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OPTHT801 > Conjunctiva + Orbicularis Oculi > Flashcards

Conjunctiva + Orbicularis Oculi Flashcards

1
Q

What is the difference between orbital and preseptal cellulitis?

A

Preseptal: anterior to orbital septum
Orbital: posterior to orbital septum

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2
Q

What raises/depresses the eyebrow?

A

Raised by frontalis muscle
Depressed by procerus, corragtor supercilii and orbicularis oculi
Innervated by facial nerve branches

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3
Q

What are the origins and insertion of the frontalis muscle?

A

Originates midway from epicranial aponeurosis and SOM

Inserts onto thick skin of the eyebrows not to bone

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4
Q

Describe the corrugator muscle

A 
Lies beneath frontalis and orbicularis oculi
Supratrochlear nerve passes through
Supraorbital nerve passes under it
Inserts onto underside of frontalis
Pulls eyebrows medially and inferiorly
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5
Q

Describe the procerus muscle

A

Pulls forehead inferiorly-aging frown lines
Fat protrudes under each edge to assist movement
Extends vertically between the eyebrows
Merges with frontalis

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6
Q

What is the embryological origin of the eyelid?

A

ECTODERM (surface)-> skin
ECTODERM (inner layer) -> conjunctiva
Fusion of eyelids occurs at 9 weeks and the eyelids separate at 25 weeks

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7
Q

Describe the surface anatomy of the eyelid

A

30-32mm horizontal
8-11mm vertical
Laterally eyelid is contact with the globe
Medially eyelid is displaced from the globe
Point of maximum concavity: UL medial to pupil. LL lateral to pupil.

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8
Q

What is normal upper lid height and which muscles maintain this?

A

1-2mm below superior limbus
Maintained by balance between upper eyelid retractors+protractors (levator muscle, Muller’s muscle, frontalis muscle and orbicularis oculi)

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9
Q

What is the definition of the ptosis?

A

Marginal reflex distance of <2.5mm
Mild 2mm
Moderate 3mm
Severe 4mm

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10
Q

What are the gender differences in eyebrows?

A

Male: straight heavy low brow
Female: high arch brow, more defined eye crease

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11
Q

What is the eyelid margin?

A

Transition zone between skin and conjunctiva
Keratanised squamous epithelium-> non keratin SSE-> columnar epithelium of conjunctiva
Posterior margin applied to globe, anterior margin holds eyelashes

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12
Q

What is the grey line?

A

Junction between anterior and posterior lamellae

Meibomian glands open behind the grey line

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13
Q

What are the glands of the eyelids?

A

Sebaceous glands: Meibomian glands-not associated with follicles. 25 UL, 20LL
-> form chalazion when blocked
Apocrine glands
Eccrine glands (sweat)

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14
Q

Describe the eyelashes

A

3-4 layers UL
1-2 layers LL
Entropion can cause lash ptosis

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15
Q

What are the layers of the eyelid?

A

Anterior lamellae: skin, orbicularis oculi
Posterior lamellae: tarsal plate, conjunctiva

6 structural planes: Skin (very thin)
Loose connective tissue (no fat)
Orbicularis oculi (CN VII)
Orbital septum (dense fibrous sheet)
Tarsal plates/ meibomian glands
Levator palpebrae superioris (superior lid only CN III) + Muller muscle (sympathetic)
Palpebral conjunctiva
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16
Q

Describe the skin of the eyelid?

A 
Epidermis: 3-4 cell layers thick
Thinnest skin in body
Attached loosely to orbicularis
Firmly attached to canthal tendons
No subcutaneous fat, ideal for skin grafts for reconstruction of lower eyelid
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17
Q

Describe the orbicularis oculi muscle

A

Closes lids
Flat sheet muscles encircling lids
Orbital
Preseptal + Pretarsal layers

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18
Q

Describe the attachments of the orbital part of the OO

A

Attached from supraorbital notch of frontal bone to near infraorbital foramen
Spreads onto forehead, covers corrugator, continues laterally over anterior temporalis fascia
Covers origins of elevator muscles of upper lip and the origin of the masseter

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19
Q

Describe where the preseptal and pretarsal muscles lie

A

Fixed medially and laterally and the canthal tendons
Circumnavigates around the eye

Preseptal: lies anterior to orbital septum + helps in lacrimal pump
Pretarsal: lies on tarsal plate

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20
Q

Describe the two heads of the pretarsal orbicularis

A

Superficial/ anteror: forms anterior limb of medial canthal tendon. Lies anterior to canaliculus and inserts onto maxillary bone
Deep/posterior: horner’s muscle. Inserts into lacrimal fascia and posterior lacrimal crest

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21
Q

What is at the medial canthus?

