Flashcards in Orbit Volume 1 Deck (35)
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1
What is the average distance between the two medial walls of the orbit?
25 mm
2
Where is the location of the widest portion of the orbit?
1 mm behind the orbital rim
3
What is the volume of the average adult orbit?
30 cc
4
What are the average dimensions of the adult orbit?
35 x 40 x 45 mm
5
What is the average distance from the posterior globe to the optic foramen?
18 mm
6
Name the 7 bones of the orbit.
Ethmoid, frontal, lacrimal, maxillary, palatine, sphenoid, and zygomatic
7
Where is the trochlea fossa located?
5 mm behind the superior nasal orbital rim
8
What structures are located within the supraorbital notch?
Supraorbital blood vessels and supraorbital nerve
9
What bones make up the roof of the orbit?
Frontal bone and lesser wing of the sphenoid
10
What bones make up the lateral walls of the orbit?
Zygomatic bone and greater wing of the sphenoid
11
What is the thickest and strongest orbital wall?
Lateral wall
12
What bones make of the medial orbit?
Ethmoid,lacrimal, maxillary, and sphenoid bones
13
Name the two thinnest walls of the orbit.
Lamina papyracae and maxillary bone
14
What is a common source of spread of infection in children with orbital cellulitis and proptosis?
Transmission from the ethmoid sinuses through the lamina papyracae
15
What bones make up the floor of the orbit?
Maxillary, palantine, and zygomatic bones
16
What is the shortest wall of the orbit?
Orbital floor
17
Name the contents of the infraorbital groove.
Infraorbital artery and maxillary division of the trigeminal nerve
18
What separates the greater and lesser wings of the sphenoid?
Superior orbital fissure
19
Name the contents of the superior orbital fissure.
CN Ill, IV,and VI, First divisions of CN V, and branches of the orbital vein
20
What nerve is commonly damaged in blowout fractures of the orbital floor?
Infraorbital nerve (branch of the maxillary nerve)
21
What is the average length of the optic canal?
8 to 10 mm
22
What is the average length of the intraorbital optic nerve?
30 mm
23
What is the average diameter of the optic nerve?
4 mm
24
What is the common origin of the 4 rectus muscles?
Annulus of Zinn
25
What is the only cranial nerve that innervates an extraocular muscle but does not pass through muscle cone when entering the omit?
CN IV
26
Name the three major branches of the ophthalmic artery.
1. Extraocular muscular branches 2.Central retinal artery 3.Posterior ciliary arteries
27
What vessel provides the main venous drainage of the orbit?
Superior ophthalmic vein
28
Name the 3 main brandies of the ophthalmic division of the maxillary nerve.
1. Frontal nerve 2. Lacrimal nerve 3. Nasociliary nerve
29
What nerve innervates the medial canthus?
Supratrochlear nerve
30
