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Spring '20/ L. A&P > the eye > Flashcards

the eye Flashcards

1
Q

superior rectus

A

Oculomotor (III) elevation, adduction, medial rotation of eyeball

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2
Q

inferior rectus

A

Oculomotor (III) depression, adduction, lateral rotation of eyeball

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3
Q

medial rectus

A

oculomotor (III) adduction of eyeball

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4
Q

Lateral rectus

A

abducent(VI) abduction of eyeball

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5
Q

Superior Oblique

A

Trochlear (IV) depression, abduction, medial rotation of eyeball

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6
Q

inferior oblique

A

Oculomotor (III)elevation, abduction, lateral rotation of eyeball

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7
Q

levator palpebra superioris

A

Oculomotor (III)elevation of upper eyelid

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8
Q

blind spot

A

located about 15 degrees lateral to the central point of vision no rods or cones in this area, called the optic disc, exit point for axons of the ganglion cells

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9
Q

Emmetropia- normal.

A

Light focuses on retina

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10
Q

Hypertropia-farsighted

A

Light focuses behind the retina and is corrected with a convex lens

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11
Q

Myopia- nearsighted

A

Light focuses in front of retina and is corrected with a biconcave lens.

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12
Q

Astigmatism

A

Curvature of the lens is not uniform and is corrected with a cylindrical lens Bumpy Cornea

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13
Q

Presbyopia

A

This is loss of accommodation power of the lens that occur with aging. The near point (closest point on which one can focus by accommodation of the lens) moves farther from the eye and is corrected with a convex lens. Caused by progressive denaturation of the proteins of the lens. Makes the lens less elastic. Begins about 40-50 years of age.

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14
Q

Cataracts

A

Cloudy or opaque area of the lens Caused by coagulation of lens proteins

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15
Q

Miosis

A

constriction of pupillary aperture due to stimulation of parasympathetic nerves that excite the pupillary sphincter muscle

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16
Q

Mydriasis

A

dilation of pupillary aperture due to stimulation of sympathetic nerves that excite the radial fibers of the iris

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17
Q

Intraocular fluid

A

keeps the eyeball round and distended. 2 fluid chambers

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18
Q

Aqueous Humor

A

Freely flowing fluid In front of lens

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19
Q

Vitreous Humor

A

Gelatinous mass between lens and retina Little flow

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20
Q

Production of Aqueous Humor

A

It is produced by the ciliary processes of the ciliary body at a rate of 2-3 microliters/min. Flows between the ligaments of the lens, through the pupil into the anterior chamber, goes between the cornea and the iris, through a meshwork of trabeculae to enter the canal of Schlemm which empties into aqueous veins and then into extraocular veins.

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21
Q

Glaucoma

A

due to resistance to fluid flow through trabecular spaces , causes increase IOP MCC of blindness due to compression necrosis of the axons of the optic nerve

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22
Q

Eye Cones

A

light cones

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23
Q

rods

A

night rods

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24
Q

Kerotin

A

from carrots

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25
Q

Light receptors

A

Consist of rods and cones (not present on the optic disk –blind spot ) Pigment layer of the retina contains the black pigment melanin that prevents light reflection in the globe of the eye Lack of pigmentation in albinos results poor visual acuity because of the scattering of light

26
Q

vitamin a deficiency

A

Vitamin A deficiency causes Night Blindness

27
Q

Pigement layer of retina

A

Pigment layer of the retina contains the black pigment melanin that prevents light reflection in the globe of the eye Lack of pigmentation in albinos results poor visual acuity because of the scattering of light

28
Q

RODS

A

Sensitive to low-intensity light; night vision. low visual acuity dark adaptation- rods adapt later no color vision

29
Q

CONES

A

Sensitive to high intensity light; day vision. higher visual acuity. cones adapt first to dark adaptation yes for color vision

30
Q

nasal field of vision

A

nasal field located on the temporal side of the retina

31
Q

temporal field of vision

A

temporal field located on the nasal side of the retina

32
Q

fields of vision interruption

A

interruption of the visual pathway at different points leads to very specific visual field defects

33
Q

Blinds spots

A

located about 15 degrees lateral to the central point of vision no rods or cones in this area, called the optic disc, exit point for axons of the ganglion cells

34
Q

cutting the optic nerve

A

causes blindness in the ipsilateral eye

35
Q

cutting the optic chiasm

A

causes heteronymous bitemporal hemianopia (tunnel vision in pituitary gland adenoma)

36
Q

Cutting of the optic tract

A

Cutting of the optic tract causes homonymous contralateral hemianopia

37
Q

Cutting the geniculocalcarine tract

A

Cutting the geniculocalcarine tract causes homonymous hemianopia with mecular sparing

38
Q

Optic Pathways and Lesions

A

…

39
Q

optic chiasm

A

Growing adenoma of the pituitary grand will slice the optic chiasm.

