Medical Definition of apex
plural apex·es or api·ces \ˈā-pə-ˌsēz\play
: a narrowed or pointed end of an anatomical structure: asa: the narrow somewhat conical upper part of a lung extending into the rootb: the lower pointed end of the heart situated in humans opposite the space between the cartilages of the fifth and sixth ribs on the left sidec: the extremity of the root of a tooth
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