Plastics

Question 1

Orbit dimensions

Answer 1

40-45 mm deep
45 mm wide (max width ~1 cm behind rim)
35 mm high
30 cc volume

Question 2

Bones and structures of SOF

Answer 2

Greater and lesser sphenoid wings

Transmits CN 3, 4, v1 and 6; SOV, symp fibers to iris dilator

Question 3

Bones and structures of optic canal

Answer 3

Within lesser wind of sphenoid

Transmits optic nerve, ophthalmic artery and sympathetic nerves to blood vessels

Question 4

Bones and structures of the inferior orbital fissure

Answer 4

Bordered medially by maxillary bone, anteriorly by zygomatic bone and laterally by greater wing of sphenoid, palatine
Transmits CN V2, zygomatic nerve, inferior ophthalmic vein, venous comm. btwn ophth vein & pterygoid/sphenopalatine plexus

Question 5

Foramen ovale, rotundum, lacerum

Answer 5

Ovale: V3
Rotundum: v2
Lacerum: ICA
Spinosum: MMA

Question 6

Central retinal artery entry into optic nerve

Answer 6

13 mm posterior to globe

Question 7

Ant/post ethmoidal foramen

Answer 7

Jxn of frontal and ethmoid bones

Question 8

SOF structures inside/outside annulus

Answer 8

In: CN 3 (sup/inf), nasociliary, CN 6,
Out: lacrimal n, frontal n, trochlear n, SOV

Question 9

Parasympathetic and sympathetic innervation pathways

Answer 9

Parasympathetic via short ciliary nerves through ciliary ganglion
sympathetic via long ciliary nerves

Question 10

Pre tarsal orbicularis heads

Answer 10

Superficial: extends from ant lac crest to form part of MCT then inserts on zygomatic bone

Deep: extends from post lac crest to surround canaliculi (horners muscle), forms part of LCT, then inserts onto lat orbital tubercle

Question 11

Preseptal orbicularis

Answer 11

Anterior limb from MCT & post lac crest/lac sac fascia (Surrounds sac), then continues to lat palpebral raphe

Question 12

Orbital orbicularis

Answer 12

Inserts at medial canthal tendon and interdigitates with frontalis muscle superiorly at brow

Question 13

Forehead muscles and functions

Answer 13

1. Frontalis: moves scalp anterior and post; raises eyebrows; innervated by CN 7; independent muscle
2. Corrugator: pulls medial eyebrow inf/med producing vertical glabellar wrinkle; Originates from nasal process of frontal bone; innervated by CN 7; part of orbital orbicularis
3. Procerus: pulls forehead and medial brow inferiorly producing horizontal lines in nose; interdigitates with inf edge of frontalis

Question 14

LPS horns

Answer 14

Muscular portio (40 mm), aponeurotic (15-20 mm; 2 horns)

Lateral: Inserts into lateral orbital tubercle; divides lacrimal gland

Medial: Inserts onto posterior lacrimal crest; inserts onto lower half of Tarsus to form eyelid crease

Question 15

Whitnalls ligament

Answer 15

10 mm above superior edge of tarsus
Attachments: medially to trochlea; laterally to lacrimal gland and lateral wall 10 mm ABOVE Whitnall’s tubercle
Origin of Mullers muscle
Peripheral arterial arcade found between aponeurosis and mullers muscle

Question 16

Muscle Analogous to mullers in LL

Answer 16

Inf tarsal muscle; symp innervation; arises from CPF at level of lockwood’s ligament

Question 17

Capsulopalpebral fascia

Answer 17

Analogous to levator apo.
Originates from inferior rectus sheath
Encircles inferior oblique muscle 
joins to form Lockwood ligament 
fuses c septum and inserts into inf Tarsus

Question 18

Lockwood’s ligament

Answer 18

analogous to Whitnall’s ligament

Medial and lateral horns attached to retinacula forming suspensory hammock

Question 19

Dimensions of Tarsus

Answer 19

29 mm long
1 mm thick
superior tarsal plate: 10 mm in height
Inf: 4 mm in height

Question 20

Medial canthal tendon

Answer 20

Attaches to tarsal plates; fusion of tendinous insertions of pretarsal and preseptal orbicularis

Anterior limb: attaches to frontal process of maxillary bone; passes anterior to lacrimal sac; origin of superficial head of precursor orbicularis; attaches to anterior lacrimal crest

Posterior limb attaches to posterior lacrimal crest; passes behind lacrimal sac. More important than anterior limb for lid apposition

Question 21

Lateral canthal tendon

Answer 21

Originates from lat borders of upper and lower tarsal plates
inserts onto tubercle of Whitnall
3 mm superior to MCT insertion

Question 22

Vascular supply to eyelids

Answer 22

UL: ICA to ophthalmic to superior marginal arcade
LL: ECA to facial artery to angular artery to inf marginal arcade

