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OPTHT801 > Conjunctiva + Orbicularis Oculi > Flashcards

Conjunctiva + Orbicularis Oculi Flashcards

(61 cards)

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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
Where does the orbital septum sit in terms of the lateral and medial canthal tendons
Sits in front of LCT | Passes in front of superior oblique trochlear pulley and runs backwards between OO and PL
26
Where does the orbital septum become thin and why?
Superomedially to allow passage of infratrochlear NVB and branches of superior ophthalmic vein
27
How do you identify the orbital septum during surgery?
Firm resistance to traction due to attachment to arcus marginalis Do not ever suture
28
What are the tarsal plates?
Dense fibrous tissue providing structural integrity of the eyelids 25mm horizontally 1-1.5mm thick 3.5-4mm thick in lower lid
29
What is the function of the preaponeurotic fat pad in UL
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
What is the superficial masculoaponeurotic system?
Fibromuscular layer connecting all muscles of facial expression
31
What are the orbital retaining ligaments?
Attach OO to orbital rim and beyond | Runs from periosteum to LO margin
32
Where does the lacrimal gland sit?
``` 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
What are the upper lid retractors?
Levator muscle +Mullers muscle elevate eyelid
34
What is the origin and insertions of the levator palpebrae superioris?
Arises from lesser wing of sphenoid by short tendon 35-40mm long Passes forward horizontally ends as aponeurosis vertically Supplied by occulomotor nerve
35
What is Whitnall's superior transverse ligament?
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
Describe the levator aponeurosis
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
Where does Muller's muscle sit?
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
What retracts the lower lid?
Capsulopaplebral fascia and inferior tarsal muscle | Arise as a direct extension of the inferior rectus
39
What are the 3 components of the conjunctiva?
Palpebral (connected to posterior surface tarsus) Forniceal (superior fornix is 10mm above limbus) Bulbar
40
What is the blood supply to the eyelids?
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
What does the lacrimal artery supply?
Lacrimal gland Upper Eyelids Forehead Scalp
42
What is the venous drainage of the eyelids?
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
What is the lymphatic drainage of the eyelids?
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
What is the sensory nerve supply of the lids?
V1 and V2 Infratrochlear nerve= medial UL and LL Infraorbital nerve=central LL Lateral lid, temple= zygomaticofacial nerve
45
What is the motor supply of the eyelids?
Facial nerve Runs from stylomastoid process to the mandible Enters parotid and divides into 5
46
What are the 5 branches of the facial nerve?
``` Temporal Zygomatic Buccal Mandibular Cervical ```
47
What is Horner's syndrome?
An interruption of the sympathetic pathway from the hypothalamus to the orbit
48
What are 3 orders of neurons involved in Horner's syndrome?
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
What are the clinical features of Horner's syndrome?
``` Ptosis Miosis Anisocoria Apparent enophthalmos Ipsilateral facial hyperemia ```
50
What is different about the asian eyelid?
Absent skin crease | Septum inserts lower on aponeurosis
51
How do the eyelids change over time?
``` Loss of collagen Atrophic dermis Atrophy of orbital fat Laxity of orbital septum Entropion and exotropion Brow ptosis Loss of lacrimal secretion ```
52
How does the lateral canthus differ from the medial canthus?
Lateral canthus 2mm higher than medial
53
What are the two potential spaces of the eyelid?
Pretarsal space- visible surgically | Preseptal space-not visible surgically as the orbicularis muscle is firmly adherent to the underlying septum
54
What are the boundaries of the pretarsal space?
``` 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
What are the borders of the preseptal space?
Triangular Anterior: OO Posterior: Septum and aponeurosis fibres piercing the OO muscle
56
What are the key differences between the upper and lower lids?
- 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
What separates the muscle of Riolan from the pretarsal orbicularis?
Glands of moll | Can be both superficial and deep to Meibomian glands
58
What is the Jones muscle?
The deep portion of the preseptal orbicularis oculi muscle
59
Where do vessels of the orbit run relative to the connective tissue?
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
What smooth muscle is present in the orbit, superiorly, inferiorly, medially and laterally?
Superior: Muller's muscle Inferior: inferior palpebral muscle Medial: scattered fibres in tenons capsule Lateral: none
61
What is the most common muscular eye issue in the case of trauma to the orbit?
Deficient upgaze

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