canal

canal,

an artificial waterway constructed for navigation or for the movement of water. The digging of canals for irrigation probably dates back to the beginnings of agriculture, and traces of canals have been found in the regions of ancient civilizations. Canals are also used to provide municipal and industrial water supplies. The drainage of wet lands may be accomplished by means of a canal; by this method the FensFens, the,
district, E England, a flat lowland, W and S of The Wash. Extending c.70 mi (110 km) from north to south and c.35 mi (60 km) from east to west, it is traversed by numerous streams.
..... Click the link for more information. of England and the Zuider ZeeZuider Zee
, former shallow inlet of the North Sea, c.80 mi (130 km) long, indenting NE Netherlands. In ancient times Lake Flevo, it was joined to the North Sea by a great flood in the 13th cent.
..... Click the link for more information. in the Netherlands were drained. Canals can be used for flood control by diverting water from threatened areas into storage basins or to other outlets. In some cases canals are used to generate electricity; the Moscow-Volga Canal is used for this purpose.

Navigation canals developed after irrigation canals and for a long time were level, shallow cuts or had inclined planes up which vessels were hauled from one level to the next; locks (see lock, canallock, canal,
stretch of water enclosed by gates, one at each end, built into a canal or river for the purpose of raising or lowering a vessel from one water level to another. A lock may also be built into the entrance of a dock for the same purpose.
..... Click the link for more information. ) developed separately in China (10th cent.) and Europe (Holland; 13th cent.). Over the years canals have been expanded in width and depth in order to accommodate larger craft, and they have, in some cases, been constructed to form bridges or to pass through tunnels to overcome topographic difficulties. Movement on canals was long accomplished by animal tows or by poling; in the 20th cent. mechanized tows and self-propelled barges appeared.

The Grand CanalGrand Canal,
Chinese Da Yunhe [large transit river], longest in the world, extending c.1,000 mi (1,600 km) from Beijing to Hangzhou, E China, and forming an important north-south waterway on the North China Plain. The canal was started in the 6th cent. B.C.
..... Click the link for more information. of China (the longest in the world) was completed in the 13th cent. and is the most notable of the early canals. France, Belgium, Holland, and Germany were the first in Europe to develop inland waterway systems by using canals to connect rivers; these countries now have a dense network of waterways (see Rhine CanalsRhine Canals.
Among the chief canals linking the Rhine with other river systems are the Rhine-Rhône Canal, 217 mi (349 km) long (built 1784–1833, now unimportant), connecting with the Rhône River through the Saône River; the Rhine-Marne Canal, 195 mi (314
..... Click the link for more information. ; Midland CanalMidland Canal,
Ger. Mittelland Kanal, artificial waterway system of Germany, extending eastward c.200 mi (320 km) along the North German plain from the Dortmund-Ems Canal, Germany, to Magdeburg, Germany, on the Elbe River.
..... Click the link for more information. ). Canal building was widespread in the 18th and 19th cent. During that period England developed an elaborate canal network, and there was also a canal-building boom in the United States in the 19th cent., especially after the completion of the Erie CanalErie Canal,
artificial waterway, c.360 mi (580 km) long; connecting New York City with the Great Lakes via the Hudson River. Locks were built to overcome the 571-ft (174-m) difference between the level of the river and that of Lake Erie.
..... Click the link for more information. . However, the rise of railroads brought a decline in the building and use of canals as inland waterways. Canals have been built to shorten sea voyages or to make them less hazardous, e.g., the Suez CanalSuez Canal,
Arab. Qanat as Suways, waterway of Egypt extending from Port Said to Port Tawfiq (near Suez) and connecting the Mediterranean Sea with the Gulf of Suez and thence with the Red Sea. The canal is somewhat more than 100 mi (160 km) long.
..... Click the link for more information. , the Panama CanalPanama Canal,
waterway across the Isthmus of Panama, connecting the Atlantic (by way of the Caribbean Sea) and Pacific oceans, built by the United States (1904–14, on territory leased from the republic of Panama) and expanded by Pamana (2007–16).
..... Click the link for more information. , and the Kiel CanalKiel Canal,
artificial waterway, 61 mi (98 km) long, in Schleswig-Holstein, N central Germany, connecting the North Sea with the Baltic Sea. At sea level, the canal extends from Kiel on the Baltic to Brunsbüttelkoog at the mouth of the Elbe River.
..... Click the link for more information. . Canals improve conditions on natural waterways by bypassing falls (the Welland Ship CanalWelland Ship Canal,
27.6 mi (44.4 km) long, SE Ont., Canada, connecting Lake Ontario with Lake Erie and bypassing Niagara Falls. Built between 1914 and 1932 by Canada to replace a canal opened in 1829, it can accommodate (minimum depth 27 ft/8 m) the largest lake ships.
..... Click the link for more information. ), shallows, or swift currents (the Sip Canal in the Danube River's Iron Gate gorge). Canals may provide inland cities with direct access to the sea (the Manchester Ship CanalManchester Ship Canal,
35.5 mi (57 km) long with a minimum depth of 28 ft (8.5 m), connecting Manchester, W England, with the Mersey estuary at Eastham, above Birkenhead. Begun in 1887, it was opened in 1894 and changed Manchester from a river port to a seaport.
..... Click the link for more information. ), or shorten the distance between cities (the Albert CanalAlbert Canal,
waterway, c.80 mi (130 km) long, N Belgium, from the Meuse River to the Scheldt River; constructed 1930–39. The canal connects the important industrial region around Liège with the port of Antwerp, Belgium.
..... Click the link for more information. ). In the 20th cent. canals regained importance, as modern technology provided the means to overcome greater topographic obstacles and facilitated the construction of larger canals and the expansion of existing ones. The Great LakesGreat Lakes,
group of five freshwater lakes, central North America, creating a natural border between the United States and Canada and forming the largest body of freshwater in the world, with a combined surface area of c.95,000 sq mi (246,050 sq km).
..... Click the link for more information. –Saint Lawrence SeawaySaint Lawrence Seaway,
international waterway, 2,342 mi (3,769 km) long, consisting of a system of canals, dams, and locks in the St. Lawrence River and connecting channels between the Great Lakes; opened 1959.
..... Click the link for more information. system, opened to navigation in 1959, is the world's longest deep-draft inland waterway. Including six short canals with a total length of less than 60 nautical mi (110 km), it extends from the Atlantic Ocean to Duluth, Minn. on Lake Superior, a distance of more than 2,340 mi (3,700 km), providing large oceangoing vessels passage into central North America.

