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Head and Neck > Orbit, Lacrimal Apparatus, Eye > Flashcards

Orbit, Lacrimal Apparatus, Eye Flashcards

1
Q

What two things do people include when talking about the eye?

A

Orbit

Optic Nerve

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2
Q

What makes up the orbital region?

A

orbits

eyelids

lacrimal apparatus

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3
Q

What are the accessory organs of the orbit?

A

Eyelids

Oculomotor Muscles

Oculomotor Nerve

Vessels

Conjuctiva of eyelids

Space occupied by fat

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4
Q

What lines the orbit?

A

Lined by periorbita

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5
Q

What are the medial walls of the orbit separated by? What are their positions to pne another?

A

Ethmoidal sinus

Upper Nasal Cavity

They are near parallel to each other

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6
Q

What is the lateral wall of the orbit made up of?

A

Mostly Zygomatic Bone

Some of the Sphenoid Bone

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7
Q

How are the Lateral Walls of the Orbit positioned in relation to one another?

A

They lie at 90° to one another

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8
Q

How are the axes of each orbit related to each other?

A

Positioned at an angle to 45° to one another

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9
Q

How is each Optical Axis (i.e. axis through the pupil) related

A

They are parallel - when in primary position

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10
Q

What are the borders of the orbit?

A
  • Base
    • Outline of orbital margin
  • Apex
    • At optic canal (in lesser wing of sphenoid - medial to superior orbital fissure)
  • Medial
    • Orbital plate of Ethmoid
    • Contributions of frontal processes of:
      • Maxilla
      • Lacrimal
      • Sphenoid
  • Lateral
    • Frontal process of Zygomatic
    • Greater wing of Sphenoid
  • Superior
    • Orbital part of Frontal Bone
    • Lesser wing of Sphenoid
  • Inferior/Floor
    • Mostly Maxilla
    • Partly Sphenoid and Palatine Bones
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11
Q

What are the characteristics of the base of the orbit

A

Reinforced

Orbital Septum is attached to it

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12
Q

What are the characteristics of the medial wall of the Orbit?

A
  • Indented by:
    • Lacrimal Groove
    • Fossa for Lacrimal Gland
  • Trochlea lies superiorly
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13
Q

What are the characteristics of the Lateral wall of the orbit?

A

Strongest Wall

Thickest Wall

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14
Q
A
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15
Q

What are the Tarsi? Explain their structure?

A

Dense Connective tissue that strengthens the eyelids.

Embedded with tarsal glands - secrete lipids that prevent eyelids sticking together.

Split into superior and inferior tarsi.

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16
Q

What are the attachments of the medial palpebral ligament

A

tarsi

medial orbital margin

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17
Q

What are the attachments of the lateral palpebral ligament

A

tarsi

lateral orbital margin

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18
Q

Where is the orbital septum located? What is its function?

A

Fibrous membrane spanning tarsi

Keeps orbital fat contained

Contributes posterior fascia of Orbicularis Oculi

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19
Q

Explain the external and internal structure of the eyelids

A
  • External
    • Thin skin
    • Lined by eyelashes (cilia)
      • Associated with Ciliary Glands
  • Internal
    • Palpebral Conjunctiva
    • Continuous with Bulbar Conjunctiva of the eye
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20
Q
A

Superior Conjuctival Fornix

Inferior Conjuctival Fornix

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21
Q

Explain the position of the Lacrimal Gland. What is it’s size?

A

Lies within lacrimal fossa (of Frontal Bone), near superolateral margin.

Approx. 2cm long gland

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22
Q

What are the two parts of the Lacrimal Apparatus

A

Orbital Part

Palpebral Part

Separated by tendon of levator palpebrae superioris.

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23
Q

Where does the lacrimal caniliculi start and end? What is it’s function?