40
Q

Eye injury during anesthesia

A

The eyes are vulnerable to injury secondary to prolonged lateral decubitus or prone position Retinal ischemia / blindness Dryness of cornea

41
Q

Eye injury during anesthesia-prevention

A

Padding around the orbit Eye lubricants

42
Q

Outer ear

A

Directs the sound wave into the auditory canal

43
Q

Middle ear

A

Is air-filled Contains the tympanic membrane (ear drum) and the auditory ossicles (malleus, incus and stapes). The stapes inserted into the oval window, a membrane between the middle ear and the inner ear. Ossicles amplify sound. Sound waves cause the tympanic membrane to vibrate. In turn , the ossicles vibrate , pushing the stapes into the oval window (in and out like piston) and displacing fluid in the inner ear (ripple effect)

44
Q

Inner ear

A

Is fluid-filled Consist of a bony labyrinth (semicircular canals, cochlea and vestibule ) and series of ducts within bony labyrinth are membranous labyrinth. The fluid outside the ducts is perilymph; the fluid inside the ducts is endolymph.

45
Q

Structure of the cochlea: three tubular canals

A

The scala vestibuli and scala tympani contain perilymph , which has a increase Na+ The scala media contains endolymph , which has a increase K+ The scala media is bordered by the basilar membrane, which is the site of organ of Corti

46
Q

Organ of Corti number 28

A

Is located on the basilar membrane Is located on the basilar membrane Contains the receptor cells (inner and outer hair cells) for auditory stimuli. Cilia protrude from the hair cells and are embedded in the Tectorial membrane. Outer hair cells > Inner hair cells Spiral ganglion contains the cell bodies of auditory nerve (CN VIII ) ,which synapse on the hair cells Sound wave causes vibration of organ of Corti, this causes bending of hair cells against the tectorial membrane Bending in one direction Depolarization Bending in other direction  Hyperpolarization This changing potential of the hair cells causes intermittent firing of cochlear nerves. Fibers ascend to auditory cortex

47
Q

Base of basilar membrane

A

Base of basilar membrane (close to oval window) responds best to high frequencies

48
Q

Apex

A

of basilar membrane responds best to low frequencies

49
Q

Ear infection

A

goes into the inner ear- loose high frequency

50
Q

Conductive deafness

A

Defects in external or middle ear Defects in transmission of sound to the inner ear due to wax, foreign body, destruction of auditory ossicals, thickening of ear drum due to repeated middle ear infection. Bone conductance > Air conductance

51
Q

Nerve deafness- sensory

A

Defects in inner ear or vestibulocochlear nerve ( CN VIII) Both bone & air conductance are reduced Adverse effect of aminoglycoside –gent, neomycin

52
Q

what is ear wax

A

its an insect repellant

53
Q

Pressure changes in middle ear during Nitrous oxide (N2O) anesthesia

A

There is significant increase in middle ear pressure during administration of Nitrous oxide. Therefore , nitrous oxide should be used with caution in presence of mild middle ear diseases (e.g. otitis media , sinusitis) with obstructed Eustachian tube. This may result hearing loss or tympanic membrane rupture. Nitrous oxide is contraindicated in tympanoplasty, as the pressure difference between middle and external ear can jeopardize the success of operation.

54
Q

taste

A

Taste pathways Taste receptor cells line the taste bud Innervation Anterior 2/3 –VII (Facial nerve for salty & sweet taste)- Chorda tympani (a branch of VII) Posterior 1/3 – IX (Glossopharyngeal nerve for sour & bitter taste) Back of throat – X (vagus nerve) Medulla solitary tract solitary nucleus Thalamus  taste cortex

55
Q

Olfaction AP

A

Second order neuron form olfactory tract and project to prepiriform cortex

Stimulus activates receptor cells lead to activation of G proteins lead to activation of adenylate cyclase which increases cAMP leading to Na+ channels open then AP is generated and propagated

56
Q

Olfaction

A

Receptor cells Located in the olfactory epithelium

CN I carries information to olfactory bulb

Fracture of cribriform plate of ethmoid bone , causes hyposmia or anosmia

57
Q

Nasal cavity considerations…

A

Nasal cavity is frequent site of bleeding due to high vascularity. Before insertion nasal airways, nosgastric catheters or nasotracheal tubes should be lubricated and advanced at an angle perpendicular to the face to avoid injury to nose Vasoconstrictors are used to cause mucosal shrinkage.

58
Q

olfactory epithelium supplied by which cranial nerve

A

Olfactory epithelium is also supplied by CN V (trigeminal), which detect noxious or painful odor like ammonia

59
Q

Stretch Reflex – Knee jerk

A

Is monosynaptic. Muscle stretch leadings to excitation of M. Spindles which stimulate group Ia afferents Stimulation of alpha motoneuron in the spinal cord Contraction of the muscle (Extrafusal fibers) and returning to its original length. Knee jerk reflex: tapping on patellar tendon causes the quadriceps to stretch leading to stimulation of afferent fibers leading to activation of alpha motor neurons leading to contraction of quadriceps. Knee jerk increase in upper motor neuron lesion (due to loss of inhibition) , and decrease in lower motor neuron lesions.

60
Q

Golgi Tendon Reflex

A

Is opposite or inverse of the stretch reflex Active muscle contraction stimulates the Golgi tendon organs and group Ib Ib afferent stimulates inhibitory interneuron in spinal cord leading to inhibit alpha motoneurons and causes relaxation of the muscle that was originally contracted

61
Q

Flexor withdrawal reflex(Touching a hot stove)

A

Is polysynaptic. Flexion on ipsilateral side and extension on contralateral side Somatosensory and pain afferent fibers elicit withdrawal of the stimulated body part from the noxious stimulus (hot stove) Afterdischarge prevents the muscle from relaxing for some time.

Spring '20/ L. A&P (21 decks)

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