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VAna 101 Doc Je an > Sense Organs (Eyes) > Flashcards

Sense Organs (Eyes) Flashcards

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1
Q

(the organ for vision) develops as a neuroectodermal outgrowth of the embryonic prosencephalon that contacts surface ectoderm and is enveloped by induced mesodermal and neural crest mesenchyme.

A

Eyes

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2
Q

The definitive eye and its adnexa are contained within an orbit that is only partly bony

A

Eyes

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3
Q

Associated with the bulb of the eye are extraocular muscles that move it; periorbital fascia and fat that surround and cushion it; eyelids and conjunctiva that protect it; and a lacrimal apparatus that keeps its surface moist, provides the first barrier to infection, and helps to nourish the
cornea.

A

Eyes

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4
Q
  • As a consequence of its dual origin, the eye has both central and peripheral neural elements.
  • The optic nerve is a central nervous system structure with myelin formed by oligodendroglial cells, whereas the nerves of the extraocular muscles and iris are peripheral nervous system structures with lemmocyte (Schwann cell) sheaths for myelin.
  • The vascular and fibrous tunics surrounding the optic nerve are homologous to the meninges surrounding the brain and spinal cord.
  • The intervaginal space of the optic nerve is continuous with the subarachnoid space of the brain and contains cerebrospinal fluid.
A

Eyes

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5
Q

Structures of the Eye

A
  • Orbit
  • The eyeball or Globe
    – Fibrous tunic (outer)
    – Vascular tunic (middle)
    – Nervous tunic (inner)
  • Adnexa
    – Eyelids and Conjunctiva
    – Nictitating membrane
    – Lacrimal Apparatus
    – Extraocular muscles
    – Vessels and nerves within the orbit
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6
Q

Structures of the Eye– The eyeball or Globe

A

– Fibrous tunic (outer)
– Vascular tunic (middle)
– Nervous tunic (inner

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7
Q

Structures of the Eyes– Adnexa

A

– Eyelids and Conjunctiva
– Nictitating membrane
– Lacrimal Apparatus
– Extraocular muscles
– Vessels and nerves within the orbit

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8
Q

*deep bony cavity in the rostral surface of the skull
*it houses the globe and adnexa

A

The Orbit

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9
Q

Composed of very dense collagenous and elastic tissue and fibrocytes

A

Fibrous Tunic

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10
Q

Functions:
– gives the eyes its shape and stiffness by resisting pressure of internal fluid
– protects internal vascular and light sensitive portions of the eye from environment
– refracts (bends) the light and conducts light to retina
– provide site for attachment of extraocular muscles

A

FIbrous Tunic

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11
Q

TWO PARTS OF FIBROUS TUNIC

A

Sclera and Cornea

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12
Q

Opaque/white portion of the eye, approximately 75 % of the globes surface
– consists of a dense network of collagen and elastic fibers and their fibrocytes

A

Sclera

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13
Q

– Transparent/clear portion of the eye, approximately 25% of anterior segment of fibrous tunic
– avascular, nutrients arrive thru the capillary loops at the limbus
– innervation: long ciliary nerves enters the cornea at the limbus

A

Cornea

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14
Q

border where sclera and cornea meets

A

Limbus Corneae

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15
Q
  • Referred to as “uvea” (latin: grape)
  • Lies internal to fibrous tunic
  • Extremely vascular and heavily pigmented
A

Vascular Tunic

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16
Q

The three regions of Vasular Tunic

A
  • Choroid
  • Ciliary body
  • iris
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17
Q
  • Posterior part, consists of dense meshwork of blood vessels
A

Choroid

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18
Q

Functions:
– provide nutrient and oxygen to retina
– limits light scatter
– improves vision in low-light situations

A

Choroid

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19
Q

– structure adapted to increase light intensity under low-lighting situations
– avascular region of choroid
– contains rod shaped crystals that refract incoming light
– Present in all domestic mammals except the pigs
– exquisitely sensitive to the toxic effects of a beta adrenergic blocking agent but no toxic effects to Beagles since it inherit an aplasia of the tapetum

A

Tapetum Lucidum

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20
Q
  • forms from thickening of choroid that is raised inward into posterior chamber of the eye
  • suspends the lens within the eyes
  • acts to change the thickness of the lens
    (accommodation)
  • muscles are smooth muscle bundles that originate on the sclera and attach to the base of the ciliary body
A

