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Gross Anatomy 2 > Orbit > Flashcards

Orbit Flashcards

1
Q

Name the 3 bones forming the majority of the orbit

A
  1. Frontal
  2. Maxilla
  3. Zygomatic
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2
Q

What are the orbits

A

Bilateral bony cavities in the facial skeleton that resemble hollow, quadrangular pyramids

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3
Q

What is related to the notch of the frontal bone on the superior ridge of the orbit

A

Supraorbital artery and nerve

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4
Q

Name the orbital foramen the maxilla forms, and the structure that passes through

A

Infraorbital foramen; infraorbital branch of CNV2 exits the skull to provide sensory information to the face

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5
Q

Name the 3 minor bones that contribute to the bony wall of the orbit

A
  1. Ethmoid
  2. Lacrimal
  3. Sphenoid (greater and lesser wings)
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6
Q

Name the 5 contents of the orbit

A
  1. Eyeball
  2. Fat and connective tissues
  3. Extraocular muscles
  4. Nerves
  5. Blood vessels
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7
Q

What structure carries excess lacrimal fluid into the nasal cavity

A

The nasolacrimal duct

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8
Q

What are the eyelids covered by externally, and internally

A 
Externally = thin skin
Internally = transparent mucous membrane, the palpebral conjunctiva
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9
Q

What is the palpebral conjunctiva continuous with on the surface of the eyeball

A

The bulbar conjunctiva

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10
Q

What ligaments support the corners of the eye

A

Medial and lateral palpebral ligaments

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11
Q

Name the dense connective tissue that forms the eyelids

A

The superior and inferior tarsus

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12
Q

What are the functions of the tarsal plates

A
  1. Physically protects the eye

2. Releases oily and watery secretions to lubricate the surface of the eye (through tarsal glands)

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13
Q

What ligaments support the eyeball

A

The suspensory ligaments

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14
Q

What is the action of the check ligaments

A

They restrict the movements of the medial and lateral recti

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15
Q

Name the 2 layers of the outer coat of the eyeball

A
  1. Cornea (fibrous layer covering anterior 1/6th)

2. Sclera (fibrous layer covering posterior 5/6th)

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16
Q

Name the 3 layers of the vascular (middle) coat

A
  1. Iris
  2. Ciliary body
  3. Choroid
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17
Q

Name the single layer of the inner coat

A

Retina

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18
Q

What is the choroid

A

Dark red layer between the sclera and the retina; lines most of the sclera

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19
Q

What is the ciliary body

A

Ring-like thickening of the vascular layer posterior to the corneoscleral junction (muscular and vascular)

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20
Q

What are the functions of the ciliary body

A
  1. Connects the choroid with the circumference of the iris

2. Provides attachment for the lens

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21
Q

What is the iris

A

Contractile diaphragm on the anterior surface of the lens with a central aperture, the pupil, for transmitting light

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22
Q

Name the two involuntary muscles that control the size of the pupil

A
  1. Sphincter pupillae (parasympathetic) decreases its diameter
  2. Dilator pupillae (sympathetic) increases its diameter
23
Q

Name the two layers of the optic part of the retina

A
  1. Neural layer: light receptive

2. Pigmented layer: reduces scattering of light in the eyeball (light-absorbing property)

24
Q

What is the space between the lens and the cornea called, and what is it filled with

A

The anterior chamber, filled with aqueous humor

25
Q

What produces aqueous humor, and where

A

The ciliary body in the posterior chamber

26
Q

What is the function of the aqueous humor

A

It helps to maintain intraocular pressure

27
Q

Where does aqueous humor drain

A

Into the corneoscleral junction, via the canal of Schlemm

28
Q

What causes sphincter-like contraction of the ciliary muscle

A

Parasympathetic stimulation via the oculomotor nerve (CN III)

29
Q

Where is the vitreous humor located

A

The meshes of the vitreous body in the posterior 4/5ths of the eyeball posterior to the lens

30
Q

What are the functions of the vitreous humor

A
  1. Transmits light
  2. Holds the retina in place
  3. Supports the lens
31
Q

