Isthmus

An isthmus ( /ˈɪsθməs/ or /ˈɪsməs/;[1] plural: isthmuses; from Ancient Greek: ἰσθμός, romanizedisthmós, lit. 'neck')[2] is a narrow piece of land connecting two larger areas across an expanse of water by which they are otherwise separated.[3] A tombolo is an isthmus that consists of a spit or bar, and a strait is the sea counterpart of an isthmus.

Canals are often built across isthmuses, where they may be a particularly advantageous shortcut for marine transport. For example, the Panama Canal crosses the Isthmus of Panama, connecting the North Atlantic and Pacific Oceans; the Suez Canal connects the Mediterranean Sea and the Red Sea, cutting across the western side of the Isthmus of Suez, formed by the Sinai Peninsula; and the Crinan Canal crosses the isthmus between Loch Crinan and Loch Gilp, which connects the Kintyre peninsula with the rest of Scotland. Another example is the Welland Canal in the Niagara Peninsula (technically an isthmus). It connects Lake Ontario to Lake Erie. The city of Auckland in the North Island of New Zealand is situated on an isthmus.

The Neck Bruny Island
The sandy isthmus or tombolo "The Neck" connecting North and South Bruny Island in Tasmania, Australia

Isthmus vs land bridge vs peninsula

Isthmus and land bridge are related terms with isthmus having a broader meaning. A land bridge is an isthmus connecting the Earth's major landmasses. The term land bridge is usually used in biogeology to describe land connections that used to exist between continents at various times and were important for migration of people, and various species of animals and plants, e.g. Bering Land Bridge.[4]

An isthmus is a land connection between two bigger landmasses, while a peninsula is rather a land protrusion which is connected to a bigger landmass on one side only and surrounded by water on all other sides. Technically, an isthmus can have canals running from coast to coast (e.g. the Panama Canal), and thus resemble two peninsulas; however, canals are artificial features distinguished from straits.

Major isthmuses

Major isthmuses include the Isthmus of Panama and the Isthmus of Tehuantepec in the Americas, the Isthmus of Kra in South-East Asia, the Isthmus of Suez between Africa and Asia, and the Karelian Isthmus in Europe. Of historic importance was the Isthmus of Corinth in Greece.

See also

Aerial perspective of the isthmus of Bruny Island
Aerial perspective of the isthmus of Bruny Island

Notes

  1. ^ "Isthmus". Collins English Dictionary. Collins. Retrieved 19 December 2016.
  2. ^ LSJ entry ισθμός
  3. ^ "Isthmus". Britannica. Retrieved September 22, 2013.
  4. ^ britannica.com
Auckland City

Auckland City is the part of Auckland urban area covering the isthmus and most of the islands of the Hauraki Gulf. The core of Auckland City is the Auckland CBD, a major financial and commercial centre, surrounded by many suburbs. It was formerly the name of a local authority district that was governed by Auckland City Council; it lay within the wider Auckland Region, which was governed by Auckland Regional Council. Auckland City was disestablished as a local government district on 1 November 2010, when Auckland City Council was amalgamated with other councils of the Auckland Region into the new Auckland Council.

Auckland City was the most populous district in the country, with a population of 450,000 at 30 June 2010. In 2009, Auckland was rated the fourth-best place to live in the world, in human resources consultancy Mercer's annual survey.

Avalon Peninsula

The Avalon Peninsula is a large peninsula that makes up the southeast portion of the island of Newfoundland. It is 9,220 square kilometres (3,560 sq mi) in size.The peninsula is home to 262,410 people, about 51% of Newfoundland's population, according to the 2011 Canadian Census. The peninsula is the location of St. John's, the provincial capital and largest city. It is connected to the main section of the island by the 5 km (3 mi) wide Isthmus of Avalon. The peninsula protrudes into the rich fishing zones near the Grand Banks. Its four major bays (Trinity Bay, Conception Bay, St. Mary's Bay and Placentia Bay) have long been the centre of Newfoundland's fishing industry.

Disputed status of the isthmus between Gibraltar and Spain

The Gibraltar territory currently contains an 800-metre (2,625 ft) long section of the isthmus that links the Rock with mainland Spain. Spain does not acknowledge British sovereignty over Gibraltar beyond the fortified perimeter of the town as at 1704. The United Kingdom claims the southern part of the isthmus on the basis of continuous possession over a long period.

As well as the airport, there are two substantial housing estates, a sports stadium, a secondary school, a marina, and a beach on this land, which de facto is an integral part of the territory of Gibraltar.

Fallopian tube

The fallopian tubes, also known as uterine tubes or salpinges (singular salpinx) are uterine appendages, lined from inside with ciliated simple columnar epithelium, leading from the ovaries of female mammals into the uterus, via the uterotubal junction. They enable the passage of egg cells from the ovaries to the uterus. In non-mammalian vertebrates, the equivalent structures are just called oviducts.

