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Pédiatrie > 4 - Physiologie motrice > Flashcards

4 - Physiologie motrice Flashcards

1
Q

Expliquer la loi de Sherrington dans l’innervation musculaire et donner un exemple

A

Augmentation de l’innervation d’un MEO = diminution réciproque de l’innervation de son antagoniste

Ex : abduction de l’oeil droit = augmentation de l’innervation du droit latéral et diminution innervation du droit médial

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2
Q

Quelles sont les actions primaires, secondaires et tertiaires des muscles droits sup/inf et oblique sup/inf

A

Droit sup : élévation, intorsion, adduction
Droit inf : dépression, extorsion, adduction

Oblique sup : intorsion, dépression, abduction
Oblique inf : extorsion, élévation, abduction

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3
Q

Comment on positionne l’oeil du patient pour obtenir un mouvement de dépression pur ?

A

23° en abduction (angle origine-insertion du droit inf = 23°)

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4
Q

Comment on positionne l’oeil du patient pour obtenir un mouvement de torsion pur ?

A

Abduction de 39° (angle origine-insertion des muscles obliques = 51°)

Positionné à 51° d’adduction, on obtient une action principale verticale

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5
Q

Qu’est-ce que la loi de Hering ?

A

When the eyes move into a gaze direction, there is a simultaneous and equal increase in innervation to the yoke muscles for that direction

The amount of innervation supplied to both eyes is always determind by the fixating eye -> c’est pourquoi l’angle de déviation varie selon quel oeil fixe (dominant vs dévié)

Déviation primaire : déviation quand l’oeil sain fixe

Déviation secondaire : déviation quand l’oeil affecté fixe (plus grande)

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6
Q

Un ratio AC/A élevé tend à produire quelle déviation ? Et un ratio AC/A diminué ?

A

Élevé : ésotropie à la fixation de près

Diminué : Moins d’éso vs exotropie à la fixation de près

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7
Q

Quelles sont les amplitudes de vergence normales ? (convergence, divergence, vergence vertical, cyclovergence)

A

Convergence : 15-20 Δ distance / 25 Δ near

Divergence : 6-10 Δ distance / 12-14 Δ near

Vertical : 2-3 Δ

Cyclovergence : 8°

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8
Q

Vitesse maximale de mouvements des yeux lors de saccades ? Lors de la poursuite ?

A

saccades : 400-500° par seconde

Mvt de poursuite : 30-60° par seconde

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9
Q

Pourquoi faut il prendre la mesure de déviation en strabisme alors que le pt est éveillé vs endormit en SOP ?

A

Convergence tonique : Because of the anatomical shape of the bony orbits and the position of the rectus muscle origins, the position of the eyes during complete muscle paralysis is divergent -> there is a constant innervational tone to the rectus medial when a person is awake that is called tonic convergence

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10
Q

(Ocular Rotations)

Définir la loi de Donder?

A

Ocular rotations are clinically considered as
* Horizontal rotations about a vertical axis, corresponding to medial and lateral gaze;
* Vertical rotations about a horizontal axis, corresponding to upward and downward gaze;
* Torsional rotations about the line of sight.

If a change in gaze position is broken down into a series of separate rotations about the horizontal and vertical axes, the final torsion of the eye for a given gaze direction could theoretically vary, depending on the sequence in which the rotations are applied.

In practice, the final torsion of the eye is always the same for a given gaze direction, regardless of the sequence by which it arrives there (Donder’s law).

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11
Q

(Ocular Rotations)

Définir la loi de Listing?

A

Listing’s law specifies this relationship by stipulating that the orientation in a given gaze position is equivalent to that which would result from a single rotation around an axis lying in Listing’s plane.

Donder’s law : the final torsion of the eye is always the same for a given gaze direction, regardless of the sequence by which it arrives there .

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12
Q

(Positions of Gaze)

Qu’est-ce que le primary position (PP)?

A

Primary position is the position of the eyes when they are fixating straight ahead.

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13
Q

Quelles sont les secondary diagnostic positions?

A

Secondary diagnostic positions are
* Straight up
* Straight down
* Right gaze
* Left gaze

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14
Q

Quelles sont les tertiary diagnostic positions?

A

Tertiary diagnostic positions are the 4 oblique positions of gaze:
* Up and right
* Up and left
* Down and right
* Down and left
* Right and left head- tilt positions

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15
Q

Quelles sont les positions cardinales?

A

Cardinal positions, which correspond to the primary fields of action of the extraocular muscles (EOMs) are
* Up and right
* Up and left
* Right
* Left
* Down and right
* Down and left

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16
Q

Pour l’insertion de chacun des MEO est large?

A

The width of the insertion of each EOM serves to stabilize the eye and mitigate changes in action that would other wise occur in different eye positions.