Bibliography

See C. Hadfield, World Canals (1986); R. Spangenburg and D. Moser, The Story of America's Canals (1992); R. E. Shaw, Canals for a Nation: The Canal Era in the United States, 1790–1860 (1993); J. M. Bracken, American Waterways: The Role of Canals in America (1997).

Canal

A channel or groove as in the recessed portions of the face of a triglyph.

Canal

in hydraulic engineering, a regularly shaped man-made channel (waterway) built in the earth, with nonpressured movement of the water. Canals are built in open excavations or in embankments (when crossing gorges or ravines) and sometimes half in excavations and half in embankments (a canal on a slope). According to purpose, a distinction is made among navigation canals (man-made waterways), power-engineering canals (diversion channels), irrigation canals, water-supply canals, drainage canals, lumber-flotation canals, fish-ladder canals, and general-purpose canals.

Connecting navigation canals join navigable rivers, lakes, and seas (for example, the V. I. Lenin VolgaDon Ship Canal, the Moscow Canal, the Dnieper-Bug Canal, and the Panama Canal). Bypass canals are built to improve navigation conditions and to avoid rapids in rivers and turbulent sections of large lakes and seas (the Ladoga canals, the Onega Canal, and the Gulf Intracoastal Canal). Straightening canals eliminate meandering of a navigation route and reduce the length of the waterway (the Khoroshevo Canal on the Moscow River and the canal on the Don River below the Tsimliansk Hydroelectric Power Plant). Approach canals provide an approach to large cities, inland port areas, and industrial enterprises from a sea, lake, or river (the Leningrad and Astrakhan sea canals and the Manchester Ship Canal).

Navigation canals are also divided into open and lock canals. Open canals are built by joining waterways whose water levels are almost the same; canals with locks are used when there is a difference in levels or when the route of the canal crosses a high water divide. Lock canals usually consist of several sections, called races, on different levels; locks or ship hoisters are installed between them. Bypass and approach canals are generally open; connecting canals have locks. The water in navigation (lock) canals may move by gravity flow (free-flowing canals), or it may be pumped by pumping stations (machine canals). Navigation canals are characterized by great length (for example, the coastal canal from New York to Florida in the USA is about 1, 800 km long, the Baltic-White Sea Canal is 227 km long, and the Dnieper-Bug Canal is 196 km long; among sea canals, the Suez Canal is 171 km long and the Panama Canal is 81.6 km long) and by broad transverse dimensions (the Suez Canal is 120–150 m wide across the top and 12–13 m deep).

Diversion channels take water from a river, reservoir, or lake to a hydroelectric power plant or draw off water that has passed through the turbine. Such canals are typically very short; delivery canals are usually not more than 5–10 km long (maximum of 30 km), and return canals are seldom more than a few kilometers long. The water flow (carrying capacity) of diversion channels varies; in some cases it is more than 1,000 m³/sec (for example, the carrying capacity of the diversion channel of the Montélimar Hydroelectric Power Plant in France is 1, 860 m³/sec). In the USSR the Zemo-Avchala, Rioni, and Kondopoga hydroelectric power plants and the Sevan grid have diversion channels.

Irrigation canals are designed to supply water to irrigated lands. They usually form a system of main canals, distribution canals, the irrigation canals themselves, and drainage canals. Water enters irrigation canals by gravity flow or is fed by pumps. In large irrigation systems the length of the main canals may be several hundred kilometers (the Karakum Canal’s first section, up to the city of Ashkhabad, is more than 800 km long, the North Crimean Canal is more than 400 km long, and the Bol’-shoi Fergana Canal is about 300 km long). The water flow at the head of these canals is 250–500 m³/sec.

