Midterm 1: Kinematics 2 Flashcards
4 major laws of kinematics
- Sherrington’s Law
- Hering’s Law
- Donder’s Law
- Listing’s Law
Sherington’s Law of Reciprocal Innervation (antagonistic law)
When a muscle contracts, its direct antagonist relaxes to an equal extent on the same eye. Neural excitation of muscle contracting has to equal neural inhibition of the muscle it is relaxing.
Why do our eyes move smoothly instead of jerking? What law is this relevant to?
Relevant to Sherrington’s Law. Since neural excitation = neural inhibition, it allows for a smooth movement.
Hering’s Law of Equal Innervation (agonist)
Synergistic EOMs receive equal and simultaneous innervation.
Contraction of one EOM occurs with equal and simultaneous contraction of the contralateral agonist
Yoked muscles are pairs of muscles that act ________.
together
Example of yoked muscle on physiological H
Superior rectus on the right eye physiological H and inferior oblique on the left eye physiological H.
If you see a problem during EOM physiological H, what do you do first?
Do each eye monocularly to see if the problem is still there.
You see a problem during EOM physiological H, you test the eye monocularly and still see a problem. What do you do next?
Forced duction test
What is forced duction test? Results?
Test you do after you find a problem during EOM physiological H on monocular. Open the eye, grab the conjunctiva and pull it in the direction that you think is the problem. If the eye resists going in the direction it’s being pulled, the test is positive and there is an issue within the orbit. If the test is negative and the eye moves freely, the issue is not with the muscles but with the nerves.
The eyes are in ______ motion.
constant
Does it matter what way your eye turns first?
Yes, since it is a 3D rotation, it is not commutive and does matter.
What is pitch, roll, and yaw?
X axis = pitch
y axis = roll
z axis = yaw
Describe translations in 3 dimensions
End position can be described by 3 Cartesian coordinates (X, Y, Z)
Center of the eye is reference
translation is flat movement in Euclidean space
A single translation never results in returning to original position
Describe rotations in 3 dimensions
End position can NOT be described by only 3 coordinates
The space for all rotations is CURVED
If you keep rotating, you get back to the same orientation eventually!
A single rotation can result in returning to original position
How many degrees of freedom does the eye have?
3