For example,
* When the eye looks upward, the insertion of the medial rectus muscle also shifts upward.
* But this also tightens the inferior fibers and slackens the superior fibers, in effect shifting the net

DONC : stabiliser l’œil et atténuer les changements d’action des MEOs

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17
Q

Définir les Muscle pulleys? Quelles sont les fonctions de celles-ci?

A
  • The 4 rectus muscles are surrounded by fibroelastic pulleys that maintain the position of the EOMs relative to the orbit.
  • The pulleys consist of collagen, elastin, and smooth muscle, enabling them to contract and relax.
  • The pulleys may also serve to stabilize the muscle path, preventing sideslipping or movement perpendicular to the muscle axis.
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18
Q

Définir l’arc de contact?

A

In primary position, each muscle wraps around the globe for several millimeters before reaching its insertion on the sclera.

The length of muscle in contact with the globe is called the arc of contact.

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19
Q

Quel est l’arc of contact des différents MEOs?

A
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20
Q

Quel est l’arc de contact (en mm) du rectus médial?

A

7 mm

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21
Q

Quel est l’arc de contact (en mm) du rectus latéral?

A

12 mm

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22
Q

Quel est l’arc de contact (en mm) du rectus supérieur?

A

6,5 mm

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23
Q

Quel est l’arc de contact (en mm) du rectus inférieur?

A

6,5 mm

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24
Q

Quel est l’arc de contact (en mm) de l’oblique supérieur?

A

7-8 mm

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25
Q

Quel est l’arc de contact (en mm) de l’oblique inférieur?

A

15 mm

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26
Q

Qu’est-ce que l’effective insertion of the muscle?

A

The point where the muscle first contacts the globe is the effective insertion of the muscle.

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27
Q

Que se passe-t-il avec the effective insertion et l’arc of contact lorsque le MEO se contracte?

A

As the muscle contracts and the eye rotates toward the muscle, the effective insertion moves forward on the globe, toward the scleral insertion point, as the arc of contact decreases.

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28
Q

Qu’est-ce qu’un unité motrice?

A

An individual motor nerve fiber and its several muscle fibers constitute a motor unit.

Unité motrice = 1 motoneurone + fibres musculaires

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29
Q

Qu’est-ce que le recrutement d’unités motrices?

A
  • Recruitment is the orderly increase in the number of activated motor units, thus increasing the strength of muscle contraction.
  • For example, as the eye moves farther into abduction, more and more lateral rectus motor units are activated and brought into play by the brain to help pull the eye temporally.
  • In addition, as the eye fixates farther into abduction, the firing frequency of each motor unit increases until it reaches a peak (several hundred per second, for some motor units).
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30
Q

Qu’est-ce qu’une duction?

A

Ductions are monocular rotations of the eye.

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31
Q

Définir un muscle qui est « synergist »?

A

Synergist: the muscle in the same eye as the agonist that acts with the agonist to produce a given movement.

Ex. the inferior oblique muscle is a synergist with the agonist superior rectus muscle for elevation of the eye

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32
Q

Qu’est-ce que la loi de Sherrington?

A

Sherrington’s law of reciprocal innervation states that increased innervation of a given EOM is accompanied by a reciprocal decrease in innervation of its antagonist.

For example, as the right eye abducts, innervation of the right lateral rectus muscle increases and innervation of the right medial rectus muscle decreases.

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33
Q

Qu’est-ce qu’un field of action? Clinical significance des fields of action?

A

Field of action refers to the gaze position (one of the cardinal positions) in which the effect of the EOM is most readily observed.

The clinical significance of fields of action is that a deviation (strabismus) that increases with gaze in some directions may result
* From weakness of the muscle normally pulling the eye in that direction
* From restriction of its action by its antagonist muscle
* Or from a combination of these 2 factors

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34
Q

Primary, secondary, and tertiary actions des MEOs

A
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35
Q

Les muscle planes du rectus supérieur pour isoler les différents actions (en degrés) ?

A
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36
Q

Les muscle planes du rectus inférieur pour isoler les différents actions (en degrés) ?

A
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37
Q

Les muscle planes de l’oblique supérieur pour isoler les différents actions (en degrés) ?

A
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38
Q

Les muscle planes de l’oblique inférieur pour isoler les différents actions (en degrés) ?

A
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39
Q

Définir le terme version.

A

When binocular eye movements are conjugate and the eyes move in the same direction, such movements are called versions.

40
Q

Définir le terme vergence.

A

When the eye movements are dysconjugate and the eyes move in opposite directions, such movements are known as vergences.

41
Q

Définir Dextroversion

A

Right gaze (dextroversion) is movement of both eyes to the patient’s right.

42
Q

Synonyme/Terme pour décrire : Right gaze, movement of both eyes to the patient’s right.