Agricultural water-supply canals deliver water to waterless and arid regions for the needs of agriculture (primarily for livestock raising). Examples are the agricultural water-supply canals in the lower regions of the Volga and the canals of the Terek-Kuma Water-Supply System. Since small, oasis-like irrigated areas are usually formed when water is supplied to arid lands, agricultural water-supply canals are often at the same time irrigation canals (for example, the Nevinnomyssk and Kuban’-Kalaus canals).

Drainage canals collect water that comes from a drainage network (on swampy or overly moist terrain) and conduct it to a river, lake, or sea by gravity flow or through the use of pumping stations. Drainage canals are usually routed along the lowest points of the territory being drained (along thalwegs).

Water-supply canals deliver water from the source of supply to the place of consumption (an industrial region, city, or community). Among the large water-supply canals in the USSR are the Irtysh-Karaganda Canal, with a total length of about 460 km and a carrying capacity of 75 m³/sec at its head, and the Severskii Donets-Donbas Canal, which is about 130 km long, with a water flow of 25 m³/sec at its head. Operating conditions and public-health requirements sometimes necessitate the covering of water-supply canals (for example, the canal—about 30 km long—that delivers water from the Ucha Reservoir to Moscow).

Timber-flotation canals are built to float timber (as individual logs or in rafts), usually from the place where it is cut to a river that is suitable for flotation or to a sawmill. Flotation canals are also built in the area of hydraulic-engineering complexes to direct floating timber around hydraulic-engineering structures.

Fish-ladder canals supply water to man-made breeding grounds, provide a connection between rivers and isolated bodies of water (lakes) in which fish are found, and supply fresh water to estuaries (for example, in the lower course of the Kuban’ River).

General-purpose canals are built to accomplish several water-management tasks simultaneously. Such canals have been developed on a particularly large scale in the USSR in connection with multiple use of river resources. For example, the Moscow Canal delivers water for navigation and water supply for the city of Moscow, the V. I. Lenin Volga-Don Canal (together with the Tsimliansk Hydroelectric Power Plant) is a navigation-irrigation-water-supply and power complex, and the Irtysh-Karaganda Canal solves irrigation problems in Central Kazakhstan, in addition to its primary task of water supply.

The cross section of a canal depends on the purpose of the canal, the structural features of the ground, and the conditions for earthwork. The most common shapes of canal cross sections built in soft soils are trapezoidal and polygonal. The latter is usually used in building large navigational canals. A rectangular profile is advisable when canals are built in rock excavations. Sometimes (for example, when a canal route passes through populated areas or in sloping sectors) the rectangular cross section in soft soils is reinforced by constructing vertical retaining walls.

The dimensions of a canal’s cross section are determined by hydraulic calculations for a given water flow and the current velocity that is permissible for the particular conditions; for navigation and timber-flotation canals the size of ships and rafts that will be passing through must also be taken into account. The ratio between the area of the clear section of navigation canals and the area of the midship section of the hypothetical ship should not be greater than 4:1 for canals on first-category waterways, 3.5:1 for second-category waterways, and 3:1 for the third and fourth categories. If the ratio is smaller, resistance to the movement of ships increases substantially.

The slope of canal walls is determined by the nature of the soil. Where excavations are very deep, and also under difficult geological conditions, the strength of the walls is checked through calculations.

The velocity of water current in canals has maximum and minimum values: the maximum, to avoid erosion of the bed of the canal, and the minimum, so that the bed does not become silted or overgrown with vegetation. For example, for canals in soft ground (sand and sandy loam), with a water depth of more than 3 m, current velocities of 0.4−1.5 m/sec present no danger of erosion; in hard rock (marl or sandstones), the velocities may be 3.1−5.6 m/sec. Formulas based on the principle of the so-called alluvium-transporting capability of a current are used to determine silt-free water velocities. Minimum canal velocities for preventing overgrowth with vegetation are 0.3 m/sec for small canals and 0.5 for large canals.

The bed of the canal is lined to protect it against erosion by the current and waves, to reduce water losses from seepage into the soil, and to decrease the roughness of the bottom and walls (to increase the carrying capacity of the canal). Lining that serves only to protect the walls of the canal against erosion is made of rock paving, fill, and laying and of concrete and rein-forced-concrete slabs. This kind of lining is usually used on navigation canals. For irrigation, agricultural water-supply, and drainage canals, sod-brushwood, wicker, and other types of rein forcements are sometimes used. Antiseepage lining (screens) is usually made of clay, sandy loam, and well-decomposed peat. The screens are covered with a layer of sand or gravel to protect them against mechanical damage and the effects of temperature. Concrete, reinforced-concrete, and asphalt-concrete linings are the most versatile; they provide reliable protection against erosion for the canal bed, ensure its watertightness, increase its carrying capacity and, at the same time, make possible complete mechanization of construction work. In addition to installing lining or screens, silt deposition, mechanical packing of the soil, and films made of synthetic materials are used to combat seepage in canals.

