如何从python中的列表的特定索引开始循环?

我有此数据的csv文件:

1 this_is_x, this_is_y
2 info about x, info about y
2 10,20
3 10,10
4 5,10

with open('my_file.csv') as csv_file:
csv_reader = csv.reader(csv_file, delimiter=',')
next(csv_reader)
for row in csv_reader:
    x, y = row
    list_x.append(x)
    list_y.append(y)

如何从10,20开始循环?