Medullary cavity, also known as the marrow cavity or the medulla, is a hollow space located within the long bones of the body, such as the humerus, femur, and tibia. It is filled with a soft, spongy tissue called bone marrow, which plays a vital role in the production of red and white blood cells and platelets.
Structure
The medullary cavity is lined with a thin layer of connective tissue called the endosteum, which contains a network of blood vessels, lymphatics, and nerve fibers. The bone marrow within the medullary cavity is composed of hematopoietic stem cells, which are responsible for the production of all types of blood cells. There are two types of bone marrow: red and yellow. Red bone marrow, also known as myeloid tissue, is the main site of blood cell production in the body and is found in the spongy bone tissue of the medullary cavity. Yellow bone marrow, on the other hand, is mostly composed of fat cells and is found in the central cavity of long bones and in the pelvis.
Location
The medullary cavity is located within the diaphysis, or the shaft, of long bones. It is surrounded by a layer of hard, dense bone tissue called the cortex, which provides structural support and protection to the bone. The medullary cavity can be seen in cross-section of a long bone, with the cortex on the outer surface and the medullary cavity in the center.
Function
The primary function of the medullary cavity is to produce blood cells, which are essential for maintaining the overall health of the body. Hematopoietic stem cells within the bone marrow give rise to red blood cells, white blood cells, and platelets. Red blood cells are responsible for carrying oxygen to the body’s tissues, white blood cells play a crucial role in the immune system, and platelets are involved in blood clotting.
In addition to its role in blood cell production, the medullary cavity also acts as a storage site for fat and minerals, such as calcium and phosphorus. These nutrients can be mobilized during times of need, such as during periods of physical activity or illness.
Clinical significance
The medullary cavity and bone marrow have a number of clinical applications. For example, bone marrow aspiration and biopsy are diagnostic procedures that involve the removal of a small sample of bone marrow from the medullary cavity for analysis. These procedures are used to diagnose a variety of conditions, including anemia, leukemia, and lymphoma.
Bone marrow transplantation is another medical procedure that involves the replacement of damaged or diseased bone marrow with healthy bone marrow from a donor. This procedure is used to treat conditions such as aplastic anemia and leukemia, in which the bone marrow is not functioning properly.
Medullary cavity also plays a role in the management of bone fractures. When a bone is fractured, the medullary cavity may be damaged, leading to the release of bone marrow into the surrounding tissues. This can cause significant bleeding and complications, such as compartment syndrome, which occurs when the pressure within a closed space (such as a muscle compartment) increases, leading to decreased blood flow and tissue damage.