Ciliary Body

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21
Q
  • Most anterior, smallest segment of vascular tunic
  • Thin, flat circular structure attached to ciliary body
A

Iris

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22
Q

responsible for eye coloration

A

Melanin Granules

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23
Q

is the only pigment present in the iris

A

Melanin

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24
Q

central opening in the iris; round in dogs; has set of smooth muscles

A

Pupil

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25
Q

radially arranged; draws pupil open and admits more light; sympathetic

A

pupillary dilator

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26
Q

circumferentially arranged; draws the pupil closed; parasympathetic

A

pupillary constrictor (sphincter)

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27
Q

the innermost layer of the eye that contains the retina

A

Nervous Tunic

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28
Q

inner most layer; having 3 parts and a divisionary zone

A

Retina

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29
Q

Retina –visual

A

Optic

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30
Q

Retina– Non-visual

A

Ciliary and Iridial

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31
Q

3 Parts of the Retina

A

-optic part (pars optica retinae)
-ciliary part (pars ciliaris retinae)
-iridial part (pars iridica retinae)

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32
Q

boundary between visual (optical) and non-visual (ciliary and iridial) parts of retina

A

Ora Serrata

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33
Q

– has the photoreceptor layer, in which are found the specialized neural receptor cells of the visual system, the rods and cones
– largest part, relatively thick with 10 layers of cells; has pigment that gives the pupil black color
– presence of light sensitive cells that are layer 9 out of 10
– optic disc, a “blind” spot because no photoreceptors are present, leaves the globe to become optic nerve
– central area is the area of particularly acute vision

A

Optic Part (pars optica retinae)

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34
Q

– produces aqueous humor via active secretion

A

Ciliary part (pars ciliaris retinae)

35
Q

– bilayered epithelial layer
– covering posterior surface of iris

A

Iridial part (pars iridica retinae)

36
Q
  • solid yet soft, transparent, deformable structure situated in hyaloid fossa: a depression in the anterior surface of vitreous body
  • composed of elongate epithelial cells (lens fibers); fixed in position by a delicate suspensory apparatus, the zonula ciliaris
  • enveloped by elastic capsule; avascular in adult dogs
A

Lens

37
Q
  • Functions:
    – Brings images into focus in the retina
A

Lens

38
Q

– process by which ciliary processes zonules and ciliary muscles alter the shape of the lens to change the distance at which objects are focused

A

Lens accommodation

39
Q

Chambers of the Eye (interior)

A

-Anterior
-Posterior
-Vitreous Chamber

40
Q

– the space bounded by the cornea anteriorly and the iris and anterior lens surface posteriorly

A

Anterior Chamber

41
Q

– bounded anteriorly by the iris, posteriorly by the lens capsule and anterior face of the vitreous, and peripherally by the zonule and ciliary epithelium

A

Posterior Chamber

42
Q

these two chambers has direct communication thru the pupil and filled with aqueous humor: produced by ciliary part of the retina

A

Anterior Chamber and Posterior Chamber

43
Q

– approximately 80% of the volume of the globe (a chamber of the Eye)

A

Vitreous Chamber

44
Q

– a clear gel that fills the vitreous chamber
– almost 98% water, other components are solid (eg. Protein) and fine fibers
– normally acellular
– tightly adheres to lens capsule, ciliary part of retina, and optic disc

A

Vitreous Body

45
Q

mucous membrane that covers certain regions of the eye

A

Conjunctiva

46
Q

lines inner surface of upper, lower and third
eyelid

A

Palpebral conjunctiva

47
Q

Covers the Sclera

A

Bulbar conjunctiva

48
Q

point of reflection of palpebral ang bulbar
conjunctiva

A

Conjunctival fornix

49
Q
  • mobile skin folds, upper and lower
  • closes over the corneal surface to protect the cornea, exclude light and spread essential tear film
  • upper eyelid more mobile and larger; in dog only the superior eyelid has eyelashes (cilia)
    *medial and lateral commisures
    *medial and lateral angles (canthi)
    *lacrimal caruncle
A

Eyelids (Palpebrae)

50
Q

Glands of the eyelids:

A

Sebaceous glands
Tarsal Glands

51
Q

Found in the follicles of the cilia

A

Sebaceous glands

52
Q

Present in the free edges of of both eyelids

A

Tarsal glands

53
Q

Ligaments of the eyelids:

