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65-412: 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 the back to the thoracic vertebrae and are numbered from 1 to 12 according to the vertebrae to which they attach. The first rib

130-418: 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

195-421: 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

260-496: A common cartilaginous connection to the sternum, while the last two (eleventh and twelfth ribs) are termed floating ribs . They are attached to 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

325-437: 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

390-408: A matrix of canals. They form a ring in between the membranes, and begin to expand outwards. As they expand they make a bony matrix. This hardened matrix forms the body of the bone. Since flat bones are usually thinner than the long bones , they only have red bone marrow , rather than both red and yellow bone marrow (yellow bone marrow being made up of mostly fat). The bone marrow fills the space in

455-399: 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

520-400: 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

585-460: 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 . Flat bone Flat bones are bones whose principal function is either extensive protection or

650-491: 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

715-411: A variable quantity of cancellous bone , which is the location of red bone marrow . In an adult, most red blood cells are formed in flat bones. In the cranial bones , the layers of compact tissue are familiarly known as the tables of the skull; the outer one is thick and tough; the inner is thin, dense, and brittle, and hence is termed the vitreous (glass-like) table. The intervening cancellous tissue

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780-424: 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

845-401: 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 the rib lies next to a vertebra. The ribs connect to the vertebrae with two costovertebral joints, one on

910-494: Is called the diploë , and this, in the nasal region of the skull, becomes absorbed so as to leave spaces filled with air–the paranasal sinuses between the two tables. Ossification is started by the formation of layers of undifferentiated connective tissue that hold the area where the flat bone is to come. On a baby, those spots are known as fontanelles . The fontanelles contain connective tissue stem cells , which form into osteoblasts , which secrete calcium phosphate into

975-399: 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

1040-405: 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

1105-435: 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 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

1170-412: Is separated from the lower abdomen by the thoracic diaphragm which controls breathing. When 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

1235-415: 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

1300-401: 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

1365-417: 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 ,

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1430-432: 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

1495-414: The myotome , dermatome , and the sclerotome . The vertebrae and ribs develop from 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

1560-501: 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 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

1625-433: 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

1690-470: 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 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

1755-513: 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

1820-482: 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

1885-441: The angle of each rib, and ossification continues in the direction away from 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

1950-450: 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,

2015-470: The bone grows, its shape changes. The osteoclasts dissolve the part of the bone that must change. [REDACTED] This article incorporates text in the public domain from page 79 of the 20th edition of Gray's Anatomy (1918) Thoracic diaphragm The thoracic diaphragm , or simply the diaphragm ( / ˈ d aɪ ə f r æ m / ; Ancient Greek : διάφραγμα , romanized :  diáphragma , lit.   'partition'),

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2080-406: The bone. A third type of bone cell found in flat bones is called an osteoclast , which destroys the bone using enzymes. There are three reasons that osteoclasts are normally used: the first is for the reparation of bones after a break. They destroy sections of bone that protrude or make reformation difficult. They are also used to obtain necessary calcium that osteoclasts are used is for growing. As

2145-406: 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

2210-421: The central tendon is drawn down, compressing the cavity underneath and expanding 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 –

2275-439: 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

2340-419: 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

2405-419: 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

2470-458: 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

2535-444: 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,

2600-418: 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

2665-527: 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

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2730-414: 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

2795-406: 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

2860-444: 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

2925-414: 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 the rib to the vertebra of the same number, at the intervertebral disc . Another ligament , the radiate ligament joins

2990-415: 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 is that between the tubercle on the neck and the transverse process of the joining thoracic vertebra of the same rib number, and this

3055-419: 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

3120-427: 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

3185-405: 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

3250-422: 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 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

3315-408: 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

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3380-476: 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

3445-431: 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

3510-514: The muscle mass. Tetrapods , however, only ever have 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

3575-415: 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

3640-403: 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

3705-447: 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

3770-425: The provision of broad surfaces for muscular attachment. These bones are expanded into broad, flat plates , as in the cranium ( skull ), the ilium, ischium, and pubis ( pelvis ), sternum and the rib cage . The flat bones are: the occipital , parietal , frontal , nasal , lacrimal , vomer , sternum , ribs , and scapulae . These bones are composed of two thin layers of compact bone enclosing between them

3835-406: The ribs. In the sixth week, the costovertebral joints begin to develop and separate 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

3900-413: The ring of osteoblasts, and eventually fills the bony matrix. After the bone is completely ossified, the osteoblasts retract their calcium phosphate secreting tendrils, leaving tiny canals in the bony matrix, known as canaliculi . These canaliculi provide the nutrients needed for the newly transformed osteoblasts, which are now called osteocytes . These cells are responsible for the general maintenance of

3965-405: 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,

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4030-464: 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,

4095-413: 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

4160-407: The vertebral column. The second set, 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

4225-435: 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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