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59-410: A rib is a bone attached to the spine, in vertebrate animals. Rib , ribs or RIB may also refer to: Rib Human ribs are flat bones that form part of the rib cage to help protect internal organs. Humans usually have 24 ribs, in 12 pairs. 1 in 500 people have an extra rib known as a cervical rib . People may have a cervical rib on the right, left or both sides. All are attached at

118-418: 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 radiate outward from the central tendon. While the diaphragm is one muscle, it is composed of two distinct muscle regions: the costal, which serves as

177-421: A pneumoperitoneum , in which there is gas in the abdomen. An X-ray may also be used to check for herniation. The adoption of a deeper breathing pattern typically occurs during physical exercise in order to facilitate greater oxygen absorption. During this process the diaphragm more consistently adopts a lower position within the body's core. In addition to its primary role in breathing, the diaphragm also plays

236-437: A lower position to facilitate a higher IAP. Therefore, if a person's diaphragm position is lower in general, through deep breathing, then this assists the strengthening of their core during that period. This can be an aid in strength training and other forms of athletic endeavour. For this reason, taking a deep breath or adopting a deeper breathing pattern is typically recommended when lifting heavy weights. The existence of

295-399: A membrane separating the pharynx from the stomach can be traced widely among the chordates . Thus the model organism , the marine chordate lancelet , possesses an atriopore by which water exits the pharynx, which has been claimed (and disputed) to be homologous to structures in ascidians and hagfishes . The tunicate epicardium separates digestive organs from the pharynx and heart, but

354-400: A secondary role in strengthening the posture of the core. This is especially evident during deep breathing where its generally lower position increases intra-abdominal pressure, which serves to strengthen the lumbar spine. The key to real core stabilization is to maintain the increased IAP while going through normal breathing cycles. [...] The diaphragm then performs its breathing function at

413-459: A single set of ribs which are probably homologous with the dorsal ribs of fishes. In the earlier choanates , every vertebra bore a pair of ribs, although those on the thoracic vertebrae are typically the longest. The sacral ribs were stout and short, since they formed part of the pelvis , connecting the backbone to the hip bones . In most true tetrapods, many of these early ribs have been lost, and in living amphibians and reptiles , there

472-576: A slab; five or more is known as a rack , as in a rack of lamb . Short ribs are ribs of beef either served singly or several as a plate . A rib steak from beef is a popular choice used in many cuisines . Pork ribs , including spare ribs are popular in European and Asian cuisine . Thoracic diaphragm The thoracic diaphragm , or simply the diaphragm ( / ˈ d aɪ ə f r æ m / ; Ancient Greek : διάφραγμα , romanized :  diáphragma , lit.   'partition'),

531-491: A thin diaphragm leads to greater lung compliance, which can contribute to respiratory failure. Furthermore, reduction in diaphragm thickness during the early stages of disease can serve as a prognostic marker in sepsis patients, and COVID-19 patients. The diaphragm is also involved in non-respiratory functions. It helps to expel vomit , feces , and urine from the body by increasing intra-abdominal pressure, aids in childbirth, and prevents acid reflux by exerting pressure on

590-457: Is a rough elevation and affords attachment to the ligament of the tubercle. The tubercle is much more prominent in the upper ribs than in the lower ribs. The first seven sets of ribs, known as " true ribs ", are attached to the sternum by the costal cartilages . The first rib is unique and easier to distinguish than other ribs. It is a short, flat, C-shaped bone, and attaches to the manubrium. The vertebral attachment can be found just below

649-424: Is a sheet of internal skeletal muscle in humans and other mammals that extends across the bottom of the thoracic cavity . The diaphragm is the most important muscle of respiration , and separates the thoracic cavity , containing the heart and lungs , from the abdominal cavity : as the diaphragm contracts, the volume of the thoracic cavity increases, creating a negative pressure there, which draws air into

