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Head and Neck Anatomy > Muscles around the Eye > Flashcards

Muscles around the Eye Flashcards

1
Q

What are the functions of the eye?

A
  1. Self-focus light
  2. Adjust for light intensity
  3. Converts light into electrical impulses interpreted by brain
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2
Q

What is the bony orbit?

A
  • Pyramidal bony cavity of facial skeleton
  • Lined by periorbita (fascia sheath of the eye)
    > continuous at optic canal, superior orbital fissure, inferior orbital fissure, dural fascia
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3
Q

What are the contents of the bony orbit?

A
  1. Eyeballs and their extraocular muscles
  2. Nerves and vessels
  3. Lacrimal apparatus
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4
Q

Which bones make up the orbital margin?

A

frontal, maxillary and zygomatic bones

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5
Q

What are the walls of the orbit?

A
  1. apex
  2. 4 walls
    - superior
    - inferior
    - medial
    - lateral
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6
Q

What is the superior wall of the orbit formed by?

A
  1. orbital part of the frontal bone
    – has lacrimal fossa with lacrimal gland
  2. Lesser wing of sphenoid
    – near apex
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7
Q

What is the medial wall of the orbit formed by?

A
  1. Ethmoid bone (ethmoid plate)
  2. frontal
  3. lacrimal
  4. sphenoid (body)
    > Indented by lacrimal fossa for lacrimal sac
    > The two walls are separated by ethmoid sinuses and nasal cavity
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8
Q

The inferior wall of the orbit is formed by?

A
  1. Maxilla (orbital surface)
  2. Part of zygomatic and palatine bones
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9
Q

The lateral wall of the orbit is formed by?

A
  1. frontal process of zygomatic bone
  2. Greater wing of sphenoid bone
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10
Q

Describe the location of the apex of the orbit?

A
  • at optical canal
  • in lesser wing of sphenoid
  • medial to superior orbital fissure
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11
Q

What are the clinical correlations of the orit?

A
  1. Fracture of the orbit
  2. Blowout fracture
    > Intraorbital bleeding causing exophthalmos (bulging eyes)
  3. Periorbital Ecchymosis (discoloration of the skin resulting from bleeding underneath)
    > Blows to periorbital causes bleeding and swelling
  4. Orbital tumors
    > cause exophthalmos
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12
Q

What are the contents of the orbit?

A

Eyeball
Optic nerve
Ocular muscles
Fascia
Nerves, vessels, fat, lacrimal gland
Conjunctival sac

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13
Q

What are the functions of the yebrows?

A
  1. shade
  2. shield for perspiration
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14
Q

Describe the eyelids?

A
  • skin-covered folds with “tarsal plates” connective tissue inside
  • contain tarsal glands that produce an oily substance to prevent eyelids from sticking together
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15
Q

Which muscle opens the eye?

A

levator palpebrae superioris
- only present in the superior eyelid because it is the only one that opens

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16
Q

Describe the canthus (corner of the eye)?

A
  • Lacrimal caruncle makes eye “sand” at medial corner
  • Epicanthal folds in many Asian people cover caruncle
  • Tarsal glands make oil to slow drying
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17
Q

Describe eyelashes?

A
  • ciliary gland at hair follicle
  • touch sensitive, thus blink
18
Q

What is the conjuctiva?

A

Mucous membrane that coats inner surface of eyelid (palpebral part) and then folds back onto surface of eye (ocular part)

19
Q

Describe the histology of the conjuctiva?

A
  • Thin layer of connective tissue covered with stratified columnar epithelium
  • Very thin and transparent, showing blood vessels underneath (blood-shot eyes)
  • Goblet cells in epithelium secrete mucous to keep eyes moist
20
Q

Why is vitamin A necessary in the conjuctiva?

A

Vitamin A necessary for all epithelial secretions
— lack leads to conjunctiva drying up
> scaly eye

21
Q

What are tears?

A

contain mucous, antibodies, lysozyme (anti-bacterial)

22
Q

What structures produce and transport tears?

A
  1. Lacrimal glands
    — superficial/lateral in orbit, produce tears
  2. Lacrimal duct (nasolacrimal duct)
    — medial corner of eye carries tears to nasal cavity
    > frequently closed in new borns — opens by 1 year usually
23
Q

Describe the flow of tears through the lacrimal apparatus?

A

Produced by lacrimal gland
> spread over eyeball
> lacrimal lake
> lacrimal canaliculi
> lacrimal sac
> nasolacrimal duct
> inferior nasal meatus

24
Q

What are the 2 groups of muscles within the orbit?

A
  1. Extrinsic muscles of the eyeball
    - extra-ocular muscles
  2. Intrinsic muscles of the eyeball
    - control the shape of the lens and size of pupil
25
Q

Name the 3 nerves that innervate the eye muscles?

A
  1. Occulomotor
  2. Abducens
  3. trochlear
26
Q

Name the extrinsic eye muscles?

A
  1. superior oblique
  2. lateral rectus
  3. medial rectus
  4. superior rectus
  5. inferior rectus
  6. inferior oblique
27
Q

State the movement, innervation and testing of the superior oblique muscle?

A

movement = depresses eye + medial rotation
innervation = CN IV Trochlear
test = look medially and downward

28
Q

State the movement, innervation and testing of the lateral rectus muscle?

A

movement = lateral rotation
innervation = CN VI Abducens
test = look laterally

29
Q

State the movement, innervation and test of the medial rectus muscle?

A

movement = medial rotation
innervation = CN III Oculomotor nerve
test = look medially

30
Q

State the movement, innervation and testing of the superior rectus muscle?

A

movement = elevates
innervation = CN III Oculomotor nerve
test = look medially and upward

31
Q

State the movement, innervation and testing of the inferior rectus muscle?

A

movement = depresses
innervation = CN III Oculomotor
test = look laterally and downward

32
Q

State the movement, innervation and testing of the inferior oblique muscle?

A

movement = elevates eye + lateral rotation
innervation = CN III Oculomotor nerve
test = look laterally and upward

33
Q

What is intorsion?

A

medial (inward) rotation of upper pole (12 o’clock position) of cornea
> caused by superior oblique and superior rectus

34
Q

What is extorsion?

A

Lateral (outward) rotation of superior pole of the cornea
> caused by inferior rectus and inferior oblique

35
Q

What will happen to the position of the eyes if there is damage to the right abducent nerve - the sixth cranial nerve?

A

right eye rotates medially

36
Q

What will happen if there is damage to the trochlear nerve - the fourth cranial nerve?

A

eye rotates laterally and upward

37
Q

What will happen if there is damage to the third cranial nerve - the oculomotor nerve?

A

eye rotates laterally and downward

38
Q

Name the 3 layers that support and maintain the eye?

A
  1. Outer fibrous layer
  2. Middle vascular (pigmented) layer
  3. Inner layer
39
Q

What are the consequences of a lesion of the CN III nerve?

A

complete ptosis
- drooping of the upper eyelid

39
Q

State the origin, insertion, innervation and action of the levator palpebrae superioris?

A

Origin: lesser wing of shpenoid
Insertion: anterior surface of the tarsal
Innervation: Occulomotor nerve (CNIII)
Action: Elevation of upper eyelid

Head and Neck Anatomy (37 decks)

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