Anatomy Block II*- Orbit 1: Bony and Extraocular Muscles

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1

what is the palpebra?

refers to eyelid

2

what is the bulbar?

refers to eyeball

3

what is the orbit?

bony socket that encases the eyeball

4

what is the tarsal?

means eyelid

5

what bones make up the roof of the orbit?

frontal bone and lesser wing of sphenoid

6

what bones make up the medial wall of the orbit?

ehtmoid, maxilla, and lacrimal bones

7

what bones make up the floor of the orbit?

maxilla, zygomatic, and small part of palatine bones

8

what bones make up the lateral wall of the orbit?

zygomatic, frontal, and greater wing of sphenoid bones

9

what air is medial to the orbit

ethmoidal air sinus

10

what sinus is inferior to the orbit

maxillary air sinus

11

what is directly superior to the orbit?

anterior cranial fossa

12

what are the openings within the orbit?

optic canal

superior orbital fissure

inferior orbital fissure

13

what does the optic canal connect?

middle cranial fossa to orbit

14

what does the optic canal transmit?

transmits optic nerve and ophthalmic artery

15

what does the superior orbital fissure connect?

middle cranial fossa to orbit

16

what does the superior orbital fissure transmit

oculomotor nerve CN III, CN IV, branches of ophthalmic nerve CN V1, abducens nerve, superior and inferior ophthalmic veins

17

what does the inferior orbital fissure connect?

connects pterygopalatine fossa, infratemporal fossa, and temporal fossa to orbit

18

what does the inferior orbital fissure transmit

transmits the infraorbital artery (branch of maxillary), infraorbital nerve and a branch from the inferior opthalmic vein (to pterygoid venous sinus)

19

what things are contained within the bony orbit?

eyeball
BVs (ophthalmic artery and veins
nerves (CN II-V1, VI)
ciliary ganglion
lacrimal gland
extraocular muscles
orbital fat
fascial sheath of eyeball

20

what type of innervation is the ciliary ganglion

parasympathetic

21

what are the extraocular muscles with a common origin and what is it

superior rectus, inferior rectus, medial rectus, lateral rectus, wich a common origin, the common tendinous ring (annulus tendineus)

22

what comprises the fascial sheath of the eyeball and what does it do?

bulbar fascia, vagina bulbi, Tenon's capsule

surrounds the eyeball and provides a tissue socket for eyeball

23

what large nerves innervate the orbit?

ophthalmic nerve, oculomotor nerve, trochlear nerve, abducens nerve

24

what type of general innervation does the ophthalmic nerve supply to the orbit?

sensory to eyeball, lacrimal gland, nasal mucosa, frontal sinus, external nose, upper eyelid, forehead, scalp

25

what are the branches of the ophthalmic nerve?

frontal nerve, with two branches, supraorbital and suptratrochlear

lacrimal nerve
nasociliary nerve

26

where does the lacrimal nerve run

lacrimal: in upper portion of orbit

27

where does the nasociliary nerve run

nasociliary: in medial portion of orbit, gives off many branches

28

what type of general innervation does the oculomotor nerve supply to the orbit?

somatic motor and parasympathetics

29

what does the oculomotor nerve innervate (muscles)

levator palpebrae superioris
superior rectus
medial rectus
inferior rectus
inferior oblique

30

what type of general innervation does the trochlear nerve supply to the orbit

somatic motor only

31

what muscle does trochlear nerve innervate in the orbit

superior oblique

32

what type of general innervation does the abducens nerve supply to the orbit

somatic motor only

33

what eye muscles does abducens innervate

lateral rectus

34

what are the extraocular muscles?

levator palpebrae superioris
medial rectus
lateral rectus
superior rectus
inferior rectus
superior oblique
inferior oblique

35

what innervates the levator palpebrae superioris? what does it do?

CN III
elevates eyelid

36

what innervates the medial rectus? what does it do?

CN III, adducts the eyeball

37

where does the medial rectus run

runs from tendionous ring to anterior-medial part of eye,

38

what innervates the lateral rectus? what does it do?

CN VI, abducts the eyeball

39

where does the lateral rectus run?

starts at tendinous ring to anterior lateral part of eye

40

what innervates the superior rectus? where does it run? what does it do?

CN III, when this muscle contracts it elevates and adducts the eye

41

where does the superior rectus run

runs from tendinous ring to anterior-superior part of eye,

42

what innervates the inferior rectus? what does it do?

CN III depresses and adducts the eye

43

where does the inferior rectus run?

from tendinous ring to anterior-inferior part of eye,

44

what innervates the superior oblique? w what does it do?

CN IV

depresses and abducts eyeball

45

where does the superior oblique run?

runs directly along medial wall of orbit, then muscle tendon passes through fibrous ring (trochlea) and the muscle fibers change direction and then run back to attach to posterior-superior part of eyeball

46

what innervates the inferior oblique? what does it do?

CN III

elevates and abducts the eyeball

47

where does the inferior oblique run

starts on anterior floor of orbit and attaches to posterior-inferior part of eyeball

48

do eye muscles work together or by themselves?

together

49

how many cardinal directions of gaze are there? what does this mean? are these the same as anatomic movements of the eye?

six; this is where the function of a single eye muscle predominates

no, often different

50

why are the cardinal directions of gaze different than anatomic directions?

muscle movement is most powerful if you line the long axis (sagittal axis) of the eye with the long axis of the direction of the muscle fibers

51

how would you test the superior rectus muscle?

if eye is first turned laterally, the long axis of the eye is now parallel with the long axis of the muscle fibers

now if you contract the superior rectus muscle, the eye is pulled superiorly
it is in this direction (first looking laterally, then superiorly) that the function of the superior rectus is most powerful

52

how could damage to the nerves to the orbit manifest itself?

could paralyze one or more of eye muscles on the affected side

53

what is strabismus

deviation of eyes from normal aligned position

54

what is diplopia

double vision

55

what can happen with oculomotor nerve injury?

eye will be directed laterally due to unopposed lateral rectus muscle and inferiorly due to unopposed superior oblique

ptosis due to paralyzed levator palpebrae superioris

56

what can happen with trochlear nerve injury

paralysis of superior oblique muscle on affected side

if you suspect a left CN IV injury, have the patient look medially, then inferiorly
- patient's inferior rectus and left superior oblique muscles can be tested in this position
- if patient's left eye looks medially, but NOT inferiorly, suspect the superior oblique is paralyzed/weakness

57

what can happen with abducens nerve injury?

paralysis of lateral rectus muscle on affected side (eye may be deviated medially)

affected eye will not be able to be moved laterally