Theme 8b

Question 1

What are the the Contents of the Orbit?

Answer 1

1. Eyeball
2. Extraocular Muscles – move the eyeball
3. Levator Palpebrae Superioris – elevates upper eyelid
4. Optic nerve (CN-II)
5. Oculomotor nerve (CN-III)
6. Trochlear nerve (CN-IV)
7. Abducent nerve (CN-VI)
8. Ophthalmic division of trigeminal nerve (CN-V1)
9. Infraorbital nerve (branch of CN-V2)
10. Ciliary ganglion
11. Lacrimal gland

Question 2

What does the Superior Orbital Fissue transmit?

Answer 2

1. Oculomotor nerve (superior & inferior divisions)
2. Trochlear nerve
3. Abducent nerve
4. Lacrimal & nasociliary nerves: branch of frontal nerve, branch of ophthalmic nerve
5. Orbital branch of middle meningeal artery
6. Superior ophthalmic vein

Question 3

What is the common origin for most muscles of the orbit?

Answer 3

Tendinous ring, posteiror to eyeball

Question 4

What are the Muscles of the Eye & their roles?

Answer 4

Medial rectus: adduction inwards

Lateral rectus: adduciton outwards

Superior rectus: upwards & adduction inwards

Inferior oblique: Elevation & abduction outwards

Inferior rectus: Depression & adduciton outwards

Superior oblique: Depression & abduction inwards

Superior tendinous ring: (most superiuor tendinous ring to) upper eyelid to open it

Adduction: movement of a limb or other part towards the midline of the body

Question 5

Innveration of Muscles of the Eye

Answer 5

LR₆₍SO₄)₃

Lateral rectus = CNVI

Superior Oblique = CNIV

Rest = CNIII

Question 6

Ophthalmic Division of Trigeminal Nerve

Where does it leave the orbit?

What are its 4 branches?

Answer 6

Leaves at the superior orbital fissure

1. Lacrimal: lateral wall of orbit
2. Frontal: roof of orbit - divides into supratrochlea & supraorbital
3. Nasociliary: gives branches to the lateral wall of the nose, skin of face, ciliary ganglion & eye

​Ciliary ganglion: very small ganglion located between the optic nerve & lateral rectus

• Hangs off the nasociliary branch of V1 in the orbit

Question 7

What are the coats of the eyeball?

Answer 7

Fibrous coat: sclera (opaque whites) & cornea

Vascular coat: choroid (many capillaries), ciliary body (surrounds lens) & iris (pigmented part with pupillae muscles)

Neural coat: retina (contains light receptors)

Question 8

Lacrimal Gland

1. What type of gland is it?
2. Role?

Answer 8

1. Serous gland
2. Secretes tears - wash medially across the eye, aided by eyelids

Question 9

Cillary ganglion

What innervates its roots & what do they innervate?

What are its branches of distribution called?

Answer 9

Motor root: CNIII - motor to sphuniter pupillae & cillary muscle

Sympathetic root: Sympathetic plexus - motor to eye blood vessels

Sensory root: Nasocillary nerve - sensory to cornea & iris

Branches of distribution: short cillary nerves