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ANATOMY - head, neck & spine > L13 bony orbits and eye movements > Flashcards

L13 bony orbits and eye movements Flashcards

1
Q

what 7 bones contribute to the orbital cavity?

A
  1. orbital plate of** ethmoid**
  2. sphenoid
  3. orbital surface of maxilla
    4.** zygomatic** bone
    5.** lacrimal **bone
  4. palatine bone
    7.** frontal** bone
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2
Q

what bones make up the roof of the orbit?

A
  • orbital plate of frontal bone
  • lesser wing of sphenoid bone
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3
Q

what bones make up the floor of the orbit?

A
  • orbital surface of maxillary bone
    * zygomatic bone
  • orbital surface of **palatine bone **
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4
Q

what bones make up the** lateral wall** of the orbit?

A
  • **greater wing **of sphenoid bone
  • orbital surface of **zygomatic bone **
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5
Q

what are the foramina / fissures of the orbit?

A
  • superior orbital fissure
  • inferior orbital fissure
  • optic canal
  • infraorbital foramen
  • supraorbital foramen
  • infra orbital groove
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6
Q

what bone that makes up the roof of the orbit separates the orbit from the anterior cranial fossa?

A

the frontal bone

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7
Q

what bone that contributes to the floor of the orbit seperates the orbit from the underlying maxillay sinus?

A

the maxilla

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8
Q

what bones make up the medial wall of the orbit?

A
  • the ethmoid
  • maxilla
  • lacrimal
  • sphenoid bone
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9
Q

what are the** contents of the orbit**?

A
  • eyeball
  • fascia
  • muscles
  • vessels
  • nerves
  • lacrimal gland
  • orbital fat
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10
Q

what vessel does the eye primarily receive blood from?

A

the ophthalamic artery

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11
Q

what veins drain the orbit?

A

venous drainage via the superior and inferior ophthalamic veins

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12
Q

what **cranial nerves **supply the eye and its structures?

A
  • optic nerve
  • oculomotor nerve
  • trochlear nerve
  • trigeminal nerve (via ophthalmic nerve branch)
  • abducens nerve
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13
Q

what is the function of the orbital fat?

A

it cushions the eye and **stabilises extraocular muscles **

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14
Q

what are the 3 main foramina by which structures can enter and leave the orbit?

A
  1. optic canal
  2. superior orbital fissure
  3. inferior orbital fissure
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15
Q

what** 3 structures **(2 vessels and 1 nerve) pass through the optic canal?

A
  1. optic nerve (CNII)
  2. Opthlamic artery
  3. central retinal vein
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16
Q

what region of the orbit does the ophthalamic artery supply?

A

the **medial wall **of the orbit

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17
Q

what is the function of the central retinal vein?

A
  • drains blood from capillaries of retina into the superior opthalamic vein or cavernous sinus directly
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18
Q

what** 8 structures** pass through the superior orbital fissure?

A
  • cranial nerve III,IV,VI
  • **lacrimal nerve **- CNV1
    * frontal nerve - CNV1
  • Nasociliary nerve - CNV1
  • orbital branch of middle meningeal artery
  • recurrent branch of lacrimal artery
  • superior orbital vein
  • superior opthalamic vein
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19
Q

what are the** cavernous sinuses**?

A
  • one of the dural venous sinuses of the head
  • network of veins that sit in a cavity
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20
Q

what 2 structures does the superior orbital fissure connect to?

A
  • cavernous sinus
  • intracranial space
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21
Q

what structures pass through the** inferior orbital fissure**?

A
  • infraorbital nerve
  • maxillary nerve (branch of CN V)
  • zygomatic nerve
  • parasympathetics to lacrimal gland
  • infraorbital artery
  • infraorbital vein
22
Q

what are other minor openings into the orbital cavity?

A
  • the nasolacrimal canal - drains tears from eye to nasal cavity
  • supra orbital foramen and infraorbital canal - carry small neurovascular structures
23
Q

what are the** extrinsic muscles of the eye** called?

A

extraocular muscles

24
Q

what are the intrinsic muscles of the eye called?

A

intraocular eye muscles

25
Q

what are the** 7 extraocular muscles** ?

