As long as we're still twirling away here in off-topic territory... :lol
I see the TMP image posted above is from a set of early publicity photos that were shot right at the start of production... at the time, Nimoy was supposed to wear the same type of uniforms as everybody else, with the low rounded collars (only Shatner got to wear a high stiff collar, on the Admiral dress whites we first see him in).
Somehow apparently Nimoy convinced them to give him, and only him, a high dark collar. Because, after all, there's no denying that he looks especially silly in the low rounded collars. :rolleyes
The treatment of collars in TOS is a whole other topic unto itself... Spock in the earliest first season, gets a ridiculous ascot-style collar, which swallows him up practically (as seen in my current avatar)
Of course in those days, everybody had high collars... check out the first couple of acts of "Corbomite Maneuver".
Eventually by the third season, they had settled on giving everybody collars that lay right at the junction of neck and shoulder. Everybody actually looked pretty good in those... but subconsciously, high collars still connote authority, and that's why they went back to high ribbed collars for Wrath of Khan.