The article focuses on certain elements of J.S. Bach’s handwritten musical notation, and in particular on his sinusoidal form of beaming in groups of eighths. Bach’s later manuscripts typically display an increasing use of descending sinusoids implemented by flexion movement of the wrist, indicating disturbance to the blood supply to the brain. This identifiable trait of Bach’s handwriting negates the traditional view that the engraver of the bifolio with canons and the Fuga canonica from the Musical Offering was Johann Heinrich Schübler, and instead enables attribution of the preparation of its engraving copy (Abklatschvorlage) to J.S. Bach himself.