What do the extraocular muscles function as

A

Move the eyeball as a whole or raise the upper eyelid

32
Q

How many extraocular muscles are there, and name them

A

There are 7:

  1. Levator palpebrae superioris
  2. Superior recti
  3. Inferior recti
  4. Medial recti
  5. Lateral recti
  6. Superior oblique
  7. Inferior oblique
33
Q

Where do the recti muscles pass from, and to

A

Annular ring to the sclera

34
Q

Where do the superior, and inferior obliques pass from, and to

A

Lesser wing of the sphenoid and the orbital floor, respectively, to the sclera

35
Q

Describe the innervation to the extraocular muscles

A 
LPS = oculomotor (CN III)
SR = oculomotor (CN III)
IR = oculomotor (CN III)
MR =oculomotor (CN III)
LR = abducent (CN VI)
SO = trochlear (CN IV)
IO = oculomotor (CN III)
36
Q

Describe the action of the extraocular muscles

A 
LPS = raises the upper eyelid
SR = elevation, abduction, intorsion
IR = depression, abduction, extorsion
MR = adduction
LR = abduction
SO = intorsion, depression, abduction
IO = extorsion, elevation, abduction
37
Q

What area do the nerves have to pass through before they reach the superior orbital fissure

A

The cavernous dural venous sinus

38
Q

Why is the abducent nerve the ‘odd one out’ as it passes through the cavernous dural venous sinus

A

It passes close by to the internal carotid artery; the others pass along the walls close to the dura

39
Q

Describe the exit process of the optic nerve out of the orbit

A

Optic nerve formed and myelinated as it passes through the lamina cribrosa of the sclera (through the optic disc)

40
Q

What do the optic nerves form before they form the optic tracts

A

Chiasm over the pituitary fossa then optic tracts are sent to the brain (e.g. thalamus)

41
Q

What is the function of the optic radiations

A

Take information to be processed in the primary visual cortex

42
Q

What are the 3 terminal branches of CNV1

A
  1. Frontal
  2. Nasociliary
  3. Lacrimal
43
Q

Describe the pathway of the terminal branches of CNV1

A

Pass through the superior orbital fissure and supply structures related to the anterior orbit, face, and scalp

44
Q

What are the terminal branches of the frontal branch of CNV1 (and what do they supply)

A
  1. Supraorbital
  2. Supratrochlear
    Pass onto the face to supply sensory innervation to the skin of the forehead
45
Q

Name the branches of the nasociliary branch of CNV1

A

Ethmoidal branches which pass through the ethmoid bone

46
Q

What is the function of the lacrimal branch (nerve)

A

Acts as a carrier for parasympathetic secretomotor fibres from the facial nerve

47
Q

What is the main supply to the orbit, and how does it enter the orbit

A

Ophthalmic (from internal carotid artery); it enters the orbit through the optic canal with the optic nerve

48
Q

Where does the infra-orbital artery branch from

A

The external carotid artery

49
Q

Name the branches of the ophthalmic artery

A 
Forehead and scalp:
1. Supraorbital
2. Supratrochlear
3. Zygomaticotemporal
Nose:
1. Dorsal nasal
2. Ethmoidal
50
Q

Describe the venous drainage of the orbit

A

Super and inferior ophthalmic veins

51
Q

Describe the pathways of the orbital veins

A

Can pass through the:

  1. Superior orbital fissure and enter the cavernous sinus
  2. Inferior orbital fissure and enter the pterygoid venous plexus
  3. Facial vein
52
Q

What specific veins drain the vascular layer of the eyeball

A

The vorticose veins, and into the inferior ophthalmic vein

53
Q

Describe the innervation to the lacrimal apparatus

A

From facial nerve (CN VII) carried in trigeminal nerve (CNV1)

54
Q

How are the tears collected across your eye

A

Gathered through lacrimal punctum into the lacrimal canaliculi, and then into a membrane lined space called the lacrimal sac

Gross Anatomy 2 (28 decks)

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