Discuss the materials that make up the thoracic cageIdentify the parts of the sternum and define the sternal angleDiscuss the components of a rib and rib classifications

The thoracic cage (rib cage) creates the thorax (chest) portion of the body. It is composed of the 12 pairs of ribs through their costal cartilages and the sternum (Figure 7.5.1). The ribs space anchored posteriorly come the 12 thoracic vertebrae (T1–T12). The thoracic cage protects the heart and lungs.

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Figure 7.5.1 – Thoracic Cage: The thoracic cage is formed by the (a) sternum and also (b) 12 pairs of ribs with their costal cartilages. The ribs are anchored posteriorly come the 12 thoracic vertebrae. The sternum is composed of the manubrium, body, and also xiphoid process. The ribs space classified together true ribs (1–7) and also false ribs (8–12). The last two pairs that false ribs are also known as floating ribs (11–12).Sternum

The sternum is the elongated bony structure that anchors the anterior thoracic cage. It is composed of three parts: the manubrium, body, and also xiphoid process. The manubrium is the wider, superior part of the sternum. The optimal of the manubrium has actually a shallow, U-shaped border referred to as the jugular (suprasternal) notch. This deserve to be conveniently felt at the anterior base of the neck, in between the medial ends of the clavicles. The clavicular notch is the shallow depression located on either next at the superior-lateral spare of the manubrium. This is the website of the sternoclavicular joint, between the sternum and also clavicle. The first ribs also attach come the manubrium.

The elongated, central portion of the sternum is the body. The manubrium and body join together in ~ the sternal angle, so called because the junction between these two contents is no flat, yet forms a slim bend. The second rib attaches to the sternum in ~ the sternal angle. Due to the fact that the very first rib is concealed behind the clavicle, the second rib is the highest rib that can be established by palpation. Thus, the sternal angle and 2nd rib are important landmarks for the identification and also counting that the lower ribs. Ribs 3–7 connect to the sternal body. When assessing a patient’s level the alertness sometimes a sternal rub is performed with the knuckles to check out if castle respond to pain.

The inferior reminder of the sternum is the xiphoid process. This little structure is cartilaginous early in life, however gradually becomes ossified starting during middle age.


Each rib is a curved, flattened bone that contributes to the wall surface of the thorax. The ribs articulate posteriorly through the T1–T12 thoracic vertebrae, and also most connect anteriorly via their costal cartilages come the sternum. There space 12 pairs of ribs. The ribs are numbered 1–12 in accordance v the thoracic vertebrae.

Parts that a usual Rib

The posterior end of a typical rib is referred to as the head of the rib (see thing 7.3 number 7.3.8). This region articulates mostly with the costal facet situated on the body of the same numbered thoracic vertebra and also to a lesser degree, with the costal facet situated on the human body of the next higher vertebra. Lateral come the head is the narrowed neck the the rib. A tiny bump on the posterior rib surface is the tubercle of the rib, which articulates with the facet situated on the transverse procedure of the exact same numbered vertebra. The remainder the the rib is the body the the rib (shaft). Simply lateral to the tubercle is the angle of the rib, the suggest at i beg your pardon the rib has its greatest level of curvature. The angle of the ribs form the most posterior level of the thoracic cage. In the anatomical position, the angles align through the medial border of the scapula. A shallow costal groove for the i of blood vessels and a nerve is discovered along the worse margin of every rib.

Rib Classifications

The bony ribs execute not expand anteriorly fully around to the sternum. Instead, each rib ends in a costal cartilage. This cartilages space made the hyaline cartilage and also can prolong for several inches. Most ribs room then attached, either straight or indirectly, to the sternum via your costal cartilage (see number 7.5.1). The ribs room classified right into three groups based upon their connection to the sternum.

Ribs 1–7 room classified together true ribs (vertebrosternal ribs). The costal cartilage from every of these ribs attaches straight to the sternum. Ribs 8–12 are referred to as false ribs (vertebrochondral ribs). The costal cartilages from these ribs execute not affix directly to the sternum. For ribs 8–10, the costal cartilages are attached come the cartilage that the next greater rib. Thus, the cartilage of rib 10 attaches come the cartilage of rib 9, rib 9 then attaches come rib 8, and also rib 8 is attached come rib 7. The last two false ribs (11–12) are likewise called floating ribs (vertebral ribs). This are brief ribs that execute not affix to the sternum at all. Instead, their tiny costal cartilages terminate within the musculature that the lateral ab wall.

Chapter Review

The thoracic cage protects the heart and lungs. It is composed of 12 pairs of ribs through their costal cartilages and the sternum. The ribs are anchored posteriorly come the 12 thoracic vertebrae. The sternum is composed of the manubrium, body, and xiphoid process. The manubrium and body space joined in ~ the sternal angle, i beg your pardon is likewise the website for attachments of the 2nd ribs.

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Ribs room flattened, curved bones and also are numbered 1–12. Posteriorly, the head that the rib articulates with the costal facets situated on the bodies of thoracic vertebrae and the rib tubercle articulates with the facet located on the vertebral transverse process. The edge of the ribs creates the many posterior part of the thoracic cage. The costal groove in the inferior margin of every rib dead blood vessels and also a nerve. Anteriorly, every rib end in a costal cartilage. True ribs (1–7) connect directly come the sternum via your costal cartilage. The false ribs (8–12) either connect to the sternum indirectly or not at all. Ribs 8–10 have actually their costal cartilages attached to the cartilage of the next higher rib. The floating ribs (11–12) room short and do not affix to the sternum or to another rib.