medulla

https://doi.org/10.1351/goldbook.10925
  1. [medulla oblongata] Lower part of the brain stem continuous with the spinal cord, containing neural centers regulating the autonomic functions of breathing, heart rate, and blood pressure.
  2. Middle (central) part of an organ, as in adrenal medulla, renal medulla, or the medulla of a lymph node.
Source:
PAC, 2016, 88, 713. (Glossary of terms used in developmental and reproductive toxicology (IUPAC Recommendations 2016)) on page 776 [Terms] [Paper]