Clinical Anatomy Glossary: M

mandible: The jawbone.

manubrium: The superior part of the sternum.

mastication: Chewing.

matrix: A structural component made of water, collagen fibers, and crystallized calcium salts.

medial: Closer to the midline of the body. The big toe is medial to the little toe.

medial epicondyle: A bony prominence proximal to the medial condyle.

medial rotation: To turn a body part around its long axis, with the anterior surface moving toward the midline, like when you turn your whole lower extremity so that your foot points inward.

median: At the midline of the body. For example, the nose is a median structure.

mediastinum : The compartment that takes up the middle portion of the thoracic cavity.

medullary cavity: Open space inside the bone.

meninges: Coverings of the brain. They protect the brain by housing a fluid-filled space, and they function as a framework for blood vessels.

metabolism: The chemical reactions that convert food into energy.

midsagittal plane: An imaginary vertical plane that clinical anatomy uses to divide the body into left and right halves.

multinucleated: Containing more than one nucleus.

myoblasts: Embryonic muscle cells.

myocardium: Muscle of the heart.