Japanese to English Medical Medical (general)

I can't reproduce the kanji under the question mark above electronically because it's a PDF file, and for some reason the character does not come up anywhere, even when I draw it by hand with the guessing tool. (I don't know if it's a typo or what.)

Left side of the question-mark character: Same as the left side of this: 怪
Right side of the question-mark character: Same as the right side of this: 膀

Context:
麻酔：
頚・胸・腰？背椎神経ブロック（局所麻酔剤またはボツリヌス毒素使用）

Can anyone tell me what the translation of 腰？背椎 should be?
Thanks in advance.