Orbit: osteology and myology

Question 1

orbital fascia (what does it form):

Answer 1

slide 3, it forms the periosteum of the orbit

Question 2

what gland and canals do we find surrounding the orbit ?

Answer 2

• lacrimal gland
• excretory lacrimal canal
• superior lacrimal canal
• inferior lacrimal canal
  (slide 3)

Question 3

orbital vs visual axis:

Answer 3

• orbital = 45, on the sides
• visual = 90, straight forward
• medial wall extends further anteriorly than lateral wall
• lateral wall is more exposed
  (slide 4)

Question 4

composition of the supra-orbital margin:

Answer 4

• frontal lobe with supra-orbital notch (lateral 2/3rds) + (medial 1/3rd)

Question 5

composition of the infra-orbital margin:

Answer 5

• zygomatic bone laterally and maxilla medially + anterior lacrimal crest (just beside maxilla)

Question 6

composition of medial orbital margin:

Answer 6

• fusion of frontal above + lacrimal crest of frontal process of maxilla medially

Question 7

composition of lateral orbital margin:

Answer 7

• fusion of frontal above and frontal process of zygoma below

Question 8

walls of the orbital cavity: (roof, floor, lateral and medial walls):

Answer 8

• roof = lesser wings of sphenoid + orbital plate of frontal bone
• medial wall: sphenoid body + orbital plate of ethmoid bone + lacrimal bone
• lateral wall: zygomatic process of frontal bone + greater wings of sphenoid + orbital plate of zygomatic bone
• floor: zygomatic bone + orbital surface of maxilla + orbital process of palatine
  (look at slide 10 to imagine how it’s drawn on sphenoid)

Question 9

in medial and lateral walls we find: (slide 15)

Answer 9

medial wall:
- facial sheath of eyeball (Tenon’s capsule)
- medial ligament of rectus muscle
lateral wall:
- periorbita
- episcleral space (surrounding eye)
- lateral ligament of rectus muscle

Question 10

relation between orbital plate and anterior cranial fossa:

Answer 10

superior surface of orbit (= orbital plate) = part of the floor of the anterior cranial fossa

Question 11

what are the foramina of the orbit ?

Answer 11

• optic foramen
• superior orbital fissure
• inferior orbital fissure
• optic canal
• anterior ethmoidal foramen
• posterior ethmoidal foramen
• nasolacrimal canal
  (slide 17)
  (the optic canal + sup + inferior orbital fissures are found in the sphenoid body)

Question 12

what passes through the optic canal:

Answer 12

optic nerve + ophthalmic artery, as they make their way to the ocular bulb

Question 13

what passes through the inferior orbital fissure and the superior orbital fissure:

Answer 13

• superior orbital fissure: 346
• inferior orbital fissure: inferior ophthalmic vein, infraorbital (a,v,n), zygomatic nerve

Question 14

what passes through the anterior ethmoidal foramen and the posterior one ?

Answer 14

• anterior: anterior ethmoidal a,v,n
• posterior: posterior ethmoidal a,v,n

Question 14

what passes through the nasolacrimal canal:

Answer 14

nasolacrimal duct

Question 15

muscle insertion of orbital cavity:

Answer 15

slide 21
(superior + inferior division of oculomotor nerve, trochlear nerve, abducens, inf + sup ophthalmic veins)
slide 22 (y a bcp plus de turcs)
slide 24

Question 16

neurovascular contents of superior orbital fissure:

Answer 16

FINALISTS (slide 26)

Question 17

neurovascular contents of inferior orbital fissure:

Answer 17

ZOIII (slide 26)

Question 18

muscles of orbital cavity that do abduction (and other things):

Answer 18

• LR: abd
• IO: abd + elv + er
• SR: abd + dep + ir

Question 19

extraocular muscles that do adduction (and other things):

Answer 19

• SR: add + elv + ir
• IR: add + dep + er
• MR: add

Question 20

innervation of extraocular muscles:

Answer 20

• LR6SO4
• the rest = CN III (oculomotor)