There are two muscles found in the thoratic wall of the cat that  are not found in humans. Those two are, the xiphihumeralis and the  pectiantebrachiales.
Sternum - Structure. 1  The sternum is a long, flat bone, forming the middle portion of the front of the chest. 2  Manubrium. 3  Xiphoid process. 4  In its natural position, the sternum is angled obliquely, downward and forward. 5  The manubrium (Latin: handle) is the broad upper part of the sternum. It has a quadrangular shape, narrowing from the top, which gives it four borders. The suprasternal notch (jugular notch) is located in the middle at the upper broadest part of the manubrium. This notch can be felt between the two clavicles. On either side of this notch are the right and left clavicular notches. The manubrium joins with the body of the sternum, the clavicles and the cartilages of the first pair of ribs.
Home > Skeletal System > Bones of the Chest and Upper Back > Sternum. The sternum, commonly known as the breastbone, is a long, narrow flat bone that serves as the keystone of the rib cage and stabilizes the thoracic skeleton. Several muscles that move the arms, head, and neck have their origins on the sternum. It also protects several vital organs of the chest, such as the heart, aorta, vena cava, and thymus gland that are located just deep to the sternum. The sternum is located along the bodyâs midline in the anterior thoracic region just deep to the skin.