Zero is the only integer (whole number) that is neither positive nor negative. In a sense, zero makes negative numbers possible, as a negative number added to its positive counterpart always equals zero. When zero is added to or subtracted from a number, it leaves the number at its original value. Zero is essential as a position holder in the system known as positional notation. In the number 203, for example, there are two hundreds, zero tens, and three ones. Zero indicates that the value of the tens place is zero. In the number 1024, zero indicates that the value of the hundreds place is zero. Scientists use the term absolute zero (0Â° Kelvin) to refer to the (unattainable) theoretically lowest possible temperature, at which the kinetic energy of molecules is zero.
The thin, flat muscle forming the wall of the cheek. buccinator. the main muscle of the cheek, one of the 12 muscles of the mouth. It is pierced by the duct of the parotid gland opposite the second molar tooth. The buccinator, innervated by buccal branches of the facial nerve, compresses the cheek, acting as an important accessory muscle of mastication by holding food under the teeth. Buccinator.
home / medterms medical dictionary a-z list / pulmonary trunk definition Medical Definition of Pulmonary trunk Pulmonary trunk: A vessel that arises from the right ventricle of the heart, extends upward, and divides into the right and left pulmonary arteries that convey unaerated blood to the lungs. When the right ventricle contacts, the blood inside it is put under pressure and the tricuspid valve between the right atrium and ventricle closes.