Structures on canals. In addition to special structures related to the operation of canals, such as locks (on navigation canals), pumping stations (on machine canals), and flood gates, many other hydraulic-engineering structures for various purposes are also erected along all canals. Among them are structures in places where the canal intersects streams (pipes, inverted siphons, and aqueducts), at intersections with transportation routes (viaducts, tunnels, bridges, and ferry crossings), and in places where there is a sharp break in the relief of the terrain (knickpoints and races).

Historical survey. Long before the Common Era, in the ancient states of the Southeast and East, the development of irrigation and water-supply canals became necessary as farming developed. For example, irrigation was known in the valley of the Nile River in Egypt in 4400 B.C. and in China (on the Yangtze River) in the third millennium B.C. The construction of navigation canals—for example, the canal from the Nile to the Red Sea, sixth century B.C., and the Chinese Grand Canal—also began in ancient times.

In the Middle Ages navigation canals were constructed primarily in Holland, France, and England. The invention of the chamber lock in Holland in the 15th century was of great importance for the construction of navigation canals. In the 16th and 17th centuries the development of trade and early industrial manufacture required an improvement in transportation routes and the design of navigation canals. In the 17th and 18th centuries and the first half of the 19th century, waterways were the primary and most economical transportation arteries. Among the most important structures of that period are the navigation canals in France (the Seine-Loire, Languedoc and Central canals), Germany (Vinow, Oder-Spree, Oder-Vistula, and Elbe-Havel), and England (Bridgewater and Caledonian). Sea canals (Suez, Kiel, and Panama) were built in the second half of the 19th century and in the 20th century in connection with the extensive development of world trade and for strategic purposes.

Canals for irrigation were built on the territory of the USSR as early as the eighth to sixth centuries B.C., in the ancient states of Khwarizm and Urartu. Irrigation canals were built in the 12th and 13th centuries A.D. in Georgia (Alazani and Samgori). Later canal building developed primarily for purposes of improving river navigation (for example, the navigation canal on the Sukhona River, 13th century), for hydraulic-engineering purposes (for supplying water to water-powered mills), and sometimes for drainage of land. Intensive construction of canals developed during the reign of Peter I. The Oka River was linked to the headwaters of the Don by the Ivanovskii Canal, the Vyshnii Volochek Water System was built to connect the Volga with the Msta River and the Baltic Sea, the Ladoga canals were built, and later, various connecting navigation canals, such as the Mariinskii, Tikhvin, Oginskii, and Severnaia Dvina, were added.

A new stage in the construction of navigation and irrigation canals and diversion channels in the USSR began after the Great October Socialist Revolution. Surveying for the Volga-Don Canal was under way as early as 1918. In the period of reconstruction—and especially during the prewar five-year plans— extensive construction of canals that were of great general importance to the national economy of the USSR was carried on. The plan of GOELRO (State Commission for the Electrification of Russia) played a large role in the construction of power-engineering canals; a number of hydroelectric power plants with diversion channels (for example, the Zemo-Avchala and Kondopoga plants) were built on the basis of this plan. The largest irrigation complex of the prewar five-year plans was the Bol’shoi Fergana Canal. The Baltic-White Sea and Moscow canals, as well as a number of irrigation canals in Middle Asia and the Caucasus, were built during the 1930’s.

After the Great Patriotic War (1941–5) canal construction was even more extensive. The following canals were built and put into operation: the V. I. Lenin Volga-Don Canal, the Karakum Canal (up to Ashkhabad), the Golodnaia Step’ Canal, the Don Main Canal, the Northern Crimean Canal, the Severskii Donets-Donbas Canal, the Dnieper-Krivoi Rog Canal, and the Amu-Bukhara Canal.

REFERENCES

Uginchus, A. A. Kanaly i sooruzheniia na nikh. Moscow, 1953.
Askochenskii, A. N. Oroshenie i obvodnenie v SSSR. Moscow, 1967.
Grishin, M. M. Gidrotekhnicheskie sooruzheniia. Moscow, 1968.

P. N. KORABLINOV

What does it mean when you dream about a canal?

As a waterway that must be constructed (in contrast to a stream or a river), dreaming about a canal might be about channeling or directing our feelings. It could also be emblematic of our goals.

canal

[kə′nal] (biology) A tubular duct or passage in bone or soft tissues. (civil engineering) An artificial open waterway used for transportation, waterpower, or irrigation. (design engineering) A groove on the underside of a corona. (geography) A long, narrow arm of the sea extending far inland, between islands, or between islands and the mainland. (nucleonics) A water-filled trench or conduit associated with a nuclear reactor, used for removing and sometimes storing radioactive objects taken from the reactor; the water acts as a shield against radiation.

Canal

An artificial open channel usually used to convey water or vessels from one point to another. Canals are generally classified according to use as irrigation, power, flood-control, drainage, or navigation canals or channels. All but the last type are regarded as water conveyance canals.

Canals may be lined or unlined. Linings may consist of plain or reinforced concrete, cement mortar, asphalt, brick, stone, buried synthetic membranes, or compacted earth materials. Linings serve to reduce water losses by seepage or percolation through pervious foundations or embankments and to lessen the cost of weed control. Concrete and other hard-surface linings also permit higher water velocities and, therefore, steeper gradients and smaller cross sections, which may reduce costs and the amount of right-of-way required.