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708-399: Is about 3 cm long. Its anterior surface is flat and smooth, whilst its posterior is perforated by numerous foramina and its surface rough, to give attachment to the ligament of the neck. Its upper border presents a rough crest ( crista colli costae ) for the attachment of the anterior costotransverse ligament ; its lower border is rounded. A tubercle of rib on the posterior surface of

767-400: Is great variation in rib structure and number. For example, turtles have only eight pairs of ribs, which are developed into a bony or cartilaginous carapace and plastron , while snakes have numerous ribs running along the full length of their trunk. Frogs typically have no ribs, aside from a sacral pair, which form part of the pelvis. In birds, ribs are present as distinct bones only on

826-405: Is higher up (superior) to the left half, since the large liver rests beneath the right half of the diaphragm. There is also speculation that the diaphragm is lower on the other side due to heart's presence. Other mammals have diaphragms, and other vertebrates such as amphibians and reptiles have diaphragm-like structures, but important details of the anatomy may vary, such as the position of

885-402: Is that between the tubercle on the neck and the transverse process of the joining thoracic vertebra of the same rib number, and this is known as the costotransverse joint . The superior costotransverse ligament attaches from the non-articular facet of the tubercle to the transverse process of the vertebra. The neck of the rib is a flattened part that extends laterally from the head. The neck

944-415: The cardia of the stomach and the oesophagus disappear. Not all hiatus hernias cause symptoms however, although almost all people with Barrett's oesophagus or oesophagitis have a hiatus hernia. Hernias may also occur as a result of congenital malformation, a congenital diaphragmatic hernia . When the pleuroperitoneal membranes fail to fuse, the diaphragm does not act as an effective barrier between

1003-401: The esophagus as it passes through the esophageal hiatus . In some non-human animals, the diaphragm is not crucial for breathing; a cow, for instance, can survive fairly asymptomatically with diaphragmatic paralysis as long as no massive aerobic metabolic demands are made of it. If either the phrenic nerve , cervical spine or brainstem is damaged, this will sever the nervous supply to

1062-417: The inferior vena cava and left suprarenal vein . The sternal portion of the muscle is sometimes wanting and more rarely 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 ,

1121-432: The internal intercostal muscles used in conjunction with the abdominal muscles , which act as an antagonist paired with the diaphragm's contraction. Diaphragm dysfunction is a well-known factor associated with various complications in patients, such as prolonged respiratory failure, difficulties in weaning from mechanical ventilation, extended hospitalization, increased morbidity, and mortality. Studies have reported that

1180-424: The neck at the first thoracic vertebra, and the majority of this bone can be found above the level of the clavicle . Ribs 2 through 7 then become longer and less curved as they progress downwards. The following five sets are known as " false ribs ", three of these sharing a common cartilaginous connection to the sternum, while the last two (eleventh and twelfth ribs) are termed floating ribs . They are attached to

1239-433: The thorax and abdomen , fluid abnormally present in the thorax, or air abnormally present in the abdomen, may collect on one side of the diaphragm. An X-ray may reveal this. Pleural effusion , in which there is fluid abnormally present between the two pleurae of the lungs , is detected by an X-ray of the chest, showing fluid collecting in the angle between the ribs and diaphragm . An X-ray may also be used to reveal

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1298-426: The ventral ribs arise from the vertebral column just below the dorsal ribs, and enclose the lower body, often joining at the tips. Not all species possess both types of rib, with the dorsal ribs being most commonly absent. Sharks , for example, have no ventral ribs, and only very short dorsal ribs. In some teleosts , there may be additional rib-like bones within the muscle mass. Tetrapods , however, only ever have

1357-446: The vertebrae only, and not to the sternum or cartilage coming off of the sternum. In general, human ribs increase in length from ribs 1 through 7 and decrease in length again through rib 12. Along with this change in size, the ribs become progressively oblique (slanted) from ribs 1 through 9, then less slanted through rib 12. The rib cage is separated from the lower abdomen by the thoracic diaphragm which controls breathing. When

