View source for Pulmonary artery

{{Short description|Artery in pulmonary circulation carrying deoxygenated blood from heart to lungs}}
{{Infobox artery
| Name        = Pulmonary artery
| Latin     = arteria pulmonalis
| Image    = Diagram of the human heart (cropped).svg
| Caption     = Anterior (frontal) view of the opened heart. White arrows indicate normal blood flow. (Pulmonary artery labelled at upper right.)
| BranchFrom  = [[Right ventricle]]
| BranchTo    =
| System      = [[Cardiovascular system|Cardiovascular]], [[Respiratory system|respiratory]]
| Precursor   = [[Truncus arteriosus]]
| Supplies    =
}}
A '''pulmonary artery''' is an [[artery]] in the [[pulmonary circulation]] that carries deoxygenated [[blood]] from the right side of the [[heart]] to the [[lung]]s. The largest pulmonary artery is the ''main pulmonary artery'' or ''pulmonary trunk''  from the [[heart]], and the smallest ones are the [[arteriole]]s, which lead to the [[Capillary|capillaries]] that surround the [[Pulmonary alveolus|pulmonary alveoli]].

== Structure ==
The pulmonary arteries are [[blood vessel]]s that carry [[Circulatory system|systemic venous blood]] from the right ventricle of the heart to the [[capillary|microcirculation]] of the lungs. Unlike in other organs where arteries supply oxygenated blood, the blood carried by the pulmonary arteries is deoxygenated, as it is venous blood returning to the heart. The main pulmonary arteries emerge from the right side of the heart and then split into smaller arteries that progressively divide and become [[arteriole]]s, eventually narrowing into the capillary microcirculation of the lungs where gas exchange occurs.{{cn|date=November 2023}}

===Pulmonary trunk===
[[File:3D CT of thorax, annotated.jpg|thumb|350px|[[Volume rendering]] of a [[high resolution computed tomography|high resolution]] [[CT scan]] of the [[thorax]]. The anterior thoracic wall, the airways and the pulmonary vessels anterior to the [[root of the lung]] have been digitally removed to visualize the different levels of the pulmonary circulation.]]

In order of blood flow, the pulmonary arteries start as the '''pulmonary trunk''' that leaves the fibrous pericardium ([[pericardium|parietal pericardium]]) of the [[ventricular outflow tract]] of [[right ventricle]] (also known as [[Infundibulum (heart)|infundibulum or conus arteriosus]].<ref name="Ryan 2011"/> The outflow track runs superiorly and to the left, posterior to the [[pulmonary valve]].<ref name="Ryan 2011"/> The pulmonary trunk bifurcates into right and left pulmonary arteries below the [[arch of aorta]] and in front of the left main bronchus.<ref name="Ryan 2011">{{cite book |last1=Ryan |first1=Stephanie |title=Anatomy for diagnostic imaging |date=2011 |publisher=Elsevier Ltd. |isbn=9780702029714 |pages=126, 133|edition=Third |chapter=2}}</ref> Pulmonary trunk is short and wide{{snd}}approximately {{convert|5|cm|in}} in length<ref name="Chatterjee 2011"/> and {{convert|2|cm|in}}-{{convert|3|cm|in}} in diameter.<ref>{{Cite journal |last1=Edwards |first1=P D |last2=Bull |first2=R K |last3=Coulden |first3=R |date=1998-10-01 |title=CT measurement of main pulmonary artery diameter. |url=https://www.birpublications.org/doi/abs/10.1259/bjr.71.850.10211060 |journal=The British Journal of Radiology |volume=71 |issue=850 |pages=1018–1020 |doi=10.1259/bjr.71.850.10211060 |pmid=10211060 |issn=0007-1285|url-access=subscription }}</ref><ref>{{Cite journal |last1=Truong |first1=Quynh A. |last2=Massaro |first2=Joseph M. |last3=Rogers |first3=Ian S. |last4=Mahabadi |first4=Amir A. |last5=Kriegel |first5=Matthias F. |last6=Fox |first6=Caroline S. |last7=O'Donnell |first7=Christopher J. |last8=Hoffmann |first8=Udo |date=2012-01-01 |title=Reference Values for Normal Pulmonary Artery Dimensions by Noncontrast Cardiac Computed Tomography |journal=Circulation: Cardiovascular Imaging |volume=5 |issue=1 |pages=147–154 |doi=10.1161/CIRCIMAGING.111.968610 |pmc=3275437 |pmid=22178898}}</ref>

