Thoracic diaphragm 321567 222662533 2008-06-30T14:20:48Z Les boys 7373191 Reverted edits by [[Special:Contributions/75.16.213.120|75.16.213.120]] to last version by Gracillis (using [[WP:HG|Huggle]]) {{Infobox Anatomy | Name = Diaphragm | Latin = diaphragma | GraySubject = 117 | GrayPage = 404 | Image = Respiratory system.svg | Caption = Respiratory system | Image2 = | Caption2 = batty | Artery = [[Pericardiacophrenic artery]], [[Musculophrenic artery]], [[Inferior phrenic arteries]] | Vein = [[Superior phrenic vein]], [[Inferior phrenic vein]] | Nerve = [[Phrenic nerve|phrenic]] and lower [[intercostal nerves]] | Lymph = | Action = [[Respiration (physiology)|respiration]] | Precursor = [[septum transversum]], pleuroperitoneal folds, body wall <ref>{{EmbryologyUNC|mslimb|012}}</ref> | MeshName = Diaphragm | MeshNumber = A02.633.567.900.300 | DorlandsPre = d_15 | DorlandsSuf = 12293509 | }} :''For other types of diaphragm, see [[Diaphragm]].'' In the [[anatomy]] of [[mammal]]s, the '''thoracic diaphragm''' is a sheet of [[muscle]] extending across the bottom of the [[ribcage]]. The diaphragm separates the [[thoracic cavity]] from the [[abdominal cavity]] and performs an important function in [[Respiration (physiology)|respiration]]. A [[diaphragm]] in anatomy can refer to other flat structures such as the [[urogenital diaphragm]] or [[pelvic diaphragm]], but "the diaphragm" generally refers to the thoracic diaphragm. Other vertebrates such as [[amphibian]]s and [[reptile]]s have diaphragms or diaphragm-like structures, but important details of the anatomy vary, such as the position of lungs in the abdominal cavity. ==Function== The diaphragm is crucial for [[breath]]ing and [[Respiration (physiology)|respiration]]. During inhalation, the diaphragm contracts, thus enlarging the thoracic cavity (the [[intercostal muscle|external intercostal muscles]] also participate in this enlargement). This reduces intra-thoracic pressure: in other words, enlarging the cavity creates suction that draws air into the [[lung]]s. When the diaphragm relaxes, air is exhaled by elastic recoil of the lung and the tissues lining the thoracic cavity in conjunction with the [[abdominal muscle]]s which act as an [[Antagonist (muscle)|antagonist]] paired with the diaphragm's contraction. It is not responsible for all the breathing related to [[voice]], a common misconception espoused by many teachers but few great singers. One has more control over the [[abdominals]] and [[Intercostal muscle|intercostals]] than the actual diaphragm, which has relatively few [[proprioceptive]] nerve endings. By training proper posture and balance in the rest of the body, the diaphragm naturally strengthens and works in concert with surrounding structures rather than in isolation. The diaphragm is also involved in non-respiratory functions, helping to expel [[vomit]], [[feces]], and [[urine]] from the body by increasing intra-abdominal pressure, and preventing [[acid reflux]] by exerting pressure on the [[esophagus]] as it passes through the [[esophageal hiatus]]. ==Anatomy== The Diaphragm is a dome-shaped musculofibrous septum which separates the thoracic from the abdominal cavity, its convex upper surface forming the floor of the former, and its concave under surface the roof of the latter. Its peripheral part consists of muscular fibers which take origin from the circumference of the [[thoracic outlet]] and converge to be inserted into a central tendon. The muscular fibers may be grouped according to their origins into three parts: {| class="wikitable" | '''Part''' || '''Origin''' |- | sternal || two fleshy slips from the back of the [[xiphoid process]]. |- | costal || the inner