The Anatomy of the Ribs

Protecting the Thoracic Cavity and Vital Organs

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The ribs are a set of bones that course from your spinal column, around your body, and attach to your sternum, or breastbone. These bones serve to protect the contents of your thoracic cavity. They also serve as an attachment point for many muscles and are active during respiration. You have 24 ribs in total; there are 12 on each side of your body.

Anatomy

There are two types of ribs, namely typical and atypical. Typical ribs have a normalized general structure, while atypical ribs have slight variations.

Typical Ribs

Ribs three through nine are considered the typical ribs and are alike in structure and function. Each rib arises from the thoracic vertebra for which it is named; rib number three arises from your third thoracic vertebrae and rib number seven arises from your seventh thoracic vertebrae.

There are three parts to each rib: the head, the neck, and the shaft, or body, of the rib.

The head of your ribs are shaped like a wedge and have two specific areas called facets. These facets articulate with your spinal vertebrae.

The upper facet on each rib connects with the vertebrae above it, and the lower facet on the head of a rib connects with its numerically corresponding vertebrae. These articulations form the costovertebral joints of your ribs.

The neck of each typical rib attaches the head with the shaft. It is a slightly narrowed area of the rib bone and contains another facet that articulates with the transverse process of its corresponding vertebrae. This articulation is called the costotransverse joint. Thus, each typical rib has three points of articulation with a thoracic spinal vertebrae.

The shaft of a rib is curved and flat. There is a small groove in each rib called the costal groove. This groove protects the vein, nerve, and artery that courses along the rib.

The ribs slightly rotate as they course around your body, turning into cartilage called the costal cartilage. This cartilage attaches to your sternum in the front of your thorax.

Atypical Ribs

Ribs number one, two, and 10 through 12 are considered atypical ribs due to the fact that each have slightly varied structures.

Rib number one is a short and thick bone. Its head only has one facet joint, since it arises from the first thoracic vertebrae and there is no thoracic vertebrae above it where it can attach.

There are two small grooves in the upper surface of the first rib that house the subclavian vein, nerve, and artery. (Subclavian means "below the clavicle," or collar bone.)

Your second rib is longer and narrower than rib one, and it has two facet joints in its head to attach to thoracic vertebrae one and two. There is a rough area on the second rib that serves as an attachment point for the serratus anterior muscle.

Rib number 10 is atypical because its head only has one facet joint that articulates with thoracic vertebrae number 10. The 10th rib courses around your body and attaches to a network of cartilage with the eighth and ninth ribs above it. This cartilage then attaches to your lower sternum. These ribs are also called "false ribs" since they do not attach directly to the sternum.

Ribs number 11 and 12 are considered atypical because they do not attach to the sternum. They simply course around your thoracic and have no attachment point. For this reason, they are often called floating ribs.

Interestingly, occasionally a person will have an extra rib above rib number one. This is often called a cervical rib. A cervical rib often causes no problems, but sometimes it may interfere with normal function of the nerves, veins, and arteries near your collar bone. This may lead to a condition called thoracic outlet syndrome.

Function

There are several functions of your ribs. These functions include:

  • Protecting your thoracic contents
  • Aiding in normal breathing and respiration
  • Provide a place for muscles and tendons to attach

Protection of the thoracic contents is most important. Organs in your thorax include your lungs, heart, trachea, esophagus, and diaphragm as well as many muscles, nerves, and vascular structures. The ribs provide a bony cavity that wraps around your body, keeping your organs safe and sound within your body.

When you breathe, your diaphragm muscle in the lower thorax moves downward. While this is happening, small intercostal muscles near your ribs contract, moving your ribs up and expanding your thorax.

This expansion creates a pressure differential between the air in your body and the ambient air outside your body. Ambient air rushes into your lungs where they do their job of gas exchange. The diaphragm then relaxes, the ribs move downward, and the pressure of your thorax increases, pushing air out.

Your ribs are essential movers in your thorax to allow breathing to occur. They move and act as 12 pairs of bucket handles, moving up and down while you breathe.

Associated Conditions

There are several conditions that may affect your ribs. These may include:

  • Rib fracture: Severe trauma to a rib may cause it to break, leading to pain, difficulty moving, and difficulty breathing.
  • Costochondritis: Inflammation to the cartilage that attaches your ribs to your sternum may lead to pain and difficulty breathing and maintaining certain positions.
  • Rib dislocation or derangement. A dislocated rib occurs as the result of trauma, leading to pain, difficulty moving, and problems with breathing. A rib derangement occurs at the facet joint where your rib attaches to your vertebrae. This may result in a feeling of muscle spasm in your back.
  • Osteoporosis. Osteoporosis is bone weakening, often leading to increased risk of rib fractures as the result of a fall.
  • Tumor. Rib tumors are rare, but insidious onset of pain may indicate that a benign or malignant tumor is present in a rib.

If you are having pain in your mid back or near your sternum, difficulty breathing, or difficulty maintaining a position due to muscle spasms in your mid back, you may have a rib problem. If you suspect this, visit your healthcare practitioner right away. They can assess your condition and make an accurate diagnosis so you can get started on treatment.

Since most of your ribs have three points of attachment to your thoracic vertebrae, they are considered very stable joints and not susceptible to serious injury unless you experience a significant trauma.

Treatment of Rib Problems

If you have a problem with one or more ribs, you may benefit from specific treatments. Trauma that causes a rib fracture or dislocation typically requires a period of rest and immobilization. Usually ribs heal within a period of six to eight weeks.

There is no need to use a wrap or brace while your rib is healing; simply taking it easy, using ice for pain, and taking over-the-counter pain medication should be enough.

Once your fractured rib has healed, you may benefit from performing progressive breathing exercises to improve rib movement and function while breathing. An incentive spirometer may be used to improve breathing.

Irritation of your costal cartilage may result in costochondritis. This is typically treated with rest, ice for pain and inflammation, and postural control exercises. The exercises help to keep pressure off your rib cartilage, allowing the structures to heal properly.

A rib derangement may cause pain in your mid back, and is often treated successfully with physical therapy. Your therapist can show you exercises designed to reduce your joint derangement and to prevent problems. Postural exercises may help to keep your pain and spasm away.

By understanding rib anatomy, you can be sure to quickly and safely recover in the unfortunate event of a rib injury.

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Article Sources
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