myelos

Myelos is a Greek noun meaning marrow. In medical terminology it serves as the basis for the combining form myelo- (or myel-), used to indicate either bone marrow or the spinal cord depending on context. The root derives from Greek μυελός (myelos).

In modern usage, the sense of myelo- is determined by the medical field and the accompanying terms. When referring to bone marrow and hematologic processes, myelo- denotes bone marrow. Examples include myeloblast (a precursor cell in the bone marrow), myelogenous leukemia (a cancer of bone marrow-derived cells), myelodysplasia (disordered bone marrow cell development), myelofibrosis (fibrous replacement of bone marrow tissue), and myelosuppression (suppression of bone marrow activity). Myeloma denotes a tumor arising from plasma cells in the bone marrow, most notably multiple myeloma.

When the context involves the nervous system, especially the spinal cord, myelo- is used with terms such as myelopathy (disease of the spinal cord), myelitis (inflammation of the spinal cord), and myelography (imaging of the spinal canal). The same root thus spans two related but distinct anatomical domains, with the intended meaning inferred from the term it appears in.

Note that terminology can be nuanced, and precise meaning is guided by the clinical context and the suffixes used. The root myelos highlights the historical link between marrow-related terms and spinal cord terminology in medical language.