surfaces of the cartilages and adjacent portions of the lower six ribs on either side, interdigitating with the [[Transversus abdominis]]. |- | lumbar || aponeurotic arches, named the [[lumbocostal arches]], and from the [[lumbar vertebrae]] by two pillars or crura. |} There are two lumbocostal arches, a [[Medial arcuate ligament|medial]] and a [[Lateral arcuate ligament|lateral]], on either side. ===Innervation=== The diaphragm is innervated by the [[phrenic nerve]]. ===Crura and central tendon=== At their origins the [[Crus of diaphragm|crura]] are tendinous in structure, and blend with the [[anterior longitudinal ligament]] of the [[vertebral column]]. The [[Central tendon of diaphragm|central tendon]] of the diaphragm is a thin but strong aponeurosis situated near the center of the vault formed by the muscle, but somewhat closer to the front than to the back of the [[thorax]], so that the posterior muscular fibers are the longer. ===Openings in the Diaphragm=== [[Image:Gray391.png|thumb|right|400px|Inferior view of the human '''diaphragm''', showing openings]] The diaphragm is pierced by a series of apertures to permit of the passage of structures between the thorax and abdomen. Three large openings—the [[aorta|aortic]], the [[oesophagus|esophageal]], and the [[inferior vena cava|vena cava]]—and a series of smaller ones are described. {| class="wikitable" | '''opening''' || '''level''' || '''structures''' |- | [[caval opening]] || T8 || [[inferior vena cava]], and some branches of the right [[phrenic nerve]] |- | [[esophageal hiatus]] || T10 || [[esophagus]], the [[vagus nerve]]s, and some small [[esophageal arteries]] |- | [[aortic hiatus]] || T12 || the [[aorta]], the [[azygos vein]], and the [[thoracic duct]] |- | two lesser aperture of [[right crus of diaphragm|right crus]] || || greater and lesser [[right splanchnic nerves]] |- | three lesser aperture of [[left crus of diaphragm|left crus]] || || greater and lesser [[left splanchnic nerves]] and the [[hemiazygos vein]] |- | behind the diaphragm, under the [[medial lumbocostal arches]] || || [[sympathetic trunk]] |- | areolar tissue between the sternal and costal parts (see also [[foramina of Morgagni]]) || || the [[superior epigastric branch]] of the [[internal mammary artery]] and some [[lymphatics]] from the abdominal wall and convex surface of the [[liver]] |- | areolar tissue between the fibers springing from the medial and [[lateral lumbocostal arch]]es || || This interval is less constant; when this interval exists, the upper and back part of the [[kidney]] is separated from the [[pleura]] by [[areolar tissue]] only. |} [[Image:Diaphragm_Arthur_Keith_1.jpg|thumb|300 px|Diaphragm and pleural cavities in amphibian (left), bird (center), mammal (right). a, [[mandible]]; b, [[genio-hyoid]]; c, [[hyoid]]; d, [[sterno-hyoid]]; e, [[sternum]]; f, [[pericardium]]; g, [[septum transversum]]; h, [[rectus abdominis]]; i, [[abdominal cavity]]; j, [[pubis (bone)|pubis]]; k, [[esophagus]]; l, [[Vertebrate trachea|trachea]]; m, cervical limiting membrane of abdominal cavity; n, dorsal wall of body; o, [[lung]]; o', [[Bird anatomy#respiratory system|air-sac]].<ref name="Keith">{{cite web|url=http://books.google.com/books?id=2ecDAAAAYAAJ|title=The nature of the mammalian diaphragm and pleural cavities|author=Arthur Keith, M.D.|journal=Journal of Anatomy and Physiology|year=1905}}</ref>]] ===Comparative anatomy and evolution=== The existence of some membrane separating the pharynx from the stomach can be traced widely among the [[chordate]]s. Thus [[amphioxus]] possesses an [[atrium]] by which water exits the pharynx, which has been argued (and disputed) to be homologous to structures in [[ascidian]]s and [[hagfish]]es.