A

Lacrimal drainage apparatus
Medial canthal tendon
Rounded angle and hollowing

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22
Q

Describe the 3 limbs of the medial canthal tendon

A

Superior: inserts onto orbital process frontal bone. Provides vertical support and lacrimal pump mechanism
Anterior: inserts onto orbital process of maxilla anterior and above ALC, provides main support
Posterior: passes posteriorly between superior and inferior canaliculi, keeps lid apposed to the globe. May or may not exist

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23
Q

Describe the lateral canthal tendon

A

Y shaped fibrous thickening in the orbital septum runs from the end of the tarsal plates Whitnall’s tubercle

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24
Q

Describe the orbital septum

A

Originates at acrus marginalis at orbital rim
Divides eyelid into anterior and posterior
Keeps orbital fat posterior
Fuses with upper lid near superior tarsal border and capsulopalpebral fascia of the lower lid

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25
Q

Where does the orbital septum sit in terms of the lateral and medial canthal tendons

A

Sits in front of LCT

Passes in front of superior oblique trochlear pulley and runs backwards between OO and PL

26
Q

Where does the orbital septum become thin and why?

A

Superomedially to allow passage of infratrochlear NVB and branches of superior ophthalmic vein

27
Q

How do you identify the orbital septum during surgery?

A

Firm resistance to traction due to attachment to arcus marginalis
Do not ever suture

28
Q

What are the tarsal plates?

A

Dense fibrous tissue providing structural integrity of the eyelids
25mm horizontally
1-1.5mm thick 3.5-4mm thick in lower lid

29
Q

What is the function of the preaponeurotic fat pad in UL

A

Cushion to eyelid
Important surgical landmark as eyelid retractors are immediately posterior
UL : medial and centrl fat pads
LL: 3 fat pads, medial, central and temporal
IO separates medial from central fat pads

30
Q

What is the superficial masculoaponeurotic system?

A

Fibromuscular layer connecting all muscles of facial expression

31
Q

What are the orbital retaining ligaments?

A

Attach OO to orbital rim and beyond

Runs from periosteum to LO margin

32
Q

Where does the lacrimal gland sit?

A 
Superolateral orbit in lacrimal fossa
Wrapped around posterior border lateral horn levator aponeurosis
Anterior: orbital septum
Posterior: orbital fat
Inferior: IR laterally
Palpebral part 1/3 size of orbital part
33
Q

What are the upper lid retractors?

A

Levator muscle +Mullers muscle elevate eyelid

34
Q

What is the origin and insertions of the levator palpebrae superioris?

A

Arises from lesser wing of sphenoid by short tendon
35-40mm long
Passes forward horizontally ends as aponeurosis vertically
Supplied by occulomotor nerve

35
Q

What is Whitnall’s superior transverse ligament?

A

Thickens LPS
Inserts medially onto trochlea, bone and SON
Inserts laterally onto capsule of lacrimal gland and orbital wall
Part of circum-orbital fascial ring with Lockwoods ligament
Should not be severed during ptosis surgery
Contributes to suspensory ligament of superior fornix

36
Q

Describe the levator aponeurosis

A

2 horns
30mm wide
Inserts into OO at level skin crease below anterior surface
Medial horn more tenuous than lateral- accounts for lateral shift of superior tarsus in the elderly- should not be severed
Lateral horn inserts onto zygomatic bone. Severed in surgery for thyroid eye disease but should not be damaged in ptosis surgery

37
Q

Where does Muller’s muscle sit?

A

Arises under LPS
15-20mm wide
Descends between levator aponeurosis and conjunctiva to insert on upper border of the tarsal plate
Adherent to conjunctiva and very vascular
Supplied by sympathetic nerves

38
Q

What retracts the lower lid?

A

Capsulopaplebral fascia and inferior tarsal muscle

Arise as a direct extension of the inferior rectus

39
Q

What are the 3 components of the conjunctiva?

A

Palpebral (connected to posterior surface tarsus)
Forniceal (superior fornix is 10mm above limbus)
Bulbar

40
Q

What is the blood supply to the eyelids?

