Orbit components

Question 1

Name the 2 Orbital Margins, and what bones form them.

Answer 1

1) Supraorbital Margin, formed by
- Frontal Bone
* note: Supra-orbital Notch

2) Infra-orbital Margin, formed by
- Zygomatic bone (Laterally)
- Maxilla (Medially)

Question 2

What are the bones of the orbit? (Roof, Floor, Lateral Wall, Medial wall)

Answer 2

Roof

• Frontal bone
• Lesser wing of Sphenoid

Floor

• Maxilla
• Zygomatic (cheek) bone
• Palatine

Lateral wall

• Zygomatic bone
• Greater wing of Sphenoid

Medial wall

• Maxilla
• Lacrimal bone (v. delicate)
• Ethmoid
• Body of Sphenoid

Question 3

Describe features + functions of Sclera

Answer 3

• White
• Forms 5/6th of eyeball

Functions

• Maintains shape of globe (offering resistance to Internal + external forces)
• Provides attachments for EOMs

Question 4

Describe features + functions of Cornea

Answer 4

• Anterior 1/6th of eye
• 5 layers Histologically
  (Epithelium, Bowman’s layer, stroma, Desement’s membrane, Endothelium)

Function

• Principal refracting component of eye
• Optimum for vision (Avascular + transparent)

Question 5

Why is the cornea transparent?

Answer 5

Collagen fibrils

• uniform in diameter
• evenly spaced
• run parallel to each other

Question 6

Why is Sclera opaque?

Answer 6

Composition of Stroma
Hydration
Size + distribution of Collagen

Question 7

What is the Anterior Chamber and Angle? Function?

Key structures?

Answer 7

Junction between

• Iris
• Cornea

Function
- Aqueous humour drains out of eye

Key structures?

• Cornea
• Trebeculae meshwork
• Canal of Schlemm
• Ciliary body

Question 8

What is the Uvea?

Answer 8

• Middle Coat
• Vascular + nutrient supply
• Consists of
• – Choroid
• – Ciliary Body
• – Iris

Question 9

What are the 3 coats (Outer, Middle, Inner)?

Answer 9

Outer (Sclera + Cornea)
Middle (Uvea – Vascular/nutrient supply + Choroid+Ciliary Body+ Iris)
Inner (Retina)