Fauces (throat)

The fauces, isthmus of fauces, or the oropharyngeal isthmus, is the opening at the back of the mouth into the throat. It is a narrow passage between the pharynx and the base of the tongue.The fauces is a part of the oropharynx directly behind the oral cavity as a subdivision, bounded superiorly by the soft palate, laterally by the palatoglossal and palatopharyngeal arches, and inferiorly by the tongue. The arches form the pillars of the fauces. The anterior pillar is the palatoglossal arch formed of the palatoglossus muscle. The posterior pillar is the palatopharyngeal arch formed of the palatopharyngeus muscle. Between these two arches on the lateral walls of the oropharynx is the tonsillar fossa which is the location of the palatine tonsil. The arches are also known together as the palatine arches.

Each arch runs downwards, laterally and forwards, from the soft palate to the side of the tongue. The approximation of the arches due to the contraction of the palatoglossal muscles constricts the fauces, and is essential to swallowing.

Isthmus of Corinth

The Isthmus of Corinth is the narrow land bridge which connects the Peloponnese peninsula with the rest of the mainland of Greece, near the city of Corinth. The word "isthmus" comes from the Ancient Greek word for "neck" and refers to the narrowness of the land. The Isthmus was known in the ancient world as the landmark separating the Peloponnese from mainland Greece. In the first century AD the geographer Strabo noted a stele on the Isthmus of Corinth, which bore two inscriptions. One towards the East, i.e. towards Megara, reading: "Here is not Peloponnesus, but Ionia" (τάδ᾽ οὐχὶ Πελοπόννησος, ἀλλ᾽ Ἰωνία) and the one towards the West, i.e. towards the Peloponnese: "Here is Peloponnesus, not Ionia" (τάδ᾽ ἐστὶ Πελοπόννησος, οὐκ Ἰωνία); Plutarch ascribed the erection of the stele to the Attic hero Theseus, on his way to Athens.To the west of the Isthmus is the Gulf of Corinth, to the east the Saronic Gulf. Since 1893 the Corinth Canal has run through the 6.3 km wide isthmus, effectively making the Peloponnese an island. Today, two road bridges, two railway bridges and two submersible bridges at both ends of the canal connect the mainland side of the isthmus with the Peloponnese side. Also a military emergency bridge is located at the west end of the canal.

Isthmus of Panama

The Isthmus of Panama (Spanish: Istmo de Panamá), also historically known as the Isthmus of Darien (Istmo de Darién), is the narrow strip of land that lies between the Caribbean Sea and the Pacific Ocean, linking North and South America. It contains the country of Panama and the Panama Canal. Like many isthmuses, it is a location of great strategic value.

The isthmus formed around 2.8 million years ago, separating the Atlantic and Pacific Oceans and causing the creation of the Gulf Stream. This was first suggested in 1910 by North American paleontologist Henry Fairfield Osborn. He based the proposal on the fossil record of mammals in Central America. This conclusion provided a foundation for Alfred Wegener when he proposed the theory of continental drift in 1912.

Isthmus of Perekop

The Isthmus of Perekop (Ukrainian: Перекопський перешийок; translit. Perekops'kyy pereshyyok; Russian: Перекопский перешеек; translit. Perekopskiy peresheek Crimean Tatar: Or boynu, Turkish: Orkapı; Greek: Τάφρος; translit. Taphros) is the narrow, 5–7 kilometres (3.1–4.3 mi) wide strip of land that connects the Crimean Peninsula to the mainland of Ukraine. The isthmus is located between the Black Sea to the west and the Sivash to the east. The isthmus takes its name of Perekop from the Tatar fortress of Or Qapi.

The border between the Crimea republic and Ukraine's Kherson Oblast runs though the northern part of the isthmus. The cities of Perekop, Armyansk, Suvorovo and Krasnoperekopsk are situated on the isthmus. The North Crimean Canal ran through the isthmus, supplying Crimea with fresh water from the Dnieper River. The canal was closed by Ukraine in 2014, and the water supply was replaced by other local and Russian sources.

South of Perekop, there are rich salt ores which still are very important commercially for the region.

Isthmus of Tehuantepec

The Isthmus of Tehuantepec (Spanish pronunciation: [tewanteˈpek]) is an isthmus in Mexico. It represents the shortest distance between the Gulf of Mexico and the Pacific Ocean. Prior to the opening of the Panama Canal, it was a major shipping route known simply as the Tehuantepec Route. The name is taken from the town of Santo Domingo Tehuantepec in the state of Oaxaca; this was derived from the Nahuatl term tecuani-tepec ("jaguar hill").

