The Anatomy of a Floating Rib

Floating rib injuries are caused, in part, by a vulnerability in human anatomy. That's because the rib cage, made up of 12 pairs of ribs, doesn't fully attach to other bones in the same way at all points.

Seven pairs of ribs attach directly to the sternum, at the front of the chest, through cartilage that forms at the end of each rib. But the next tier attach only to the cartilage of the rib above and the last two pairs of ribs do not attach to the sternum at all, making them more prone to injury.

This article explains how these floating ribs, associated with a rare and painful condition called "slipping rib syndrome," can be easily injured. It presents the symptoms and causes, as well as what can be done to treat a floating rib syndrome.

Rib Anatomy and Structure

Your ribs are located in the chest, also called the thoracic cavity. Each rib has five parts: head, neck, body or shaft, tubercle, and angle. The 12 pairs of ribs in the body are numbered based on their attachment to the sternum, a bony process at the front of the rib cage, which serves as an anchor point.

The first rib attaches to the sternum below the clavicular attachment; it is shorter and more curved than the others. The next six ribs are both longer and become progressively more open (rather than curved) as the rib cage continues down the length of the torso.

The remaining ribs (8 through 12) are called "false ribs" as they do not attach to the sternum directly. Instead, they are attached to the costal cartilage of the sternum.

However, the last two pairs of ribs at the very bottom, also known as "floating ribs," do not attach at the front of the rib cage at all—only to the vertebrae in the back.

Rib Cage Function

The ribs are part of what's called the axial skeleton and are classified as flat bones. The primary job of flat bones is to protect underlying structures.

Other flat bones in the human body are found in the pelvis and skull. Red blood cells are made in the marrow of flat bones.

The thoracic cage, though, has the critical mission of protecting the heart and lungs, which are among the body's most vital organs.

Slipping Rib Syndrome

While it is not as common as an injury to the chest wall, "slipping rib syndrome" is a curious ailment that can cause distress for people who have it but are not aware of why it occurs.

Slipping rib syndrome, also called Cyriax syndrome, occurs when the floating ribs move. The movement of these lower ribs is often felt as a slipping, clicking, or popping sensation.

The sensation typically only occurs on one side of the rib cage (unilateral), but the pain may radiate to the back on the affected side. The sensation can be very painful or simply a source of discomfort.

The syndrome seems to be reported most often by middle-aged females, though cases have occurred in all people and at all ages. The exact cause of slipping rib syndrome isn't known, but common risk factors are overuse or rib trauma.

Broken or Bruised Ribs

As with any bone in the human body, ribs can fracture or break. They also may be referred to as bruised when the fascia surrounding the rib cage is injured.

In terms of broken or fractured ribs, these two terms refer to the same injury or one that occurs in the bone. While a bruised rib might not sound as severe as a broken rib, injury to the tissues that surround and support the rib cage can be extremely painful.

Although ribs commonly fracture due to injury, they also can break due to reasons like the pressure of prolonged coughing. Older people, and people with certain underlying health conditions like osteoporosis, may be more at risk of a rib fracture.

The key difference between broken, bruised, and fractured ribs is whether the bones of the rib cage are involved or if the injury was primarily to the tissue of the chest wall. In some cases, both are involved.

Floating Rib Diagnosis

Floating rib symptoms may be suspected when a healthcare provider has ruled out other causes for a person's discomfort, such as:

• Rib fracture
• Esophagitis
• Pleuritic chest pain

The gold standard for diagnosing the condition is a simple hooking maneuver, which can be performed in the office, that can help to determine if the lower ribs are hypermobile.

Floating Rib Treatment

Treatment depends on the severity of the associated pain. Unlike with other bones of the body, such as an arm or leg, the chest cannot be immobilized if a bone is broken. There are limits to how much mobility can be reduced because the chest needs to move as a person breathes.

These injuries usually heal on their own, given adequate time and supportive care and pain management. The primary focus is on controlling pain and any exacerbating factors, such as a cough. Treatment may include:

• Using heat or ice packs at the pain site
• Limiting activity
• Stabilizing the ribs with a chest bandage wrap

If a person with slipping rib syndrome has continued pain that is not well controlled with over-the-counter pain relievers, temporary activity limitations, and use of icepacks, a healthcare provider may prescribe nerve blocks.

A Word From Verywell

Slipping rib syndrome may cause a painful interruption to one's activities, but it does not put you at greater risk for injury or for a more severe condition involving the chest wall or rib cage. For most people, a floating rib is not serious and will heal without significant complications.