Editing Lung (section)

=== Anatomy ===
[[File:Illu bronchi lungs.jpg|upright=1.5|thumb|right]]
In humans the lungs are located in the [[thoracic cavity|chest]] on either side of the [[heart]] in the [[rib cage]]. They are conical in shape with a narrow rounded '''apex''' at the top, and a broad concave '''base''' that rests on the convex surface of the [[thoracic diaphragm|diaphragm]].<ref name=GRAYS /> The apex of the lung extends into the root of the neck, reaching shortly above the level of the [[sternum|sternal]] end of the [[Rib cage#Bones|first rib]]. The lungs stretch from close to the [[vertebral column|backbone]] in the rib cage to the front of the [[thorax|chest]] and downwards from the lower part of the trachea to the diaphragm.<ref name=GRAYS>{{cite book|last1=Drake |first1=Richard L.|last2=Vogl|first2=Wayne|last3=Mitchell|first3=Adam W.M.|title=Gray's anatomy for students|date=2014|publisher=[[Churchill Livingstone]]/[[Elsevier]]|location=Edinburgh|isbn=978-0-7020-5131-9|pages=167–174|edition=3rd}}</ref> 

The left lung shares space with the heart, and has an indentation in its border called the '''cardiac notch of the left lung''' to accommodate this.<ref name="Betts">{{cite book|last1=Betts|first1=J. Gordon|title=Anatomy & physiology|date=2013|isbn=978-1-938168-13-0|url=http://cnx.org/content/m46676/latest/?collection=col11496/latest|access-date=11 August 2014|pages=787–846|publisher=OpenStax College, Rice University }}</ref><ref name="GRAYS40TH" /> The front and outer sides of the lungs face the ribs, which make light indentations on their surfaces. The medial surfaces of the lungs face towards the centre of the chest, and lie against the heart, [[great vessels]], and the [[carina of trachea|carina]] where the trachea divides into the two main bronchi.<ref name="GRAYS40TH" />  The '''cardiac impression''' is an indentation formed on the surfaces of the lungs where they rest against the heart.

Both lungs have a central recession called the [[root of the lung|hilum]], where the [[blood vessel]]s and [[Bronchus|airways]] pass into the lungs making up the [[root of the lung]].<ref name="Moore K"/> There are also [[tracheobronchial lymph node|bronchopulmonary lymph nodes]] on the hilum.<ref name="GRAYS40TH" />

The lungs are surrounded by the [[pulmonary pleurae]]. The pleurae are two [[serous membrane]]s; the outer [[parietal pleura]] lines the inner wall of the [[rib cage]] and the inner [[visceral pleura]] directly lines the surface of the lungs. Between the pleurae is a [[potential space]] called the [[pleural cavity]] containing a thin layer of lubricating [[pleural fluid]].

====Lobes====
{| class="wikitable" style="float:right;margin-left:10px"
|+ Lobes and bronchopulmonary segments<ref name="pmid1" />
|-
! Right lung !! Left lung
|-
| '''Upper'''
* Apical
* Posterior
* Anterior
'''Middle'''
* Lateral
* Medial
'''Lower'''
* Superior
* Medial
* Anterior
* Lateral
* Posterior 
|| '''Upper'''
* Apicoposterior
* Anterior
'''Lingula'''
* Superior
* Inferior
'''Lower'''
* Superior
* Anteriomedial
* Lateral
* Posterior
|}

Each lung is divided into sections called lobes by the infoldings of the visceral pleura as fissures. Lobes are divided into segments, and segments have further divisions as lobules. There are three lobes in the right lung and two lobes in the left lung.

====Fissures====
The fissures are formed in early [[prenatal development]] by invaginations of the visceral pleura that divide the lobar bronchi, and section the lungs into lobes that helps in their expansion.<ref name="Koster">{{cite journal |last1=Koster |first1=TD |last2=Slebos |first2=DJ |title=The fissure: interlobar collateral ventilation and implications for endoscopic therapy in emphysema. |journal=International Journal of Chronic Obstructive Pulmonary Disease |date=2016 |volume=11 |pages=765–73 |doi=10.2147/COPD.S103807 |pmid=27110109|pmc=4835138 |doi-access=free }}</ref><ref name="Lung fissures">{{cite web|last1=Hacking|first1=Craig|last2=Knipe|first2=Henry|title=Lung fissures|url=http://radiopaedia.org/articles/lung-fissures|website=Radiopaedia|access-date=8 February 2016}}</ref> The right lung is divided into three lobes by a '''horizontal fissure''', and an '''oblique fissure'''. The left lung is divided into two lobes by an oblique fissure which is closely aligned with the oblique fissure in the right lung. In the right lung the upper horizontal fissure, separates the upper (superior) lobe from the middle lobe. The lower, oblique fissure separates the lower lobe from the middle and upper lobes.<ref name=GRAYS /><ref name="Lung fissures" />

[[Lung#Variation|Variations]] in the fissures are fairly common being either incompletely formed or present as an extra fissure as in the [[azygos lobe|azygos fissure]], or absent. Incomplete fissures are responsible for [[collateral ventilation|interlobar collateral ventilation]], airflow between lobes which is unwanted in some [[lung volume reduction]] procedures.<ref name="Koster" />

====Segments====
The primary bronchi enter the lungs at the hilum and initially branch into [[Bronchus|secondary bronchi]] also known as lobar bronchi that supply air to each lobe of the lung. The lobar bronchi branch into [[Bronchus|tertiary bronchi]] also known as segmental bronchi and these supply air to the further divisions of the lobes known as [[bronchopulmonary segment]]s. Each bronchopulmonary segment has its own (segmental) bronchus and [[artery|arterial supply]].<ref>{{cite web|last1=Jones|first1=Jeremy|title=Bronchopulmonary segmental anatomy {{!}} Radiology Reference Article {{!}} Radiopaedia.org|url=https://radiopaedia.org/articles/bronchopulmonary-segmental-anatomy-1|website=radiopaedia.org|language=en}}</ref> Segments for the left and right lung are shown in the table.<ref name="pmid1">{{cite journal|last1=Arakawa|first1=H|last2=Niimi|first2=H|last3=Kurihara|first3=Y|last4=Nakajima|first4=Y|last5=Webb|first5=WR|title=Expiratory high-resolution CT: diagnostic value in diffuse lung diseases|journal=American Journal of Roentgenology|date=December 2000|volume=175|issue=6|pages=1537–1543|pmid=11090370|doi=10.2214/ajr.175.6.1751537}}</ref> The segmental anatomy is useful clinically for localising disease processes in the lungs.<ref name="pmid1" /> A segment is a discrete unit that can be surgically removed without seriously affecting surrounding tissue.<ref name="Harper">{{cite book|last1=Tortora |first1=Gerard |title=Principles of anatomy and physiology |date=1987 |publisher=Harper and Row| location=New York |isbn=978-0-06-350729-6 |page=564 |edition=5th}}</ref>
{{multiple image|caption_align=center|header_align=center|align=center
 | total_width = 480
 | image1 = Gray973.png
 | alt1 = The left lung
 | image2 = Gray972.png
 | alt2 = The right lung
 | footer = The left lung (left) and right lung (right). The lobes of the lungs can be seen, and the central [[root of the lung]] is also present.
}}
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