Navigation canals are artificial inland waterways for boats, barges, or ships. A canalized river is one that has been made navigable by construction of one or more weirs or overflow dams to impound river flow, thereby providing navigable depths. Locks may be built in navigation canals and canalized rivers to enable vessels to move to higher or lower water levels. A lock is a chamber equipped with gates at both upstream and downstream ends. Water impounded in the chamber is used to raise or lower a vessel from one elevation to another. The lock chamber is filled and emptied by means of filling and emptying valves and a culvert system usually located in the walls and bottom of the lock. See Transportation engineering, Water supply engineering

canal, canalis

A channel or groove, as a hollow between the fillets of the volutes of an Ionic capital.

canal

1. an artificial waterway constructed for navigation, irrigation, water power, etc. 2. any of various tubular passages or ducts 3. any of various elongated intercellular spaces in plants 4. Astronomy any of the indistinct surface features of Mars originally thought to be a network of channels but not seen on close-range photographs. They are caused by an optical illusion in which faint geological features appear to have a geometric structure

See canal

canal

[kah-nal´] a relatively narrow tubular passage or channel.adductor canal Hunter's canal.Alcock's canal a tunnel formed by a splitting of the obturator fascia, which encloses the pudendal vessels and nerve.alimentary canal see alimentary canal.anal canal the terminal portion of the alimentary canal, from the rectum to the anus.atrioventricular canal the common canal connecting the primordial atrium and ventricle; it sometimes persists as a congenital anomaly.birth canal the canal through which the fetus passes in birth.carotid canal one in the pars petrosa of the temporal bone, transmitting the internal carotid artery to the cranial cavity.cervical canal the part of the uterine cavity lying within the cervix.condylar canal an occasional opening in the condylar fossa for transmission of the transverse sinus; called also posterior condyloid foramen.canal of Corti a space between the outer and inner rods of Corti.femoral canal the cone-shaped medial part of the femoral sheath lateral to the base of Gimbernat's ligament.haversian canal any of the anastomosing channels of the haversian system in compact bone, containing blood and lymph vessels, and nerves.Hunter's canal a fascial tunnel in the middle third of the medial part of the thigh, containing the femoral vessels and saphenous nerve. Called also adductor canal.hypoglossal canal an opening in the occipital bone, transmitting the hypoglossal nerve and a branch of the posterior meningeal artery; called also anterior condyloid foramen.infraorbital canal a small canal running obliquely through the floor of the orbit, transmitting the infraorbital vessels and nerve.inguinal canal the oblique passage in the lower anterior abdominal wall on either side, through which passes the round ligament of the uterus in the female, and the spermatic cord in the male.medullary canal 1. spinal canal.2. marrow cavity.optic canal a passage for the optic nerve and ophthalmic artery at the apex of the orbit; called also optic foramen.pulp canal root canal.root canal that part of the cavity" >pulp cavity extending from the pulp chamber to the apical foramen. Called also pulp canal.sacral canal the continuation of the spinal canal through the sacrum.Schlemm's canal sinus of sclera" >venous sinus of sclera.semicircular c's see semicircular canals.spinal canal (vertebral canal) the canal formed by the series of vertebral foramina together, enclosing the spinal cord and meninges.Volkmann's c's canals communicating with the haversian canals, for passage of blood vessels through bone.

ca·nal

(kă-nal'), [TA] A duct or channel; a tubular structure.
See also: channel, duct. Synonym(s): canalis [TA] [L. canalis]

canal

(kə-năl′)n. Anatomy A tube, duct, or passageway.

canal

Anatomy
A furrow or conduit.
Vox populi
A narrow, usually manmade body of water which provides a route of maritime transportation.

ca·nal

(kă-nal') [TA] A duct or channel; a tubular structure.
Synonym(s): canalis [TA] . [L. canalis]

canal

(ka-nal') [L. canalis, channel] A narrow tube, channel, tunnel, or passageway. See: duct; foramen; groove; space

adductor canal

A connective tissue channel, through which the femoral artery, femoral vein, and saphenous nerve pass inside the lower half of the inner thigh between the femoral triangle and the popliteal fossa. The channel is surrounded by the vastus medialis, adductor longus, and adductor magnus muscles, and it is covered by the sartorius muscle. Synonym: Hunter canal; subsartorial canal

Alcock canal

Pudendal canal. See: Alcock canal

alimentary canal

The digestive tract from the mouth through the anus.

alveolar canal

In the skull, any of the two or three channels leading from small holes along the middle of the infratemporal surface of the maxilla. These channels transmit the posterior superior alveolar blood vessels and nerves, which supply the upper molars and their surrounding gums. Synonym: superior alveolar canal ; maxillary canal

ANAL CANAL

anal canal

The 4 cm long terminal section of the large intestine, beginning where the rectum passes downward and forward through the pelvic diaphragm and ending in the anus. The entire length of the anal canal is surrounded by sphincter muscles, and the canal remains closed except during defecation and passage of flatus. See: illustration

