunctival sac. (AKA why contacts cannot go behind your eye)

Answer 4

Palpebral, forniceal, and bulbar.

Palpebral= lines the underside of eyelids.
Forniceal- Junctional region between the palpebral and bulbar conj.
Bulbar- Covers a portion of the anterior globe.

Question 5

Palpebral conjunctiva divisions

Answer 5

1. Marginal conjunctiva. Present at the eyelid margin. Forms the mucocutanous junction and contains the lid wiper region.
2. Tarsal conjunctiva. Present in the area of the tarsal plate and firmly adheres, providing a smooth tarsal surface.
3. Orbital conjunctiva. Present at the edge of the tarsal plate to the forniceal conjunctiva. Loose tissue that allows for movement of the globe.

Question 6

Forniceal conjunctiva

Answer 6

Cul-de-sac connecting palpebral and bulbar conjunctiva. Deepest laterally, extending posterior to the equator of the globe. Not present medially (place and caruncle are present here instead). Loose tissue that allows for free movement of the globe.

Question 7

Bulbar conj

Answer 7

Lines the anterior globe. Covers anterior tenon’s capsule, sclera, and EOM insertions. 360 degrees around.
Layers become continuous with the cornea.

Question 8

The bulbar conjunctiva contains which 2 specialized areas medially

Answer 8

The plica semilunaris and caruncle.

Question 9

Role of plica semilunaris

Answer 9

Crescent-shaped fold of bulbar conjunctiva.
Allows full lateral movement of the eye without tissue stretching.
Makes up the floor of the lacrimal lake
Contains high concentration of goblet cells

Question 10

Role of caruncle

Answer 10

Mound of bulbar conjunctiva/skin
(skin elements= Hair follicles, sebaceous glands, sweat glands. Conjunctiva elements= Non-keratinized epithelial cells, goblet cells, accessory lacrimal glands of krause and wolfing)
Overlies the medial edge of the plica
Function is poorly understood, possibly to trap oil, mucous and debris.

This is not part of the lacrimal lake.

Question 11

Surface and underlying layer of the conj

Answer 11

Surface- non keratinized epithelial cells over a deeper layer of connective tissue.

Question 12

Function of the epithelial layer of the conj

Answer 12

Barrier to the outside environment. Prevents microbes from causing infections in underlying tissues.

Question 13

Composition of epithelial layer of conj

Answer 13

Non keratinized epithelial cells, goblet cells, melanocytes, lagerhands cells, lymphocytes.

Question 14

What is the most abundant cell type in the conjunctival epithelium?

Answer 14

non-keratinized epithelial cell. Mostly stratified columnar cells, but stratified squamous cells are found at the mucocutaneous junction and limbus.

Question 15

Describe non-keratinized epithelial cells of the epithelium

Answer 15

Microvilli are present at the apex. Helps bind mucin to the conjunctival surface.
Secretes the glycocalyx from the apex of the surface cell. This consists of a transmembrane mucins or glycoproteins. MUC1, MUC4, and MUC16 are the glycoproteins in the glycocalyx.

Question 16

Describe the role of goblet cells in the conjunctival epithelium

Answer 16

Epithelial cell that secretes gel-forming mucins (glycoproteins). MUC5AC is a glycoprotein that is a component of the tear film.

Question 17

Melanocyte role in the conjunctival epithelium

Answer 17

Functions to filter UV light

Question 18

The stromal layer of the conj is divided into which 2 layers

Answer 18

Composed of loose connective tissue and divided into the Outer lymphoid layer and the deep fibrous layer

Question 19

What is another name for the stromal layer of the conj?

Answer 19

Substantia propria

Question 20

What is contained within the outer lymphoid layer of the conj stroma?

Answer 20

Lymphocytes and plasma cells. Protect underlying tissues from pathogens.

Question 21

What is contained within the deep fibrous layer of the conj stroma?

Answer 21

This layer contains the accessory glands of krause and wolfring, which produce the aqueous component of the tear film.

The wolfring gland is found in the forniceal conj and the krause gland is found in the palpebral conj.

This layer also is rich in blood vessels, lymphatic vessels, and nerves.

Question 22

Which areas of the conj have the highest concentration of goblet cells?

Answer 22

Inferior nasal

Question 23

Main overall functions of the conjunctiva?

Answer 23

1. Plays a role in immunological defense. This is the most outer layer in contact with the world. Pathogens and particles become trapped in mucus, preventing entry into deeper tissues. The epithelial and stromal layer both contain white blood cells and the glycocalyx also provides a barrier against pathogens.
2. Ensures smooth movement of the eyelids over the globe. Goblet cells provide mucus with a major component being mucin.

Question 24

Nerve Innervation of the conj

Answer 24

Innervation is the exact same as the innervation to the eyelids for the palpebral and forniceal conj.

EXCEPT: Bulbar conj is only innervated by long ciliary nerve of the nasociliary nerve only.

Question 25

How do the palpebral arcades supply the conj?

Answer 25

The peripheral arcades supply the forniceal conj.

The marginal arcades supply the palpebral conj.

Question 26

How is the bulbar conj supplied with blood?

Answer 26

Anterior and posterior conjunctival arteries supply the bulbar conj.

Pathway:

Lacrimal gland, lateral palpebral arteries anastomose with the medial palpebral arteries to form the palpebral arcades they loop posteriorly to form the posterior conjunctival arteries.

The muscular artery is a brach from the ophthalmic artery after it enters the orbit, the muscular artery branches into the ciliary arteries (~7), the ciliary arteries branch to form the anterior conjunctival artery.

They both anastomose and supply blood to the bulbar conj.