A

Anterior lamellae: branches of external carotid (transverse facial, superficial temporal and angular arteries)
Posterior lamellae: arcades- superior medial palpebral artery and superior lateral palpebral artery (from lacrimal)
Multiple anastomoses between supratrochlear and supraorbital arteries, infraorbital and facial arteries

41
Q

What does the lacrimal artery supply?

A

Lacrimal gland
Upper Eyelids
Forehead
Scalp

42
Q

What is the venous drainage of the eyelids?

A

Veins are in fornices
Medial: Angular vein drains into superior orbital vein posteriorly and inferiorly into the facial vein
Lateral: superficial temporal artery and vein
Venous blood drains inferior ophthalmic vein

43
Q

What is the lymphatic drainage of the eyelids?

A

Lateral 2/3 UL and later 1/3 LL to preauricular lymph nodes

Medial 1/3 UL and medial 2/3 LL to submandibular lymph nodes

44
Q

What is the sensory nerve supply of the lids?

A

V1 and V2
Infratrochlear nerve= medial UL and LL
Infraorbital nerve=central LL
Lateral lid, temple= zygomaticofacial nerve

45
Q

What is the motor supply of the eyelids?

A

Facial nerve
Runs from stylomastoid process to the mandible
Enters parotid and divides into 5

46
Q

What are the 5 branches of the facial nerve?

A 
Temporal
Zygomatic
Buccal
Mandibular
Cervical
47
Q

What is Horner’s syndrome?

A

An interruption of the sympathetic pathway from the hypothalamus to the orbit

48
Q

What are 3 orders of neurons involved in Horner’s syndrome?

A

1st order- posterolateral hypothalamus runs to lower cervical upper thoracic spinal cord

Preganglionic (2nd)-leave spinal cord, travel up apex lung around subclavian artery to the superior cervical ganglion at the angle of mandible

3rd- ascends along carotid sheath, may follow ophthalmic artery through cavernous sinus, travels along CNV through ciliary ganglion

49
Q

What are the clinical features of Horner’s syndrome?

A 
Ptosis
Miosis
Anisocoria
Apparent enophthalmos
Ipsilateral facial hyperemia
50
Q

What is different about the asian eyelid?

A

Absent skin crease

Septum inserts lower on aponeurosis

51
Q

How do the eyelids change over time?

A 
Loss of collagen
Atrophic dermis
Atrophy of orbital fat
Laxity of orbital septum
Entropion and exotropion
Brow ptosis
Loss of lacrimal secretion
52
Q

How does the lateral canthus differ from the medial canthus?

A

Lateral canthus 2mm higher than medial

53
Q

What are the two potential spaces of the eyelid?

A

Pretarsal space- visible surgically

Preseptal space-not visible surgically as the orbicularis muscle is firmly adherent to the underlying septum

54
Q

What are the boundaries of the pretarsal space?

A 
Fusiform in shape
Anterior: levator aponeurosis+OO
Posterior: Tarsal plate +Mullers muscle
Apex:Mullers muscle and levator muscles
Lower edge: insertion of aponeurosis into tarsal plate
55
Q

What are the borders of the preseptal space?

A

Triangular
Anterior: OO
Posterior: Septum and aponeurosis fibres piercing the OO muscle

56
Q

What are the key differences between the upper and lower lids?

A
  • size of tarsal plates
  • # and rows of eyelashes
  • direction of eyelashes
  • development of retractor complex
  • distribution of accessory lacrimal glands
  • absence of LL peripheral arterial archade
  • definition of skin crease
  • number of fat pads
57
Q

What separates the muscle of Riolan from the pretarsal orbicularis?

A

Glands of moll

Can be both superficial and deep to Meibomian glands

58
Q

What is the Jones muscle?

A

The deep portion of the preseptal orbicularis oculi muscle

59
Q

Where do vessels of the orbit run relative to the connective tissue?

A

Orbital arteries are not enclosed within connective tissue septa but are enclosed within
Veins are embedded within the septae
The superior ophthalmic vein lies in a connective tissue hammock

60
Q

What smooth muscle is present in the orbit, superiorly, inferiorly, medially and laterally?

A

Superior: Muller’s muscle
Inferior: inferior palpebral muscle
Medial: scattered fibres in tenons capsule
Lateral: none

61
Q

What is the most common muscular eye issue in the case of trauma to the orbit?

A

Deficient upgaze

OPTHT801 (20 decks)

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