The pulmonary trunk splits into the '''right''' and the '''left main pulmonary artery'''.<ref>{{cite web|url=https://www.med-ed.virginia.edu/courses/rad/cxr/anatomy6chest.html|title=Pulmonary Vasculature|website=[[University of Virginia School of Medicine]]|date=2013|access-date=2017-06-24}}</ref> The left main pulmonary artery is shorter than the right,<ref name="Ryan 2011"/> passes behind and downwards the descending aorta and above the left main bronchus to the root of the left lung. Above, the left main pulmonary artery is connected to the concavity of the proximal [[descending aorta]] by the [[ligamentum arteriosum]].<ref name="Chatterjee 2011">{{cite book | veditors = Chatterjee K | vauthors = Cheitlin MD, Ursell PC |chapter-url=https://books.google.com/books?id=7DhFdgp3rfkC&pg=PA6 |title=Cardiology: An Illustrated Textbook |chapter=Cardiac Anatomy |page=6 |publisher=JP Medical Ltd. |year=2011 |isbn=9789350252758}}</ref> The right pulmonary artery pass across the midline of the body, below the [[carina of trachea]], and comes in front of the right main bronchus.<ref name="Ryan 2011"/>

===Branches===
[[File:Alveolus diagram.svg|thumb|At the far end, pulmonary arteries (labelled at the bottom) become capillaries at the [[Pulmonary alveolus|pulmonary alveoli]].]]

The left main pulmonary artery then divides into two lobar arteries, one for each lobe of the left lung.<ref>{{Cite journal |last1=Kandathil |first1=Asha |last2=Chamarthy |first2=Murthy |date=June 2018 |title=Pulmonary vascular anatomy & anatomical variants |journal=Cardiovascular Diagnosis and Therapy |volume=8 |issue=3 |pages=201–207 |doi=10.21037/cdt.2018.01.04 |issn=2223-3652 |pmc=6039811 |pmid=30057869 |doi-access=free }}</ref>

At the right [[root of the lung]], it bifurcates into artery that supplies the right upper lobe of the lung, in front of the right upper lobe bronchus, and interlobar artery that supplies the right middle and inferior lobes of the lung, running together with bronchus intermedius.<ref name="Ryan 2011"/>

The right and left main pulmonary (lungs) arteries give off branches that supplies the corresponding [[lung lobe]]s. In such cases it is termed '''lobar arteries'''.<ref name="virginia 2013"/> The lobar arteries branch into '''segmental arteries''' (roughly 1 for each segment). Segmental arteries run together with segmental bronchi, at the posterolateral surfaces of the bronchi.<ref name="virginia 2013"/> These in turn branch into '''subsegmental pulmonary arteries'''.<ref name="virginia 2013">{{cite web|url=https://www.med-ed.virginia.edu/courses/rad/ctpa/02anat/anat-01-01.html|title=Pulmonary Artery Anatomy|website=[[University of Virginia School of Medicine]]|date=2013|access-date=2017-06-24}}</ref> These eventually form '''intralobular arteries'''.<ref>{{cite journal | vauthors = Takahashi M, Fukuoka J, Nitta N, Takazakura R, Nagatani Y, Murakami Y, Otani H, Murata K | display-authors = 6 | title = Imaging of pulmonary emphysema: a pictorial review | journal = International Journal of Chronic Obstructive Pulmonary Disease | volume = 3 | issue = 2 | pages = 193–204 | year = 2008 | pmid = 18686729 | pmc = 2629965 | doi = 10.2147/COPD.S2639 | doi-access = free }}</ref> The pulmonary arteries supply the alveoli of the lungs. In contrast, [[bronchial arteries]], that has different origins, supply the bronchi of the lungs.<ref name="Ryan 2011"/>

