The human bone tissue in its macroscopic form is also called substantia spongiosa. This spongy substance consists of fine trabeculae. As such, the macroscopic bone platelets are known.
The macroscopic structure of the bone tissue is abbreviated to also referred to as cancellous bone. In flat bones, on the other hand, there is sometimes talk of Diploë instead of cancellous bone. To distinguish these macroscopic bone forms is the so-called mesh bone, which arises at the beginning of osteogenesis. The woven bones are made of cartilage or are formed directly from stem cells of the connective tissue. Like spongiosa, braid bones have fine bone beams.
However, the spongiosa bars are not directly intertwined and, unlike those of the woven bone, do not form a structurally organized whole. In addition to the Substantia spongiosa in the interior of the bone is mainly formed by the substantia compacta in the outer area, which, unlike the adaptive spongiosa is rather static and corresponds to the stable portion of the bone.
The cancellous bone is located inside the bones. Outwardly, the substance is surrounded by the cortex. Within the cavities lies the bone marrow between the individual spongiosa bars. Overall, the cancellous bone corresponds to an enormously closely meshed framework.
The bars of the cancellous bone communicate with each other and form a lattice-like structure. Many of the trabeculae lie within the cancellous bone, especially along the loading lines of individual bones. In this context, tension trajectories are often discussed. The architecture of cancellous bone strongly depends on the pressure conditions in the bone. For example, if a certain portion of the bone is exposed to excessive pressure, the cancellous bone in this area will adapt to the pressure requirements.
The same applies to bending or torsional forces, as they act on the femoral head, for example. Due to its lightweight principle, the spongiosa saves bone substance and thus ensures the minimal weight of the bones.
In osteogenesis, first of all, the woven bone is formed. In chondral osteogenesis, osteoblasts form the woven bone of cartilage. This ossification is the indirect one. In direct ossification, the woven bone is created by the bone-building osteoblasts directly from the stem cells of the connective tissue.
For this reason, the process of direct or desmal osteogenesis is mentioned. On the surface of each woven bone, there is a compression of the substance. In addition, in the course of osteogenesis, additional bone substance accumulates from the outside. This substance corresponds to the cortex. Inside, the bone substance breaks down into cancellous bone. The bone-degrading osteoclasts are involved in this reconstruction work. They degrade parts of the bone matrix, while osteoblasts recreate bone at the same time.
From the work of the osteoblasts arise inside the characteristic bone beams of cancellous bone. The resulting lattice structure adjusts itself after completed work of osteogenesis lifelong and dynamically to the newly arising loads of the individual bones. Thus, the function of the spongiosa corresponds above all to bone stabilization and bone adaptation to altered loads. The cancellous bone is thus responsible in particular for the carrying capacity of a bone.
One of the most important diseases of the spongiosa is osteoporosis. By osteoporosis is meant a morbid loss of bone material which far exceeds physiologically normal bone loss as part of the natural aging process.
The normal aging process usually does not diminish more than half of the existing bone mass and begins at the age of 30 years. Vertebral fractures occur during normal aging processes only when a corresponding accident occurs. In patients with osteoporosis, vertebral fractures also occur without external influence. Unlike the age atrophy, osteoporosis reduces all parts of the bone. Especially the cancellous substance of the bones is affected by the osteoporosis. This significantly reduces the carrying capacity of the individual bones. For a long time, there are no symptoms due to the onset of osteoporosis.
Bone degradation progresses slowly, causing atypical fractures at some point in time. The fractures on the vertebral bodies preferably occur in the lower back. Either they are preceded by light bumps or they happen without any identifiable cause. A vertebral fracture causes pain to patients, often perceived as diffuse, vaguely localized pain. The vertebral fractures deform the spine and cause a so-called widow's hump. Sometimes the height of the body decreases by a few centimeters. Patients are more prone to fractures than healthy individuals of the same age and, for example, often suffer from femoral neck fractures after a mundane household accident.
Depending on its causes, osteoporosis is divided into two types. Primary osteoporosis occurs without the influence of chronic diseases. In addition to old age, genetic components are discussed as the cause of occurrence. The consumption of alcohol, coffee and cigarettes can negatively influence and accelerate the course of the disease. Physical inactivity also plays a role in primary osteoporosis. The same is true for a lack of calcium or vitamin D. The secondary osteoporosis occurs in the context of chronic diseases or is triggered by certain drugs. Hormonal disorders, sugar diseases and intestinal diseases are often associated with the outbreak.