1416-513: The abdomen and thorax. Herniation is usually of the left, and commonly through the posterior lumbocostal triangle , although rarely through the anterior foramen of Morgagni . The contents of the abdomen, including the intestines , may be present in the thorax, which may impact development of the growing lungs and lead to hypoplasia . This condition is present in 0.8 - 5/10,000 births. A large herniation has high mortality rate, and requires immediate surgical repair. Due to its position separating

1475-482: The alligator diaphragmaticus muscle does not insert on the esophagus and does not affect pressure of the lower esophageal sphincter. The lungs are located in the abdominal compartment of amphibians and reptiles, so that contraction of the diaphragm expels air from the lungs rather than drawing it into them. In birds and mammals, lungs are located above the diaphragm. The presence of an exceptionally well-preserved fossil of Sinosauropteryx , with lungs located beneath

1534-450: The anus returns to the upper compartment to discharge wastes through an outgoing siphon. Thus the diaphragm emerges in the context of a body plan that separated an upper feeding compartment from a lower digestive tract, but the point at which it originates is a matter of definition. Structures in fish, amphibians, reptiles, and birds have been called diaphragms, but it has been argued that these structures are not homologous . For instance,

1593-425: The back to the thoracic vertebrae and are numbered from 1 to 12 according to the vertebrae to which they attach. The first rib is attached to thoracic vertebra 1 (T1). At the front of the body, most of the ribs are joined by costal cartilage to the sternum . Ribs connect to vertebrae at the costovertebral joints . The parts of a rib includes the head, neck, body (or shaft ), tubercle, and angle. The head of

1652-406: The center of the vault formed by the muscle, closer to the front than to the back of the thorax . The central part of the tendon is attached above to pericardium . The both sides of the posterior fibres are attached to paracolic gutters (the curving of ribs before attaching to both sides of the vertebral bodies). There are a number of openings in the diaphragm through which structures pass between

1711-440: The cervical and lumbar ribs are found only as tiny remnants fused to the vertebrae, where they are referred to as transverse processes . In general, the structure and number of the true ribs in humans is similar to that in other mammals. Unlike reptiles, caudal ribs are never found in mammals. Ribs as food are widely used from many animals. The ribs are the less meaty part of the meat chop and they are often cooked as part of

1770-419: The cervical spinal cord (C3,4, and 5). As the septum transversum descends inferiorly, the phrenic nerve follows, accounting for its circuitous route from the upper cervical vertebrae, around the pericardium , finally to innervate the diaphragm. The diaphragm is the main muscle of respiration and functions in breathing . During inhalation, the diaphragm contracts and moves in the inferior direction, enlarging

1829-419: The diaphragm as in crocodiles, has been used to argue that dinosaurs could not have sustained an active warm-blooded physiology, or that birds could not have evolved from dinosaurs. An explanation for this (put forward in 1905), is that lungs originated beneath the diaphragm, but as the demands for respiration increased in warm-blooded birds and mammals, natural selection came to favor the parallel evolution of

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1888-399: The diaphragm contracts, the thoracic cavity is expanded, reducing intra-thoracic pressure and drawing air into the lungs. This happens through one of two actions (or a mix of the two): when the lower ribs the diaphragm connects to are stabilized by muscles and the central tendon is mobile, when the muscle contracts the central tendon is drawn down, compressing the cavity underneath and expanding

1947-458: The diaphragm receives blood from branches of the internal thoracic arteries , namely the pericardiacophrenic artery and musculophrenic artery ; from the superior phrenic arteries , which arise directly from the thoracic aorta ; and from the lower internal intercostal arteries . From below, the inferior phrenic arteries supply the diaphragm. The diaphragm drains blood into the brachiocephalic veins , azygos veins , and veins that drain into

2006-444: The diaphragm. The diaphragm is primarily innervated by the phrenic nerve which is 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 (T5–T11) and subcostal nerves (T12). Arteries and veins above and below the diaphragm supply and drain blood. From above,

