The Neapolitan “Shirt Sleeve” (la spalla a camicia) has the quality of having a wide sleeve with a high armhole. The wide sleeve allows for more movement, while a high armhole creates a sharper silhouette.
The “wrinkles”, or gathering, creates more ease that allows for more movement:
The wide armscye seems to push most of the width to the back of the suit, which keeps the silhouette sharper in front while allowing for a lot more movement in the armhole.
The high armhole (with low arymscye height) creates a sharper silhouette:
With the silhouette sharpened, it allows for the tailor to add more ease around the waist without compromising the total look of the jacket:
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