Sternum Anatomy

Sternum Anatomy

This article will talk about the anatomy of the sternum, and also understand the thorax region of the human body. Have a look...
Bodytomy Staff
A few of the most vital organs of the human body, the human heart and the lungs, are located in the thoracic region. This region is protected by the mild cone-shaped and a slightly flexible set of bones called the ribcage. There are 12 pairs of ribs, thoracic vertebra, costal cartilage, and the anteriorly placed sternum. The functions of the ribcage consists of protecting of the visceral organs, enclosing the thoracic visceral organs, and help in the general mechanism by aiding the breathing process. The ribcage helps provide support to the upper body as well as the pectoral girdle.

Anatomy of the Sternum

So, where is the breastbone located? The breastbone/sternum anatomy is not very complicated to understand. The sternum is an elongated long bone that looks like a capital T. On an average, the sternum is about 17 cm in length. It is a flat bone that is divided into three parts―the manubrium, sternum body (gladiolus), and the xiphoid process. It is located in the middle of the thorax and between two sets of ribs. Initially, the sternum is divided into 3 regions, called the sternebra.

When you see the sternum, the upper end supports the clavicles, that is, the collar bones. The top part of sternum is connected to the Sternocleidomastoid muscle. As we move downward, it gets divided into the three parts, that have been mentioned above.

The word manubrium in Latin means a handle. It is broad, upper part of the sternum that is located ventrally with a quadrangular shape. It articulates with the clavicles and the first two ribs. It is wide superiorly and narrower inferiorly.

Body of the Sternum (Gladiolus)
The body of sternum or gladiolus is longer, narrower and thinner than the manubrium. It is widest towards the lower end. The anterior surface of sternum is nearly flat and directed upward and forward due to three transverse ridges. At the sternal origin of Pectoralis major, there are attachments on either side of this bone. On the posterior side, the bone is slightly concave and is also marked by transverse lines. These lines are less distinct and the Transversus thoracis originates from either sides.

The superior border of the bone is oval, articulating with the manubrium. The sternal angle is formed at the junction of the two bones. The inferior border is narrow articulating with the xiphoid process. The lateral border consists of articular depressions, where the corresponding cartilages from the third, fourth, fifth, and sixth ribs are received. At the inferior angle, there is a small facet that forms a notch for the seventh rib cartilage.

Xiphoid Process
The xiphoid process is a small cartilaginous process that is ossified in adults. It forms a fibrous joint with the body of sternum by the age of 15 to 29 years. There is natural bifurcation of the xiphoid process and sometimes are perforated.

The anatomy of the sternum shows that it articulates with the clavicle on either side and the upper seven costal cartilages. Fracture of the sternum is a very uncommon condition. It occurs due to trauma from a car accident or repeated punches or beatings, called 'sternum punches'. These punches are very common in sports like football and rugby. A sternum fracture is called a comminuted fracture, and is associated with pulmonary contusions and long tissue bruising.

The sternum is the medical name for the commonly known breastbone. It helps in connecting the ribs to the cartilages, and its primary function includes protection of the heart, lungs, and blood vessels in the chest from injury. Vascular tissues make up the sternum, with only a thin layer of bone present outside the tissue.