<ref>{{cite web|url=http://dev.biologists.org/cgi/reprint/126/6/1295.pdf|title=Characterization of an amphioxus paired box gene, AmphiPax2/5/8|author=Zbynek Kozmik et al.|year=1999|journal=Development|volume=126|pages=1295-1304}}</ref> The urochordate epicardium separates digestive organs from the pharynx and heart, but 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 which 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, the alligator diaphragmaticus muscle does not insert on the [[esophagus]] and does not affect pressure of the lower esophageal sphincter.<ref>{{cite web|url=http://jeb.biologists.org/cgi/content/full/208/16/3047|title=Structure and function of the esophagus of the American alligator (''Alligator mississippiensis'')|author=T. J. Uriona et al.|journal=Journal of Experimental Biology|year=2005|volume=208|pages=3047-3053}}</ref> 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 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.<ref>{{cite web|url=http://cas.bellarmine.edu/tietjen/images/lung_fossils_suggest_dinos_breat.htm|title=Lung fossils suggest that dinos breathed in cold blood}}</ref> An explanation for this state of affairs is that when 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 the herniation of the lungs from the abdominal cavity in both lineages.<ref name="Keith" /> ===Variations=== 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. [[Image:Chest labeled.png|thumb|right|300px|[[X-ray]] of chest, showing top of diaphragm.]] ===Pathology=== A ''[[hiatal hernia]]'' can result from a tear or weakness in the diaphragm near the [[gastroesophageal junction]]. If the diaphragm is struck, or otherwise [[spasm]]s, breathing will become difficult. This is called "[[having the wind knocked out of you]]." A [[hiccup]] occurs when the diaphragm contracts periodically without voluntary control. Diaphragmatic injuries result from either blunt or penetrating trauma. Gas under the diaphragm may be [[pneumoperitoneum]]. ==Additional images== <gallery> Image:Gray806.png|The phrenic nerve and its relations with the vagus nerve. Image:Gray845.png|Plan of right sympathetic cord and splanchnic nerves. Image:Gray846.png|Thoracic portion of the sympathetic trunk. Image:Gray1032.png|The position and relation of the esophagus in the cervical region and in the posterior mediastinum. Seen from behind. Image:Gray1034.png|Front view of the thoracic and abdominal viscera. Image:Gray1098.png|The duodenum and pancreas. Image:Gray1224.png|Topography of thoracic and abdominal viscera. Image:BauchOrgane wn.png|Organs of abdomen Image:Peritoneopericardial_diaphragmatic_hernia.JPG|Peritoneopericardial [[diaphragmatic hernia]] in a cat. Image:Hiatalhernia.gif|[[Hiatal hernia]] Image:Diaphragm def 1707.png|Probably the first dictionary definition of "diaphragm" </gallery> ==See also== *[[midriff]] ==References== <references/> ==External links== * {{GPnotebook|483393594}} * {{MuscleLoyola|dph}} {{Gray's}} {{Torso general}} [[Category:Thorax]] [[Category:Respiratory system]] [[Category:Muscles of the trunk]] {{Link FA|de}} [[ar:حجاب حاجز]] [[ca:Diafragma (múscul)]] [[cs:Bránice]] [[de:Zwerchfell]] [[es:Diafragma (anatomía)]] [[eu:Diafragma]] [[fr:Diaphragme (organe)]] [[it:Diaframma (anatomia)]] [[he:סרעפת]] [[la:Diaphragma]] [[lt:Diafragma]] [[hu:Rekeszizom]] [[mk:Дијафрагма]] [[nl:Middenrif]] [[ja:横隔膜]] [[nn:Mellomgolv]] [[pl:Przepona (mięsień)]] [[pt:Diafragma (músculo)]] [[ru:Диафрагма (анатомия)]] [[sq:Diafragma (organ)]] [[simple:Diaphragm]] [[sk:Bránica (časť tela)]] [[sl:Trebušna prepona]] [[fi:Pallea]] [[sv:Mellangärde]] [[th:กะบังลม]] [[uk:Діафрагма (анатомія)]] [[fiu-vro:Vaheliha]]