i doubt that you need to know your dermatomes, myotomes and reflexes until you do neurological examination. even then it is only finals where you are expected to be make clinical findings on the examination so not something i would have bothered with at your stage.
upper limb
-radial nerve supplies the extensors e.g. triceps, wrist extensors.
radial 'saturday night' nerve palsy = wrist drop
-medial nerve supplies most of the rest of the muscles in the arm and those of the thumb.
medial nerve palsy - 'carpal tunnel syndrome'
(wastage of the thenar muscle, weakened thumb abduction, positive phanlen's + tinel's test)
-ulnar nerve supplies all the muscles to the finger.
ulnar nerve palsy - claw hand + small muscle wastage of the fingers
UCL is very big on clinical application and you must play the game. the brachial plexus is a waste of time. similarly learning every muscle is as well, as for making models, dont get me started !
when i did second year people only failed on the meq and everyone work focused toward this. in this eaxm it tended to be a clinical case with questions relating to it. in my second year, for example, i had to explain browns sequards syndrome - which is hard. if you dont know what this is you have lost 5%. learn your basic neurology - differentiating between UMN / LMN - bound to be asked. endocrine is also very big on clinical application. acromegaly/addisons/cushings/hypothyroid/hyperthyroid/hyperparathyroid etc.
play the game and work smart. good luck children x