Gross Anatomy Lecture Notes - The Orbit

Gross Anatomy Lecture Notes - The Orbit - D503/D850 Gross...

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D503/D850 Gross Anatomy Lecture Notes 11/14/11 – The Orbit Head 5 - In the orbit, things are very small: be careful, be patient when cleaning fat. - To enter the orbit, we have to break through the orbital plate of the frontal bone. o The orbital plate is the shell of an egg (it’s quite delicate) o Once this is reflected, you’ll see a fibrous membrane known as the periorbita Periosteum that lines the bones of the orbit. Then you’ll see the contents of the orbit once that’s removed. - Optic canal o CN II, ophthalmic artery enter the orbit through this canal. - Superior orbital fissure o Between lesser and greater wing of sphenoid o CN III, IV, V1, VI, and superior ophthalmic vein o These go into the orbit too. - The orbit is a four-sided pyramid (apex is posterior and medial) o The base is what you see in front of the face o Bordered by the frontal bone, maxilla, and zygomatic o The roof is formed by the frontal bone o The lateral wall is formed by the zygomatic bone and the greater wing of sphenoid o The floor is formed by the maxilla There is a membrane lined air-filled space called the maxillary sinus Floor of the orbit is the roof of the maxillary sinus. o The medial wall is the ethmoid bone and lacrimal bone and maxilla. The lacrimal sac sits in the lacrimal fossa of the lacrimal bone. o The medial and lateral walls are thin. The medial wall is referred to as the lamina papyravea. Behind the ethmoid bone are honeycomb looking structures called the ethmoid air cells which are part of our paranasal sinuses. If we have fractures of the medial wall, these are called blowout fractures. o Principal bones that are fractured are the medial fall and the floor. o Bones in the orbit are lined by periorbita. Forms a conical surrounding to the orbit. - We have openings into and out of the orbit o Optic canal is an opening in the lesser wing of the sphenoid ophthalmic artery and CN II o Superior orbital fissure connects the medial cranial to the orbit CN III, IV, V1, VI, and superior ophthalmic vein o Greater wing of the sphenoid and maxillary is the inferior orbital fissure (connects the pyterygopalatine fossa and infraorbital fossa to the orbit)
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Zygomatic branch of CN V2 and the infraorbital nerve which is also a branch of CN V2. The zygomatic nerve enters along the lateral aspect of the orbital floor. o There is a communicating branch which conveys postganglionic parasympathetic fibers to the lacrimal nerve to the lacrimal gland. These two guys come from the pterygopalatine fossa before they enter the orbit. On the floor of the orbit, we have an infraorbital groove which then becomes a canal which then exits as a foramen. Out of this we see the infraorbital VAN
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Gross Anatomy Lecture Notes - The Orbit - D503/D850 Gross...

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