jittery note

[user_gary]

Abdur Razzak took three wickets, while Mashrafe Mortaza and Saqibul Hasan took two each to leave Bermuda reeling. Bangladesh, too, started on a jittery note as they lost three quick wickets for 37 runs, but overhauling a target of 95 was only a mere formality.

I know jittery = having feelling of nervousiness.
But I couldn't understnd what is `jittery note' in the above context.
Could you explain it please?

[Anglika]

• noun 1 (the jitters) a feeling of raw nervousness. 2 slight, irregular variation in an electrical signal. • verb 1 act nervously. 2 suffer from jitter.
— DERIVATIVES jitteriness noun jittery adjective

In the context you have given, the idiom uses the second meaning; "note" is extrapolated from musical note. A jittery musical note is one that has an irregular and interrupted sound.