5 Bony Orbit and Extraocular Muscles

Question 1

Give the bones making up the roof of the bony orbit.

Answer 1

Frontal

Lesser wing of sphenoid

Question 2

Give the bones making up the medial wall of the orbit.

Answer 2

Maxilla
Lacrimal
Ethmoid
Sphenoid

Question 3

Give the bones making up the lateral wall of the orbit

Answer 3

Zygomatic

Lesser wing of sphenoid

Question 4

Give the bones making up the floor of the bony orbit.

Answer 4

Maxilla

Zygomatic

Question 5

Give the bones forming the apex of the orbit

Answer 5

Optic foramen (opening to canal) in the sphenoid bone.

Question 6

Give the bones forming the base of the orbit.

Answer 6

Orbital rim:
Frontal
Zygomatic
Maxilla

Question 7

What structures pass through the superior orbital fissure? What bone is this in?

Answer 7

CNIII
CNIV
CNV1
CNVI
Superior ophthalmic vein

Sphenoid

Question 8

What structures pass through the inferior orbital fissure? What bone is this in?

Answer 8

Inferior ophthalmic vein

Sphenoid bone

Question 9

What structures pass through the optic canal? What bone is this in?

Answer 9

Optic nerve
Ophthalmic artery (Central retinal artery is branch)
Central retinal vein

Question 10

Give the extra ocular muscles and their innervation.

Answer 10

CNIII (Superior branch)
Levator palpebrae superioris
Superior rectus

CNIII (Inferior Branch)
Inferior rectus
Medial rectus
Inferior oblique

CNIV
Superior Oblique

CNVI
Lateral rectus

Question 11

Give the attachments and function of the levator palpebrae superioris.

Answer 11

Lesser wing of sphenoid, above optic foramen to the superior tarsal plate of upper eyelid

Elevates superior eyelid
- Contains sympathetic nervous fibres to superior tarsal muscle.

Question 12

Give the attachments and function of the Superior rectus.

Answer 12

Superior common tendinous ring to anterior and superior aspect of sclera.

1. Elevates eye
2. Adduction
3. Medial rotation

Question 13

Give the attachments and function of the inferior rectus.

Answer 13

Inferior common tendinous ring to anterior inferior aspect of sclera.

1. Depresses eye
2. Abduction
3. Lateral rotation

Question 14

Give the attachments and function of the medial rectus.

Answer 14

Medial common tendinous ring to medial anterior aspect of sclera

Adducts eye

Question 15

Give the attachments and function of the lateral rectus.

Answer 15

Lateral common tendinous ring to the anterolateral aspect of the sclera.

Abducts eye.

Question 16

Give the attachments and function of the superior oblique.

Answer 16

Bondy of sphenoid
Via trochlear to sclera posterior to superior rectus

1. Intorsion
2. Depression (primarily in adducted position) *DOWN AND IN
3. Abduction (down and out if acting alone)

Question 17

Give the attachments and function of the inferior oblique

Answer 17

Anterior orbital floor to sclera of eye posterior to lateral rectus

1. Extorsion
2. Elevation (only muslce that can elevate fully adducted eye)
3. Abduction (up and out)