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Structure and Function Test 1 > Orbit and Extraocular Muscle Testing Pt. 1 > Flashcards

Orbit and Extraocular Muscle Testing Pt. 1 Flashcards

1
Q

What are the three layers of the eyeball?

A
  1. ) Outter = Sclera & Cornea
  2. ) Middle = Choroid, ciliary body, iris
  3. ) Inner = Retina
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2
Q

Tough, white fibrous layer into which the extraocular muscles insert

A

Sclera

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3
Q

Transparent anterior portion of the outter layer of the eyeball

A

Cornea

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4
Q

The middle layer of the eyeball is composed of the

A

Choroid, ciliary body, and the iris

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5
Q

The vascular layer of the eyeball

A

Choroid

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6
Q

Made up of the ciliary muscle and the ciliary process

A

Ciliary body

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7
Q

Smooth muscle for accommodation of the lense

A

Ciliary Muscle

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8
Q

Secretes aqueous humor

A

Ciliary processes

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9
Q

The pigmented region that contains smooth muscle that controls the size of the pupil

A

Iris

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10
Q

Which two smooth muscles control size of the pupil?

A

Dilator papillae and sphincter papillae

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11
Q

Contains the visual receptor cells (rods and cones) and nerve cells of the visual pathway

A

Retina

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12
Q

The region of the retina from which all of the nerve fibers emerge to form the optic nerve is the

A

Optic disk

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13
Q

There are no receptors in the optic disk, hence it is referred to as the

A

“Blind Spot”

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14
Q

The region of the retina with the greatest density of cone (receptor) cells is the

A

Fovea

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15
Q

The fovea is located

A

Slightly lateral to the optic disk

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16
Q

The fovea is in the center of a pigmented area known as the

A

Macula lutea (yellow spot)

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17
Q

When viewing an object, the eye is positioned so that the light from the object is positioned on the

-gives greatest accuity of vision

A

Fovea (central vision)

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18
Q

Obtained from light striking on the more peripheral parts of the retina

A

Peripheral vision

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19
Q

Recignition of movement is greatest, but acuity and colorof vision is less in

A

Peripheral vision

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20
Q

Suspended from the ciliary body by the suspensory ligaments

A

Lens

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21
Q

Controls the shape of the lens by controlling the shape of the ciliary body

A

Ciliary muscle (a smooth muscle)

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22
Q

What effect on the lens does contraction of the ciliary muscle have?

A
  • Decreases radius of ciliary body
  • Suspensory ligaments slack
  • Lens becomes thicker and more refractive (For focus on near objects)
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23
Q

Contracting the ciliary muscle causes the lens to become thicker and more refractive. This is done for focus on

A

Near objects (accommodation reflex)

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24
Q

What effect on the lens does relaxation of the ciliary muscle have?

A

-Suspensory ligaments stretch the lens, thus the lens becomes thinner and less refractive

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25
Q

Relaxation of the ciliary muscle causes the lense to become thinner and less refractive. This is done for focus on

A

Distant objects

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26
Q

With aging, the lens loses elasticity so that even when the ciliary muscle contracts, the lens is unable to become thicker. This compromises

A

Near vision (presbyopia)

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27
Q

In addition to the change in the shape of the lens, the reflex response for near vision (“near reflex”) includes

A

Constriction of the pupil by the sphincter papillae muscle and convergence of the eyes (by both medial rectus muscles)

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28
Q

The region posterior to the lens is the

A

Vitreous body

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29
Q

The region anterior to the lens contains the

A

Aqueous humor

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30
Q

The region anterior to the lens is divided into the

A

Anterior chamber (between cornea and iris) and posterior chamber (between iris and lens)

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31
Q

The anterior and posterior chambers communicate through the

A

Iris

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32
Q

Aqueous humor is secreted into the posterior chamber by the ciliary processes, passes through the pupil, and then enters venous channels in the

A

Anterior chamber

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33
Q

Provides nutrients and oxygen to the avascular cornea and lens

A

Aqueous humor

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34
Q

Excess secretion or inadequate drainage of aqueous humor will result in increased intraocular pressure and may lead to

A

Glaucoma

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35
Q

Occurs when light passes through the cornea, the aqueous humor, the lens, and the vitreous humor

A

Refraction of light

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36
Q

Greatest refraction occurs at the

A

Cornea

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37
Q

Abnormalities in the curvature of the cornea result in refractive errors which cause images to not focus properly on the

A

Retina

38
Q

This can be corrected with

A

Glasses or contacts or remodelling of the shape of the cornea (LASIK)

39
Q

The only variable component of the various refractive media and is therefore important for changing focal distances when changing gaze between near and far objects

A

Lens

40
Q

Has four walls and an apex

A

Orbit

41
Q

The roof of the orbit is formed mostly by the frontal bone and is related to the

A

Frontal sinus and the anterior cranial fossa (contains frontal lobe of the brain)

42
Q

The floor of the orbit is formed mostly by the

A

Maxilla

43
Q

The floor of the orbit is formed mostly by the maxilla and is related to the

A

Maxillary sinus

44
Q

The medial wall of the orbit is formed mostly by the

A

Ethmoid and Sphenoid bones

45
Q

The medial wall of the orbit is formed mostly by the ethmoid and sphenoid bones and is related to the

A

Ethmoid air cells and nasal cavity

46
Q

The lateral wall of the orbit is formed mostly by the

A

Zygoma and sphenoid bones

47
Q

The lateral wall of the orbit is formed mostly by the zygoma and sphenoid bones and is related to the

A

Temporal fossa and middle cranial fossa (contians temporal lobe of brain)