2065-418: The diaphragm. The most common damage to the phrenic nerve is by bronchial cancer , which usually only affects one side of the diaphragm. Other causes include Guillain–Barré syndrome and systemic lupus erythematosus . A hiatus hernia is a hernia common in adults in which parts of the lower esophagus or stomach that are normally in the abdomen pass/bulge abnormally through the diaphragm and are present in

2124-527: The driver in the work of breathing, and crural diaphragm, which serves as an "anchor;" attaching the muscle to the lower ribs and lumbar vertebrae. The costal diaphragm is further divided into ventral, medial, and dorsal costal portions. The vertebral part of the diaphragm arises from the crura and arcuate ligaments. Right crus arises from L1-L3 vertebral bodies and their intervertebral discs. Smaller left crus arises from L1, L2 vertebral bodies and their intervertebral discs. Medial arcuate ligament arises from

2183-414: The fascia thickening from body of L2 vertebrae to transverse process of L1 vertebrae, crossing over the body of the psoas major muscle. The lateral arcuate ligament arises from the transverse process of L1 vertebrae and is attached laterally to the 12th rib. The lateral arcuate ligament also arises from fascia thickening that covers the quadratus lumborum muscle. The median arcuate ligament arises from

2242-406: The fibrous parts of right and left crura where descending thoracic aorta passes behind it. No diaphramatic muscle arises from the median arcuate ligament. Both adrenal glands lie near the diaphragmatic crus and arcuate ligament. The costal part of diaphragm arises from the lower four ribs (7 to 10) costal cartilages. The central tendon of the diaphragm is a thin but strong aponeurosis near

2301-444: The fixed-volume, non-expansive lungs. A complicated system of valves and air sacs cycles air constantly over the absorption surfaces of the lungs so allowing maximal efficiency of gaseous exchange. Thus, birds do not have the reciprocal tidal breathing flow of mammals. On careful dissection, around eight air sacs can be clearly seen. They extend quite far caudally into the abdomen. [REDACTED] This article incorporates text in

2360-403: The head and neck. During adolescence secondary ossification centers are formed in the tubercles and heads of the ribs. In jawed fish , there are often two sets of ribs attached to the vertebral column. One set, the dorsal ribs , are found in the dividing septum between the upper and lower parts of the main muscle segments, projecting roughly sideways from the vertebral column. The second set,

2419-419: The heart. The aorta does not pierce the diaphragm but rather passes behind it in between the left and right crus. There are several structures that pierce through the diaphragm, including: left phrenic nerve pierces through the central tendon, greater, lesser, and least thoracic splanchnic nerves pierces through bilateral crura, and lymphatic vessels that pierce throughout the diaphragam, especially behind

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2478-427: The herniation of the lungs from the abdominal cavity in both lineages. However, birds do not have diaphragms. They do not breathe in the same way as mammals and do not rely on creating a negative pressure in the thoracic cavity, at least not to the same extent. They rely on a rocking motion of the keel of the sternum to create local areas of reduced pressure to supply thin, membranous airsacs cranially and caudally to

2537-405: The insertion (central tendon) which works in conjunction with other muscles to allow the ribs to slide and the thoracic cavity to expand laterally and upwards. When the diaphragm relaxes (moves in the superior direction), air is exhaled by elastic recoil process of the lung and the tissues lining the thoracic cavity. Assisting this function with muscular effort (called forced exhalation ) involves

2596-408: The lower ribs are stabilized and the central tendon of the diaphragm is mobile, a contraction brings the insertion (central tendon) towards the origins and pushes the lower cavity towards the pelvis, allowing the thoracic cavity to expand downward. This is often called belly breathing . When the central tendon is stabilized and the lower ribs are mobile, a contraction lifts the origins (ribs) up towards

2655-476: The lungs in the thoracic cavity. The diaphragm is an upward curved, c-shaped structure of muscle and fibrous tissue that separates the thoracic cavity from the abdomen. The superior surface of the dome forms the floor of the thoracic cavity, and 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

