(defun my/narrow-from-point ()
  "Narrow the buffer from point to end of the (narrowed) buffer."
  (interactive)
  (narrow-to-region (point) (point-max)))

(defun my/narrow-to-point ()
  "Narrow the buffer the start of a (narrowed) buffer up to point."
  (interactive)
  (narrow-to-region (point-min) (point)))