Ribs 3 to 9 are considered typical ribs. Major landmarks of a typical rib are the following: head, neck, tubercle, and body of a rib. The head of each rib is wedge-shaped and has two articular facets, which are separated by the crest of the head. The larger of the two facets is for articulation with the superior costal facet of its corresponding thoracic vertebral body, while the smaller facet articulates with the inferior costal facet on the body of the vertebra above.
The neck of the rib is a flat part of the bone that connects the head of the rib with its body. The tubercle is a bony prominence located on the posterior side of each typical rib at the junction between the neck and the body.
It consists of two parts, a smooth articular part for articulation with the transverse process of the corresponding vertebra, and a rough non-articular part which provides an attachment site for the costotransverse ligament.
The body of each rib is thin, flat, and curved. The most prominent part of the curve is the costal angle, which also provides attachment sites for some deep back muscles to the ribs. The internal surface of the costal body is concave and contains the costal groove for the passage and protection of the intercostal nerve and blood vessels.
Ribs 1, 2, 10, 11, and 12 are considered atypical ribs, because they have features that are not common with most of the ribs. Ribs 1—7 are classified as true ribs vertebrosternal ribs. The costal cartilage from each of these ribs attaches directly to the sternum.
Ribs 8—12 are called false ribs vertebrochondral ribs. The costal cartilages from these ribs do not attach directly to the sternum. For ribs 8—10, the costal cartilages are attached to the cartilage of the next higher rib. Thus, the cartilage of rib 10 attaches to the cartilage of rib 9, rib 9 then attaches to rib 8, and rib 8 is attached to rib 7.
The last two false ribs 11—12 are also called floating ribs vertebral ribs. These are short ribs that do not attach to the sternum at all. Instead, their small costal cartilages terminate within the musculature of the lateral abdominal wall. It is composed of 12 pairs of ribs with their costal cartilages and the sternum. The ribs are anchored posteriorly to the 12 thoracic vertebrae. The sternum consists of the manubrium, body, and xiphoid process.
The manubrium and body are joined at the sternal angle, which is also the site for attachment of the second ribs. Ribs are flattened, curved bones and are numbered 1— Posteriorly, the head of the rib articulates with the costal facets located on the bodies of thoracic vertebrae and the rib tubercle articulates with the facet located on the vertebral transverse process. The angle of the ribs forms the most posterior portion of the thoracic cage.
The costal groove in the inferior margin of each rib carries blood vessels and a nerve. Anteriorly, each rib ends in a costal cartilage.
True ribs 1—7 attach directly to the sternum via their costal cartilage. The false ribs 8—12 either attach to the sternum indirectly or not at all. Ribs 8—10 have their costal cartilages attached to the cartilage of the next higher rib. The floating ribs 11—12 are short and do not attach to the sternum or to another rib. The thoracic cage is formed by the 12 pairs of ribs with their costal cartilages and the sternum. The ribs are attached posteriorly to the 12 thoracic vertebrae and most are anchored anteriorly either directly or indirectly to the sternum.
The thoracic cage functions to protect the heart and lungs. The manubrium forms the expanded, superior end of the sternum. It has a jugular suprasternal notch, a pair of clavicular notches for articulation with the clavicles, and receives the costal cartilage of the first rib.
The manubrium is joined to the body of the sternum at the sternal angle, which is also the site for attachment of the second rib costal cartilages. The body receives the costal cartilage attachments for ribs 3—7. The small xiphoid process forms the inferior tip of the sternum. A typical rib is a flattened, curved bone. The head of a rib is attached posteriorly to the costal facets of the thoracic vertebrae. Citation, DOI and article data.
Palipana, D. Typical ribs. Reference article, Radiopaedia. Musculoskeletal , Chest. URL of Article. On this page:. Read it at Google Books - Find it at Amazon 2. Snell RS. Clinical Anatomy by Regions. Read it at Google Books - Find it at Amazon 3. Last's Anatomy. Churchill Livingstone. Read it at Google Books - Find it at Amazon 4. Brant WE, Helms C. Fundamentals of Diagnostic Radiology.
Read it at Google Books - Find it at Amazon 5. Standring, Susan, and Henry Gray. Gray's anatomy: the anatomical basis of clinical practice. Related articles: Anatomy: Thoracic. Promoted articles advertising. Figure 1: typical ribs Gray's illustration Figure 1: typical ribs Gray's illustration.
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