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Special Senses > ORBIT > Flashcards

ORBIT Flashcards

1
Q

Name the bones that make up the orbit

A

Frontal, zygomatic, maxilla, lacrimal, ethmoid, sphenoid

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2
Q

Name the layers that constitute the eyelid- from superficial to deep

A 
Skin
Subcutaneous tissue
Orbicularis oculi
Orbital septum
Tarsus
Conjunctiva
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3
Q

Where can fluid accumulate after eye trauma

A

Subcutaneous layer, causing racoon eye

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4
Q

What nerve damage may cause inability to close the eyelid and what muscle is effected

A

Frontotemporal branch of facial nerve.

Orbicularis occuli

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5
Q

What nerve damage may cause ptosis and what muscles are effected

A

Occulomotor nerve supplying Levator palpebrae

Sympathetic fibres supplying superior tarsal (can get ptosis following sympathetic dissection for excessive sweating)

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6
Q

Name the neurovascular structures that enter and exit the orbital cavity through the optic canal (2)

A

Ophthalmic artery

Optic verve

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7
Q

Name the neurovascular structures that enter and exit the orbital cavity through the superior orbital fissure (8)

A 
Superior ophthalmic vein
Lacrimal branch of V1
Frontal branch of V1
CIV
Superior branch of CIII
Nasocilliary branch of V1
CVI
Inferior branch of CIII
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8
Q

Name the neurovascular structures that enter and exit the orbital cavity through the inferior orbital fissure (4)

A

Infraorbital vein
Infraorbital artery
Maxillary branch of V2
Vein to pterygoid plexus

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9
Q

Describe the common tendinous ring

A

A thickening of the periosteum in the posterior part of the orbit. Surrounds optic canal and central part of superior orbital fissure. Point of origin of the extra ocular muscles (rectus)

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10
Q

Name the 7 extrinsic muscle and their innervations

A 
Levator palpebrae superious (CIII)
Superior rectus (CIII)
Inferior rectus (CIII)
Medial rectus (CIII)
Lateral rectus (CVI)
Superior oblique (CIV)
Inferior oblique (CIII)
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11
Q

What is the blood supply to the orbital cavity

A

Ophthalmic artery branched from internal carotid

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12
Q

What muscles make up the common tendonous ring

A

The four rectus muscles

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13
Q

What neuromuscular structures are found in the common tendonous ring

A

Optic nerve, opthlamic artery, inferior and superior division of oculomotor, nasocilliary, abducenct

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14
Q

What are the constituents of the lacrimal apparatus

A

Lacrimal gland, lacrimal canaliculi, lacrimal sac, nasolacrimal duct

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15
Q

Where does the lacrimal gland sit

A

Lateral superior aspect of eye. Split in two by the tendon of elevator palpebrae superioris

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16
Q

Where does the lacrimal sac sit

A

On the lacrimal fossa on the medial side

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17
Q

What is dacryocystocele

A

A congenital condition whereby the nasolacrimal duct is closed. When cry fills up with tears balloons out of nostril

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18
Q

What supplies the lacrimal gland

A

The lacrimal branch of the ophthalmic artery

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19
Q

Venous drainage of orbit

A

Superior and inferior ophthalmic veins

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20
Q

What extrinsic muscle are not innervated by occulomotor

A

Lateral rectus and superior oblique

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21
Q

What innervate palpebrae levator superiors and what happens if its damages

A

Superior branch of CIII. Complete ptosis

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22
Q

If there is damage to medial orbit (around cribriform plate) what muscle maybe affected

A

Superior oblique.

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23
Q

Describe superior oblique

A

Two bellies. origin just outside of tendonous ring, sling in medial orbit attaches to eye. Innervated by trochlea. Moves eyeball down and medially

24
Q

Ophthalmic nerve branches

A

Lacrimal nerve
Frontal nerve
Nasociliary nerve

25
Q

What may occur with superior orbital fracture

A

Frontal nerve splits into two branches which both exit the orbit around the superior obit to innervate skin on eyelid forehead and scalp. May get numbness if damaged.

26
Q

Describe the path of the ophthalmic nerve until it branches

A

From trigeminal ganglion. V1 divides into three frontal, lacrimal and nasociliary just before the orbit. Frontal and lacrimal enter orbit outside of tendons ring, nasocillary within. All via superior orbital fissure.