Arnold canal

See: Arnold, Friedrich

atrioventricular canal

In the embryo, the segment of the heart tube between the developing atria and ventricles. This segment will eventually give rise to the mitral and tricuspid valves and to portions of the interatrial and interventricular septa.

auditory canal

Either the external auditory canal or the internal auditory canal. See: external auditory canal ; internal auditory canal

birth canal

The passageway comprising the cervix, vagina, and vulva, through which the products of conception, including the fetus, pass during labor and birth.

bony semicircular canal

Any of several canals located in the bony labyrinth of the internal ear and enclosing the three semicircular ducts (superior, posterior, and lateral) that open into the vestibule. They are enclosed within the petrous portion of the temporal bone.

carotid canal

The channel followed by the internal carotid artery (and its accompanying sympathetic nerves) as it passes through the bone of the skull. The oval external opening is in the petrous portion of the temporal bone just in front of the opening to the jugular canal. The carotid canal runs forward until, passing over the foramen lacerum, it turns up and opens into the middle cranial fossa along a groove at the base of the sella turcica.

central canal of bone

The Haversian canal of an osteon.

central canal of neural tube

The central lumen of the neural tube of the embryo. It is lined by the foot-processes of radial glial cells. Later, the central canal of the neural tube will become the ependyma-lined ventricles of the brain and the central canal of the medulla of the brainstem.

central canal of spinal cord

The remnant of the lumen of the neural tube. Largely obliterated in the adult spinal cord.

cervical canal

The passageway through the center of the cervix.

Cloquet canal

See: Cloquet canal

cochlear canal

Within the petrous portion of the temporal bone of the skull, the spiral space forming the outer wall the cochlea. This canal is a short spiral bony tube. Three fluid-filled, membranous tubes spiral fill the cochlear canal: the cochlear duct, containing the auditory receptor cells (the organ of Corti), is sandwiched between the scala vestibuli above and the scala tympani below. The cochlear canal is one segment of an interconnected series of bone cavities called the bony (osseus) labyrinth, which encloses the vestibulo-cochlear sensory apparatus of the inner ear. See: cochlea

condylar canal

A hole in the occipital bone of the skull for passage of the emissary vein from the transverse sinus. It opens anterior to the occipital condyle.

canal of Corti

See: Corti

craniopharyngeal canal

In the embryo, a temporary tubular space in the cartilage of the base of the sphenoid bone, enclosing the developing pituitary gland.

dental canal

Any of the channels in the maxilla (alveolar canals) or mandible (mandibular canals) through which pass the nerves and blood vessels to the teeth and the surrounding gums.

Dorello canal

See: Dorello canal

ethmoidal canal

Either of two grooves running transversely across the lateral mass of the ethmoid bone to the cribriform plate and lying between the ethmoid and frontal bones. The anterior ethmoidal canal transmits the anterior ethmoidal vessels and the nasociliary nerve; the posterior ethmoidal canal transmits the posterior ethmoidal vessels and nerve.

external auditory canal

The open, tubular passageway from the pinna (auricle) of the ear to the tympanic membrane (ear drum). It is lined by thin, sensitive skin, which continues as the outer covering of the tympanic membrane. Its outer edge is a channel in the temporal bone of the skull. The cartilage inside the pinna extends as a middle layer between the skin and the bone in the first third of the canal. See: external auditory meatus

facial canal

The tunnel followed by the facial nerve through the temporal bone. Inside the skull, the facial canal begins in the internal auditory canal; outside the skull, it ends at the stylomastoid foramen. Within the bone, the canal makes two bends as it bypasses the inner ear. The first bend houses the geniculate ganglion, which sends sensory axons toward the brainstem as the intermediate component of the facial nerve. Near the second bend, the facial nerve gives off a branch to the stapedius muscle. In the final segment of the canal, the facial nerve gives off the chorda tympani nerve; thus, only motor axons remain as the facial nerve exits the canal.

fallopian canal

A canal in the petrous portion of the temporal bone. The facial nerve passes through it. Synonym: aqueductus Fallopii

femoral canal

1. The medullary (central) canal inside the shaft of the femoral bone. 2. The most medial compartment of the femoral sheath. A femoral hernia is a bulge of intestine that has been pushed down into the femoral canal through its upper opening, the femoral ring.

gastric canal

A longitudinal groove extending from the esophagus to the pylorus on the inner surface of the stomach following the lesser curvature.

Guyon canal

See: Guyon canal

Haversian canal

In compact bone, tiny channels in the center of concentric cylinders of mineralized tissue. Nerves and blood vessels run through these channels, all of which interconnect. Each Haversian canal is the center of an osteon. See: bone; Havers, Clopton

Huguier canal

See: Huguier canal

Hunter canal

Adductor canal. See: Hunter canal

Huschke canal

See: Huschke, Emil

hyaloid canal

Canalis hyaloideus; a canal in the vitreous body of the eye extending from the optic papilla to the central posterior surface of the lens. It serves as a lymph channel. In the fetus the canal contains the hyaloid artery. This normally disappears 6 weeks before birth.

hypoglossal canal

A hole in the skull, just above the foramen magnum in the occipital bone, through which the hypoglossal nerve and a branch of the ascending pharyngeal artery pass. Synonym: anterior condyloid foramen

inferior alveolar canal

Mandibular canal.

infraorbital canal

An anterior-posterior bony canal or groove in the floor of the orbit. The infraorbital artery and nerve run in this canal, which opens anteriorly as the infraorbital foramen.

