Orbit and the Eye Pt. 1

Question 1

Seven Bones of the Orbit

Answer 1

Frontal
Ethmoid
Sphenoid
Maxilla
Zygomatic
Palatine
Lacrimal

Question 2

Four walls of the orbits

Answer 2

Lateral, medial, roof and floor

Question 3

Lateral Wall consists of:

Answer 3

zygomatic bone and greater wing of the sphenoid bone.

Question 4

Medial wall

Answer 4

Ethmoid and lacrimal bones

(and includes the anterior and posterior ethmoidal foramina int he frontosphenoid suture)

Question 5

Roof

Answer 5

Orbital plate of the frontal bone

Question 6

Floor

Answer 6

Orbital surface of the maxilla, very thin.

Question 7

The inferior orbital fissure is continuous with the ___________ canal which opens onto the face via the infraorbital foramen.

Answer 7

infraorbital canal

Question 8

Eyeball is about ____ cm in diameter

Answer 8

2.5

Question 9

True/False: There are no lymph vessels in the orbit.

Answer 9

True.

Question 10

The orbit contains (8):

Answer 10

eye
optic nerve
EOMs
lacrimal apparatus
fat
fascia
nerves
vessels

Question 11

(2) orbital fascia

Answer 11

periorbita (periosteum lining bones of orbit)

common tendinous ring (origin of the four rectus muscles)

Question 12

Rectus muscle origin and insertion?

Answer 12

Origin: common tendinous ring
Insert: anterior half of the eye

Question 13

Obliques and levator origin and insertion

Answer 13

origin: bones of orbit
insert: obliques - posterior half of eye
levator palpebrae superioris - superior tarsus (upper eyelid)

Question 14

Lateral and medial rectus actions?

Answer 14

Lateral: ABducts eye
Medial: ADducts eye

Question 15

Inferior and superior oblique muscle actions?

Answer 15

Inferior Oblique: Up and Out

Superior Oblique: Down and Out

Question 16

Superior and inferior rectus muscle actions?

Answer 16

Superior Rectus: Up and In

Inferior Rectus: Down and In

Question 17

SR + SO Intort/extort eye?

Answer 17

Intort eye

Question 18

IR + IO intort/extort eye?

Answer 18

Extort eye

Question 19

elevation by?

Answer 19

IO and SR

Question 20

Depression by?

Answer 20

SO and IR

Question 21

ABduction by?

Answer 21

LR + IO + SO

Question 22

ADduction by?

Answer 22

MR + IR + SR

Question 23

SO and IO raise and lower eye when held in AB/ADduction?

Answer 23

ADduction

Question 24

SR and IR raise and lower eye when held in AB/ADduction?

Answer 24

ABduction!

Question 25

Special Afferent (SA)

Answer 25

Optic Nerve (II)
Optic nerve carries SA fibers from retina to the visual centers of the brain. Has dural coverings; extension of the brain.

Question 26

General Afferent (GA)

Answer 26

Ophthalmic Nerve (V1) which contains:

1. Frontal n.
2. Lacrimal n.
3. Nasociliary n.

Long ciliary nerves (general afferents from the eye)

Question 27

General Efferent (GE)

Answer 27

Oculomotor Nerve (III) --> all EOMs except:
Trochlear Nerve (IV) --> sup. oblique m.
Abducent nerve (VI) --> lat rectus m.

Question 28

VI Lesion

Answer 28

• Loss of LR m (out)
• affected eye turns medially
• diplopia

Question 29

IV lesion

Answer 29

• loss of SO m (down and out)
• Head is tilted away from the affected side
• Affected eye is slightly higher and deviated medially.
• may have diplopia.

Question 30

III lesion; oculomotor palsy

Answer 30

paralysis of all EOMs except LR and SO.
- upper eyelid ptosis
Pupilary dilation
- poor near focus

Question 31

Ophthalmic artery, where is it from and what does it branch off to?

Answer 31

From the Internal carotid artery

1. lacrimal artery
2. Central retinal artery