Periph and marginal arcades allow for anastomosis between ICA and ECA

Question 23

Spencer’s Triad

Answer 23

Optociliary shunts, optic atrophy, optic nerve meningioma

Question 24

Risk of systemic lymphoma by location in orbit

Answer 24

1. eyelids 67%
2. orbit 35%
3. conjunctiva 20%

Location is more important than histopathology

Question 25

Fibrous histiocytoma Characteristics

Answer 25

Benign in 90% distinguished from hemangiopericytoma only on biopsy pathology: storiform nebular pattern; spindle cell tumor

Question 26

Rule of 50s

Answer 26

50% of lacrimal gland lesions are inflammatory or lymphoproliferative 50% of lacrimal grand tumors are of epithelial origin 50% of epithelial tumors are benign pleomorphic adenoma 50% of malignant tumors are adenoid cystic carcinoma

Question 27

Work up of sinus mucocele

Answer 27

Must rule out encephalocele and meningocele | Also a/w CF

Question 28

Most common primary source of orbital Mets in adults

Answer 28

Women: breast carcinoma – can cause fibrous response, enophthalmos, and ophthalmoplegia Men: lung carcinoma

Question 29

Lid reconstruction options by size of defect

Answer 29

Upper lid Less than 33%: direct closure 33-50% defect: tenzel flap greater than 50% defect: Cutler-Beard flap (tarsoconj) Lower lid Less than 33%: direct closure 33-50% defect: tenzel flap greater than 50% defect: Hughes flap flap tarsoconj)

Question 30

DDX hemifacial spasm

Answer 30

CPA tumor, MS 2/2 compression of CN 7 Present during sleep

Question 31

Types of ectropion

Answer 31

1. involutional 2. paralytic 3. cicatricial number 4. mechanical 5. Congenital (ie blepharophimosis)

Question 32

Types of entropion

Answer 32

1. Congenital 2. Spastic 3. Involutional 4. Cicatricial

Question 33

Most common locations for basal cell carcinoma

Answer 33

Lower lid (50%) medial canthus (Worse prognosis) upper lid outer canthus

Question 34

Most common location of squamous cell carcinoma

Answer 34

Lower lid

Question 35

Tendon of insertion length of recti

Answer 35

LR = IR > SR > MR > SO > IO (1 mm) | LR/sr: 7 mm Mr: 4.5 mm Sr: 6 mm Ccw to spiral of tillaux

Question 36

Arc of contact for extraocular muscles

Answer 36

IO > LR > SO > MR> SR = IR 15, 12, 7-8, 7, 6.5

Question 37

Blepharophimosis syndrome

Answer 37

Blepharoptosis, telecanthus, epicanthus inversus AND ectropion AD inheritance; can be a/w trisomy 18

Question 38

Location of ostium in DCR surgery

Answer 38

Middle turbinate

Question 39

Walls of orbit

Answer 39

Roof (FLS): frontal, lesser sphenoid Medial (SMELs): lesser sphenoid, maxillary, ethmoid, lacrimal Floor (MoPZ): maxillary, palatine, zygomatic Lateral (ZiGs): zygomatic, greater sphenoid

Question 40

Location of IO in relation to fat pads

Answer 40

Separates medial and central pads

Question 41

Strongest wall of orbit

Answer 41

lateral

Question 42

Most frequent site of BCC on eyelids

Answer 42

LL > MC > UL > LC

Question 43

Most common cause of conjunctivitis --> cellulitis in kids

Answer 43

H flu

Question 44

Systemic conditions associated with blepharophimosis syndrome

Answer 44

Premature ovarian failure in BPES Type 1

Question 45

Risk of systemic disease for peri ocular lymphoma

Answer 45

Lids: 67% Orbit: 35% Conj: 20%

Question 46

Path of NL canal thru lateral nasal wall

Answer 46

Downward, posterior, and LATERAL | MEEI peds #33, pg 251

Question 47

1. Heerfordt Syndrome 2. Lofgren syndrome 3. Mikulicz Syndrome

Answer 47

All are systemic forms of sarcoidosis 1. Heerfordt- granulomatous uveitis, parotid swelling, CN VII palsy 2. Lofgren- bilateral hilar LAD, arthropathy, fever, erythema nodosum 3. Mikulicz- lacrimal gland enlargement, salivary gland enlargement, KCS

Question 48

optic nerve blood supply

Answer 48

Retrolaminar nerve -- pial vessels and short posterior ciliary arteries (SPCAs) Laminar nerve -- SPCAs, branches of circle of Zinn-Haller Prelaminar nerve -- SPCAs, recurrent choroidal arteries Nerve fiber layer -- central retinal artery (CRA) Intraorbital optic nerve -- proximally - pial vessels and branches of ophthalmic artery; distally - branches of CRA Intracanalicular optic nerve -- ophthalmic artery Intracranial optic nerve -- ophtalmic artery and internal carotid artery

Question 49

Sinuses and corresponding meatus

Answer 49

Sphenoid-- sphenoethmoidal recess Posterior ethmoidal sinus- superior meatus Frontal, ant/med ethmoidal, maxillary-- middle meatus Nasolacrimal duct- inferior meatus