Orbit and Extraocular Muscle Testing Pt. 1 Flashcards Preview

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Flashcards in Orbit and Extraocular Muscle Testing Pt. 1 Deck (91):
1

What are the three layers of the eyeball?

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

2

Tough, white fibrous layer into which the extraocular muscles insert

Sclera

3

Transparent anterior portion of the outter layer of the eyeball

Cornea

4

The middle layer of the eyeball is composed of the

Choroid, ciliary body, and the iris

5

The vascular layer of the eyeball

Choroid

6

Made up of the ciliary muscle and the ciliary process

Ciliary body

7

Smooth muscle for accommodation of the lense

Ciliary Muscle

8

Secretes aqueous humor

Ciliary processes

9

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

Iris

10

Which two smooth muscles control size of the pupil?

Dilator papillae and sphincter papillae

11

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

Retina

12

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

Optic disk

13

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

"Blind Spot"

14

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

Fovea

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The fovea is located

Slightly lateral to the optic disk

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

Macula lutea (yellow spot)

17

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

-gives greatest accuity of vision

Fovea (central vision)

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

Peripheral vision

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

Peripheral vision

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Suspended from the ciliary body by the suspensory ligaments

Lens

21

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

Ciliary muscle (a smooth muscle)

22

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

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

23

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

Near objects (accommodation reflex)

24

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

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

25

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

Distant objects

26

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

Near vision (presbyopia)

27

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

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

28

The region posterior to the lens is the

Vitreous body

29

The region anterior to the lens contains the

Aqueous humor

30

The region anterior to the lens is divided into the

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

31

The anterior and posterior chambers communicate through the

Iris

32

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

Anterior chamber

33

Provides nutrients and oxygen to the avascular cornea and lens

Aqueous humor

34

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

Glaucoma

35

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

Refraction of light

36

Greatest refraction occurs at the

Cornea

37

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

Retina

38

This can be corrected with

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

39

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

Lens

40

Has four walls and an apex

Orbit

41

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

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

42

The floor of the orbit is formed mostly by the

Maxilla

43

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

Maxillary sinus

44

The medial wall of the orbit is formed mostly by the

Ethmoid and Sphenoid bones

45

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

Ethmoid air cells and nasal cavity

46

The lateral wall of the orbit is formed mostly by the

Zygoma and sphenoid bones

47

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

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

48

Contains the temporal lobe of the brain

Middle cranial fossa

49

The posterior openings of the orbit are the

Optic canal, superior orbital fissure, and inferior orbital fissure

50

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

Optic nerve and opthalmic artery

51

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

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

52

The superior orbital fissure communicates the superior opthalmic vein to the

Cavernous sinus

53

The inferior orbital fissure communicates with the

Infratemporal fossa (lateral) and pterygopalatine (medial)

54

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

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

55

The opthalmic veins (emissary veins) communicate with the

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

56

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

Opthalmic veins

57

On the anterior surface of the orbit are the

Supraorbital and infraorbital foramen

58

The supraorbital foramen conveys the

Supraorbital nerve, artery, and vein

59

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

Infraorbital foramen

60

The infraorbital foramen conveys the

Infraorbital nerve, artery, and vein

61

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

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

62

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

Lacrimal gland

63

The lacrimal gland secretes lacrimal fluid through multiple ducts into the

Conjunctival sac

64

Lacrimal fluid flows across the lacrimal sac from

Lateral to Medial

65

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

Lacrimal canaliculi

66

The lacrimal canaliculi lead into the

Nasolacrimal duct

67

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

Nasal cavity

68

From the nasal cavity it can pass into the

Nasopharynx and be swallowed

69

Receives both parasympathetic and sympathetic innervation

Lacrimal gland

70

The parasympathetic pathway of the lacrimal gland includes

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

71

The parasympathetic innervation has a secremotor function, meaning it stimulates

Secretion from the gland

72

The sympathetic pathway of the lacrimal gland includes

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

73

The sympathetic function of the lacrimal gland serves the function of

-can modify composition of lacrimal fluid

Vasoconstriction

74

What are the 7 extraocular muscles of the eye?

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

75

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

Levator palpebrae superioris

76

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

Superiot, inferior, lateral, and medial rectus muscles

77

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

Wall of the orbit near the back

78

The inferior oblique muscle originates from the

Front of the orbit

79

The four rectus muscles insert on the

Front half of the eyeball

80

The two oblique muscles insert on the

Back half of the eyeball

81

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

Trochlea

82

The lateral rectus muscle is innervated by the

Adducens nerve

83

The superior oblique muscle is innervated by the

Trochlear nerve (IV)

84

All other extraocular muscles are innervated by the

Oculomotor nerve (III)

85

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

Elevation of the eyeball

86

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

Depression of the eyeball

87

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

1.) Skeletal muscle part = Oculomotor nerve (III)
2.) Smooth muscle part = sympathetic nerves

88

Drooping of the eyelid

Ptosis

89

Ptosis can be caused by either a

CN III lesion or a sympathetic lesion

90

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

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

91

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

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

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