Isthmus of cingulate gyrus

The cingulate gyrus commences below the rostrum of the corpus callosum, curves around in front of the genu, extends along the upper surface of the body, and finally turns downward behind the splenium, where it is connected by a narrow isthmus with the parahippocampal gyrus.

Karelian Isthmus

The Karelian Isthmus (Russian: Карельский перешеек, romanized: Karelsky peresheyek; Finnish: Karjalankannas; Swedish: Karelska näset) is the approximately 45–110 km (30–70 mi) wide stretch of land, situated between the Gulf of Finland and Lake Ladoga in northwestern Russia, to the north of the River Neva. Its northwestern boundary is the relatively narrow area between the Bay of Vyborg and Lake Ladoga. If the Karelian Isthmus is defined as the entire territory of present-day Saint Petersburg and Leningrad Oblast to the north of the Neva, the isthmus' area covers about 15,000 km2 (6,000 sq mi).

The smaller part of the isthmus to the southeast of the old Russia-Finland border is considered historically as Northern Ingria, rather than part of the Karelian Isthmus itself. The rest of the isthmus was historically a part of Finnish Karelia. This was conquered by the Russian Empire during the Great Northern War in 1712 and included within the autonomous Grand Duchy of Finland (1809–1917) of the Russian Empire. When Finland became independent in 1917, the isthmus (except for the territory roughly corresponding to present-day Vsevolozhsky District and some districts of Saint Petersburg) remained Finnish. Finnish Karelia was ceded to the Soviet Union by Finland following the Winter War (1939–1940) and Continuation War (1941–1944). In 1940–1941, during the Interim Peace, most of the ceded territories in the isthmus were included within the Karelo-Finnish SSR. However, since World War II the entire isthmus has been divided between the city of Saint Petersburg (mostly Kurortny District), as well as Priozersky District, Vsevolozhsky District and Vyborgsky District of Leningrad Oblast.

According to the 2002 census, the population of the Kurortny District of Saint Petersburg and the parts of Leningrad Oblast situated on the Karelian Isthmus amounts to 539,000. Many Saint Petersburg residents also decamp to the Isthmus during their vacations.

Kra Isthmus

The Kra Isthmus (Thai: คอคอดกระ, pronounced [kʰɔ̄ː kʰɔ̂ːt kràʔ]; Malay: Segenting Kra/Segenting Kera) is the narrowest part of the Malay Peninsula, in southern Thailand.The western part of the isthmus belongs to Ranong Province and the eastern part to Chumphon Province, both in Thailand. The isthmus is bordered to the west by the Andaman Sea and to the east by the Gulf of Thailand.The Kra Isthmus marks the boundary between two sections of the central cordillera, the mountain chain which runs from Tibet through the Malay peninsula. The southern part is called the Phuket chain, which is a continuation of the greater Tenasserim range, extending further northwards for over 400 km (250 mi) beyond the Three Pagodas Pass.On 8 December 1941 local time, the Imperial Japanese Army landed near Songkhla, Thailand and Kota Bharu, Malaya, thus beginning the Pacific War, and launching both the invasion of Thailand and the Malayan campaign, the latter of which culminated in the capture of Singapore.The Thai Canal is a proposal to join the Gulf of Thailand with the Andaman Sea. It was originally envisioned as crossing the isthmus.

Licence to Kill

Licence to Kill is a 1989 American-British spy film, the sixteenth in the James Bond film series produced by Eon Productions, and the last to star Timothy Dalton in the role of the fictional MI6 agent James Bond. It is the first one not to use the title of an Ian Fleming story. It is also the fifth and final consecutive Bond film to be directed by John Glen, also the last film to feature Robert Brown as M & Caroline Bliss as Miss Moneypenny. The story has elements of two Ian Fleming short stories and a novel, interwoven with aspects from Japanese Rōnin tales. The film sees Bond being suspended from MI6 as he pursues drug lord Franz Sanchez, who has ordered an attack against his CIA friend Felix Leiter and the murder of Felix's wife during their honeymoon. Originally titled Licence Revoked in line with the plot, the name was changed during post-production due to American test audiences associating the term with driving.

Budgetary reasons resulted in Licence to Kill becoming the first Bond film to be shot entirely outside the United Kingdom: principal photography took place on location in Mexico and the US, while interiors were filmed at Estudios Churubusco instead of Pinewood Studios. The film earned over $156 million worldwide, and enjoyed a generally positive critical reception, with ample praise for the stunts, but attracted some criticism for its significantly darker tone than its predecessors, which carried into Dalton's portrayal of the character.

Melville Peninsula

Melville Peninsula is a large peninsula in the Canadian Arctic north of Hudson Bay. To the east is Foxe Basin and to the west the Gulf of Boothia. To the north the Fury and Hecla Strait separates it from Baffin Island. To the south Repulse Bay and Frozen Strait separate it from Southampton Island at the north end of Hudson Bay. On the southwest it is connected to the mainland by the "Rae Isthmus" named after arctic explorer Dr John Rae.

