[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Anatomy](https://durgical.com/en/anatomy/) › [Chest](https://durgical.com/en/anatomy/region/chest/) › Left lower lobe [Respiratory system](https://durgical.com/en/anatomy/system/respiratory-system/) · [Chest](https://durgical.com/en/anatomy/region/chest/) # Left lower lobe The left lower lobe is the bottom part of the left lung, filling the lower back of the [chest](https://durgical.com/en/anatomy/region/chest/), much of it hidden behind the heart on X-ray. Official name: Inferior lobe of left lung [See in 3D →](https://durgical.app/?from=durgipedia&lang=en#region=thorax&select=left_lower_lobe&side=r) Opens in the Durgical app, no sign-up needed. ## What it is The lower lobe of the left lung, below the oblique fissure, behind the heart. ## What it does Fills the lower back of the left chest. ## Key points - It lies behind the heart, so disease here hides in the retrocardiac area: on a frontal X-ray the area behind the heart is checked for density and for the descending aorta outline - It is the lobe heard over most of the left back, from about T3 down to about T10 in quiet breathing - Collapse of this lobe is common after cardiac surgery ## Key facts **Where** Below oblique fissure, posteroinferior; segments superior, anteromedial, lateral and posterior basal **Blood supply** Pulmonary artery branches (gas exchange); bronchial arteries (nourish lung tissue) **Nerve** Pulmonary plexus: vagus (bronchoconstriction, secretion); upper thoracic sympathetic (bronchodilation) **Function** Gas exchange; consolidation blurs left hemidiaphragm (not heart border) on X-ray ## Relations **Above** [Left upper lobe](https://durgical.com/en/anatomy/superior-lobe-of-left-lung/) across the upper part of the oblique fissure **In front** The lingula across the oblique fissure, and the [pericardium](https://durgical.com/en/anatomy/pericardium/) over the [left ventricle](https://durgical.com/en/anatomy/left-ventricle/) below the hilum **Medial** Descending [thoracic aorta](https://durgical.com/en/anatomy/thoracic-aorta/), which grooves the lobe behind the hilum, and the [esophagus](https://durgical.com/en/anatomy/esophagus-abdominal-part/) low down near the [diaphragm](https://durgical.com/en/anatomy/diaphragm/) **Below** Left dome of the diaphragm, with the [spleen](https://durgical.com/en/anatomy/spleen/) and the fundus of the [stomach](https://durgical.com/en/anatomy/stomach/) beneath it **Behind** Posterior [ribs](https://durgical.com/en/anatomy/ribs/) and intercostal spaces; the costodiaphragmatic recess extends below its lower edge ## How to find it Heard over the back from the medial end of the [spine](https://durgical.com/en/anatomy/region/spine/) of the [scapula](https://durgical.com/en/anatomy/scapula/) (about T3) down to about T10, and low in the left axilla. Like the [right lower lobe](https://durgical.com/en/anatomy/inferior-lobe-of-right-lung/), its base moves down in deep inspiration. ## On imaging Collapse forms a triangular density behind the heart, with a sharp edge (sail sign), loss of the medial left hemidiaphragm and of the lower descending aorta outline, and a lowered left hilum. Consolidation blurs the hemidiaphragm, not the heart border. ## Common problems - Pneumonia (infection), asthma and COPD (narrowed airways). - Lung cancer, often linked to smoking. - Pulmonary embolism: a clot blocks an artery in the lung. ## How it is diagnosed Listening to the chest, chest X-ray, CT, breathing tests (spirometry), blood oxygen. ## Treatment - Depends on the cause: antibiotics, inhalers, oxygen; surgery removes a lobe or segment for some cancers. ## Clinical notes - Retrocardiac pneumonia is easily missed on a portable frontal film, especially in children and bedridden patients - Its superior segment is a dependent site for aspiration when lying on the back, though aspiration is still more frequent on the right ## Anatomical variants - Intralobar pulmonary sequestration: a non-functioning piece of lung, most often in the posterior basal part of this lobe, supplied by an artery from the descending aorta ## Development Around week 5 the lung buds split into lobar buds: three on the right and two on the left, which is why the left lung lacks a middle lobe. On the left, the lower bud forms this lobe. ## Related conditions - [α1-antitrypsin deficiency](https://durgical.com/en/conditions/1-antitrypsin-deficiency/) - [Echinococcosis (hydatid disease)](https://durgical.com/en/conditions/echinococcosis/) - [Neonatal respiratory distress syndrome (hyaline membrane disease)](https://durgical.com/en/conditions/neonatal-respiratory-distress-syndrome/) - [Congenital diaphragmatic hernia](https://durgical.com/en/conditions/congenital-diaphragmatic-hernia/) - [Acute respiratory failure (hypoxaemic and hypercapnic)](https://durgical.com/en/conditions/acute-respiratory-failure/) - [Atelectasis](https://durgical.com/en/conditions/atelectasis/) - [Community-acquired pneumonia](https://durgical.com/en/conditions/community-acquired-pneumonia/) - [Interstitial lung disease](https://durgical.com/en/conditions/interstitial-lung-disease/) - [Acute respiratory distress syndrome (ARDS)](https://durgical.com/en/conditions/acute-respiratory-distress-syndrome/) ## Test yourself Think of the answer, then tap the question to see it. ## Why is disease of the left lower lobe easily missed on a frontal chest X-ray? Because the lobe lies behind the heart; the retrocardiac area must be checked for density and for the outline of the descending aorta. ## What does collapse of the left lower lobe look like on a frontal chest X-ray? A triangular density behind the heart with a sharp edge (sail sign), loss of the medial left hemidiaphragm and lower descending aorta outline, and a lowered left hilum. ## Which structure grooves the left lower lobe behind the hilum? The descending thoracic aorta, which lies medial to the lobe; the esophagus lies against it low down near the diaphragm. ## What is intralobar pulmonary sequestration, and where in the left lower lobe is it usually found? A non-functioning piece of lung supplied by an artery from the descending aorta, most often in the posterior basal part of the left lower lobe. [Add to my cards (4)](https://durgical.app/estudiar/?add=/en/anatomy/inferior-lobe-of-left-lung/) Educational information, not medical advice. For any symptom, see a health professional. ## Its names **Official Latin (TA2)** lobus inferior pulmonis sinistri TA2 3308 **Official Spanish (DeCS)** Lóbulo inferior del pulmón izquierdo DeCS D008168 **English (TA2)** Inferior lobe of left lung **Also called** lower lobe of left lung · lobus dorsocaudalis Sources: Terminologia Anatomica (TA2); [DeCS](https://decs.bvsalud.org/es/ths/resource/?id=8345); [Anatomy, Thorax, Lungs](https://www.ncbi.nlm.nih.gov/books/NBK470197/); [22.7 Embryonic Development of the Respiratory System](https://openstax.org/books/anatomy-and-physiology-2e/pages/22-7-embryonic-development-of-the-respiratory-system) (OpenStax (Rice University), 2022) · adapted, [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/); Anatomy of the Human Body (20th ed.): The Respiratory Apparatus (Lea & Febiger (Gray's Anatomy, 1918), 1918) · adapted, Public domain. ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/anatomy/inferior-lobe-of-left-lung/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anatomy/inferior-lobe-of-left-lung/