==Development==
The pulmonary arteries originate from the [[truncus arteriosus]] and the sixth [[pharyngeal arch]]. The truncus arteriosus is a structure that forms during the [[Heart development|development of the heart]] as a successor to the [[conus arteriosus]].<ref name="Larsen_2009">{{cite book |url=https://archive.org/details/larsenshumanembr0000unse |title=Larsen's human embryology |vauthors=Schoenwolf GC, Larsen MJ, Bleyl SR, Brauer PR, Francis-West PH |date=2009 |publisher=Churchill Livingstone/Elsevier |isbn=9780443068119 |edition=4th ed., Thoroughly rev. and updated. |location=Philadelphia |pages=Development of the Urogenital system |url-access=registration}}</ref>{{rp|157}}

By the third week of [[human embryogenesis|development]], the [[endocardial tubes]] have developed a swelling in the part closest to the heart. The swelling is known as the [[bulbus cordis]] and the upper part of this swelling develops into the [[truncus arteriosus]].<ref name = "Larsen_2009" />{{rp|159–160}} The structure is ultimately mesodermal in origin.<ref name = "Larsen_2009" />{{rp|157}} During [[Heart development|development of the heart]], the heart tissues undergo folding, and the truncus arteriosus is exposed to what will eventually be both the left and right ventricles. As a [[septum]] develops between the two ventricles of the heart, two bulges form on either side of the truncus arteriosus. These progressively enlarge until the trunk splits into the [[aorta]] and pulmonary arteries.<ref name = "Larsen_2009" />{{rp|176–179}} Failure of these processes can lead to [[pulmonary artery agenesis]].

During [[prenatal development|early development]], the [[ductus arteriosus]] connects the pulmonary trunk and the [[aortic arch]], allowing blood to bypass the lungs.<ref name = "Braunwald_1992">{{cite book|title = Heart Disease: A Textbook of Cardiovascular Medicine| vauthors = Braunwald E |edition = Fourth | date = 1992 | location = Philadelphia | publisher = W.B. Sanders }}</ref>{{rp|791}}

== Function ==
The pulmonary artery carries deoxygenated blood from the [[right ventricle]] to the lungs.<ref>{{Cite web|url=https://opentextbc.ca/anatomyandphysiology/chapter/22-4-gas-exchange/|title=22.4 Gas Exchange – Anatomy and Physiology|website=opentextbc.ca|access-date=2019-05-22|archive-date=2020-10-19|archive-url=https://web.archive.org/web/20201019234848/https://opentextbc.ca/anatomyandphysiology/chapter/22-4-gas-exchange/|url-status=dead}}</ref> The blood here passes through [[capillaries]] adjacent to [[Pulmonary alveolus|alveoli]] and becomes [[Oxygenation (medicine)|oxygenated]] as part of the process of [[Respiration (physiology)|respiration]].<ref>{{Cite web|url=https://www.msdmanuals.com/home/lung-and-airway-disorders/biology-of-the-lungs-and-airways/exchanging-oxygen-and-carbon-dioxide|title=Exchanging Oxygen and Carbon Dioxide – Lung and Airway Disorders|website=MSD Manual Consumer Version|language=en|access-date=2019-05-22}}</ref>

In contrast to the ''pulmonary arteries'', the [[bronchial arteries]] supply nutrition to the lungs themselves.<ref name = "Braunwald_1992" />{{rp|790}}

