neither short nor flat bones contain a medullary cavity.

The cellular layer is adjacent to the cortical bone and is covered by an outer fibrous layer of dense irregular connective tissue (see Figure 6.3.4a). These cells are part of the outer double layered structure called the periosteum (peri – = “around” or “surrounding”). On the outside of bones there is another layer of cells that grow, repair and remodel bone as well. These bone cells (described later) cause the bone to grow, repair, and remodel throughout life. Lining the inside of the bone adjacent to the medullary cavity is a layer of bone cells called the endosteum (endo- = “inside” osteo- = “bone”). Each epiphysis meets the diaphysis at the metaphysis. During growth, the metaphysis contains the epiphyseal plate, the site of long bone elongation described later in the chapter. When the bone stops growing in early adulthood (approximately 18–21 years), the epiphyseal plate becomes an epiphyseal line seen in the figure. Red bone marrow fills the spaces between the spongy bone in some long bones. The wider section at each end of the bone is called the epiphysis (plural = epiphyses), which is filled internally with spongy bone, another type of osseous tissue. The outer walls of the diaphysis ( cortex, cortical bone) are composed of dense and hard compact bone, a form of osseous tissue.įigure 6.3.1 – Anatomy of a Long Bone: A typical long bone showing gross anatomical features. Inside the diaphysis is the medullary cavity, which is filled with yellow bone marrow in an adult. The diaphysis is the hollow, tubular shaft that runs between the proximal and distal ends of the bone. Gross Anatomy of BonesĪ long bone has two main regions: the diaphysis and the epiphysis ( Figure 6.3.1 ). This section will examine the gross anatomy of bone first and then move on to its histology. Later discussions in this chapter will show that bone is also dynamic in that its shape adjusts to accommodate stresses. Bone is hard and many of its functions depend on that characteristic hardness. Describe how bones are nourished and innervatedīone tissue (osseous tissue) differs greatly from other tissues in the body.Identify the structures that compose compact and spongy bone.

Compare and contrast compact and spongy bone.

Describe the histology of bone tissue, including the function of bone cells and matrix.

Identify the gross anatomical features of a bone.

By the end of this section, you will be able to:ĭescribe the microscopic and gross anatomical structures of bones

Neither short nor flat bones contain a medullary cavity.