Between 1821 and 1823 its east side was mapped by William Edward Parry. Since 1999, it has been part of Nunavut. Before that, it was part of the District of Franklin. Most of the peninsula lies in Nunavut's Qikiqtaaluk Region, while its southwesternmost section, around Repulse Bay, lies in the Kivalliq Region. Communities on the peninsula include the hamlets of Repulse Bay and Hall Beach. The hamlet of Igloolik is located on an island lying just off the northeastern coast of the peninsula.

Thyroid

The thyroid gland, or simply the thyroid, is an endocrine gland in the neck, consisting of two lobes connected by an isthmus. It is found at the front of the neck, below the Adam's apple. The thyroid gland secretes three hormones, namely the two thyroid hormones (thyroxine/T4 and triiodothyronine/T3), and calcitonin. The thyroid hormones primarily influence the metabolic rate and protein synthesis, but they also have many other effects, including effects on development. Calcitonin plays a role in calcium homeostasis.Hormonal output from the thyroid is regulated by thyroid-stimulating hormone (TSH) secreted from the anterior pituitary gland, which itself is regulated by thyrotropin-releasing hormone (TRH) produced by the hypothalamus.The thyroid may be affected by several diseases. Hyperthyroidism occurs when the gland produces excessive amounts of thyroid hormones, the most common cause being Graves' disease, an autoimmune disorder. In contrast, hypothyroidism is a state of insufficient thyroid hormone production. Worldwide, the most common cause is iodine deficiency. Thyroid hormones are important for development, and hypothyroidism secondary to iodine deficiency remains the leading cause of preventable intellectual disability. In iodine-sufficient regions, the most common cause of hypothyroidism is Hashimoto's thyroiditis, also an autoimmune disorder. In addition, the thyroid gland may also develop several types of nodules and cancer.

Trichilemmal cyst

A trichilemmal cyst, is a common cyst that forms from a hair follicle. They are most often found on the scalp. The cysts are smooth, mobile and filled with keratin, a protein component found in hair, nails, skin, and horns. They are, however, clinically and histologically distinct from trichilemmal horns, which are much more rare and not limited to the scalp. Trichilemmal cysts may run in families and they may or may not be inflamed and tender, often depending on whether they have ruptured. Rarely, these cysts may grow more extensively and form rapidly multiplying trichilemmal tumors, also called proliferating trichilemmal cysts, which are benign but may grow aggressively at the cyst site. Very rarely, trichilemmal cysts can become cancerous.

Two Harbors, California

Two Harbors, colloquially known as "The Isthmus", is a small unincorporated community island village on Santa Catalina Island, California, with a population of 298 (Census of 2000). It is the second center of population on the island, besides the city of Avalon. It is mainly a resort village. It has only one restaurant, one hotel and one general store. The village has about 150 permanent residents who live on the isthmus year-round. One notable feature was the one-room schoolhouse which closed in 2014.

Winter War

The Winter War was a military conflict between the Soviet Union (USSR) and Finland. It began with a Soviet invasion of Finland on 30 November 1939, three months after the outbreak of World War II, and ended three and a half months later with the Moscow Peace Treaty on 13 March 1940. The League of Nations deemed the attack illegal and expelled the Soviet Union from the organisation.

The conflict began after the Soviets sought to obtain some Finnish territory, demanding among other concessions that Finland cede substantial border territories in exchange for land elsewhere, claiming security reasons—primarily the protection of Leningrad, 32 km (20 mi) from the Finnish border. Finland refused, so the USSR invaded the country. Many sources conclude that the Soviet Union had intended to conquer all of Finland, and use the establishment of the puppet Finnish Communist government and the Molotov–Ribbentrop Pact's secret protocols as evidence of this, while other sources argue against the idea of the full Soviet conquest. Finland repelled Soviet attacks for more than two months and inflicted substantial losses on the invaders while temperatures ranged as low as −43 °C (−45 °F). After the Soviet military reorganised and adopted different tactics, they renewed their offensive in February and overcame Finnish defences.

Hostilities ceased in March 1940 with the signing of the Moscow Peace Treaty. Finland ceded 11 percent of its territory representing 30 percent of its economy to the Soviet Union. Soviet losses were heavy, and the country's international reputation suffered. Soviet gains exceeded their pre-war demands and the USSR received substantial territory along Lake Ladoga and in northern Finland. Finland retained its sovereignty and enhanced its international reputation. The poor performance of the Red Army encouraged Adolf Hitler to think that an attack on the Soviet Union would be successful and confirmed negative Western opinions of the Soviet military. After 15 months of Interim Peace, in June 1941, Nazi Germany commenced Operation Barbarossa and the Continuation War between Finland and the USSR began.

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