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Ocular Motility > Ocular Kinematics and Muscle Anatomy > Flashcards

Ocular Kinematics and Muscle Anatomy Flashcards

1
Q

What is the branch of classical mechanics that describes the motion of points, bodies, and systems of bodies, without consideration of the forces that cause it

A

kinematics

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2
Q

What does kinematics focus on and exclude?

A

Focuses on motion, excludes forces

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3
Q

Describe the CN innervation of the 6 EOMS

A

CN 3 Innervations the superior, inferior, and medial rectus in addition to the inferior oblique; the superior oblique is innervated by CN 4; the lateral rectus is innervated by CN 6

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4
Q

The ____ is not a contractile tissue, but force direction comes from the muscle

A

superior oblique tendon

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5
Q

Where does the muscle attach to the bony orbit?

A

origin

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6
Q

Where does the muscle attach to the globe?

A

insertion

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7
Q

What forms the muscle cone?

A

The recti muscles, Origin at Annulus of Zinn

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8
Q

What goes thru the SOF and above the Annulus of Zinn?

A

lacrimal, frontal, trochlear, superior ophthalmic vein

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9
Q

What goes thru the SOF and Annulus of Zinn?

A

nasociliary, oculomoter superior and inferior, and abducens

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10
Q

What goes thru the optic canal?

A

optic nerve and ophthalmic artery

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11
Q

What goes thru the IOF?

A

zygomatic, infraorbital nerve artery and vein, and the inferior ophthalmic vein

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12
Q

What is optic neuritis and what are the signs?

A

inflammation of the optic nerve; pain on EOMS is a sign, if retrobulbar there is APD

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13
Q

Superior Rectus: innervation, origin, insertion, and fun fact

A

CN 3; superior annulus of zinn; 23 degree angle w/ primary gaze on superior sclera, 7.4 mm from limbus (furthest); connected sheath w/ levator= coordinated eye movements with eyelids

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14
Q

Superior rectus actions:

A

elevation, adduction, and intorsion

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15
Q

Inferior Rectus: innervation, origin, insertion, and fun fact

A

CN 3; inferior annulus of zinn, 23 degree angle w/primary gaze on inferior sclera (6.7 mm from limbus); IR passes of IO and fascia below both contributes to lockwoods ligament

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16
Q

Inferior rectus actions

A

depression, adduction, extorsion

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17
Q

Lateral Rectus: innervation, origin, insertion, and fun fact

A

CN 6; upper and lower limb of annulus AND process of greater sphenoid wing; parallel to medial recuts 6.9 mm from limbus; fascial expansion from muscle sheath of lateral check ligament; whitnall’s tubercle has attachment at lateral wall of orbit

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18
Q

Lateral rectus action

A

abduction

19
Q

Medial Rectus: innervation, origin, insertion, and fun fact

A

CN 3; upper and lower annulus AND optic nerve sheath; 5.5 mm from limbus (most anterior); medial check ligament fascial expansion from muscle sheath attaches to medial orbit

20
Q

Medial rectus action

A

adduction

21
Q

What is the spiral of tilleaux?

A

The nature of insertions of EOMS; medial is most anterior and superior is least anterior; most surgical correction done on medial rectus then lateral rectus

22
Q

Superior Oblique: innervation, origin, insertion, and fun fact

A

CN 4; ANATOMICAL origin is lesser wing of sphenoid, PHYSIOLOGICAL origin is cartilaginous trochlea of the superior medial orbital wall (muscle ends before trochlea and tendon passes thru); insertion lateral posterior globe

23
Q

Superior oblique actions

A

Intorsion, Abduction, Depression

24
Q

Explain the three superior oblique vector forces:

A

primary gaze- straight ahead
adduction- 54 degrees medial
abduction- 36 degrees lateral

25
Q

Inferior Oblique: innervation, origin, insertion, and fun fact

A

CN 3; originates in ANTERIOR ORBIT at maxillary bone inferior to the nasolacrimal fossa; inserts posterior-lateral globe, mostly inferior at 51 degree angle

26
Q

Inferior oblique actions

A

Extorsion, abduction, elevation

27
Q

What is the tangential point?

A

Where the center of the muscle or tendon first touches the globe; tangent indicates direction of pull; position changes when the muscle contracts or relaxes and the eye moves. THIS IS NOT THE INSERTION

28
Q

What is the arc of contact?

A

The arc formed between the tangential point and the center of the insertion on the sclera; varies in lengths as the muscle contracts

29
Q

What is the muscle plane?

A

Determined by a tangential point and the center of rotation; describes direction of pull of the muscle; determines the axis of rotation

30
Q

Strabismus Sx ReSECTion

A

To remove a section of the medial of lateral rectus; shorter muscle=more pull

31
Q

Strabismus Sx ReCESSion

A

To slide backwards; medial or lateral rectus is cut and sutured to the sclera more distally; muscle doesn’t reach as far=less pull

32
Q

Strabismus Sx

A

Can use resection and recession in combination; results in new insertion, new arch and new tangential

33
Q

Strab Sx Transposition

A

For vertical deviations; move lateral or medial rectus up or down on the globe; very small change in position

34
Q

What is the field of fixation

A

An area within which central fixation is possible by moving ONLY the eyes aka the area the fovea can hit w/o moving your head

35
Q

Explain the relationship between bino and mono fixation

A

In bino fixation, both foveas must be pointed at the same place at the same time, this area is actually smaller than monocular fixation

36
Q

What differences are there in field of fixation?

A

Large individual differences, limits depending on eye structure and refraction of globe, age-dependent decreases from EOM restriction starting the the 60s

37
Q

What is practical field of fixation?

A

The area central fixation is possible including head movements

38
Q

What is primary gaze/position?

A

The reference point for ocular rotation, lines of sight are horizontal and perpendicular to the line between their centers of rotation

39
Q

What is secondary position?

A

The position assumed when the eye moves from primary position along the horizontal or vertical axis

40
Q

What is tertiary position?

A

The position assumed when the eye moves to any other location

41
Q

What is a duction?

A

A rotation of a single eye; add, abd, supra, infra

42
Q

What is a version?

A

A rotation of both eyes

43
Q

What is a vergence?

A

Binocular eye movements in opposite directions; convergence and divergence

44
Q

What is cyclotorsion?

A

Rotation (counter)clockwise- difficult to treat surgically and therapeutically; intorsion- 12 to nose; extorsion 12 to ear

Ocular Motility (13 decks)

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