2714-431: The lungs. Its high oxygen consumption is noted by the many mitochondria and capillaries present; more than in any other skeletal muscle. 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" generally refers to the thoracic diaphragm. In humans, the diaphragm is slightly asymmetric—its right half

2773-429: The neck of the rib, has two facets (surfaces) one articulating and one non-articulating. The articular facet, is small and oval and is the lower and more medial of the two, and connects to the transverse costal facet on the thoracic vertebra of the same rib number. The transverse costal facet is on the end of the transverse process of the lower of the two vertebrae to which the head is connected. The non-articular portion

2832-415: The opening is stretched open every time inspiration occurs. However, there has been argument that the caval opening actually 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

2891-403: The presumptive esophagus, forming a barrier that separates the peritoneal and pleuropericardial cavities. Furthermore, dorsal mesenchyme surrounding the presumptive esophagus form the muscular crura of the diaphragm. Because the earliest element of the embryological diaphragm, the septum transversum, forms in the cervical region, the phrenic nerve that innervates the diaphragm originates from

2950-447: 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 gut and 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

3009-399: The rib lies next to a vertebra. The ribs connect to the vertebrae with two costovertebral joints, one on the head and one on the neck. The head of the rib has a superior and an inferior articulating region, separated by a crest. These articulate with the superior and inferior costal facets on the connecting vertebrae. The crest gives attachment to the intra-articulate ligament that joins

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3068-404: The rib to the vertebra of the same number, at the intervertebral disc . Another ligament , the radiate ligament joins the head of the rib to both the body of the upper vertebra and to the body of the lower vertebra. The smaller middle part of the ligament connects to the intervertebral disc. This plane joint is known as the articulation of the head of the rib . The other costovertebral joint

3127-399: The ribs from the vertebrae. The first seven pairs of ribs, the true ribs join at the front to the sternal bars. By the fetal stage the sternal bars have completely fused. The ribs begin as cartilage that later ossifies – a process called endochondral ossification . Primary ossification centers are located near the angle of each rib, and ossification continues in the direction away from

3186-414: The sclerotomes. During the fourth week ( fertilization age ) costal processes have formed on the vertebral bodies. These processes are small, lateral protrusions of mesenchyme that develop in association with the vertebral arches. During the fifth week the costal processes on the thoracic vertebrae become longer to form the ribs. In the sixth week, the costovertebral joints begin to develop and separate

3245-425: The thoracic cavity downward. When the central tendon is stabilized and the lower ribs are mobile, a contraction of the diaphragm elevates the ribs, which works in conjunction with other muscles to expand the thoracic indent upward. Early in the developing embryo , somites form and soon subdivide into three mesodermal components – the myotome , dermatome , and the sclerotome . The vertebrae and ribs develop from

3304-406: The thoracic region, although small fused ribs are present on the cervical vertebrae . The thoracic ribs of birds possess a wide projection to the rear; this uncinate process is an attachment for the shoulder muscles. Usually dogs have 26 ribs. Mammals usually also only have distinct ribs on the thoracic vertebra, although fixed cervical ribs are also present in monotremes . In therian mammals,

3363-464: The thorax and abdomen. There are three large openings — one for the aorta ( aortic hiatus ), one for the esophagus ( esophageal hiatus ), and one for the inferior vena cava (the caval opening ), as well as a series of smaller openings. 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,

3422-413: The thorax. Hernias are described as rolling , in which the hernia is beside the oesophagus, or sliding , in which the hernia directly involves the esophagus. These hernias are implicated in the development of reflux, as the different pressures between the thorax and abdomen normally act to keep pressure on the esophageal hiatus . With herniation, this pressure is no longer present, and the angle between

3481-435: The volume of the thoracic cavity and reducing intra-thoracic pressure (the external intercostal muscles also participate in this enlargement), forcing the lungs to expand. In other words, the diaphragm's movement downwards creates a partial vacuum in the thoracic cavity, which forces the lungs to expand to fill the void, drawing air in the process. Cavity expansion happens in two extremes, along with intermediary forms. When

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