A 32-year-old male presents to the emergency department after a motor vehicle accident. On examination, he has multiple areas of skin abrasion over the right shoulder and forearm with embedded dirt and gravel. The abrasions are painful but do not bleed. On the left side of his chest, there is a well-demarcated area of bluish-purple discoloration measuring 8 cm × 6 cm, which is tender to palpation but the skin is intact. What is the most likely explanation for the difference in appearance and mechanism of injury between the shoulder abrasions and the chest discoloration?