A

Lateral palpebral ligament
Medial palpebral ligament

54
Q

poorly developed, anchors
the lateral commisure to zygomatic arch

A

Lateral palpebral ligament

55
Q

anchors medial commisure to frontal bone, serves as origin and insertion of orbicularis oculi muscle

A

Medial palpebral ligament

56
Q
  • fold of tissue on ventromedial region of medial canthus
  • large and very mobile, capable of covering the entire cornea
  • when eye is open, it is withdrawn completely into the medial canthus
A

Third eyelid ( Semilunar Fold) / Nictitating Membrane

57
Q

– mixed seromucous gland that surrounds the base of the cartilage plate
– tear film

A

Superficial gland of the 3rd eyelid

58
Q

responsible for production, dispersion and disposal of tears

A

Lacrimal Apparatus

59
Q

Tear Producing Structures:

A

– lacrimal gland
– tarsal gland
– conjunctival goblet cells
– superficial gland of the 3rd eyelid

60
Q

Tear Disposing Structures:

A

– lacrimal puncta
– lacrimal canaliculi
– lacrimal sac
– nasolacrimal duct

61
Q

Composition of Tear Film

A

-superficial oily layer
-middle aqueous layer
-deep mucous layer

62
Q

Produced by tarsal glans

A

Superficial oily layer

63
Q

produced by lacrimal gland and gland of
the 3rd eyelid

A

Middle aqueous layer

64
Q

produced by the goblet cells of the
conjunctiva

A

Deep mucous layer

65
Q

Functions:
– plays an absolute essential role in maintaining health of the eyes
and normal transparency of the cornea
– keep cells of cornea moist
– washes foreign body away from the eyes
– facilitates diffusion of respiratory gases and nutrients to and
from the avascular cornea
– contains antimicrobial substance and dissolves antibodies that
help protect against infection.

A

Tear Film

66
Q

Musculature of the Eye

A
  • intraocular muscles (intrinsic)
  • extraocular muscles (extrinsic)
  • muscles of the eyelids (palpebral muscles)
67
Q

all smooth muscles lies entirely with-in the globe
– ciliary muscles
– pupillary dilator
– pupillary constrictor

A

Intraocular Muscles

68
Q

all skeletal muscles, 7 extra orbital muscles: 4 rectus muscles, 2 oblique muscles, 1 retractor muscle

A

Extraocular muscles

69
Q

rotate the globe upward

A

Dorsal rectus

70
Q

rotate the globe downward

A

Ventral rectus

71
Q

rotate the globe medially

A

Medial rectus

72
Q

rotate the globe laterally

A

Lateral rectus

73
Q

*all are innervated by oculomotor nerve except lateral rectus which is innervated by abducent nerve

A
  • dorsal rectus
    – ventral rectus
    – medial rectus
    – lateral rectus
74
Q

rotate the dorsal surface of the globe medially,
innervated by TROCHLEAR NERVE

A

dorsal oblique

75
Q

rotate the dorsal surface of the globe laterally,
innervated by OCULOMOTOR NERVE

A

Ventral oblique

76
Q

withdraws the globe deeper into the
orbit, innervated by ABDUCENT NERVE

A

Retractor bulbi / oculi

77
Q

– move the eyelid to open or close the eye
– adjust eyelid position in response to positional changes of the globe

A

Palpebral muscles

78
Q

Muscles of the Eyelids

A

-Palpebral Muscles
1) Orbicularis oculi – facial nerve
2) Levator palpebrae superioris – oculomotor
nerve
3) Retractor anguli oculi superioris – facial nerve
4) Palpebral part of the deep sphincter of the neck
5) Superior and Inferior tarsal muscles

79
Q

– orbital part surrounds the bony orbit
– palpebral part within the upper and lower eyelid

A

Orbicularis oculi – facial nerve

80
Q

– primary muscle that act to raise the upper eyelid
– ptosis ( drooping upper eyelid)

A

Levator palpebrae superioris – oculomotor
nerve

81
Q

– draws the lateral canthus caudally
– assists in closure of the eye

A

Retractor anguli oculi superioris – facial nerve

82
Q

– depresses the lower lid assists in opening the eye
– Innervated by buchal branches of facial nerve

A

Palpebral part of the deep sphincter of the neck

83
Q

– assists in holding the eyelids open
– innervated by sympathetic fibers

A

Superior and inferior tarsal muscles

VAna 101 Doc Je an (4 decks)

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