Anatomy Of Eye & Adnexa Flashcards

1
Q

Purpose of vision

A

Taking in info from surroundings
Energy from environment is converted to neural activity via conversion of photon into electrical signal in the retina

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2
Q

Vision of carnivores

A

More binocular, less peripheral

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3
Q

herbivore vision

A

Opposite of carnivores, less binocular and more peripheral vision

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4
Q

Bony orbit in species

A

Dog & cat - incomplete, finished w orbital ligament
Herbivores - complete by postorbital bar

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5
Q

Supraorbital fossa

A

Space dorsal & caudal to orbit
Houses extension of retrobulbar fat pad
Coronoid process of mandible extends into space

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6
Q

Pterygopalatine fossa

A

Bony orbital rim
Houses globe & adnexa, contains specific for foramina transmitting arteries, veins & nerves serving the globe & adnexa

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7
Q

Nerves that travel through pterygopalatine fossa

A

CN II
(Orbital fissure)
CN III, IC, V- ophthalmic, VI
Rostral alar foramen
CNV - maxillary

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8
Q

Eyelids

A

Palpebrae
Superior eyelid
Inferior eyelid
Internal - palpebral fissure

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9
Q

Lateral and medial canthus

A

Respective edges where two lids meet
Form the medial and lateral angles of the eye

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10
Q

Palpebrae stuctures

A

Levator palpebrae superior
Orbicularis oculi
Tarsal glands

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11
Q

Medial and lateral palpebral ligaments

A

Anchoring eyelids medially & laterally so they close in a horizontal line rather than a circle when the orbicularis oculi contracts

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12
Q

Levator palpebrae superioris

A

Narrow strip of muscle running longitudinally into upper lid
Contraction raises the upper lid
Innervated by CNIII
Simultaneous contraction of two muscles that ensure globe rotates upward & upper lid is raised

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13
Q

Muscles of eyelid

A

Various other small muscles
Levator anguli oculi medialis
Retractor anguli oculi lateralis

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14
Q

Orbital adnexa

A
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15
Q

Third eyelid

A

Cartilage supported by connective tissues that is anchored in medial canthus
Cartilage often t-shaped but shape varies
Can be carried across the anterior globe like a windshield wiper

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16
Q

Bulbar surface well-provided with lymphoid tissue

A
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17
Q

Mechanism of third eyelid movement

A

Held in traction by tonic contraction of the orbitalis (SM)
Contraction is under sympathetic control
Motion over the eye is passive
When eye is retracted into the orbit, 3rd lid slides over globe

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18
Q

Lacrimal apparatus

A

Flow of tears from Dorso lateral to Ventrolateral
Exit of tears from eye through medial canthus to nasal vestibule via nasolacrimal duct

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19
Q

Apparatus structures

A

Tear producing glands
Duct system conducting tears from medial canthus into nasal vestibule for evaporation

20
Q

Tear producing glands

A

Scattered small accessory glands within eyelids
Glands of 3rd eyelid

21
Q

Lacrimal gland

A

Positioned dorsolaterally within orbit
Secretion into conjunctival sac from Dorso lateral aspect
Blinking distributes secretions across globe in a ventromedial direction
Secretion washes over bulbar conjunctiva towards medial canthus

22
Q

Lacrimal lake

A

Accumulations of tear fluid near medial canthus

23
Q

Lacrimal caruncle

A

Lump in the lake

24
Q

Lacrmal puncta - superior and inferior

A

One tiny duct opening in each lid at medial -most margin of lid

25
Q

Minor species variation

A

Only pigs dorsally

26
Q

Lacrimal canaliculi - superior and inferior

A

Tiny ducts, one from each punctum going medially from each punctum
Two canaliculi fuse
Enlargement called the lacrimal sac is present at the fusion site

27
Q

Nasolacrimal duct

A

With or without the sac, two canaliculi fuse into the larger duct, nasolacrimal duct
NLD passes rostrally to empty into the nasal vestibule
Introduction of tears into the nasal vestibule provides evaporative space

28
Q

Lacrimal apparatus

A

Lacrimal gland
Lacrimal puncta
Lacrimal canaliculi
Lacrimal sac
Nasolacrimal duct
Nasolacrimal orifice

29
Q

Extraocular muscles

A

Trochlea
Fossa for lacrimal sac
Ventral oblique
Dorsal oblique
Maxillary foramen
Levator palpebrae
Retractor bulbi
Dorsal rectus
Lateral rectus

30
Q

Oblique muscles

A

Both start medially at pterygopalatine fossa
Two take a general course that crosses orbit obliquely, both insert on respective (dorsal & ventral) lateral aspect of globe

31
Q

Dorsal (superior) oblique muscle

A

Starts near optic canal (medially)
Passes rostrally on the Dorso medial orbit wall
Turns around the trochlea, U-shaped cartilage in dosromedial orbit wall
Tendon turns almost 90 degrees (laterally)
Tendon passes to insertion of Dorso lateral side of globe
Isolated action would rotate the dorsal part of globe medially

32
Q

Ventral inferior oblique muscle

A

Originates medially in pterygopalatine fossa, more ventrally than dorsal oblique
Passes laterally to insert on Ventrolateral side of globe
Isolated action would be to move the dorsal side of globe laterally

33
Q

Retractor bulbi

A

Originates near optic canal
Radiates out as cone that surrounds optic nerve & attaches to globe in a circle just posterior to equator
Contraction retracts globe deeper into orbit, facilitates protrusion of 3rd eyelid.
ABSENT in birds & primates

34
Q

Muscle that turns globe

A

Medial rectus - turns globe nasally
Lateal rectus - turns globe temporally

35
Q

Arteries

A

Primarily delivered through external ophthalmic artery, vessel itself is a branch of maxillary artery as it courses through the pterygopalatine fossa via rostral alar foramen

36
Q

Blood delivered to eye via

A

External ophthalmic artery

37
Q

Motor nerves of eye (non autonaumic)

A

Oculomotor nerve innervates
Levator palpebrae superioris
Dorsal, ventral & medial recti
Ventral oblique
Part of retractor bulbi

38
Q

Trochlear nerve

A

Motor nerve of dorsal oblique

39
Q

Abducens nerve

A

Nerve of lateral rectus and most of retractor bulbi

40
Q

Palpebral nerve

A

Terminal branch of auriculopalpebral nerve
Supplies orbicularis oculi

41
Q

Optic nerve

A

Sensory to retina (rods & cones)

42
Q

Ophthalmic
Maxillary

A

O: sensory to upper lid & frontal region
M: general sensory to lower lid, variable area from caudal to eye to midline of frontal region, upper muzzle

43
Q

Sympathetic innervation of eye in mammals

A

Pupillary dilator
Orbitalis muscle (SM)

44
Q

Common affects of sympathetic innervation

A

Horners syndrome
Ptosis, miosis, enophthalmos, protrusion of 3rd eyelid
Sunken eye, small pupil, drooping upper lid

45
Q

PSNS innervation of eye

A

Pupillary constrictor
Ciliary body - acts on lens for accommodation of vision