Periosteum

What is the periosteum?

The periosteum is the medical definition for the membrane of blood vessels and nerves that wraps around most of your bones. Periosteum is pronounced peRRY-OSS-tee-um. It’s what delivers bones their blood supply and gives them their sense of feeling.

Special cells in the periosteum help your bones grow and develop and repairs them after a bone fracture.

What does the periosteum do?

The periosteum has three functions:

• Supplying blood to your bones.
• Giving them their sense of feeling.
• Growing and repairing your bones.

Blood vessels in the periosteum connect back to your circulatory system to supply fresh, oxygen-rich blood to your bones.

Nerves in the periosteum give your bones and the area around them feeling.

Your periosteum helps your bones grow and develop. Special cells called osteoprogenitors create osteoblasts (the cells that grow your bones). Babies and children whose bones are still growing and developing have lots of active osteoblasts in their periosteum. As you age and your bones stop growing, you have fewer osteoblasts. However, when something damages your bone — like a fracture — your osteoprogenitor cells “wake up” and create new osteoblasts to heal your bone.

Where is the periosteum located?

Almost all your bones are covered in a periosteum. It covers every part of your bones except places capped in cartilage and the spots where ligaments and tendons attach.

Bones without periosteum

The only bones not covered by periosteum are your sesamoid bones — bones that are embedded in your tendons or muscles. Your sesamoid bones are in joints throughout your body, including:

• Your patella (kneecap).
• In your hands and wrists.
• In your feet.

Because they don’t get direct blood supply from a periosteum, sesamoid bones usually take longer to heal than other bones.

Periosteum layers

The periosteum has two layers.

The outer layer protects the inner layer and the bone beneath it. It’s made of thick collagen fibers. Most of the periosteum’s blood vessels and nerves are in the outer layer.

The inner layer (sometimes called the cambium layer) contains the osteoprogenitor cells and the osteoblasts they create when your bone is growing or needs to heal.

The periosteum is thicker in kids and younger people and thins as you get older and stop developing.

Periosteum vs endosteum and perichondrium

The periosteum, endosteum and perichondrium are all layers of tissue in and around your bones.

The periosteum is the sheath outside your bones that supplies them with blood, nerves and the cells that help them grow and heal.

The endosteum is a membrane that lines the center of your bones that contain bone marrow.

The perichondrium is very similar to the periosteum. It covers the cartilage on the ends of your bones. In the same way the periosteum helps your bones grow and heal, the perichondrium has cells that stimulate new cartilage to grow in areas that need it.

What are the common conditions and disorders that affect the periosteum?

The most common issues that affect the periosteum are periostitis and bone fractures.

Periostitis

Periostitis is the medical term for inflammation of your periosteum. Overusing muscles that attach to the periosteum can irritate it. This irritation makes the periosteum to swell, which can cause pain and other symptoms.

Shin splints are the most common form of periostitis, but it can develop in the periosteum near any muscle that you overuse.

Infections can also cause periostitis. Visit your healthcare provider or go the emergency room if you have any of the following symptoms:

• Severe pain near a bone.
• Pus or discharge.
• Fever.

Bone fractures

A bone fracture is the medical term for breaking a bone. They’re usually caused by serious injuries like car accidents, falls or other traumas. Symptoms of a fracture include:

• Pain.
• Swelling.
• Tenderness.
• Inability to move a part of your body you usually can.
• Bruising or discoloration.
• A deformity or bump that’s not usually on your body.

Go to the emergency room right away if you’ve experienced a trauma or think you have a fracture.

What tests are done to the periosteum?

Usually, you won’t need any tests done on your periosteum. Most tests you’ll need on your bones are focused on your bone as a whole, rather than specifically on your periosteum.

The most common test done to check the health of one of your bones is a bone density test. It’s sometimes called a DEXA or DXA scan. A bone density test measures how strong your bones are with low levels of X-rays. It’s a way to measure bone loss as you age.

If you’ve experienced a bone fracture your provider or surgeon might need imaging tests, including:

• X-rays.
• Magnetic Resonance Imaging (MRI).
• CT scan.

You might need a biopsy if your provider thinks you have an infection or another issue.

Keeping your periosteum healthy

Following a good diet and exercise plan and seeing your provider for regular checkups will help you maintain your bone (and overall) health.

Follow these general safety tips to reduce your risk of an injury:

• Always wear your seatbelt.
• Wear the right protective equipment for all activities and sports.
• Make sure your home and workspace are free from clutter that could trip you or others.
• Always use the proper tools or equipment at home to reach things. Never stand on chairs, tables or countertops.
• Use your cane or walker if you have difficulty walking or have an increased risk for falls.

A note from Cleveland Clinic

We usually think of our bones as single, solid pieces, but they’re actually a complex network of living tissue. The periosteum that surrounds your bones helps them grow and develop, and if you ever injure a bone, it releases special cells that heal the damage.

Talk to your provider about maintaining good bone health. The stronger your bones are, the less likely it is they’ll be damaged when you experience an injury or accident.