What part of the brrain was the primary center involved in this reflex motion?

1.) while walking down the street u get startled by a passing car that honks its horn right next to u. your response is to jump away from the noise. what part of the brain was the primary center involved in this reflex motion??

2.)Lilly automobile is hit at an angle on the freeway by another car. on impact her head slams into the window causing her to black out. it is later assessed by her ER physician that she has received major injury to her cerebellum due to whiplash. list the symptoms Lillie will most likely experience??

3.)a client is admitted to the hospital with weakness in his legs, double vision, tingling in the arms, difficult speaking and tremor. he was diagnosed with multiple sclerosis. the loss of the myelin sheath would cause these symptoms  because without the sheath what specific things happen to the axons ability to perform??

4.)how is a strong nerve stimulus coded for by action potentials if all action potentials are identical??