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Volkmann's Canal
Volkmann's canals, also known as perforating holes or channels, are anatomic arrangements in cortical bones. Volkmann's canals are inside osteons. They interconnect the haversian canals with each other and the periosteum The periosteum is a membrane that covers the outer surface of all bones, except at the articular surfaces (i.e. the parts within a joint space) of long bones. Endosteum lines the inner surface of the medullary cavity of all long bones. Structu .... They usually run at obtuse angles to the haversian canals and contain anastomosing vessels between haversian capillaries. They were named after German physiologist Alfred Volkmann (1800-1878). Volkmann's canals are any of the small channels in the bone that transmit blood vessels from the periosteum into the bone and that communicate with the haversian canals. The perforating canals provide energy and nourishing elements for osteons. Additional images File:Osso por Descalcificação – HE – 40x.JPG, Bone by de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Osteons
In osteology, the osteon or haversian system (; named for Clopton Havers) is the fundamental functional unit of much compact bone. Osteons are roughly cylindrical structures that are typically between 0.25 mm and 0.35 mm in diameter. Their length is often hard to define, but estimates vary from several millimeters"Osteon," ''Encyclopædia Britannica Online'' (2009); retrieved 23 June 2009. to around 1 centimeter. They are present in many bones of most mammals and some bird, reptile, and amphibian species. Structure Each osteon consists of concentric layers, or ''lamellae'', of compact bone tissue that surround a central canal, the haversian canal. The haversian canal contains the bone's blood supplies. The boundary of an osteon is the cement line. Each haversian canal is surrounded by varying number (5-20) of concentrically arranged lamellae of bone matrix. Near the surface of the compact bone, the lamellae are arranged parallel to the surface; these are called circumf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Haversian Canals
Haversian canals (sometimes canals of Havers) are a series of microscopic tubes in the outermost region of bone called cortical bone. They allow blood vessels and nerves to travel through them to supply the osteocytes. Structure Each Haversian canal generally contains one or two capillaries and many nerve fibres. The channels are formed by concentric layers called lamellae, which are approximately 50 µm in diameter. The Haversian canals surround blood vessels and nerve cells throughout bones and communicate with osteocytes (contained in spaces within the dense bone matrix called lacunae) through connections called canaliculi. This unique arrangement is conducive to mineral salt deposits and storage which gives bone tissue its strength. Active transport is used to move most substances between the blood vessels and the osteocytes. Haversian canals are contained within osteons, which are typically arranged along the long axis of the bone in parallel to the surface. The canals a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Periosteum
The periosteum is a membrane that covers the outer surface of all bones, except at the articular surfaces (i.e. the parts within a joint space) of long bones. Endosteum lines the inner surface of the medullary cavity of all long bones. Structure The periosteum consists of an outer fibrous layer, and an inner cambium layer (or osteogenic layer). The fibrous layer is of dense irregular connective tissue, containing fibroblasts, while the cambium layer is highly cellular containing progenitor cells that develop into osteoblasts. These osteoblasts are responsible for increasing the width of a long bone and the overall size of the other bone types. After a bone fracture, the progenitor cells develop into osteoblasts and chondroblasts, which are essential to the healing process. The outer fibrous layer and the inner cambium layer is differentiated under electron micrography. As opposed to osseous tissue, the periosteum has nociceptors, sensory neurons that make it very sensitive to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alfred Volkmann
Alfred Wilhelm Volkmann (1 July 1801, Leipzig – 21 April 1877, Halle an der Saale) was a German physiologist, anatomist, and philosopher. He specialized in the study of the nervous and optic systems. Biography Alfred Wilhelm Volkmann was born in Leipzig, and enrolled in medicine there in 1821. Together with Gustav Theodor Fechner, who got his degree in medicine in 1822, and Rudolph Hermann Lotze (1817–1881) they formed a small intellectual group which dissolved only in 1837 when Volkmann received his professorship in Dorpat. In 1826 he obtained his doctorate and in 1828 he was habilitated as '' Privatdozent'' at the University of Leipzig. It was there that he became professor extraordinary of zootomy in 1834. In 1837 he went to Dorpat (now Tartu) as professor of physiology, pathology and semiotics. However, his residence in Dorpat was short: he left for Halle as early as 1843. After moving to Halle, Volkmann helped Gustav Theodor Fechner, his brother-in-law (married to V ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
