Radicals: がしら (gashira) endings?


Does somebody know for what the [がしら]{gashira} ending stands in radicals like:

  * eight (はちがしら{hachigashira})
  * winter (ふゆがしら{fuyugashira}), or 
  * short thread (いとがしら{itogashira})?

Is it part of あし{ashi} (bottom radical position) or ashi variant (center
radical position / top and bottom radical position)? I understand the other
endings (kanmuri, gamae-kamae, hen-ben, nyō, tare, etc.).

I know some of them don't have those endings and could be phonetic (sound)
parts of kanji and not semantic (meaning).




[かしら]{頭} (the 漢字 is also read あたま) means "head" and ふゆがしら etc. refer to the
top part of the component.




[かしら]{頭} (the 漢字 is also read あたま) means "head" and ふゆがしら etc. refer to the
top part of the component.

