Walls and connections of the orbit

orbit

it is a pyramidal shaped structure, consisting of a base, an apex and 4 walls.

The orbit protects the eye from mechanical injury

the base

Superior margin: frontal bone.

Inferior margin: Maxilla and zygomatic bone

Medial margin: frontal bone and frontal process of maxilla

Lateral margin: Zygomatic and zygomatic process of the frontal bone

The apex

Where the 4 walls join at the optic canal

Superior wall

• This separates the orbot from the anterior cranial fossa.

• The roof of the orbit is formed by the:

  • Orbital plate of the frontal bone.

  • Lesser wing of the sphenoid bone.

Structures in the superior wall:

• Superior orbital fissure: for the passage of CN 3, 4, V1, 6 and ophthalmic vein.

• Optic canal: passage of Optic nerve (CN 2) and opthalmic artery.

• Supraorbital foramen (lateral side) and or frontal notch (medial side)

• Fossa for the lacrimal gland- at the lateral side of the wall

Inferior wall

It separates the orbit from the maxillary sinus. The floor of the orbit is formed by the:

• Orbital surface of the body of maxilla.

• Orbital process of palatine bone.

Sturtures:

1. Inferior orbital fissure

2. Infraorbital groove and canal

Medial wall:

This separates the orbit from the nasal cavity.

It is formed by the:

1. frontal process process of maxilla

2. Lacrimal bone

3. Orbital plate of the ethmoid bone

4. Body of sphenoid bone

Stuctures:

1. Anterior and posterior ethmoidal foramen

2. Anterior and posterior lacrimal crest.

3. Lacrimal fossa- between the crest for the lacrimal sac.

4. Nasolacrimal canal

Lateral wall

Separates the orbit from the temporal and infratemporal fossa.

Formed by the:

1. Orbital surface of zygomatic bone

2. Greater wing of sphenoid bone.

Structures:

1. Zygomatico-orbital foramen: transmits the zygomatic nerve and vessels into the zygomatic bone.

2. Within the bone, the zygomatic nerve gives 2 branches- the zygomaticofacial and zygomaticotemporal nerves which run in their corresponding foramens and canal.

Connections of the orbit:

1. Optic canal

2. Superior orbital fissure

3. Inferior orbital fissure

4. Anterior ethmoidal foramen

5. Posterior ethmoid foramen

6. Nasolacrimal canal

7. Infraorbital groove, canal and foramen

8. Supraorbital foramen/ frontal notch

9. Trochlear notch

10. Zygomatico orbital canal