27
Q

Describe the path of the lacrimal branch of V1 after entering orbit

A

Goes to lacrimal duct traveling superior to lateral rectus.

28
Q

Describe path of frontal branch of V1 after entering the orbit

A

Frontal sensory to face outside orbit. Travels superior to levator palpebrae superioris branches into two supratrochlear and supraorbital. Both exit the skull through supraorbital notch/ foramina and innervate eyelid skin and forehead skin

29
Q

Describe the path of the nasociliary nerve after entering the orbit

A

Enters within common tendinous ring. Gives off several branches involved in sympathetic and parasympathetic eye responses, sensory to ethmoidal cells, eye, skin on nose

30
Q

What is the main factor resulting in risk of infection spreading from the facial veins to cavernous sinus

A

The direction of the blood flow, not the absence of valves. There are valves.

31
Q

What condition may occur with infection in the danger triangle

A

Cavernous sinus thrombosis. Formation of blood clot in the cavernous sinus

32
Q

31 y/o male not able to close his right eye and not able to whistle

A

Obicularis occuli affected. Damage to facial nerve, exits the skull at stylomastoid foramen can be damged in skin cancer removal around tempals.

33
Q

31 y/o male not able to close his right eye and not able to whistle

A

Obicularis occuli affected. Damage to facial nerve, exits the skull at stylomastoid foramen can be damged in skin cancer removal around tempals.

34
Q

Cat with partial ptosis

A

Sympathetic chain damage, superior tarsal muscle effected.

35
Q

64 y/o male presented to ED with no headache or neurological signs. Ct showed swelling of a muscle and has complete ptosis.

A

Damage to levator palpabrae muscle. Innervated by occulomotor.

36
Q

A patient who suffers hyperhidrosis. What are possible side effects of sympathetic chain dissection?

A

Horners syndrome. Characterised by partial ptosis, meiosis, anhidrosis.

37
Q

What bony structures form the orbit

A

Palatine bone, frontal bone, zygomatic bone, sphenoid bone, lacrimal bone, ethmoid bone, maxilla

38
Q

Major bony structures that form the roof of the orbit

A

Frontal bone

39
Q

Major bony structures of medial wall

A

Maxilla, lacrimal bone, ethmoid bone

40
Q

Name layers of the eyelid

A

Skin, subcutaneous tissue (fatty), orbicularis occuli, septum, tarsus, conjunctiva

41
Q

Two parts of obicularis oculi

A

Orbital and palpebral

42
Q

What is the innervation of superior tarsal

A

Sympathetic, partial ptosis

43
Q

What is innervation of levator palpebrae

A

Occulomotor, complete ptosis

44
Q

What is Horners syndrome made up of and what is it caused by

A

Damage to the sympathetic chain. Partial ptosis, anyhydrosis, miosis.

45
Q

What do the tarsus glands secrete

A

Oily substance

46
Q

What is a stye or hordeolum caused by

A

Blocked sweat glands at base of eyelashes/ cellulitus

47
Q

What is a chalazion from

A

Blocked tarsal glands (not painful)

48
Q

Contents of orbital cavity

A

Eyeball, extrinsic muscles of the eyeball, lacrimal gland, neurovascular structures

49
Q

What muscles are enclosed in the tendinous ring

A

The rectus muscles

50
Q

What neurovascular structures are in the tendinous ring

A

Optic nerve, opthalmic artery, occulomotor, abducent and nasocilliary

51
Q

If there is an infection in the periorbital layer which nerve/ artery are affected

A

All those in tendinous ring. Optic nerve, opthalmic artery, occulomotor, abducent and nasociliary

52
Q

Most important branch of the opthalmic artery

A

Central retinal artery

53
Q

What is the relevance of the danger triangle

A

Facial veins drain to opthalmic veins, to cavernous sinus, facial infection can lead to cavernous sinus thrombosis

54
Q

Describe the course of superior oblique muscle

A

Origin outside of tendinous ring (medial to it), runs medially to sling located on lateral side of ethmoid bone and then anterior belly attaches to superior eyeball

55
Q

Are there valves in opthalmic veins

A

Yes

Special Senses (12 decks)

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