Orbit and Eye

Question 1

Answer 1

Question 2

name the contents of superiof orbital fissure

Answer 2

CN III, IV, V-1 and VI

superior ophtalmic vein

Question 3

name the contents of the inferior orbital fissure

Answer 3

zygomatic nerve (V2)

inferior ophthalmic vein

infraorbital artery and vein

Question 4

name the contents of the optic canal

Answer 4

CN II

opthalmic artery

Question 5

describe the innervation of the conjuctiva of the upper lid and lower lid

Answer 5

• upper lid = CN V-1
• lower lid = CN V2

Question 6

Answer 6

Question 7

describe the veins in the orbit

Answer 7

• sup. and inf. ophthalmic veins join and exit via SOF to empty into cavernous sinus
• inf. ophthalmic vein can drain into (or receive blood from) the pterygoid plexus
• sup. ophthalmic v. can receive blood from angular, supratrochlear, and supraorbital veins
• ophthalmic veins provide connection between facial v. and cavernous sinus
  
  • potential route for infxn

Question 8

name the contents of the cavernous sinus

Answer 8

• on the lateral wall:
  
  • CN III
  • CN IV
  • CN V-1
  • CN V2
• within the cavernous sinus
  
  • CN VI
  • ICA

Question 9

the eye originally develops as a diverticulum of the ____ ____ ____

Answer 9

the eye originally develops as a diverticulum of the forebrain neural tube

Question 10

invagination process of optic cup extends into the ventral part of optic stalk to form a fissure called the _____ _____

inside the ____ will run the ____ _____

Answer 10

invagination process of optic cup extends into the ventral part of optic stalk to form a fissure called the retinal fissure

inside the fissure will run the hyaloid artery

Question 11

the ____ ____ within the fissure will eventually become the ____ ____ ____

Answer 11

the hyaloid artery within the fissure will eventually become the central retinal artery

Question 12

___ and ____ develop from the mesenchyme surrounding the optic cup

Answer 12

sclera and choroid develop from the mesenchyme surrounding the optic cup

Question 13

name the 3 things the cornea develops from

Answer 13

• corneal epithelium: from skin ectoderm
• fibrous stroma: from the mesodermal capsule covering the optic cup
• corneal endothelium: from the neural crest cells of optic cup

Question 14

the _____ develops from the rim of the ___ ____

and

the ____ _____ develops from the optic disk (smooth muscle from mesenchyme)

Answer 14

the iris develops from the rim of the optic cup

and

the ciliary body develops from the optic disk (smooth muscle from mesenchyme)

Question 15

describe a coloboma of the iris (aka keyhole pupil)

Answer 15

• results from the incomplete closure of the retinal fissure
• defect can extend into the ciliary body and retina

Question 16

describe the development of the retina

Answer 16

• the retina develops from the layers of the optic cup:
  
  • pigment layer of retina from the outer layer of optic cup
  • neural layer of the retina from the inner layer of optic cup

Question 17

describe detachment of retina

Answer 17

• the intra-retinal space provides an easy plane of cleavage for detachment of the retina
  
  • the detachment occurs between the neural and pigment layers of the retina
• detachment can occur secondarily during development or after birth as a result of a blow on the eye

Question 18

describe the development of the lens

Answer 18

• the lens develops from the lens vesicle (surface ectoderm)
• the epithelial cells in the posterior wall lose their nuclei and elongate forming primary lens fibers (transparent) which fill the cavity of the lens vesicle
• secondary lens fibers from the equatorial region overlap the primary fibers, increasing the lens diameter as it grows