INGUINAL CANAL/ SPERMATIC CORD CONTENTS

inguinal canal

A tube made of the transversalis fascia and the aponeuroses of the abdominal wall muscles just above the inguinal ligament. The inguinal canal is a cylindrical passageway 4 cm long from the retroperitoneal space to the subcutaneous fascia. It begins at the deep (internal) inguinal ring inside the abdominal wall, approx. halfway between the anterior superior spine of the iliac bone and the pubic symphysis, 0.50 in (1.25 cm) above the inguinal ligament. It continues downward and toward the midline, and it ends at the superficial (external) inguinal ring under the skin at the pubic crest. The inguinal canal contains an outpouching of the peritoneum, blood and lymph vessels, and the ilioinguinal nerve. In males, it contains the spermatic cord; in females, it contains the round ligament of the uterus. illustration

interdental canal

Hirschfeld canal.

internal auditory canal

The tunnel in the petrous portion of the temporal bone through which the vestibulocochlear and facial nerves exit the cranial cavity. Synonym: meatus acusticus internus

intestinal canal

The alimentary canal from the stomach to the anus.

lacrimal canal

Nasolacrimal canal.

canal of Lambert

Any of several bronchoalveolar communications in the lung. These may help to prevent atelectasis.

mandibular canal

The channel inside the body of the mandible through which the inferior alveolar blood vessels and nerve pass to supply the lower teeth and gums. Synonym: inferior alveolar canal

mandibular incisive canal

The final segment of the mandibular canal, containing the nerves and blood vessels for the lower incisors and surrounding gums.

maxillary canal

Alveolar canal.

maxillary incisive canal

One of the two channels connecting the incisive fossa (incisive foramen), in the palate behind the upper incisors, and the nasal floor. It contains the nasal terminations of the greater palatine artery and nasopalatine nerve.

medullary canal

The marrow cavity of long bones.

membranous semicircular canal

A semicircular duct. See: semicircular duct

nasolacrimal canal

A small bony passageway in the skull inside the medial wall of the orbit between the lacrimal bone and the maxilla. Its top opens into the nasolacrimal fossa, a bony depression in lower medial corner of the front of the orbit. Its bottom opens into the nasal cavity under the inferior nasal concha. It contains the membranous nasolacrimal duct, which drains tears from the eye. Synonym: lacrimal canal

neurenteric canal

A temporary canal in the vertebrate embryo between the neural and intestinal tubes. It is the temporary communication between cavities of the yolk sac and the amnion.

Nuck canal

See: Nuck canal

nutrient canal

In bone, a tiny tubular space filled by vessels and nerves running to and from the osteons and the other basic metabolic and growth units. See: bone

obturator canal

An opening in the obturator membrane of the hip bone that transmits the obturator vessels and nerve.

optic canal

In the skull, a roughly spherical opening through the lesser wing of the sphenoid bone connecting the middle cranial fossa and the superior-medial edge of the back of the orbit. The optic nerve and the ophthalmic artery pass through the optic canal. Synonym: optic foramen

greater palatine canal

In the skull, a thin vertical channel between the nasal surface of the maxillary bone and the perpendicular plate of the palatine bone that contains the greater (anterior) and lesser (middle and posterior) palatine nerves and the greater and lesser palatine vessels.

pericardioperitoneal canal

Pleuroperitoneal canal.

Petit canal

See: Petit, François Pourfour du

pharyngeal canal

A canal between the sphenoid and palatine bones that transmits branches of the sphenopalatine vessels.

pleuroperitoneal canal

A tubular space extending ventrally and laterally from the coelom inside each half of the embryo and destined to form the pleural cavity for the lung. Synonym: pericardioperitoneal canal

portal canal

The connective tissue (a continuation of Glisson capsule) and its contained vessels (interlobular branches of the hepatic artery, portal vein, and bile duct and lymphatic vessel) located between adjoining liver lobules.

pterygoid canal

In the skull, a small horizontal channel beginning inside the canal of the foramen lacerum (in the middle cranial fossa), passing through the root of the pterygoid process of the sphenoid bone, and opening into the pterygopalatine fossa behind and below the medial wall of the orbit. It transmits the pterygoid nerve and vessels to the pterygopalatine ganglion. Synonym: vidian canal

pterygopalatine canal

Canalis palatinus major, a canal between the maxillary and palatine bones that transmits the descending palatine nerves and artery.

pudendal canal

A tunnel inside the obturator fascia along the lower pelvic surface of the internal obturator muscle and running along the inner lower edge of the ramus of the ischium. It contains the pudendal nerve and vessels. Synonym: Alcock canal

pulp canal

Root canal (1).

pyloric canal

The cavity inside constricted region of the pyloric segment of the stomach that opens through the pyloric sphincter into the duodenum.

