Complex sentence: It supplies the surrounding muscles, and anastomoses with the sublingual artery and with the mylohyoid branch of the inferior alveolar artery; at the symphysis menti it turns upward over the border of the mandible and divides into a superficial and a deep branch.
Split into simpler sentences: It supplies the surrounding muscles, and anastomoses with the sublingual artery and with the mylohyoid branch of the inferior alveolar artery; at the symphysis menti it turns upward over the border of the mandible. When the submental artery turns upward over the border of the mandible it divides into a superficial and a deep branch.