What is marrow cavity?

The marrow cavity, also known as the medullary cavity, is the hollow space within the long bones of the body such as the femur (thigh bone) and humerus (upper arm bone). It is found in the diaphysis, which is the main shaft of the long bone, and contains bone marrow.

Here are some key points about the marrow cavity:

Bone marrow production: The marrow cavity is the primary site of hematopoiesis, which is the process of blood cell production. Hematopoietic stem cells reside in the marrow cavity and give rise to all types of blood cells, including red blood cells, white blood cells, and platelets.

Fat storage: In adults, the marrow cavity in certain bones may contain yellow bone marrow which stores fat cells. Yellow bone marrow is composed of adipocytes and serves as an energy reserve for the body. In times of increased energy demand, the adipocytes in yellow bone marrow can be broken down and released into the bloodstream as fatty acids to be used as fuel.

Vascularization: The marrow cavity is highly vascularized, meaning it has an abundant supply of blood vessels. This ensures the delivery of oxygen and nutrients to the bone marrow cells and proper hematopoiesis.

Bone strength: While the cortical bone (the dense outer layer of the long bone) provides strength and rigidity, the marrow cavity contributes to weight reduction and overall bone metabolism.

Bone development: During bone growth and development, the marrow cavity is initially filled with red bone marrow, which is responsible for producing blood cells necessary for growth. As individuals reach adulthood, some of the red bone marrow is replaced by yellow bone marrow.

Overall, the marrow cavity plays a crucial role in blood cell production, energy storage, bone metabolism, and maintaining the structural integrity of long bones.