Medullary cavity

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Medullary Cavity
Structure of a Long Bone.png
A long bone, with medullary cavity labeled near center.
Latincavitas medullaris
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; the area has been detected in fossil bones despite the fossilization process.[2]

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.
  2. ^ Peterson, J. E.; Lenczewski, M. E.; Reed, P. S. (October 2010). Stepanova, Anna (ed.). "Influence of Microbial Biofilms on the Preservation of Primary Soft Tissue in Fossil and Extant Archosaurs". PLoS ONE. 5 (10): 13A. doi:10.1371/journal.pone.0013334. PMC 2953520. PMID 20967227.

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