A

Dextroversion

43
Q

Définir Levoversion.

A

Left gaze (levoversion) is movement of both eyes to the patient’s left.

44
Q

Synonyme/Terme pour décrire : Left gaze, movement of both eyes to the patient’s left.

A

Levoversion

45
Q

Définir Sursumversion

A

Elevation, or upgaze (sursumversion), is an upward rotation of both eyes.

46
Q

Synonyme/Terme pour décrire : Elevation, or upgaze an upward rotation of both eyes.

A

Sursumversion

47
Q

Définir Deorsumversion

A

Depression, or downgaze (deorsumversion), is a downward rotation of both eyes.

48
Q

Synonyme/Terme pour décrire : Depression, or downgaze a downward rotation of both eyes.

A

Deorsumversion

49
Q

Définir Dextrocycloversion

A

Dextrocycloversion is rotation of the superior pole of the vertical meridian of both eyes to the patient’s right.

50
Q

Terme pour décrire : rotation of the superior pole of the vertical meridian of both eyes to the patient’s right.

A

Dextrocycloversion

51
Q

Définir Levocycloversion

A

Levocycloversion is movement of both eyes so that the superior pole of the vertical meridian rotates to the patient’s left.

52
Q

Terme pour décrire : movement of both eyes so that the superior pole of the vertical meridian rotates to the patient’s left.

A

Levocycloversion

53
Q

V ou F : Each EOM in one eye has a yoke muscle in the other eye.

A

Vrai. Each EOM in one eye has a yoke muscle in the other eye.

54
Q

Définir le terme Yoke muscles

A
  • The term yoke muscles is used to describe 2 muscles (1 in each eye) that are the prime movers of their respective eyes into a given position of gaze.

For example, when the eyes move into right gaze, the right lateral rectus muscle and the left medial rectus muscle are simultaneously innervated and contracted. These muscles are said to be “yoked” together.

55
Q

Définir la Hering’s law.

A

Hering’s law of motor correspondence states that when the eyes move into a gaze direction, there is a simultaneous and equal increase in innervation to the yoke muscles for that direction.

Hering’s law has important clinical implications when the practitioner is evaluating a paralytic or restrictive strabismus.

56
Q

Pertinence clinique de la Hering’s law dans l’évaluation d’un strabisme?

A

Hering’s law has important clinical implications when the practitioner is evaluating a paralytic or restrictive strabismus.

57
Q

Dans la Hering’s law, l’amount of innervation supplied to both eyes est déterminé par quel oeil (dans un contexte de paralytic or restrictive strabismus)?

A

Because the amount of innervation supplied to both eyes is always determined by the fixating eye, the angle of deviation varies according to which eye is fixating.

58
Q

Pourquoi l’amount of innervation supplied pour les yoke muscles (contexte Hering’s law) varie selon quel oeil fixe (dans un contexte de paralytic or restrictive strabismus)?

A

Because the amount of innervation supplied to both eyes is always determined by the fixating eye, the angle of deviation varies according to which eye is fixating.

When the sound eye is fixating (prism over the affected eye when the prism alternate cover test is performed), the amount of misalignment is called the primary deviation.

When the affected eye is fixating (prism over the sound eye when the prism alternate cover test is performed), the amount of misalignment is called the secondary deviation.

The secondary deviation is larger than the primary deviation because of the increased innervation necessary to move the affected eye to the position of fixation.

This extra innervation is shared by the yoke muscle in the sound eye, which causes excessive action of that muscle and a larger angle of deviation.

En pratique, Dr Anderson veut toujours opérer la déviation maximale donc il préférable de mesurer avec la déviation secondaire.

59
Q

Définir la déviation primaire versus déviation secondaire dans un contexte d’un strabisme paralytique ou restrictif (selon Hering’s law).

A

Because the amount of innervation supplied to both eyes is always determined by the fixating eye, the angle of deviation varies according to which eye is fixating.

When the sound eye is fixating (prism over the affected eye when the prism alternate cover test is performed), the amount of misalignment is called the primary deviation.

When the affected eye is fixating (prism over the sound eye when the prism alternate cover test is performed), the amount of misalignment is called the secondary deviation.

60
Q

Définir Convergence versus Divergence? Et les Yoke muscles impliqués?

A

Convergence is movement of both eyes nasally relative to a given starting position.

Divergence is movement of both eyes temporally relative to a given starting position.

The medial rectus muscles are yoke muscles for convergence, and the lateral rectus muscles are yoked for divergence.

61
Q

Définir vertical vergence movements

A

With vertical vergence movements, one eye moves upward, and the other moves downward.

62
Q

Définir Incyclovergence versus Excyclovergence

A

Incyclovergence is a rotation of both eyes such that the superior pole of the vertical meridian is rotated nasally

Excyclovergence is a rotation of both eyes such that the superior pole of the vertical meridian rotates temporally.

