week 2, eye and orbit

Question 1

What is the Orbit?

Answer 1

A bony cavity in the facial skeleton

Question 2

What is the orientation of the orbit?

Answer 2

it is pyramidal containing;
A base
4 walls
Apex posteriorly

Question 3

What does the orbit contain?

Answer 3

Eyeball
Optic nerve
Ocular muscles
Fascia
Nerves
Vessels
Fat 
Lacrimal gland and sac

Question 4

What is the function of the orbit?

Answer 4

Protection of the structures held within it. Serves as a vessel for the eyeball

Question 5

How many walls are there of the orbit and what are they?

Answer 5

4 walls,
Superior
Inferior
Medial
Lateral

Question 6

What is the orbit lined with?

Answer 6

Periosteum called periorbita

Question 7

What is periorbita continuous with?

Answer 7

the dura at the optic canal and the superior orbital fissure

Question 8

What is the superior wall of the orbit formed by? What does the superior wall contain?

Answer 8

The Frontal bone
The posterior aspect if formed by the greater wing of the sphenoid

It contains the fossa for the lacrimal gland

Question 9

What is the medial wall of the orbit formed by?

Answer 9

Mostly by the ethmoid bone
Frontal bone
Lacrimal bone
Sphenoid bone

Question 10

What is found anterior to the medial wall of the orbit?

Answer 10

The lacrimal fossa
the lacrimal sac
Proximal part of the nasolacrimal duct

Question 11

What separates the medial walls of the orbit?

Answer 11

The ethmoid sinuses and upper nasal cavity

Question 12

What is the inferior wall of the orbit formed by?

Answer 12

Mainly by the maxilla

Partly by the zygomatic and palatine bones

Question 13

What is the lateral wall of the orbit formed by?

Answer 13

Formed by the zygomatic bone and the greater wing of the sphenoid

Question 14

What is the orientation of both lateral walls of the orbit?

Answer 14

The two lateral walls are almost perpendicular (occur at right angles to each other)

Question 15

Where is the apex of the orbit found?

Answer 15

It is found at the optic canal in the lesser wing of the sphenoid just medial to the superior orbital foramen

Question 16

What is the function of the eyelid?

Answer 16

Protects the cornea from dust and excessive light
Covers the anterior eyeball when closed
Helps keep cornea moist by spreading lacrimal fluid

Question 17

What is found externally and internally to the eyelid?

Answer 17

Externally = Skin
Internally = palpebral conjunctiva

Question 18

What is the conjunctiva?

Answer 18

Mucous membrane that lines the inner surface of the eyelid and anterior eyeball

Question 19

What is the palpebral conjunctiva?

Answer 19

Mucous membrane that lines the eyelid

Question 20

What is the bulbar conjunctiva?

Answer 20

Mucous membrane that lines the anterior eyeball (sclera)

Question 21

What are the conjunctiva fornices?

Answer 21

The place at which the palpebral and bulbar conjunctiva meet. (both superior and inferior)

Question 22

What are the tarsal plates?

Answer 22

Dense bands of connective tissue that form the “skeleton” of the superior and inferior eyelids

Question 23

What are the tarsal glands?

Answer 23

glands that secrete lipid substance which lubricates the edges of the eyelids, preventing them from sticking together.

Found within tarsal plates

Question 24

What are the ligaments of the eyelid?

Answer 24

Lateral and Medial palpebral ligaments

These connect the tarsal plates to the orbit and nose

Question 25

What is the orbicularis occuli muscle?

Answer 25

The circular muscle surrounding the tarsal plates

Question 26

What does the lacrimal apparatus consist of?

Answer 26

``` Lacrimal glands Lacrimal ducts Lacrimal lake Lacrimal canaliculi Lacrimal sac Nasolacrimal duct ```

Question 27

What causes the release of lacrimal fluid?

Answer 27

The facial nerve

Question 28

What are the three layers of the eyeball?

Answer 28

Outer fiborous layer (sclera,cornea) Middle vascular layer (choroid, ciliary body, iris) Inner layer (retina, optic and non visual parts)

Question 29

What is the cornea?

Answer 29

The transperant part of the fiborous coat which covers the anterior 1/6 of the eyeball it is avascular and sensitive to touch

Question 30

What is the choroid and where is it found?

Answer 30

A drak brown membrane found in the middle vascular layer between the sclera and retina It absorbs excess light

Question 31

What is the cillary body? What is its function?

Answer 31

It connects the choroid with the circumference of the iris | Secretes aqueous humor which fills the anterior and posterior chambers of the eye

Question 32

How many chambers of the eye are there and what are they?

Answer 32

two; Anterior (between cornea and iris anteriorly and the iris and pupil posteriorly) Posterior (Between iris and pupil anteriorly and the lens and the ciliary body posteriorly)

Question 33

What is the iris and where is it found?

Answer 33

A thin contractile muscular diaphragm that lies anterior to the lens, it is responsible for dilating and contracting the pupil)

Question 34

What is the retina?

Answer 34

a 10 layered nervous tissue membrane which is continuous to the optic nerve it recieves visual images of external objects and transmits impulses via the optic nerve to the brain

Question 35

What are rod cells and where are they found?

Answer 35

They are photoreceptors located peripherally in the retina. they respond to dim light for black and white vision

Question 36

What are cone cells and where are they found?

Answer 36

They are photoreceptors that provide daylight colour vision and greater visual acuity They are concentrated in the fovea

Question 37

What are the muscles of the orbit?

Answer 37

There are 7: Levator Palpebrae Superioris Superior, inferior, medial and lateral rectus muscles Superior and inferior oblique muscles

Question 38

What is the nerve supply to all the eye muscles apart from one. Which muscle is the other one and what supplies it?

Answer 38

Oculomotor nerve for all muscles Apart from lateral rectus which is supplies by the abducent nerve

Question 39

What nerves innervate the orbit?

Answer 39

Occulomotor Trochlea Abducent Branches of the opthalmic nerve

Question 40

What areries supply the orbit?

Answer 40

Opthalmic artery (branch of the internal carotid artery) infraorbital artery (branch of the maxillary artery)

Question 41

What do the veins of the orbit pass through and drain into?

Answer 41

Pass through the superior orbital foramen and drain into the cavernous sinus