11. Oculomotor movements Flashcards
Why are there primary/secondary/tertiary actions for some oculomotor muscles?
If the visual Axis is in the same plane as the muscle plane of rotation you will only get one direction movement. However, the orbits are not aligned so muscle planes and visual axis do not coincide. Results in muscle pulling eye in 3 directions.
Define the visual axis?
The line joining fixation point and fovea
What is the angle that SR and IR have with the visual axis?
23 degrees.
What is the angle that SO and IO have with the visual axis?
54 degrees
What is hering’s law of equal innervation?
Coordination of muscles pairs for two eyes.
Equal innervation to synergists
What is a synergist?
2 muscles that work together in different eyes.
E.g. LLR moves left eye out. RMR moves right eye in. = Looking left.
What is sherrington’s law of reciprocal innervation?
Coordination of muscle pairs of one eye.
Agonist contracts results in inhibition of direct antagonist.
What does Agonist contracts results in inhibition of direct antagonist mean?
2 muscles that work in opposite directions in the same eye.
E.g. RSR contracts and RIR inhibited so that the eye can actually move.
What is ductions?
One eye is covered, the uncovered eye you have them follow the torch light to their limits.
Identify which nerves supply each muscle
LR6(SO4)O3