63
Q

Classification des Vergences Movements?

A
64
Q

Near reflex triad

A

Accommodation, convergence, and miosis

65
Q

Qu’est-ce que le ratio AC/A?

A

A certain amount of accommodative convergence (AC) occurs with each diopter of accommodation (A), giving the accommodative convergence/accommodation (AC/A) ratio.

66
Q

V ou F : Abnormalities of this ratio are common and are important causes of strabismus.

A

Vrai : Abnormalities of this ratio are common and are important causes of strabismus.

67
Q

Résultat d’un abnormally high AC/A ratio?

A

With an abnormally high AC/A ratio, the excess convergence tends to produce esotropia during near fixation that is greater than esotropia at distance.

68
Q

Résultat d’un abnormally low AC/A ratio?

A

An abnormally low AC/A ratio tends to make the eyes less esotropic, or even exotropic, when the patient looks at near targets.

69
Q

Définir le Fusional convergence? Quand est-il activé?

A

A movement to converge and position the eyes so that similar retinal images project on corresponding retinal areas.

Fusional convergence is activated when a target in the midline is seen with bitemporal retinal image disparity.

70
Q

Exemple d’un Proximal convergence?

A

Proximal (instrument) convergence

An induced convergence movement caused by a psychological awareness that the object of fixation is near.

This movement is particularly apparent when a person looks through an instrument such as a binocular microscope.

71
Q

Définir le Tonic convergence?

A

The constant innervational tone to the EOMs when a person is awake and alert.

Because of the anatomical shape of the bony orbits and the position of the rectus muscle origins, the position of the eyes during complete muscle paralysis is divergent.

Therefore, convergence tone is normally necessary in the awake state for the eyes to be aligned.

For example, an esotropic patient under general anesthesia may become less esotropic or even exotropic with suspension of tonic convergence.

72
Q

Définir le Voluntary convergence

A

A conscious application of the near reflex.

73
Q

Définir le Fusional divergence.

A

A movement to diverge and position the eyes so that similar retinal images project on corresponding retinal areas.

Fusional divergence is activated when a target in the midline is seen with binasal retinal image disparity.

74
Q

Où doit se situer la retinal image disparity pour activer le Fusional divergence versus le Fusional convergence?

A

Fusional DIVERGENCE is activated when a target in the midline is seen with biNASAL retinal image disparity.

Fusional CONVERGENCE is activated when a target in the midline is seen with biTEMPORAL retinal image disparity.

75
Q

Définir la Fusional vertical vergence

A

A superior movement of one eye and inferior movement of the other to reduce vertical disparity so that similar retinal images project on corresponding retinal areas.

76
Q

Définir le Fusional cyclovergence

A

Intorsion of both eyes (incyclovergence) or extorsion of both eyes (excyclovergence) to reduce torsional disparity so that similar retinal images project on corresponding retinal areas.

While it can be enhanced by special training, cyclovergence is normally very limited, and fusion of torsional disparity is mostly accomplished by sensory adaptation.

77
Q

V ou F les mouvements torsionnels sont des mouvements volontaires.

A

Faux.

78
Q

Localisation du centre de rotation?

A
79
Q
A
79
Q

Axes de Fick?

A
80
Q

Qu’est-ce les Listing’s Planes?

A
81
Q

Comment sont orientés les Axes de Fick par rapport au Listing’s Planes?

A
82
Q

Définit le point tangentiel et l’arc de contact.

A
83
Q

V ou F : La position du point tangentiel et la longueur de l’arc de contact varient avec la contraction du muscle.

A

Vrai.

84
Q

V ou F : les actions des muscles varient en fonction de la position du regard. Pertinence?

A

Vrai.

85
Q

Action principale des muscles rectus verticaux si ABD de l’oeil à 23°?

A
86
Q

Action principale des muscles rectus verticaux si ADD de l’oeil à 67°?

A
87
Q

Action principale de l’oblique supérieur si ADD de l’oeil à 54°?

A
88
Q

Action principale de l’oblique supérieur si ABD de l’oeil à 36°?

A
89
Q

Actions de l’oblique supérieur lorsque l’oeil est au repos?

A
90
Q

Actions de l’oblique inférieur lorsque l’oeil est au repos?

A
91
Q

Action principale de l’oblique supérieur si ADD de l’oeil à 51°?

A
92
Q

Action principale de l’oblique supérieur si ABD de l’oeil à 39°?

A
93
Q

Combien y a-t-il de paires de yoke muscles?

A

6 paires

94
Q

Loi de Hering

A
95
Q

V ou F : la convergence volontaire est dépendante de la fixation d’un objet.

A

Faux.

96
Q

Définir la convergence fusionnelle

A

Pédiatrie (17 decks)

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