Diaphysis of Bone: Definition & Function

An error occurred trying to load this video.

Try refreshing the page, or contact customer support.

Coming up next: Fibrous Joint: Definition & Examples

You're on a roll. Keep up the good work!

Take Quiz Watch Next Lesson
Your next lesson will play in 10 seconds
  • 0:02 What Is Diaphysis?
  • 0:25 Parts of the Diaphysis
  • 1:22 Bone Remodeling
  • 3:00 Functions
  • 4:50 Lesson Summary
Save Save Save

Want to watch this again later?

Log in or sign up to add this lesson to a Custom Course.

Log in or Sign up

Speed Speed

Recommended Lessons and Courses for You

Lesson Transcript
Instructor: Jay Mallonee

Jay is a wildlife biologist, college professor and writer. His master's degree is in neurobiology and he has studied animal behavior since 1976.

Did you know your bones are used for more than just standing upright? This lesson looks at the fascinating contributions made by the diaphysis in long bones towards your body's overall health. At the end of the lesson, you'll find a short quiz.

What Is a Diaphysis?

Did you ever watch the beginning of the movie, 2001: A Space Odyssey? In one scene, a pre-human ape picks up a long bone and uses it to violently break apart the skeleton from which it originated. Structurally, long bones are very strong, as seen in the movie. They're long because of the shaft in the middle called the diaphysis.

Parts of the Diaphysis

Compared to the other parts that make up a long bone, the diaphysis is quite different. It has a hollow inside with an open space called the medullary cavity. The cavity is filled with yellow bone marrow, along with blood vessels that supply the living bone tissue. The light color of the marrow is due to the high concentration of fat cells, as opposed to the red marrow where blood cells are made.

As a child, all of your bone marrow was red, but as you age into adulthood, much of it becomes yellow. Red marrow is found at the ends of long bones called epiphyses, which are covered with articular cartilage used to connect, or articulate, with other bones. Epiphyses are composed of spongy bone, which look like a sponge you use in the kitchen. Its tiny chambers are filled with red marrow, a very different setup from the diaphysis. The shaft is made of compact bone, a matrix of minerals, which makes it strong and useful for supporting a good deal of weight.

Bone Remodeling

The surface of the diaphysis is often slightly irregular, rather than completely smooth, and is covered in a thin layer of connective tissue called the periosteum, which provide areas where tendons and ligaments can attach, along with adhering nerves and blood vessels to the bone surface so they can enter the diaphysis. The periosteum also houses the live cells that create and remove bone material, a process called remodeling, which constantly reshapes bones. Osteoblasts create bone material, while osteoclasts break down bone material (the prefix 'osteo' means 'bone'). If a long bone becomes broken, these cells are used in the healing process to help mend the fracture site.

Although bones constantly reshape themselves, they can only grow in length during childhood and adolescence. There is also an inherent problem with bones that grow: you still need to use them. It would be easy to just add bone material to either end, but the epiphyses are being used to connect with other bones. So how does the diaphysis become longer?

There is an area between the diaphysis and the epiphysis called the metaphysis; the prefix 'meta-' refers to being 'in the middle.' In this area, we find the epiphyseal or growth plate. Other types of bone cells, called chondrocytes, produce cartilage on the joint side of the plate, while the other side becomes calcified. In other words, minerals are added which lengthens the diaphysis. By the time bones reach their full length in adulthood, the epiphyseal plate has become completely calcified. This creates a thin, detectable area called the epiphyseal line.


The diaphysis of long bones serves several purposes, including ones you may not expect.

To unlock this lesson you must be a Study.com Member.
Create your account

Register to view this lesson

Are you a student or a teacher?

Unlock Your Education

See for yourself why 30 million people use Study.com

Become a Study.com member and start learning now.
Become a Member  Back
What teachers are saying about Study.com
Try it risk-free for 30 days

Earning College Credit

Did you know… We have over 200 college courses that prepare you to earn credit by exam that is accepted by over 1,500 colleges and universities. You can test out of the first two years of college and save thousands off your degree. Anyone can earn credit-by-exam regardless of age or education level.

To learn more, visit our Earning Credit Page

Transferring credit to the school of your choice

Not sure what college you want to attend yet? Study.com has thousands of articles about every imaginable degree, area of study and career path that can help you find the school that's right for you.

Create an account to start this course today
Try it risk-free for 30 days!
Create an account