Medullary cavity

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Medullary Cavity
Structure of a Long Bone.png
A long bone, with medullary cavity labeled near center.
Latin cavitas medullaris
TA A02.0.00.037
FMA 83698
Anatomical terminology

The medullary cavity (medulla, innermost part) is the central cavity of bone shafts where red bone marrow and/or yellow bone marrow (adipose tissue) is stored; hence, the medullary cavity is also known as the marrow cavity. Located in the main shaft of a long bone (diaphysis) (consisting mostly of compact bone), the medullary cavity has walls composed of spongy bone (cancellous bone) and is lined with a thin, vascular membrane (endosteum). However, the medullary cavity is the area inside any bone (long, flat, etc.) that holds the bone marrow.[1]

This area is involved in the formation of red blood cells and white blood cells, and the calcium supply for bird eggshells.

Intramedullary is a medical term meaning the inside of a bone. Examples include intramedullary rods used to treat bone fractures in orthopedic surgery and intramedullary tumors occurring in some forms of cancer or benign tumors such as an enchondroma.


  1. ^ Martini, F.; Nath, J. L. (2009). Fundamentals of Anatomy and Physiology (8th ed.). San Francisco, CA: Pearson Education. ISBN 978-0-321-50589-7. 

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