Rivinus canal

See: Rivinus, August Quirinus

root canal

1. The channel inside the tooth that extends from the pulp chamber to the apical foramen. It contains arteries, veins, lymphatic vessels, and sensory nerve endings. Synonym: pulp canal 2. Colloquially, the procedure for preserving a tooth by removing its diseased pulp cavity.

sacral canal

The continuation of the vertebral canal into the sacrum.

canal of Schlemm

See: canal of Schlemm

semicircular canal

One of the three perpendicular tubular hollows, each forming two-thirds of a circle, that extend from the vestibule of the labyrinth in the inner ear. The semicircular canals are the bony shells that contain the similarly shaped semicircular ducts, membranous sensory organs that detect the angular acceleration and the orientation of the head.

spinal canal

Vertebral canal.

spiral canal of the cochlea

Cochlear spiral canal.

spiral canal of the modiolus

Canalis spiralis modioli; a series of irregular spaces that follow the course of the attached margin of the osseous spiral lamina to the modiolus. They transmit filaments of the cochlear nerve and blood vessels. The spiral ganglion lies in the spiral canal.

subsartorial canal

Adductor canal.

superior alveolar canal

Alveolar canal.

uterine canal

The cavity of the uterus.

uterocervical canal

The cavity of the cervix of the uterus.

uterovaginal canal

The combined cavities of the uterus and vagina.

vaginal canal

The cavity of the vagina. The vaginal walls can expand but are normally in contact with each other; thus, this cavity is a potential space.

vertebral canal

The continuous channel through the central foramina in the vertebrae, which contains the spinal cord and the spinal nerve roots in their meningeal coverings. Synonym: spinal canal

vidian canal

Pterygoid canal.

Volkmann canals

See: Volkmann canals

canal

A tubular channel which allows the passage of air, food, blood, excretions, secretions, or anatomical structures such as nerves or blood vessels.
Cloquet's canal See hyaloid canal.
Hannover's canal A space about the equator of the crystalline lens made up between the anterior and posterior parts of the zonule of Zinn and containing aqueous humour and zonular fibres (Fig. C1).
hyaloid canal A channel in the vitreous humour, running from the optic disc to the crystalline lens. In fetal life this canal contains the hyaloid artery, which nourishes the lens, but it usually disappears prior to birth. Syn. central canal; Cloquet's canal; Stilling's canal. See hyaloid remnant.
infraorbital canal A channel beginning at the infraorbital groove in the floor of the orbit and ending at the infraorbital foramen of the maxillary bone opening onto the face below the inferior orbital margin. It is a channel for the infraorbital artery and the infraorbital nerve.
nasolacrimal canal See Table O4.
optic canal A canal leading from the middle cranial fossa to the apex of the orbit in the small wing of the sphenoid bone through which pass the optic nerve and the ophthalmic artery. Syn. optic foramen. See Table O4.
canal of Petit A space between the posterior fibres of the zonule of Zinn and the anterior surface of the vitreous humour (Fig. C1).
Schlemm's canal A circular venous sinus located in the corneoscleral junction, anterior to the scleral spur and receiving aqueous humour from the anterior chamber and discharging into the aqueous and the anterior ciliary veins (Fig. C1). Syn. scleral sinus; sinus circularis iridis; sinus venosus sclerae; venous circle of Leber. See trabecular meshwork; scleral spur; aqueous vein.
Stilling's canal See hyaloid canal.

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Fig. C1 Section diagram through the anterior portion of the eye

ca·nal

(kă-nal') [TA] Duct or channel; tubular structure.
See also: channel, duct[L. canalis]

Patient discussion about canal

Q. How much does a root canal hurt? I have to get a root canal for my bottom tooth. I was wondering how much they hurt. And do you have any suggestions that help distract from the pain? Thanks.A. i did one about two years ago- even the injection wasn't too bad! didn't feel a thing. but after the anesthesia worn off it hurt. but then the dentist told me to take Advil or any other NSAID and it helped.

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REFERENCES

What does it mean when you dream about a canal?

canal

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canal, canalis

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ca·nal

canal

canal

ca·nal

canal

adductor canal

Alcock canal

alimentary canal

alveolar canal

anal canal

Arnold canal

atrioventricular canal

auditory canal

birth canal

bony semicircular canal

carotid canal

central canal of bone

central canal of neural tube

central canal of spinal cord

cervical canal

Cloquet canal

cochlear canal

condylar canal

canal of Corti

craniopharyngeal canal

dental canal

Dorello canal

ethmoidal canal

external auditory canal

facial canal

fallopian canal

femoral canal

gastric canal

Guyon canal

Haversian canal

Huguier canal

Hunter canal

Huschke canal

hyaloid canal

hypoglossal canal

inferior alveolar canal

infraorbital canal

inguinal canal

interdental canal

internal auditory canal

intestinal canal

lacrimal canal

canal of Lambert

mandibular canal

mandibular incisive canal

maxillary canal

maxillary incisive canal

medullary canal

membranous semicircular canal

nasolacrimal canal

neurenteric canal

Nuck canal