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Biomedical Human Anatomy > The orbit and eat > Flashcards

The orbit and eat Flashcards

1
Q

The Orbit

A
  • houses the eye and its accessory structures
  • bony cavity–> quadrangular pyramid shape
  • composed of 7 bones
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2
Q

Bones of the orbit

A
  1. Frontal
  2. Zygomatic
  3. Maxilla
  4. Palatine (smallest piece)
  5. Sphenoid
  6. Ethmoid
  7. Lacrimal
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3
Q

Accessory Structures of the eye

A
  • protect the eye and aid eye function
    1. Eyebrows
    2. Eyelids (palpebrae)
    3. Lacrimal apparatus
    4. Conjunctiva
    5. Extrinsic eye muscles
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4
Q

Lacrimal apparatus

A
  • lacrimal gland
  • lacrimal canaliculi (opens into papilla with punctum)
  • lacrimal sac
  • nasolacrimal duct
  • making tears and catching tears
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5
Q

Conjunctiva

A
  • transparent membrane
  • palpebral conjunctiva lines the eyelids
  • bulbar conjunctiva covers the white of the eyes
  • produces a lubricating mucous secretion
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6
Q

Extrinsic eye muscles

A
  • 6 strap-like extrinsic eye muscles
  • originate from the bony orbit
  • enable the eye to follow moving objects
  • maintain the shape of the eyeball
  • 4 rectus originate from a common tendinous ring
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7
Q

6 muscles

A
  1. lateral rectus
  2. medial rectus
  3. superior rectus
  4. inferior rectus
  5. superior oblique
  6. inferior oblique
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8
Q

Lateral rectus

A
  • moves eye laterally

- innervated by CNVI (abducens)

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9
Q

Medial rectus

A
  • moves eye medially

- innervated by CNIII (oculomotor)

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10
Q

Superior rectus

A
  • elevates eye and turns it medially

- innervated by CNIII (oculomotor)

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11
Q

Inferior rectus

A
  • depresses eye and turns it medially

- innervated by CNIII (oculomotor)

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12
Q

Inferior oblique

A
  • elevates eye and turns it laterally

- innervated by CNIII (oculomotor)

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13
Q

Superior oblique

A
  • depresses eye and turns it laterally

- innervated by CNIV (trochlear)

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14
Q

Structure of the eyeball

A
  • wall of eyeball contains 3 layers
    1. Fibrous
    2. Vascular (middle pigmented layer)
    3. Sensory (retina)
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15
Q

Fibrous layer

A
  • sclera

- Cornea

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16
Q

Cornea

A
  • transparent anterior 1/6 of fibrous layer

- bends light as it enters the eye

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17
Q

Vascular layer

A
  • 3 regions
    1. Choroid
    2. Ciliary body
    3. Iris
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18
Q

Choroid

A

-supplies blood, absorbs light

19
Q

Ciliary body

A

-controls lens shape

20
Q

Iris

A
  • regulates the amount of light entering the eye
  • surrounds the pupil
  • pupil size controlled by para. and symp. nervous system
  • sphincter pupillae m.–> parasymp.
  • dilator pupillae m.–> sympathetic
21
Q

Accomodation

A
  • changing the shape of the lens for near vision
  • relaxed ciliary muscle= thinner lens= distance vision
  • contracted ciliary muscle= fatter lens= near vision
22
Q

Sensory

A
  • retina
  • optic disc–> blind spot (where optic nerve meets retina)
  • composed of two layers
  • pigmented layer (absorbs light, stores Vit. A)
  • neural layer (contains photoreceptors to transmit impulses)
23
Q

Rods

A

-night vision (dark/light)

24
Q

Cones

A
  • color vision
  • macula lutea
  • fovea centralis
25
Q

Internal cavity of eye

A
  • filled with fluids called humors
  • 2 segments
    1. Anterior segment
    2. Posterior segment
26
Q

Anterior segment

A
  • aqueous humor (region in front of lens)
  • anterior chamber: cornea to iris
  • posterior chamber: iris to lens
27
Q

Posterior segment

A

-vitreous humor: region behind lens

28
Q

The lens

A
  • focuses light on retina

- separates the cavity into anterior and posterior segments

29
Q

Macula lutea

A

-yellow spot; high concentration of cones

30
Q

Three parts of the ear

A
  1. external
  2. middle
  3. internal (inner)
31
Q

The external ear

A
  1. Auricle (Pinna)
  2. External acoustic meatus
  3. Tympanic membrane
32
Q

Auricle

A
  • elastic cartilage

- many elevations and depressions

33
Q

External acoustic meatus

A
  • cartilage and bone
  • modified sweat glands produce cerumen
  • not a straight line
34
Q

Tympanic membrane

A
  • ear drum
  • transfer sounds to middle ear bones
  • separates external and middle ear
35
Q

The middle ear

A
  • tympanic cavity + epitympanic recess
  • 3 bones: ossicles
  • tensor tympani and stapedius muscles
  • pharyngotympanic (auditory) tube
36
Q

Ossicles

A
  1. Malleus (hammer)
  2. Incus (anvil)
  3. Stapes (stirrup): sits on oval window
    - transmit vibrations of the eardrum to the oval window
37
Q

Tensor tympani and stapedius muscles

A

-contract reflexively in response to loud sounds to prevent damage to hearing receptors

38
Q

Pharyngotympanic tube

A
  • connects the middle ear to the nasopharynx

- equalizes pressure in the middle ear cavity with the external air pressure

39
Q

The internal ear

A
  • bony labyrinth: in the temporal bone
  • 3 parts w/ membranous sacs inside
    1. vestibule
    2. semicircular canals
    3. cochlea
40
Q

Vestibule

A
  • house equilibrium receptor regions (maculae)

- respond to gravity and changes in the position of the head

41
Q

Semicircular canals

A
  • three canals (anterior, lateral, and posterior)

- crista ampullaris receptors respond to angular (rotational) movements of the head

42
Q

Cochlea

A
  • spiral, conical, bony chamber

- which houses the spiral organ (of Corti): the receptor organ of hearing

43
Q

Perilymph

A

-fills the bony labyrinth

44
Q

Endolymph

A
  • fills series of membranous sacs within the bony labyrinth

- potassium-rich

Biomedical Human Anatomy (28 decks)

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