Rib cage


The rib cage, shaped in a mild cone shape and more flexible than most bone sets, is made up of varying elements such as the thoracic vertebra, 12 equally paired ribs, costal cartilage, and held together anteriorly by the sternum.

The primary responsibilities of the ribcage involve protecting the thoracic visceral organs, enclosing the thoracic visceral organs, and is included in the general mechanics of the process of breathing.

The ribcage’s construction involves the compression and narrowing of the anterior as well as the superior angles while it widens as it travels down the body.

It provides structural support for the upper extremities as well as the pectoral girdle. There are specified bones within the ribcage that are responsible for the production of red blood cells from the active bone marrow.


Rib cage
Image: Rib Cage


The sternum is the long and flat bone structure that is actually a plate consisting of 3 separate bones. Consisting of the upper manubrium, the central body, and the lower xiphoid process, the sternum creates an anchor for the ribs meeting centrally at the midline of the body.

The xiphoid process is typically made up of cartilage. Costal notches create anchors for the costal cartilage to attach, which are formed along the lateral sides of the sternum. At the superior end of the manubrium there resides a jugular notch. On either side of the sternal notch the clavicular notch can be found. The costal cartilage of the first and second ribs meets with the manubrium.

The second through the tenth ribs meet with the body of the sternum via costal cartilage. The xiphoid process is available for muscle attachment and does not adhere to the ribs. The costal margin of the ribcage is formed by the fusion of the eight, ninth, and tenth ribs’ coastal cartilage. Where the two opposing costal margins meet at the xiphoid process is the costal angle. Between the body of the sternum and the manubrium even with the second rib the sternal angle, also known as the angle of Louis, can be found. The 3 primary angles, the costal angle, the sternal angle, and the costal margins are landmarks when determining positional suitablility concerning the thorax and the abdomen.


Image: Sternum


The twelve pairs of ribs, which are embedded within the walls of the muscular structures, attach in the posterior to a thoracic vertebra. The first 7 pairs use the sternum as their anchor via the rib’s individual costal cartilage as an attachment vessel. The first 7 pairs are also called true ribs.

Ribs 8 through 12 are deemed false ribs. The remaining 2 pairs of ribs are considered floating ribs as there is no attachment to the sternum at all. True ribs connect directly to the sternum while false ribs are connected to the sternum via additional bone structures, and floating ribs do not connect to the sternum.


Image: Ribs

Ribs do vary structurally, although the top ten pairs of ribs all come equipped with a head and a tubercle for attachment to the vertebrates. The final two pairs are equipped with a head but are lacking a tubercle. All twelve pairs have a neck, angle, and a body. The head of each rib is designed to project posteriorly and joins with the body of the corresponding thoracic vertebra. The tubercle is knobby in appearance and resides just laterally of the head. It joins with the facet on the transverse process of the thoracic vertebra.

The constricted area that is designed between the head and the tubercle is known as the neck. The main portion of the rib is curved to allow for structural support of the body. The costal groove runs along the inner surface of the body and appears as a depressed canal. The costal groove is designed to provide protection for the costal nerve and its corresponding vessels. The intercostal muscles take up the space between the ribs, which have been deemed the intercostal spaces.
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