Complex sentence: Palato-alveolar sounds are normally described as having a convex (bunched-up or "domed") tongue: the front, central part of the tongue is somewhat raised compared to the tip, back and sides, which gives it weak palatalization.
Split into simpler sentences: Palato-alveolar sounds are normally described as having a convex (a bunched-up or "domed") tongue. The front, central part of the tongue is somewhat raised compared to the tip, back and sides, which gives it a weak palatalization.