Medulla (noun)

1. The central part of an organ, especially the spinal cord or the inner core of a bone.
2. The central region of a structure, especially the lowermost part of the brainstem.

Origin:

Late 16th century: from latin, "marrow", "pith", also "medulla spinalis" (the spinal cord).

Examples:

1. The medulla controls essential functions such as heart rate and breathing.
2. The medulla of the bone was found to be diseased, causing the fracture.
3. Damage to the medulla can result in serious health problems.
4. The medulla is an important part of the nervous system.
5. Specialized cells in the medulla help regulate autonomic functions such as blood pressure and digestion.