The bony ribs do not extend anteriorly completely around to the sternum. A shallow costal groove for the passage of blood vessels and a nerve is found along the inferior margin of each rib. In the anatomical position, the angles align with the medial border of the scapula. The angles of the ribs form the most posterior extent of the thoracic cage. Just lateral to the tubercle is the angle of the rib, the point at which the rib has its greatest degree of curvature.
The remainder of the rib is the body of the rib (shaft). A small bump on the posterior rib surface is the tubercle of the rib, which articulates with the facet located on the transverse process of the same numbered vertebra. Lateral to the head is the narrowed neck of the rib. This region articulates primarily with the costal facet located on the body of the same numbered thoracic vertebra and to a lesser degree, with the costal facet located on the body of the next higher vertebra. The posterior end of a typical rib is called the head of the rib (see Chapter 7.3 Figure 7.3.8). The ribs are numbered 1–12 in accordance with the thoracic vertebrae. The ribs articulate posteriorly with the T1–T12 thoracic vertebrae, and most attach anteriorly via their costal cartilages to the sternum. RibsĮach rib is a curved, flattened bone that contributes to the wall of the thorax. This small structure is cartilaginous early in life, but gradually becomes ossified starting during middle age. The inferior tip of the sternum is the xiphoid process. When assessing a patient’s level of alertness sometimes a sternal rub is performed with the knuckles to see if they respond to pain. Thus, the sternal angle and second rib are important landmarks for the identification and counting of the lower ribs. Since the first rib is hidden behind the clavicle, the second rib is the highest rib that can be identified by palpation. The second rib attaches to the sternum at the sternal angle. The manubrium and body join together at the sternal angle, so called because the junction between these two components is not flat, but forms a slight bend. The elongated, central portion of the sternum is the body.
The first ribs also attach to the manubrium. This is the site of the sternoclavicular joint, between the sternum and clavicle. The clavicular notch is the shallow depression located on either side at the superior-lateral margins of the manubrium.
This can be easily felt at the anterior base of the neck, between the medial ends of the clavicles. The top of the manubrium has a shallow, U-shaped border called the jugular (suprasternal) notch. The manubrium is the wider, superior portion of the sternum. It consists of three parts: the manubrium, body, and xiphoid process. The sternum is the elongated bony structure that anchors the anterior thoracic cage. The last two pairs of false ribs are also known as floating ribs (11–12). The ribs are classified as true ribs (1–7) and false ribs (8–12). The sternum consists of the manubrium, body, and xiphoid process. The ribs are anchored posteriorly to the 12 thoracic vertebrae. Figure 7.5.1 – Thoracic Cage: The thoracic cage is formed by the (a) sternum and (b) 12 pairs of ribs with their costal cartilages. The thoracic cage protects the heart and lungs. The ribs are anchored posteriorly to the 12 thoracic vertebrae (T1–T12). It consists of the 12 pairs of ribs with their costal cartilages and the sternum ( Figure 7.5.1). The thoracic cage (rib cage) forms the thorax (chest) portion of the body. Discuss the parts of a rib and rib classifications.Identify the parts of the sternum and define the sternal angle.Discuss the components that make up the thoracic cage.By the end of this section, you will be able to:ĭescribe the components of the thoracic cage
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