===Pressure===
{{anchor|Pulmonary artery pressure}}
The '''pulmonary artery pressure''' ('''PA pressure''') is a measure of the [[blood pressure]] found in the main pulmonary artery. This is measured by inserting a [[Pulmonary artery catheter|catheter]] into the main pulmonary artery.<ref name=DAVIDSONS2010>{{cite book| veditors = Colledge NR, Walker BR, Ralston SH, Britton R |title=Davidson's Principles and Practice of Medicine.|year=2010|publisher=Churchill Livingstone/Elsevier|location=Edinburgh|isbn=978-0-7020-3084-0|edition=21st}}</ref> {{rp|190–191}} The mean pressure is typically 9–18 mmHg,<ref name=edwards>{{cite web | url = http://www.edwards.com/SiteCollectionImages/edwards/products/presep/ar04313hemodynpocketcard.pdf | publisher = Edwards Lifesciences LLC | title = Normal Hemodynamic Parameters – Adult | date = | archive-url = https://web.archive.org/web/20101110081655/http://www.edwards.com/SiteCollectionImages/edwards/products/presep/ar04313hemodynpocketcard.pdf |archive-date=2010-11-10 }}</ref> and the [[pulmonary wedge pressure|wedge pressure]] measured in the [[left atrium]] may be 6–12 mmHg. The wedge pressure may be elevated in [[left heart failure]],<ref name=DAVIDSONS2010 />{{rp|190–191}} [[mitral valve stenosis]], and other conditions, such as [[sickle cell disease]].<ref name="pmid18381543">{{cite journal | vauthors = Pashankar FD, Carbonella J, Bazzy-Asaad A, Friedman A | title = Prevalence and risk factors of elevated pulmonary artery pressures in children with sickle cell disease | journal = Pediatrics | volume = 121 | issue = 4 | pages = 777–782 | date = April 2008 | pmid = 18381543 | doi = 10.1542/peds.2007-0730 | s2cid = 26693444 }}</ref>

==Clinical significance==
The pulmonary artery is relevant in a number of clinical states. [[Pulmonary hypertension]] is used to describe an increase in the pressure of the pulmonary artery, and may be defined as a mean pulmonary artery pressure of greater than 25 mmHg.<ref name=DAVIDSONS2010 />{{rp|720}} A pulmonary artery diameter of more than 29&nbsp;mm (measured on a [[CT scan]]) is often used as an indicator for pulmonary hypertension.<ref>{{cite journal | vauthors = Marini TJ, He K, Hobbs SK, Kaproth-Joslin K | title = Pictorial review of the pulmonary vasculature: from arteries to veins | journal = Insights into Imaging | volume = 9 | issue = 6 | pages = 971–987 | date = December 2018 | pmid = 30382495 | pmc = 6269336 | doi = 10.1007/s13244-018-0659-5 }}</ref> In chest X-rays, a diameter of more than 16&nbsp;mm for the right descending pulmonary artery is also an indicator for pulmonary hypertension.<ref>{{cite journal | vauthors = Chang CH | title = The normal roentgenographic measurement of the right descending pulmonary artery in 1,085 cases and its clinical application. II. Clinical application of the measurement of the right descending pulmonary artery in the radiological diagnosis of pulmonary hypertensions from various causes | journal = Nagoya Journal of Medical Science | volume = 28 | issue = 1 | pages = 67–80 | date = December 1965 | pmid = 5865788 | url = https://www.med.nagoya-u.ac.jp/medlib/nagoya_j_med_sci/pdf/v28n1p67_80.pdf | access-date = 15 January 2022 }}</ref> This may occur as a result of heart problems such as [[heart failure]], lung or airway disease such as [[COPD]] or [[scleroderma]], or thromboembolic disease such as [[pulmonary embolism]] or emboli seen in sickle cell anaemia.<ref name=DAVIDSONS2010 />{{rp|720–721}} Most recently, computational fluid based tools (non-invasive) have been proposed to be at par with the current clinical tests (invasive) of pulmonary hypertension.<ref>{{cite journal | vauthors = Piskin S, Patnaik SS, Han D, Bordones AD, Murali S, Finol EA | title = A canonical correlation analysis of the relationship between clinical attributes and patient-specific hemodynamic indices in adult pulmonary hypertension | journal = Medical Engineering & Physics | volume = 77 | pages = 1–9 | date = March 2020 | pmid = 32007361 | pmc = 7069525 | doi = 10.1016/j.medengphy.2020.01.006 }}</ref>

