一縄筋 is one of the most frustrating compounds I've come across so far. 縄 means "rope," while 筋 means "muscle." The dictionary I normally use didn't list it, so I had to refer to other sources. According to Wikipedia, when those two are together, it refers to the folk belief of a road along which demons travel. Those who would sleep in a house beside it will experience mysterious chest pains and awaken to the face of a monster.
Of course, that explanation set me way, way off from what I really needed, which was 一縄筋, rather than 縄筋, which has a meaning of simply either "a piece of rope," or "an ordinary method."
So I guess the lesson learned today is that Wikipedia is a horrible and misleading place!