48
Q

Contains the temporal lobe of the brain

A

Middle cranial fossa

49
Q

The posterior openings of the orbit are the

A

Optic canal, superior orbital fissure, and inferior orbital fissure

50
Q

The optic canal communicates with the middle cranial fossa and conveys the

A

Optic nerve and opthalmic artery

51
Q

The superior orbital fissure communicates with the middle cranial fossa and conveys the

A

Superior opthalmic vein and CN III, IV, V1, and VI

52
Q

The superior orbital fissure communicates the superior opthalmic vein to the

A

Cavernous sinus

53
Q

The inferior orbital fissure communicates with the

A

Infratemporal fossa (lateral) and pterygopalatine (medial)

54
Q

The inferior orbital fissure communicates with the infratemporal fossa and the pterygopalatine fossa and conveys the

A

Inferior opthalmic vein, the infraorbital nerve (V2) and the Zygomatic Nerve (V2)

55
Q

The opthalmic veins (emissary veins) communicate with the

A

Veins of the face, cavernous sinus, and pterygoid venous plexus

56
Q

Emissary veins that can be important pathways for the spread of infection from the face to deeper intracranial or extracranial regions

A

Opthalmic veins

57
Q

On the anterior surface of the orbit are the

A

Supraorbital and infraorbital foramen

58
Q

The supraorbital foramen conveys the

A

Supraorbital nerve, artery, and vein

59
Q

The anterior opening of the infraorbital groove and canal of the floor of the orbit

A

Infraorbital foramen

60
Q

The infraorbital foramen conveys the

A

Infraorbital nerve, artery, and vein

61
Q

Exit the front of the orbit but do not have any associated foramina

A

Supratrochlear nerve (from frontal nerve) and infratrochlear nerve (from nasociliary nerve)

62
Q

Located on the superolateral wall of the orbit and secretes lacrimal fluid through multiple ducts into the conjunctival sac

A

Lacrimal gland

63
Q

The lacrimal gland secretes lacrimal fluid through multiple ducts into the

A

Conjunctival sac

64
Q

Lacrimal fluid flows across the lacrimal sac from

A

Lateral to Medial

65
Q

Lacrimal fluid flows across the lacrimal sac from lateral to medial (with assistance of movement of eyelids) to the medial angle of the eye where it drains into the

A

Lacrimal canaliculi

66
Q

The lacrimal canaliculi lead into the

A

Nasolacrimal duct

67
Q

Whatever lacrimal secretion doesn’t evaporate from the conjunctival sac is drained through the nasolacrimal duct into the

A

Nasal cavity

68
Q

From the nasal cavity it can pass into the

A

Nasopharynx and be swallowed

69
Q

Receives both parasympathetic and sympathetic innervation

A

Lacrimal gland

70
Q

The parasympathetic pathway of the lacrimal gland includes

A

Preganglionic fibers from facial nerve and post ganglionic fibers from pterygopalatine ganglion

71
Q

The parasympathetic innervation has a secremotor function, meaning it stimulates

A

Secretion from the gland

72
Q

The sympathetic pathway of the lacrimal gland includes

A

Preganglionic fibers that arrise from T1 and postganglionic fibers from superior cervical ganglion

73
Q

The sympathetic function of the lacrimal gland serves the function of

-can modify composition of lacrimal fluid

A

Vasoconstriction

74
Q

What are the 7 extraocular muscles of the eye?

A
  1. )Levator palpebra superioris
  2. ) Superior rectus
  3. ) Inferior rectus
  4. ) Superior oblique
  5. ) Inferior oblique
  6. ) Lateral rectus
  7. ) Medial rectus
75
Q

Six of the seven extraocular muscles attach tot he eyeball, but only 1 attaches to the eyelid, which one?

A

Levator palpebrae superioris

76
Q

Which four of the extraocular muscles that are attached to the eyeball originate from a common ring tendon?

A

Superiot, inferior, lateral, and medial rectus muscles

77
Q

The superior oblique muscle originates from the wall of the orbit near the back

A

Wall of the orbit near the back

78
Q

The inferior oblique muscle originates from the

A

Front of the orbit

79
Q

The four rectus muscles insert on the

A

Front half of the eyeball

80
Q

The two oblique muscles insert on the

A

Back half of the eyeball

81
Q

The tendon of the superior oblique muscle passes through a fibrocartilage pulley known as the

A

Trochlea

82
Q

The lateral rectus muscle is innervated by the

A

Adducens nerve

83
Q

The superior oblique muscle is innervated by the

A

Trochlear nerve (IV)

84
Q

All other extraocular muscles are innervated by the

A

Oculomotor nerve (III)

85
Q

What happens when the superior rectus and inferior oblique contract together?

A

Elevation of the eyeball

86
Q

What happens when the inferior rectus and superior oblique contract together?

A

Depression of the eyeball

87
Q

The levator palpebrae superioris is composed of two parts, a skeletal muscle part and a smooth muscle part. What is each innervated by?

A
  1. ) Skeletal muscle part = Oculomotor nerve (III)

2. ) Smooth muscle part = sympathetic nerves

88
Q

Drooping of the eyelid

A

Ptosis

89
Q

Ptosis can be caused by either a

A

CN III lesion or a sympathetic lesion

90
Q

When testing the extraoccular muscles, how can we test the superior and inferior rectus muscle?

A

Ask the patient to elevate (SR) and depress (IR) the eye from an abducted position

91
Q

When testing the extraocular muscles, how can we test the superior and inferior oblique muscles?

A

Ask the patient to depress (SO) and elevate (IO) the eyeball from the adducted position

Structure and Function Test 1 (61 decks)

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