Orbit Volume 1 Flashcards
What is the average distance between the two medial walls of the orbit?
25 mm
Where is the location of the widest portion of the orbit?
1 mm behind the orbital rim
What is the volume of the average adult orbit?
30 cc
What are the average dimensions of the adult orbit?
35 x 40 x 45 mm
What is the average distance from the posterior globe to the optic foramen?
18 mm
Name the 7 bones of the orbit.
Ethmoid, frontal, lacrimal, maxillary, palatine, sphenoid, and zygomatic
Where is the trochlea fossa located?
5 mm behind the superior nasal orbital rim
What structures are located within the supraorbital notch?
Supraorbital blood vessels and supraorbital nerve
What bones make up the roof of the orbit?
Frontal bone and lesser wing of the sphenoid
What bones make up the lateral walls of the orbit?
Zygomatic bone and greater wing of the sphenoid
What is the thickest and strongest orbital wall?
Lateral wall
What bones make of the medial orbit?
Ethmoid,lacrimal, maxillary, and sphenoid bones
Name the two thinnest walls of the orbit.
Lamina papyracae and maxillary bone
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
What bones make up the floor of the orbit?
Maxillary, palantine, and zygomatic bones
What is the shortest wall of the orbit?
Orbital floor
Name the contents of the infraorbital groove.
Infraorbital artery and maxillary division of the trigeminal nerve
What separates the greater and lesser wings of the sphenoid?
Superior orbital fissure
Name the contents of the superior orbital fissure.
CN Ill, IV,and VI, First divisions of CN V, and branches of the orbital vein
What nerve is commonly damaged in blowout fractures of the orbital floor?
Infraorbital nerve (branch of the maxillary nerve)
What is the average length of the optic canal?
8 to 10 mm
What is the average length of the intraorbital optic nerve?
30 mm
What is the average diameter of the optic nerve?
4 mm
What is the common origin of the 4 rectus muscles?
Annulus of Zinn
What is the only cranial nerve that innervates an extraocular muscle but does not pass through muscle cone when entering the omit?
CN IV
Name the three major branches of the ophthalmic artery.
- Extraocular muscular branches 2.Central retinal artery 3.Posterior ciliary arteries
What vessel provides the main venous drainage of the orbit?
Superior ophthalmic vein
Name the 3 main brandies of the ophthalmic division of the maxillary nerve.
- Frontal nerve 2. Lacrimal nerve 3. Nasociliary nerve
What nerve innervates the medial canthus?
Supratrochlear nerve
What nerves innervates the upper eyelid?
Lacrimal and supratrochlear nerve
What nerve innervates the forehead?
Supraorbital nerve
What nerve innervates the iris, cornea, and ciliary muscle?
Long ciliary nerve
In what bone can the optic canal be found?
Lesser wing of the sphenoid
What region of the nasal cavity does the nasolacrimal duct open into.?
Interior meatus
What structure is found in the inferior orbital fissure?
Maxillary nerve