A
  • 4x **rectus muscles **(superior, inferior, lateral, medial)
  • 2x oblique (superior , inferior)
  • 1 x **levator palpebrae superioris **- elevates eye lid
26
Q

what is the annulus of zinn?

A
  • some of the extraocular muscles either originate from the bony orbit or the common tendinous ring (annulus of zinn) and insert at specfic areas of the eye ball
27
Q

what kind of movement of the eye does the medial rectus carry out?

A

adduction

28
Q

what kind of movements of the eye does the lateral rectus muscle carry out?

A

abduction

29
Q

what 2 kind of movements of the eye does the superior rectus carry out?

A
  • elevation
  • adduction
30
Q

what kind of movements of the eye does the **inferior rectus **carry out?

A
  • depression
  • adduction
31
Q

what 3 kind of movements of the eye does the inferior oblique muscle carry out?

A
  • extorsion
  • elevation
  • abduction
32
Q

what 3 kind of movements of the eye does the superior oblique muscle carry out?

A
  • introsion
  • depression
  • abduction
33
Q

what 4 extraocular muscles originate from the** common tendinous ring**?

A
  • medial rectus
  • lateral rectus
  • inferior rectus
  • superior rectus
34
Q

what cranial nerve innervates the lateral rectus muscle? RECAP

A

CN VI - Abducens nerve

35
Q

where does the **inferior oblique **muscles originate from?

A

anterior orbital surface of maxilla

36
Q

where does the superior oblique muscle originate from?

A

the sphenoid bone

37
Q

what effect does the sympathetic outflow have on the pupil?

A

causes pupil dilation

38
Q

what effect does the parasympathetic outflow have on the pupils ?

A

causes pupil constriction - via oculomotor nerve

39
Q

what are the 3 intraocular muscles?

A
  • sphincter pupillae - parasympathetic innervation
  • dilator pupillae - sympathetic innervation
  • cilary muscle
40
Q

what is the function of the intraocular muscles?

A

they control the movement of the lens and pupil and therefore participate in the accomodation reflex

41
Q

what cranial nerve innervates the superior oblique muscle?

A

CN IV - Trochlear nerve

42
Q

what **3 cranial nerves **tranverse the cavernous sinus & pass through the superior orbital fissure to reach orbit?

A
  • oculomotor nerve CNIII
  • Trochlear nerve CNIV
  • Abducens nerve CNVI
43
Q

Describe the** course of the oculomotor nerve**

ie what does it pass through, branches? what do they supply?

A
  • CNIII extends anteriorly and divides into superior and inferior branches which both pass through the superior orbital fissure
  • superior branch innervates the superior rectus and levator palpebrae
  • the inferioer branch supplies the medial rectus, inferior rectus and inferior oblique
44
Q

what type of innervation does the inferior branch provide?

A

it provides **parasympathetic innervation **to intrinsic eye muscles (sphincter pupillae and ciliary muscles)

45
Q

what 2 nuclei are the cell bodies of the oculomotor nerve located in?

A
  • the oculomotor nucleus- midbrain
  • the edinger-westphal nucleus - midbrain
46
Q

Describe the pathway of the trochlear nerve (CN IV)

A
  • travels trough cavernous sinus
  • enters orbit through superior orbital fissure outside annulus of zinn
47
Q

descibe the pathway of the Abducens nerve (CN VI)

A
  • leaves brainstem at junction of pons and medulla
  • to reach the eye, it runs upwards between pons and clivus, pierces the dura mater to run between dura and skull
  • travels lateral to carotid artery
  • enters orbit through superior orbital fissure within the znnulus of zinn
48
Q

what makes the abducens nerve prone to injury?

A

the long course

49
Q

what clinical issues are associated with the oculomotor nerve?

A
  • affected eye is displaced laterally by the lateral rectus and inferiorly by the superior oblique muscle
  • eye adopts a down and out position
50
Q

what are clinical issues associated with the trochlear nerve?

A
  • paralysis of the superior oblique muscle
  • patient will complain of diplopia - double vision
51
Q

what clinical issues are associated with the abducens nerve?

A

paralysis of lateral rectus muscle
* the affected eye will be adducted by the resting tone of medial rectus

ANATOMY - head, neck & spine (21 decks)

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