The Orbit Anatomy

Question 1

what does the orbit do

Answer 1

encloses the eye ball and tis associated structures

Question 2

what is the apex of the orbit pyramid

Answer 2

optic foramen

Question 3

what is the base of the orbit pyramid

Answer 3

orbital margins

Question 4

what 7 bones form the orbit

Answer 4

frontal 
maxilla 
zygomatic 
sphenoid 
ethmoid 
lacrimal 
palatine

Question 5

what bone makes u the superior border of the orbital rim

Answer 5

frontal bone

Question 6

what bone makes up the medial border of the orbital rim

Answer 6

maxilla

Question 7

what bone makes up the inferior border of the orbital ring

Answer 7

maxilla and zygomatic bones

Question 8

what bones make up the lateral border of the orbital ring

Answer 8

frontal and zygomatic bones

Question 9

what bones make up the roof of the orbit

Answer 9

frontal bone

the lesser wing of the sphenoid bone

Question 10

what bones make up the floor of the orbit

Answer 10

Maxilla
Palatine
Zygomatic

(the floor is thin and can be fractured)

Question 11

what makes up the medial wall of the orbit

Answer 11

lacrimal
maxilla
ethmoid
sphenoid

(also thin and easily fractures)

Question 12

what bones make up the lateral wall of the orbit

Answer 12

the greater wing of the sphenoid

zygomatic

Question 13

what causes an orbital blow out fracture

Answer 13

direct trauma to the eye (inside the orbit) causes a major rise in pressure in the orbit

this causes the thin medial wall/floor to fracture and the contents of the eye extrudes the orbit

Question 14

how can orbital blow out fractures cause anaesthesia or paraethesia on the face

Answer 14

by affecting the nerves passing through the infraorbital foramen to the skin

Question 15

what is the contents of the orbital

Answer 15

extra-ocular muscles
Eye lids
Nerves
Blood vessels

Question 16

what artery supplies the eye with blood

Answer 16

primarily the ophthalmic artery - branches off the internal carotid

Question 17

what veins drain the eye

Answer 17

the ophthalmic veins which train into the cavernous sinus

Question 18

what are all the ways into the orbit (for vessels/nerves)

Answer 18

Optic canal 
Superior orbital fissure 
Inferior orbital fissure 
Nasolacrimal duct 
Supraorbital foramen/notch 
Infraorbital foramen 
Infraorbital groove

Question 19

what travels through the optic canal

Answer 19

optic nerve 
Ophthalmic artery (that then branches off after traveling through the foramen)

Question 20

what travels through the superior orbital fissure

Answer 20

NERVES 
lacrimal nerve
frontal nerve
trochlear nerve 
superior and inferior oculomotor nerves 
nasociliary branches of ophthalmic nerve 
Abducens nerve 

Superior ophthalmic vein

Question 21

what travels through inferior orbital fissure

Answer 21

zygomatic branch of maxillary nerve (CNV2)
Maxillary nerve
Inferior ophthalmic vein

Question 22

what passes through the nasolacrimal duct

Answer 22

drains tears into nasal cavity

Question 23

what passes though the supraorbital foramen/notch

Answer 23

nerves into the forehead supplying skin of the face

Question 24

what passes through the infraorbital foramen

Answer 24

nerves

small vascular vessels

Question 25

what is the infraorbital groove

Answer 25

passes across the floor of the orbit connecting with the infraorbital foramen which then opens up to the face