Milia are small, white cysts commonly seen around the cheeks. Overview. Milia are commonly found on the skin of people of all ages. They are formed when keratin (a substance produced by the skin) becomes entrapped beneath the outer layer of the skin, forming a tiny cyst. An individual milium (the singular of milia) is formed at the base of a hair follicle or sweat gland.
The basic first level structure of cortical bone are osteons. Trabecular bone is much more porous with porosity ranging anywhere from 50% to 90%. It is found in the end of long bones (see picture above), in vertebrae and in flat bones like the pelvis. Its basic first level structure is the trabeculae. III.
Osteons, also known as the haversian system, are the building blocks of cortical. bone. They form two-third of the cortical bone volume. An osteon is in the form of. a cylinder having concentric layers of lamellae. These lamellae are composed of. collagen fibers which are reinforced by hydroxyapatite crystals. These concentric. lamella layers surround the cylindrical cavity known as haversian canal.