Biomedical Engineering Reference
In-Depth Information
Intramuscular
arteriole and
venule
Intramuscular
perifibrillar
capillaries
Marrow
arteriole
Muscle
Cortical
precapillary
Intramuscular
and interfascicular
venules
Marrow
sinusoids
Capillary
network in
osteogenic layer
of periosteum
Arteriole and
venule in
fibrous layer
of periosteum
Cortical
sinusoid
Figure 9.6
The vascular connection between the bone
marrow, cortex, periosteum, and attached muscle. (From
figure 9.37 of Brooks and Revell [28].)
The PV occupied by interstitial fluid is the space outside the blood vessels
and nerves in the Volkmann and Haversian canals (Figures 9.2 and 9.7). This
bone interstitial fluid freely exchanges with the vascular fluids because of the thin
capillary walls of the endothelium, the absence of a muscle layer, and the sparse
basement membrane. There are both outward filtration due to a pressure gradient
and inward reabsorption due to the osmotic pressure. The function of these flows is
to deliver nutrients to, and remove wastes from, the bone interstitial fluid. Lymph is
the fluid that is formed when interstitial fluid enters the conduits of the lymphatic
system. The lymphatic system has three interrelated functions. It is responsible
for the removal of interstitial fluid from tissues. It absorbs and transports fatty
acids and fats as chyle to the circulatory system. The last function of the lymphatic
system is the transport of antigen-presenting cells, such as dendritic cells, to the
lymph nodes where an immune response is stimulated. The lymph, unlike blood,
is not pumped through the body; it is moved mostly by the contractions of skeletal
muscles.
The existence of lymphatic vessels in bones remains unclear. On the basis
of physiologic evidence, some sort of lymph circulation must be present. Large
