What type of bone primarily makes up the epiphyses?

The epiphyses of long bones are primarily composed of spongy bone, also known as cancellous bone. This type of bone is characterized by its porous, lattice-like structure, which is designed to withstand compression and provide support while remaining lightweight. The cancellous bone in the epiphyses is crucial for shock absorption during weight-bearing activities, such as walking or running.

Moreover, the presence of bone marrow within the spongy bone is significant, as it is responsible for producing blood cells and storing fat. While other types of bone and tissues may be present in the overall structure of a bone, the primary composition of the epiphysis is indeed spongy bone due to its functional advantages in load distribution and injury resilience.