Anatomy of the eye

Question 1

Name the creases on the surface anatomy of the eye.

Answer 1

Superior palpebral crease
Malar crease
Nasojugal crease
Inferior palpebral crease

Question 2

What is the volume of the orbit in adults?

Answer 2

30mls

Question 3

What is the anterior limit of the orbit called?

Answer 3

Orbital Septum

Question 4

What is the barrier between the eyelids and orbit?

Answer 4

Orbital septum

Question 5

Name the bones that make up the roof of the orbit.

Answer 5

Frontal bone and the lesser wing of the sphenoid

Question 6

Name the bones that make up the medial wall of the orbit.

Answer 6

Ethmoid bone, lacrimal bone, frontal process of maxillary bone, and palatine bone

Question 7

Name the bones that make up the lateral wall (thickest and strongest) of the orbit.

Answer 7

Zygomatic bone and the greater wing of the sphenoid

Question 8

Name the bones that make up the floor (shortest wall) of the orbit.

Answer 8

Maxilla, zygomatic bone, and palatine bone

Question 9

Name the periosteal covering of the orbital bones.

Answer 9

Periorbita

Question 9

Which openings are found at the orbital apex? (4)

Answer 9

Optic canal
Superior orbital fissure- btwn greater and lesser wings of spenoid
Inferior orbital fissure
Foramen rotundum transmits – CN 5 maxillary branch

Question 10

Name the 3 layers of the globe.

Answer 10

Fibrous layer
Vascular layer
Nervous layer

Question 11

What are the components of each layer in the globe?

Answer 11

Fibrous layer:
Cornea
Sclera
Vascular layer
Choroid coat
Ciliary Body (Ciliary muscle, Ciliary process)
Iris
Nervous layer
Retina

Question 12

Mention the approximate diameter and volume of the eye.

Answer 12

2.5 cm in diameter with a volume of 6.5 ml

Question 13

What is the average axial length of the globe?

Answer 13

24 mm (range 21–26 mm)

Question 14

What forms the optic nerve?

Answer 14

Formed by convergence of ganglion cell axons at the optic disc (beginning of nerve

Question 15

In what ratio do the cornea and sclera cover the eye?

Answer 15

Cornea forms one-sixth of the circumference of the globe and has a radius of 7.8 mm; the remaining sclera has radius of 11.5

Question 16

What borders the cornea?

Answer 16

The limbus

Question 17

Name the 5 layer of the cornea.

Answer 17

Epithelium
Bowman’s layer
Stroma
Descemet’s membrane
Endothelium

Question 18

Name the 3 anatomical parts of the sclera(tough and opaque).

Answer 18

Palpebral
Bulbar
Forniceal

Question 19

What is the Tenon capsule?

Answer 19

An envelope of elastic connective tissue deep to conj. The Tenon capsule is the cavity within which the globe moves. It is composed of compactly arranged collagen fibers and a few fibroblasts.

Question 20

Give another name for the vascular layer.

Answer 20

Uvea or Uveal tract

Question 21

Mention the 3 parts of the choroid.

Answer 21

1. the choriocapillaris, the innermost layer
2. a middle layer of small vessels
3. an outer layer of large vessels

Question 22

Name the central depression of the optic disk (1.5 mm diameter).

Answer 22

Physiological cap

Question 23

How many rods and cones are found in the retina?

Answer 23

6 million cones and 120 million rods

Question 24

Name the 3 parts of orbicularis oculi

Answer 24

Preorbital, Preseptal, Pretarsal orbicularis oculi Supplied by CN 7- Closes the eyelid

Question 25

Which muscles closes the eye?

Answer 25

Deeper- levator palpabrae superioris (CN III)

Question 26

Where do all the EOM arise from except Inferior oblique?

Answer 26

All EOMs with exception of Inferior Oblique arise from the apex of the orbit- Tendinous Ring of Zinn. The inferior Oblique originates from the medial wall of the orbit

Question 27

What is the pathway of the superior oblique?

Answer 27

Originates slightly medial to the levator muscle origin, and travels anteriorly through the trochlea on the superomedial orbital rim, where it turns posterolaterally toward the eye

Question 28

What is the pathway of inferior oblique muscle?

Answer 28

Originates in the anterior orbital floor lateral to the lacrimal sac and travels posterolaterally within the lower eyelid retractors to insert inferolateral to the macula

Question 29

What is the main blood supply of the eye?

Answer 29

Ophthalmic Arterial System 9from internal carotid) - ocular muscles Central Retinal artery- optic nerve and retina

Question 30

Which vessels compose the ciliary arterial system?

Answer 30

Posterior ciliary artery Long posterior ciliary artery- anterior segment Short posterior ciliary artery- choroid

Question 31

Where does the eye get its venous drainage? (3)

Answer 31

The vortex veins The central retinal veins The drainage through the cavernous sinus

Question 32

Where does the eye get its lymphatic drainage? (2)

Answer 32

1. a medial group that drains into the submandibular lymph nodes 2. a lateral group that drains into the superficial preauricular lymph nodes

Question 33

What makes up the secretory system of the lacrimal apparatus?

Answer 33

Lacrimal gland Accessory Lacrimal glands Gland of Wolfring Gland of Krause

Question 34

What makes up the excretory system of the lacrimal apparatus?

Answer 34

Puncta canaliculus Common canaliculus Lacrimal sac Nasal-lacrimal duct.