Thoracic diaphragm

The thoracic diaphragm, or the diaphragm, is a sheet of internal skeletal muscle in humans and other mammals that extends across the bottom of the thoracic cavity. The diaphragm separates the thoracic cavity, containing the heart and lungs, from the abdominal cavity and performs an important function in respiration: as the diaphragm contracts, the volume of the thoracic cavity increases, creating a negative pressure there, which draws air into the lungs; the term diaphragm in anatomy, created by Gerard of Cremona, can refer to other flat structures such as the urogenital diaphragm or pelvic diaphragm, but "the diaphragm" refers to the thoracic diaphragm. In humans, the diaphragm is asymmetric—its right half is higher up to the left half, since the large liver rests beneath the right half of the diaphragm. There is a theory that the diaphragm is lower on the other side due to the presence of the heart. Other mammals have diaphragms, other vertebrates such as amphibians and reptiles have diaphragm-like structures, but important details of the anatomy vary, such as the position of the lungs in the abdominal cavity.

The diaphragm is a C-shaped structure of muscle and fibrous tissue that separates the thoracic cavity from the abdomen. The dome curves upwards; the superior surface of the dome forms the floor of the thoracic cavity, the inferior surface the roof of the abdominal cavity. As a dome, the diaphragm has peripheral attachments to structures that make up the abdominal and chest walls; the muscle fibres from these attachments converge in a central tendon, which forms the crest of the dome. Its peripheral part consists of muscular fibers that take origin from the circumference of the inferior thoracic aperture and converge to be inserted into a central tendon; the muscle fibres of the diaphragm emerge from many surrounding structures. At the front, fibres insert along the costal margin. Laterally, muscle fibers insert into ribs 6–12. In the back, muscle fibres insert into the vertebra at T12 and two appendages, the right and left crus and insert into the lumbar vertebrae. Right crus arises from L1-L3 their intervertebral discs.

Left crus from L1. There are a medial and a lateral, on either side; the left and right crura are tendons that blend with the anterior longitudinal ligament of the vertebral column. The central tendon of the diaphragm is a thin but strong aponeurosis near the center of the vault formed by the muscle, closer to the front than to the back of the thorax, so that the posterior muscular fibers are the longer. There are a number of openings in the diaphragm through which structures pass between the thorax and abdomen. There are three large openings—the aortic, the esophageal, the caval opening—plus a series of smaller ones; the inferior vena cava passes through the caval opening, a quadrilateral opening at the junction of the right and middle leaflets of the central tendon, so that its margins are tendinous. Surrounded by tendons, the opening is stretched open. However, there has been argument that the caval opening constricts during inspiration. Since thoracic pressure decreases upon inspiration and draws the caval blood upwards toward the right atrium, increasing the size of the opening allows more blood to return to the heart, maximizing the efficacy of lowered thoracic pressure returning blood to the heart.

The aorta does not pierce the diaphragm but rather passes behind it in between the left and right crus. The thoracic spinal levels at which the three major structures pass through the diaphragm can be remembered by the number of letters contained in each structure: Vena Cava – Passes through the diaphragm at T8. Oesophagus – Passes through the diaphragm at T10. Aortic Hiatus – Descending aorta passes through the diaphragm at T12; the diaphragm is innervated by the phrenic nerve, formed from the cervical nerves C3, C4 and C5. While the central portion of the diaphragm sends sensory afferents via the phrenic nerve, the peripheral portions of the diaphragm send sensory afferents via the intercostal and subcostal nerves. Arteries and veins above and below the diaphragm supply and drain blood. From above, the diaphragm receives blood from branches of the internal thoracic arteries, namely the pericardiacophrenic artery and musculophrenic artery. From below, the inferior phrenic arteries supply the diaphragm.

The diaphragm drains blood into the brachiocephalic veins, azygos veins, veins that drain into the inferior vena cava and left suprarenal vein. The sternal portion of the muscle is sometimes wanting and more defects occur in the lateral part of the central tendon or adjoining muscle fibers; the thoracic diaphragm develops during embryogenesis, beginning in the third week after fertilization with two processes known as transverse folding and longitudinal folding. The septum transversum, the primitive central tendon of the diaphragm, originates at the rostral pole of the embryo and is relocated during longitudinal folding to the ventral thoracic region. Transverse folding brings the body wall anteriorly to enclose the body cavities; the pleuroperitoneal membrane and body wall myoblasts, from somatic lateral plate mesoderm, meet the septum transversum to close off the pericardio-peritoneal canals on either side of the presumptive esophagus, forming a barrier that separates the peritoneal and pleuropericardial cavities.

