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Haversian canals [i] (sometimes canals of Havers, osteonic canals or central canals) 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 .
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.
Volkmann's canals, also known as perforating holes or channels, are anatomic arrangements in cortical bones that allow blood vessels to enter the bones from periosteum. They interconnect the Haversian canals (running inside osteons ) with each other and the periosteum.
The Ohio River at Cairo is 281,500 cu ft/s (7,960 m 3 /s); [1] and the Mississippi River at Thebes, Illinois, which is upstream of the confluence, is 208,200 cu ft/s (5,897 m 3 /s). [66] The Ohio River flow is greater than that of the Mississippi River, so hydrologically the Ohio River is the main stream of the river system.
On July 3, 1827, the first canal boat on the Ohio and Erie Canal left Akron, traveled through 41 locks and over 3 aqueducts along 37 miles (60 km) of canal, to arrive at Cleveland on July 4. While the average speed of 3 mph (5 km/h) may seem slow, canal boats could carry 10 tons of goods and were much more efficient than wagons over rutted trails.
X 100. a, Haversian canals; b, lacunae seen from the side; c, others seen from the surface in lamella, which are cut horizontally. Nucleated bone cells and their processes, contained in the bone lacunae and their canaliculi respectively.
Ohio transitioned to dryland conditions in the Pennsylvanian, forming large coal swamps and the region has been dryland ever since. Until the Pleistocene glaciations erased these features, the landscape was cut with deep stream valleys, which scoured away hundreds of meters of rock leaving little trace of geologic history in the Mesozoic and ...
Havers' thesis. Clopton Havers (24 February 1657 – April 1702) was an English physician who did pioneering research on the microstructure of bone. He is believed to have been the first person to observe and almost certainly the first to describe what are now called Haversian canals and Sharpey's fibres.