Green’s Dictionary of Slang

(US black) the human shoulder.

1943		D. Burley N.Y. Amsterdam Star-News 24 Apr. 11: The shoulders [of a zoot suit] are what they call braced broads.
1944		D. Burley Orig. Hbk of Harlem Jive 104: His hideaways were slashed like canteloupe; his broads were stacked like John the Conqueror.