A

Start at lacrimal punctum on the lacrimal papilla

Drain lacrimal fluid from the lacrimal lake into the lacrimal sac

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24
Q

What is the function of the Nasolacrimal Duct

A

Coveys lacrimal fluid from lacrimal sac to the inferior nasal meatus

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25
What is the role of the nervous system in producing lacrimal fluid?
Presynaptic parasympathetic nerves: 1. Facial Nerve (CN VII) 2. Greater Petrosal Nerve 3. Nerve of Pterygoid canal 4. Pterygopalatine Ganglion 5. Zygomatic Nerve (Branch of V2) 6. Lacrimal Branch (of Opthalmic Nerve)
26
Explain the innervation of the **Lacrimal Gland**
27
What induces production of **Lacrimal Fluid**?
Parasympathetic Innervation (from the facial nerve)
28
What makes up the anterior segment of the **eye ball**?
Cornea Lens
29
What components support the **Lens**?
Suspensory Ligament - collective noun for Zonular Fibres 1. Lens Capsule (transparent membrane) attaches to Zonular Fibres 2. Attached to Ciliary Processes 3. Attached to Ciliary Body (contains main muscles)
30
What is the innervation of the **Ciliary Muscles**?
Oculomotor Nerve (CN III)
31
Explain the drainage of the **Aqueous Humour.** Where is this fluid found?
Located in anterior portion, near lens of eye. Drainage: 1. Trabecular Meshwork (at Iridiocorneal angle) 2. Scleral Venous Sinus 3. Limbus Plexus, a network of Scleral Veins 4. Tributaries of Vorticose Vein and Anterior Ciliary Vein
32
Where is the **Vitreous Humour** located?
Within *Vitreous Body* (fills the space between the lens and the retina) Posterior four-fifths of the eye
33
What are the three main layers of the **Eyeball**?
1. Fibrous Layer (outer) 2. Vascular Layer 3. Retinal Layer
34
What makes up the **Fibrous Layer of the Eyeball**?
Sclera (white of eye) Cornea (transparent layer that covers Iris)
35
What part of the eyeball is the Sclera attached to?
Posterior five-sixths
36
Explain the vascular supply of the Sclera
Mostly Avascular
37
What part of the eye provides attachment for all intrinsic and extrinsic muscles?
Sclera
38
What part of the eyeball is the Cornea found?
Anterior one-sixth
39
Explain the vasculature of the Cornea
Completely avascular
40
What is the innervation of the Cornea? What action does it enable?
Corneal Reflex (blinking reflex) Nasociliary Branch (of CN V1)
41
Explain the vasculature of the Choroid
Larger vessels externally Finer vessels internally
42
What is the **choroid**? Explain its structure.
Vascular membrane that lines most of the internal part of the sclera. _Structure:_ Dense, pigmented vascular beds
43
What is the attachment of the choroid
Attaches firmly to retina. Attaches less firmly to sclera
44
What is the postition of the **Iris**?
Anterior surface of lens
45
What are the two involuntary muscles of the Iris? Explain their functions.
Sphincter Pupillae (decreases pupil diameter) Dilator Pupillae (increases pupil diameter)
46
What is the innervation of the **sphincter pupillae**?
Parasympathetically stimulated
47
What is the innervation of the **dilator pupillae**?
Sympathetically Stimulated
48
Essentially, what is the Ciliary Body and where is it located?
Muscular and vascular thickening of layer behind *corneoscleral junction*
49
What are the components of the Ciliary Body?
Ora Serrata (outside) Ciliary Muscles (Middle) Ciliary Process (Inside)
50
What are the functions of the Ciliary Body?
* Connects choroid with circumference of Iris * Provides attachment for lens (Zonular Fibres attach it by attaching to Ciliary Processes) * Smooth muscle contraction controls thickness of lens (focus)
51
What are the parts of the Vascular Layer of the eyeball?
Choroid Iris Ciliary Body
52
What are the two main parts of the **Retina**?
Optic part Non-visual part
53
What is the location of the non-visual part of the retina?
Extends over **Ciliary Body** and **Posterior Surface of the Iris**
54
What is the fundus of the retina
Area of the posterior eye where light is focused. Includes: * Optic Disk (Blind Spot) * Macula Lutea (Yellow Spot)
55
Explain the structure of the Macula Lutea of the eyeball
Photoreceptive cones are specialised for acuity (sharpness) of vision In the centre is the Fovea Centralis - area of most acute vision
56
What is the word for medial rotation?
Intortion
57
What is the word for lateral rotation?
Extortion
58
What are the attachments of the **Rectus Muscles**? What is the exception?
_Origin:_ Common Tendinous Ring (Annulus) surrounding the Optic Canal _Insertion:_ Anterior to the equator of the eye _Exception:_ **Inferior Oblique** - *originates from anterior part of Orbit*
59
What is the innervation for the Extraocular Muscles? What are the exceptions?
Oculomotor Nerve (CN III) Abducent Nerve (CN VI) - **Lateral Rectus** Trochlear Nerve (CN IV) - **Superior Oblique**
60
What are the actions of all the Extraocular Muscles?
* Medial Rectus: * Adducts * Lateral Rectus * Abducts * Sperior Rectus * Elevates * Medial Rotation * Inferior Rectus * Depresses * Lateral Rotation * Inferior Oblique * Lateral Rotation * Abducts * Elevates * Superior Oblique * Medial Rotation * Abducts * Depresses
61
What is the Innervation of the **Levator Palpebrae Superioris**?
Oculomotor Nerve (CN III)
62
What is the function of **Levator Palpebrae Superioris**?
Elevates Superior Eyelid
63
What is the relation of **Levator Palpebrae Superioris** to other structures?
**Bilaminar Aponeurosis** divides **Lacrimal Gland** into Orbital and Palpebral parts **Tubal Muscular Sheath** fuses to that of **Superior Rectus** -- *During elevation of the eye, the superior eyelid also is further elevated*
64
What type of fibres are in the Optic Nerve (CN III)?
Purely sensory
65
Where is the beginning of the **Optic Nerve**?
Lamina Cribrosa of the Sclera
66
What surrounds the Optic Nerve (CN III)
Extensions of: * Dura Mater * Pia Mater * Arachnoid Mater * Subarachnoid Space
67
What does the Ophthalmic Nerve Supply? What are its branches?
Lacrimal Gland Eyelids Face Scalp _Through the _____ branches:_ * Nasociliary Nerve * Frontal Nerve * Lacrimal Nerve
68
Which nerve is the Ciliary Ganglion associated with?
Ophthalmic Branch of Trigeminal Nerve
69
Where does the Ciliary Ganglion lie?
Between the Lateral Rectus and Optic Nerve
70
What type of cell bodies doe the Ciliary Ganglion contain?
postsynaptic parasympathetic cell bodies
71
What are the sources from which the **Ciliary Ganglion** recieves fibres?
* **Nasociliary Root of CN V1** (sensory fibres) * **Oculomotor** (presynaptic parasympathetic fibres) * **Sympathetic Root of Internal Carotid Plexus** (postsynaptic sympathetic fibres)
72
What are the nerves that the **Ciliary Ganglion** gives rise to?
* Short Ciliary Nerve * Considered a branch of V1 * Carries sympathetic and parasympathic fibres * Long Ciliary Nerve * A true branch of Nasociliary Nerve * Bypasses Ganglion
73
What does the **Long Ciliary Nerve** supply?
Dilator Pupillae

Head and Neck (11 decks)

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