Final answer:
Periosteal arteries enter bone tissue by piercing the periosteum and passing through the nutrient foramen to nourish the bone.
Step-by-step explanation:
The periosteal arteries enter bone tissue by penetrating the outer fibrous layer of the periosteum, which forms the outer surface of bone. As they pass through the periosteum, these arteries then move through small openings in the compact bone called the nutrient foramen (plural = foramina) to nourish the bone from within. The vessel branches further to supply blood to both the outer parts of the compact bone and the inner spongy bone, where it joins with blood circulating in the marrow cavities. The oxygen and nutrients provided by these arteries are essential for bone growth, repair, and overall health.