细小的胳膊可以用英文表达为 "slender arms"。
这个表达法来自英文中的形容词 "slender"，意思是细长的、苗条的。它常常用来形容人或动物的身体特征，例如：
She has a slender build. (她体型苗条。)
The cat's tail is slender and flexible. (这只猫的尾巴又苗条又柔软。)
下面是一些使用 "slender arms" 的英文例句，并附有中文翻译：
She was wearing a sleeveless top, reveapng her slender arms. (她穿着一件无袖上衣，露出了她细小的胳膊。)
He pfted the heavy box with ease, thanks to his slender but strong arms. (他轻松地举起了沉重的盒子，多亏了他细长却又强壮的胳膊。)