Pulmonary embolism refers to an embolus that lodges in the pulmonary circulation. This may arise from a [[deep venous thrombosis]], especially after a period of immobility. A pulmonary embolus is a common cause of death in patients with cancer and stroke.<ref name=DAVIDSONS2010 />{{rp|720–721}} A large pulmonary embolus that becomes lodged in the bifurcation of the pulmonary trunk with extensions into both the left and right main pulmonary arteries is called a ''saddle embolus''.<ref>{{cite web|url=https://radiopaedia.org/articles/saddle-pulmonary-embolism| vauthors = Jones J, etal |title=Saddle pulmonary embolism|website=[[Radiopaedia]]|access-date=2017-10-08}}</ref>

[[File:The handy horse book - a manual for every American horse-owner (1883) (14579121368).jpg|thumb| (made in (1883)) <br> [[Anatomy]] of the [[horse]], with other arteries: [[spermatic artery]] (21), next to (posterior) [[vena cava]], [[venae portae]], [[External iliac artery]], and the [[Mesenteric vessels (disambiguation)|mesenteric vessels]], [[Internal iliac artery|Internal iliac]] and [[Renal artery|renal arteries]] labeled. The pulmonary artery and [[pulmonary veins]] are labelled (4) and (5), respectively. ]] 

Several animal models have been utilized for investigating pulmonary artery related pathologies. Porcine model of pulmonary artery is the most frequently used and it was recently found that their mechanical properties vary with every subsequent branching.<ref>{{cite journal | vauthors = Pillalamarri NR, Patnaik SS, Piskin S, Gueldner P, Finol EA | title = ''Ex Vivo'' Regional Mechanical Characterization of Porcine Pulmonary Arteries | journal = Experimental Mechanics | volume = 61 | issue = 1 | pages = 285–303 | date = January 2021 | pmid = 33814554 | pmc = 8011683 | doi = 10.1007/s11340-020-00678-2 }}</ref>

==Additional images==
<gallery>
File:Relations of the aorta, trachea, esophagus and other heart structures.png|Image showing ''main pulmonary artery'' coursing ventrally to the [[aortic root]] and [[vertebrate trachea|trachea]], and the ''right pulmonary artery'' passes dorsally to the [[ascending aorta]], while the ''left pulmonary artery'' passes ventrally to the [[descending aorta]].
File:Illu pulmonary circuit.jpg|Pulmonary circuit
File:Gray503.png|Transverse section of thorax, showing relations of pulmonary artery.
File:Slide16444 (1).jpg|alt=Original image from Anatomist 90|Pulmonary artery
File:Slide44uru.JPG|Pulmonary artery.Deep dissection.Anterior view.
File:Computed tomograph of pulmonary vessels.jpg|[[CT scan]] of a normal lung, with different levels of pulmonary arteries.
File:Bronchial anatomy.jpg|Bronchial anatomy
</gallery>

== See also ==
* [[Pulmonary artery sling]]
* [[Rasmussen's aneurysm]]
* [[Pulmonary vein]]
* [[Pulmonary circulation]]
* [[Bronchial artery]]
* [[Bronchial vein]]
* [[Brachial artery]]
* [[Brachial vein]]
* [[Coronary artery]]
* [[Coronary sinus]]
* [[Left gastric vein]] ([[Coronary vein]])
* [[Pulmonary valve]]

== References ==
{{Reflist}}

== External links ==
* {{SUNYAnatomyLabs|20|01|01|06}} – "Heart: The [[Pericardial sac]] and [[Great vessels]]"
* {{SUNYAnatomyLabs|20|07|01|05}} – "Heart: Openings of Great Vessels into the Pericardial Sac"
* {{SUNYAnatomyFigs|19|05|06}} – "[[Mediastinal]] surface of the [[right lung]]"
* {{SUNYAnatomyFigs|19|06|02}} – "Mediastinal surface of the [[left lung]]"
* {{BUHistology|13802loa}}

{{cardiovascular_system}}
{{Arteries of chest}}
{{Authority control}}

{{DEFAULTSORT:Pulmonary Artery}}
[[Category:Arteries of the thorax]]
[[Category:Respiratory system anatomy]]