Labs (M1) Flashcards
Where is the nucleus for CN VI (and at one level)? 1. What does it innervate? 2.
- beneath the floor of the fourth ventricle (junction of pons and medulla)
- ipsilateral LR
For Type II Duane’s Retraction syndrome is abduction or adduction impaired?
adduction
What is the yolked muscle for the superior rectus? 1. Superior oblique? 2
- inferior oblique
2. inferior rectus
What is the position the eye must be in to isolate the vertical action of the obliques?
adducting eye (54deg)
What is the ocular muscle layer that has high oxidative enzymes and supports prolonged contraction?
orbital layer
What are the signs of Inter-nuclear Ophthalmoplegia?
- adduction lag
- may have nystagmus on abduction
- convergence unaffected
Where is the origin of the MR? 1. Insertion? 2. What are the muscle movements (primary to tertiary)? 3
- annulus of Zinn
- 5-6mm behind cornea
- adduction
What are the possible paretic muscles for a right hyper deviation (left hypo) that increases in right head tilt?
RSR, RSO, LIO, LIR
While covering the paretic eye and doing the H test will the look of the covered eye be an overshoot or undershoot?
undershoot
What is the position the eye must be in to isolate the vertical action of the recti?
abducting eye (23deg)
For Type I Duane’s Retraction syndrome is abduction or adduction impaired? 1. What causes retraction? 2
- abduction
2. adduction
What parts of the brain detect motion?
- middle superior temporal lobe
2. middle temporal lobe
What is the stimulus for a saccade?
target displacement on the retina
Where is the nucleus for CN III (and at one level)? 1. What does the inferior bifurcation innervate? 2. Superior bifurcation? 3
- mesencephalon (superior colliculus)
- IR, IO, MR, parasympathetic (all ipsilateral)
- SR, LPS (all ipsilateral)
What is a partial paralysis of muscle function called?
paresis
What are the possible paretic muscles for a right hyper deviation (left hypo) in primary gaze?
RIR, RSO, LIO, LSR
What is the pathway for the left eye when making a saccade to the right?
frontal cortex through the omnipause neurons to the paramedian pontine reticular formation (PPRF) through the MLF to CN III to medial rectus