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Magill’s Medical Guide, 9th Edition

Bronchi

by Jennifer Birkhauser, , MS, MD

Category: Anatomy

Anatomy or system affected: Lungs, respiratory system

Specialties and related fields: Pulmonary medicine

Definition: The large, rigid breathing tubes that connect the trachea to the inside of the lungs.

STRUCTURE AND FUNCTIONS

The bronchi are a direct continuation of the trachea, which separates into the right and left mainstem bronchi at the level of the fifth thoracicvertebra of the spinal column. They are composed of rings of cartilage supported by thick muscle fibers with a mucous membrane interior coating. This structure renders the bronchi rigid and not easily collapsible. The left bronchus is about 5 centimeters in length and enters the lung at the level of the sixth thoracic vertebra. The right bronchus is shorter, measuring about 2.5 centimeters in length, and enters the lung at the level of the fifth thoracic vertebra. The right bronchus also differs in that it is wider and runs at a more vertical angle than its left counterpart. The bronchi join with the lung, becoming the lobar bronchi, and further branch into subsequently smaller bronchi, eventually being called the bronchioles.

The bronchi serve primarily to transport air between the trachea and the lungs. They bring freshly oxygenated air into the lungs from the outside environment and transport old, carbon dioxide-filled air out of the lungs.

DISORDERS AND DISEASES

The bronchi are susceptible to a variety of diseases and dysfunctions, the most common being bronchitis. Bronchitis is an inflammation of the bronchi and can be secondary to various mechanisms. Acute bronchitis is usually infectious and is most common during the winter season. The symptoms are nonspecific and can include fever, cough, nasal congestion, and wheezing. Acute bronchitis can becaused by viruses such as influenza and bacteria such as Mycoplasma pneumoniae and Chlamydia pneumoniae. It can also becaused by various noninfectious outdoor or household irritants. Treatment consists of antibiotics for bacterial causes, bronchodilator inhalers, over-the-counter fever reducers and cough suppressants, fluids, and rest. Chronic bronchitis is a separate disorder of inflammation of the bronchi that is common in smokers. A cough productive of sputum for three months and occurring for at least two years in a row is required for formal diagnosis. Symptoms are similar to those of acute bronchitis. There is no cure for chronic bronchitis, but treatment aimed at symptom control often involves bronchodilator inhalers, steroids, and smoking cessation.

Asthma involves chronic inflammation of the lungs with consequent narrowing of the bronchi and airway obstruction, leading to episodes of coughing, wheezing, and difficulty breathing. Treatment involves bronchodilators such as albuterol, steroids, and leukotriene modifiers.

Additionally, the precipitous downward angle of the right mainstem bronchus lends itself to foreign body impaction, especially in children. It also makes it easier for liquids to enter the right lung, causing an aspiration pneumonia.

See also: Asthma; Bronchiolitis; Bronchitis; Chest; Coughing; Emphysema; Influenza; Lung cancer; Lung surgery; Lungs; Pneumonia; Pulmonary diseases; Pulmonary medicine; Pulmonary medicine, pediatric; Respiration; Respiratory distress syndrome; Smoking; Wheezing.

For Further Information:

1 

American Lung Association. “How Lungs Work.” American Lung Association, 2013.

2 

Balch, Phyllis. “Bronchitis.” In Prescription for Nutritional Healing, edited by Phyllis Balch. New York: Avery, 2006.

3 

Lazaroff, Michael. “What Goes In Must Come Out.” In The Complete Idiot’s Guide to Anatomy and Physiology, edited by Jennifer Chisholm. New York: Alpha Books, 2004.

4 

MedlinePlus. “Bronchial Disorders.” MedlinePlus, June 26, 2013.

5 

National Heart, Lung, and Blood Institute. “The Respiratory System.” National Institutes of Health, July 17, 2012.

6 

Orenstein, David. “The Respiratory System.” In Cystic Fibrosis: A Guide for Patient and Family, edited by David Orenstein. New York: Lippincott Williams & Wilkins, 2003.

Citation Types

Type
Format
MLA 9th
Birkhauser, Jennifer. "Bronchi." Magill’s Medical Guide, 9th Edition, edited by Anubhav Agarwal,, Salem Press, 2022. Salem Online, online.salempress.com/articleDetails.do?articleName=MMG2022_0203.
APA 7th
Birkhauser, J. (2022). Bronchi. In A. Agarwal, (Ed.), Magill’s Medical Guide, 9th Edition. Salem Press. online.salempress.com.
CMOS 17th
Birkhauser, Jennifer. "Bronchi." Edited by Anubhav Agarwal,. Magill’s Medical Guide, 9th Edition. Hackensack: Salem Press, 2022. Accessed October 22, 2025. online.salempress.com.