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Anatomy and Embryology CNS > Anatomy Orbits > Flashcards

Anatomy Orbits Flashcards

1
Q

Embryology of the eye

A 
Neuroectoderm (retina, iris, optic nerve)
Surface ectoderm (lens)
Mesoderm (vascular structures, sclera, choroid)
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2
Q

Orbital bones:
Roof

Floor

Medial Wall

Lateral Wall

A

Roof: Frontal, Lesser wing sphenoid bone

Floor: Maxilla, Zygomatic bone

Medial Wall: Ethmoid bone (lamina papyracea), Lacrimal bone, Maxilla

Greater wing of sphenoid bone
Zygomatic bone

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3
Q

What is a blow out fracture?

CT findings?

A

Direct blow that results in increased intraorbital pressure

‘Trap door’ fragment
The inferior orbital rin has to be intact
Downward displacement of bone fragments
Inferior rectus m. involvement
Herniation of orbital fat into maxillary sinus
Air in the orbit -> fracture medial wall

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4
Q

Superior orbital fissure bones

A

Lesser and greater wings of the sphenoid bone

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5
Q

Inferior orbital fissure bones

A

Greater wing of sphenoid bone

Maxilla and palatine bone

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6
Q

Where is the optic canal located?

A

Orbital apex in the sphenoid bone

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7
Q

Superior orbital fissure contents

A 
Cranial nerves III, IV, VI
Lacrimal n. + frontal n. + nasociliary n. (opthalmic n)
Orbital branch middle meningeal artery
Recurrent branch lacrimal artery
Super Ophth Vein
Super Orbital vein
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8
Q

Mnemonic of the order in which the nerves pass through the superior orbital fissure

A

Lazy French Tarts Sit Naked In Anticipation

Lacrimal
Frontal
Trochlear
Sup Div Oculomotor
Nascociliary 
Infer Div Oculomotor
Abducens
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9
Q

Inferior Orbital Fissure contents

A 
Zygomatic n
Parasympathetics for lacrimal gland
Infraorbital art
Infraorbital vein
Infraorbital nerve
Inferior opthalmic vein
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10
Q

Infraorbital sulcus and foramen contents

What is the importance of the infraorbital foramen?

A

Infraorbital artery, vein, nerve

Route for spread of infection or maxillary tumours to the orbit and skull base

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11
Q

Optic canal contents

A

Optic nerve, dural sheath
Ophthalmic artery
Central retinal vein

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12
Q

What structure is known as the septum?

A

The med. palpebral ligament

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13
Q

Intraconal lesions in the orbit

A

Melanoma, Metastasis, Retinoblastoma
Meningioma, Hemangioma, Optic glioma
Pseudotumor, Cellulitis, Graves disease

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14
Q

What is the origin of melanoma in the eye?

What is the location of melanoma in the orbit?

A

From the pigmented choroidal layer

Choroid >ciliary body >iris

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15
Q

What is the most common primary intraocular neoplasm in adults?

A

Melanoma

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16
Q

Complications of melanoma in the orbit

A

Retinal detachment and vitreous haemorrhage

17
Q

What is dacryoadenitis?

What is the differential of dacryoadenitis?

A

Inflammation of the lacrimal gland

Preseptal or orbital cellulitis

18
Q

What are the imaging findings of dacryoadenitis ?

A

Diffuse lacrimal enlargement
Poorly demarcated mass
NO bone destruction

19
Q

What is chemosis of the eye?

A

Swelling of the tissue that lines the eyelids and surface of the eye (conjuctiva). Preseptal

20
Q

What is scleritis ?

A

Chronic painful inflammatory disease of the sclera and episcleral tissues.

21
Q

What is Bupthalmos ?

Which diseases are associated?

A

Enlargement of the globe due to increased intraocular pressure , secondary to obstruction of the Schlemm canal.

Sturge Weber
NF1
Cobblestone lissencephaly

22
Q

What is coloboma?

A

Congenital fissure in the globe due to incomplete closure of the embryonic optic fissure.

23
Q

What is staphyloma?

A

Protrusion of the uveal tissue through thinning of the sclera

24
Q

What is the clinical finding in retinoblastoma?

A
  • Leukoaria (white pupillary reflex) = cat eye reflex due to replacement of the vitreous humor by a white mass
  • Reduced vision, eye pain, strabismus
25
Q

What else can give a white eye?

A

Persistent hyperplastic primary vitreous

Bulb laceration

26
Q

Extraocular muscles, action and nerves

A

Lat rectus - laterally - CN6
Med Rectus - medially - CN3
Sup Rectus - elevates turns medially - CN3
Inf. Rectus - depresses turns medially - CN3
Inf Oblique - elevates, turns laterally - CN3
Sup Oblique - depresses turns laterally - CN4

27
Q

Branches of the Opthalmic artery

A

Central retinal artery

Posterior ciliary artery

28
Q

Describe the orbital vein anastomosis creating a Danger zone

A

Facial vein ->angular vein -> SOV ->cavernous sinus

Facial vein > Infraorbital vein >pterygoid plexus >cavernous sinus

29
Q

What is the Annulus of Zinn?

A

A fibrous ring formed by the common origin of the 4 rectus muscles

Anatomy and Embryology CNS (22 decks)

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