Furthermore, dorsal mesenchyme surrounding the presumptive esophagus form the


Al-Mu'ayyad was the third son of the Abbasid caliph, al-Mutawakkil and the brother of al-Muntasir and al-Mu'tazz, who both would become Caliphs as well. In 860, al-Mutawakkil seemed to favour al-Muntasir. However, this appeared to change and al-Muntasir feared his father was going to move against him. With the implicit support of the Turkish faction of the army, he ordered the assassination of al-Mutawakkil, carried out by a Turkish soldier on December 11, 861; the Turkish party prevailed on al-Muntasir to remove his brothers from the succession, fearing revenge for the murder of their father. In their place, he was to appoint his son as heir-apparent. On April 27, 862 both brothers, al-Mu ` al-Mu ` tazz, wrote a statement of abdication. Al-Muntasir's reign lasted for half a year and ended with his death of unknown causes on 862. After the death of al-Muntasir, the Turkish chiefs assembled in a council to select his successor, they did not want to elect al-Mu'ayyad or any of the brothers. In 866, al-Musta ` al-Mu ` tazz came into power.

Upon becoming the new Caliph, al-Mu'tazz had the former Caliph al-Musta'in executed. The Turkish soldiery, after a brawl with the Maghariba troops, now turned their support to al-Mu'ayyad. Enraged by this predicament, the jealous Caliph had his brother, al-Mu'ayyad, being next heir to the throne, imprisoned along with another brother, Abu Ahmad, who had bravely led the troops in the late struggle on his side; the Turks al-Mu ` tazz, the more alarmed, resolved on his death. He was smothered in a downy robe; this period saw the rise of a legend that an Abbasid prince had converted to Christianity under the influence of Theodore of Edessa, taken the name "John" and been killed for his apostasy. However, there is no Christian or Muslim record remotely associating Muayyad with Christianity or indeed, religious speculation; the motives for his murder seem to have been purely political. This text is adapted from William Muir's public domain work, The Caliphate: Its Rise and Fall

Salinas Natural Monument

The Salinas Natural Monument is a natural monument comprising saline springs and forested mountains in southern Cagayan Valley in the Philippines. It is one of four protected areas in the landlocked province of Nueva Vizcaya spanning an area of 6,675.56 hectares in the municipalities of Bambang and Aritao. The park was established on 18 May 1914 as the Salinas Forest Reserve covering the Salinas Salt Springs and surrounding forest through Executive Order No. 44 signed by Governor-General Francis Burton Harrison. In 1926, through amendments made in Proclamation No. 53 by Governor-General Leonard Wood, the forest reserve was re-established as the Salinas Deer Refuge. Salinas was declared a natural monument in 2000 under the National Integrated Protected Areas System through Proclamation No. 275 by President Joseph Estrada. The natural monument is centered on the mountain of salt mines in the barangay of the same name in Bambang municipality near the confluence of Magat River and Santa Cruz River in the Upper Magat River Basin.

This once snow-white mountain of travertine situated on the southeastern slopes of the Cordillera Central contains the Salinas Salt Springs, a popular attraction in the province during the early days of Spanish and American colonial periods. The mountain of salt was formed through the continuous flow of a natural spring containing sulfate and carbonate salts over millions of years; when the 1990 Luzon earthquake hit the area, tectonic movements caused the underground water to be diverted leaving the whitish mounds dry and causing them to turn gray. At present, this mountain at Sitio Bansing once known for its salt industry is being utilized as fishponds arranged in terraces on the mountainside for freshwater fish such as tilapia and African sharptooth catfish, including the giant freshwater prawn; the surrounding forest inhabited by numerous Philippine deers spreads over the villages of Salinas and Barat in Bambang, Mapayao and San Fabian in Kayapa, Baan in Aritao just north of Caraballo Sur.

It is located 80 kilometres south of the region's commercial center of Santiago and some 120 kilometres from the Cauayan Airport. It is accessible via a 15-kilometre road from the Pan-Philippine Highway in Bambang. On June 22, 2018, the Salinas Natural Monument was designated a national park through the Expanded National Integrated Protected Areas System Act or Republic Act No. 11038, signed by President Rodrigo Duterte. Bangan Hill National Park