Term
| What forms the bony orbit? |
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Definition
| The mesenchyme surrounding the optic vesicle |
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Term
| What are the 2 types of bone formation (ossification) that occur during the formation of the orbit? |
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Definition
| Endochondral and Membranous |
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Term
| What orbit bones are preformed in cartilage and then ossified? |
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Definition
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Term
| What orbit bones are ossified from connective tissue? |
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Definition
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Term
| The orbital walls originate from what cells? |
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Definition
| Cranial neural crest cells |
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Term
| Early in development the lateral nasal process migrates laterally and fuses with the maxillary process to form what structures? |
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Definition
| The medial, lateral, and inferior orbital walls |
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Term
| What structure forms the orbital roof? |
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Definition
| The capsule of the forebrain |
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Term
| As the globe enlarges, the connective tissue surrounding it condenses and thickens. Within these fibrous plates, what structures develop? |
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Definition
| The bones surrounding the orbit |
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Term
| At 6 weeks gestation, what is the first bone to develop embryologically? |
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Definition
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Term
| What is the only bone that forms from endochondral and membranous origins? |
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Definition
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Term
| Do the greater and lesser wings of the sphenoid develop together spatially or temporally? |
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Definition
| NO - They develop in different locations at different times |
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Term
| When do the greater and lesser wings of the sphenoid join together? |
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Definition
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Term
| At birth, ossification of the orbital walls is complete except for where? |
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Definition
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Term
| The bony orbit is designed to do what two things for the orbit and soft tissues? |
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Definition
|
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Term
| What are the seven individual bones that make up the four walls of the orbit? |
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Definition
| Frontal, maxillary, sphenoid, palantine, lacrimal, ethmoid, and zygomatic |
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Term
| The adult orbit is in the shape of what? |
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Definition
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Term
| The orbital rim is the thickest and strongest where? |
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Definition
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Term
| The attachment point of the lateral canthal ligament, the lateral rectus muscle check ligament, and aponeurosis of the levator palpebrae superioris muscle is what? Where is it located? |
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Definition
| The tubercle of the zygomatic bone. It is located just inside the lateral orbital rim |
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Term
| Is the orbital floor thin? |
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Definition
|
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Term
| What is the orbital floor made from? What shape is it in? |
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Definition
| The orbital plate of the maxillary bone. It is triangular in shape |
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Term
| Where does the orbital floor extend from? |
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Definition
| From the maxillary-ethmoid buttress to the inferior orbital fissure |
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Term
| A depression in the orbital floor is where what muscle originates? |
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Definition
| The inferior oblique muscle |
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Term
| Which area of the orbit is the most susceptible to blunt force trauma? |
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Definition
|
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Term
| The support of the weak floor is provided by what? |
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Definition
| The maxillary-ethmoid buttress and the infraorbital sulcus/canal |
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Term
| Which thin structure is uniformly supported by the "honeycombed" structure of the ethmoid sinus bony lamina? |
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Definition
| The lamina papyracea of the ethmoid bone |
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Term
| Because of the "honeycombed" support, the medial wall is _______ susceptible to fracture than the orbital floor despite both being extremely thin. |
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Definition
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Term
| Blunt force trauma to the cheek can result in a tripod fracture. What are the three fracture points? |
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Definition
The zygomaticomaxillary suture
The frontozygomatic suture
The zygomatic arch |
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Term
| Contraction of the muscle across the tripod fracture causes this complex to rotate how? |
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Definition
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Term
| These fractures (tripod fracture) need to be reduced and fixated at a minimum of how many locations? |
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Definition
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Term
| After the fracture the cheek is noted to be depressed and the patient may experience muscle spasm or difficulty opening his/her mouth. Why does this occur? |
|
Definition
| Due to the coronoid process of the mandible contracting the rotated zygomatic arch |
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Term
|
Definition
| Forward displacement of the globe |
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Term
|
Definition
| Retro-displacement of the globe posteriorly into the orbit |
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Term
| What is the forward displacement of any object called? |
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Definition
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Term
| The most common cause of exophthalmos in adults is what? |
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Definition
|
|
Term
| What is another name for thyroid eye disease? |
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Definition
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Term
| The muscle and connective tissue swell and increase in fat content and are eventually replaced by what in Grave's disease? |
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Definition
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Term
| Another cause of exophthalmos is craniofacial dystosis. What is another name for this disease and what occurs? |
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Definition
| Crouzon's syndrome - It is a premature fusion of the suture lines of the cranium. As the brain grows it cannot expand like normal due to the closed sutures. As a way to relieve pressure the brain grows forward and causes the eyes to bulge |
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Term
| What else may stimulate exophthalmos because of the enlarged, elongated globe? |
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Definition
| Severe myopia and buphthalmos |
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Term
|
Definition
| Infantile glaucoma scenario |
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|
Term
| What are some of the causes of enophthalmos? |
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Definition
| Trauma, surgery, precious irradiation |
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Term
| Metastatic lesions may lead to what in the contralateral eye? |
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Definition
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Term
| How do we measure exophthalmos? |
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Definition
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Term
| What are the normative values for exophthalmometry? |
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Definition
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Term
| In exophthalmometry, a difference of how many mm between eyes is considered significant? |
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Definition
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