Final answer:
The periosteum forms the fibrous outer layer of trabecular bone, containing blood vessels, nerves, and serving as the attachment point for tendons and ligaments. The medullary cavity within bones is lined by the endosteum, critical for bone growth and repair.
Step-by-step explanation:
The outside of trabecular bone, also known as spongy or cancellous bone, is lined by a fibrous membrane called the periosteum. This outer layer of bone is critical because it contains blood vessels, nerves, and lymphatic vessels that nourish the compact bone. The periosteum also provides the point of attachment for tendons and ligaments. The trabecular bone, which supports and protects the marrow, is found inside the compact bone and is porous with a web-like structure of trabeculae.
Meanwhile, the internal cavity of the bone, known as the medullary cavity, is lined with a delicate membrane called the endosteum. This lining is important for bone growth, repair, and remodeling. Both structures are essential for the integrity and function of bones.