Trachea Function and Anatomy

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The trachea (also called the windpipe) is the large tube that brings air from the nasal passages, throat, and larynx (the upper respiratory tract) to the two large airways that branch off into each lung (bronchi). An important function of the trachea is warming and moisturizing the air, as well as catching debris and microbes before they can enter the lungs.

The trachea can become infected, inflamed, or damaged. In rare cases, these problems can lead to tracheal stenosis, a condition where the trachea narrows and a person struggles to breathe. Tracheal cancer is another rare condition that can affect the organ. 

This article will cover the anatomy and function of the trachea, as well as what conditions can affect it.

Trachea Anatomy

The trachea is part of the lower respiratory tract, along with the lungs, bronchi, bronchioles, and alveoli. The strong, flexible tube is also called the windpipe because its main job is to move air in and out of the lungs.

Human Respiratory System Lungs Anatomy
magicmine / Getty Images

Structure

In an adult, the trachea is about 4 to 5 inches long and 1 inch around (diameter). The trachea starts just under the voice box (larynx) and runs down the center of the chest behind the breast bone (sternum) in front of the esophagus.

The trachea is connected to the larynx by a ring of cartilage (cricoid cartilage). As the trachea goes down into the chest, it is surrounded by 16 to 22 U-shaped rings of cartilage that hold it open like scaffolding so air can flow through. 

The back (posterior) wall of the trachea is not covered by cartilage. Instead, it’s made up of connective tissue and smooth muscle that can flex and expand when needed to make the windpipe bigger or smaller.

The trachea ends at a ridge of cartilage that separates and forms the junction into the bronchi (carina).

Membranes

Mucosal membranes are made up of epithelial cells, mucus-secreting goblet cells, and hair-like projections called cilia that line the inside of the trachea and help move foreign particles up and out of the airway.

Inside these membranes are submucosal glands, which act as companions to goblet cells by secreting water molecules and the gel-like component of mucus (mucin) onto the tracheal lining.

The trachea also has a network of blood vessels and lymphatic vessels. Blood vessels give the tissues oxygen and nutrients and regulate the exchange of heat inside the airway. The lymphatic vessels help remove infectious microbes on the surface of the wall of the trachea so they can be taken care of by the immune system.

Trachea Function

The function of the trachea is to be the main passageway for air to pass from the upper respiratory tract to the lungs. As air flows into the trachea during inhalation, it is warmed and moisturized before entering the lungs.

Most particles that enter the airway are trapped in the thin layer of mucus on the trachea walls. They are then moved up toward the mouth by cilia, where they can be coughed up or swallowed.

The U-shaped sections of cartilage that line the trachea are flexible and can close and open a little as the trachealis muscle at the back of the rings contracts and relaxes. These small contractions of the trachea occur involuntarily as part of normal breathing (respiration).

If any object, liquid, or irritant (like smoke) gets into the trachea, the muscles can contract violently, causing coughing to bring up the substance and get it out of the windpipe.

These contractions can also be done on purpose, such as with controlled coughing to clear the airways of people with conditions like chronic obstructive pulmonary disease (COPD) or cystic fibrosis.

What Conditions Affect the Trachea?

The trachea is vulnerable to any substances that are breathed in that can damage tissue and affect breathing. Certain infections and diseases can also affect the trachea.

Symptoms of Trachea Problems

Many people with tracheal conditions do not have any symptoms. That said, some of the common signs and symptoms that can point to a problem with the trachea include:

  • Trouble breathing 
  • Coughing (which may include coughing up blood)
  • Hoarse voice
  • Wheezing, shortness of breath 
  • Frequent upper respiratory infections and/or asthma that does not seem to get better with treatment 
  • Difficult swallowing
  • High-pitched noises when breathing (stridor) 

Having trouble breathing or swallowing is always a reason to see your provider. If these symptoms are severe, go to urgent care or the emergency room.

Choking

Coughing is the body's way of removing foreign substances from the throat, trachea, or lungs. If an object cannot be expelled from the trachea, a person can choke. 

Severe choking can prevent oxygen from getting into the lungs, which may lead to syncope (fainting), asphyxiation (suffocation), or death.

Emergency care like the Heimlich maneuver or a tracheostomy might be needed to clear out the trachea so a person can breathe. Non-life-threatening blockages can be treated with bronchoscopy, a procedure that uses a flexible scope that goes down the throat to find and remove foreign objects.

Tracheitis

Tracheitis is inflammation of the trachea. It occurs almost always only in children. It is usually linked to a bacterial infection that has spread from the upper respiratory tract. The bacteria Staphylococcus aureus is a common cause of tracheitis.

Tracheitis can be dangerous for babies and young children because any inflammation of their small windpipes can lead to a blockage and, in some cases, the inability to breathe.

High-pitched wheezing caused by airway obstruction or restriction (stridor) is a common symptom of tracheitis.

Croup (laryngotracheobronchitis) is an inflammatory, infectious illness that can lead to airway blockages in children.

Bacterial tracheitis is usually treated with antibiotics. Severe cases may need intravenous antibiotics as well as intubation and mechanical ventilation to help with breathing. 

Tracheoesophageal Fistula

tracheoesophageal fistula is an abnormal passageway between the trachea and the esophagus that lets swallowed food get inside the trachea and the lungs. 

A fistula can lead to choking, gagging, trouble breathing, and bluish skin due to the lack of oxygen (cyanosis). A complication is aspiration pneumonia.

A transesophageal fistula is rare but can happen from trauma, cancer, or a congenital defect that causes the incomplete formation of the esophagus (esophageal atresia).

Roughly one of every 4,000 children in the United States is born with a tracheoesophageal fistula. In most cases, it can be treated with surgery.

Tracheal Stenosis

If the trachea is damaged, scars can form and make the airway narrow (tracheal stenosis).

Tracheal stenosis can cause stridor and shortness of breath (dyspnea), especially with physical activity (exertion).

Causes of tracheal stenosis include:

  • Goiter
  • Sarcoidosis
  • Amyloidosis
  • Diphtheria and other severe respiratory infections
  • Wegener's granulomatosis
  • Thyroid cancer
  • Lung cancer
  • Lymphoma of the chest

Between 1% and 2% of people who have intubation and mechanical ventilation will get tracheal stenosis. People who need prolonged ventilation are at the highest risk for it.

Stenosis can be treated with stents and tracheal dilation. In severe cases, surgery is needed to fix it.

Tracheomalacia

Tracheomalacia is an uncommon condition where the trachea collapses on itself during breathing and coughing. 

It often happens after prolonged intubation and can be a complication of COPD (since there is progressive wearing down of the tracheal cartilage from chronic inflammation and coughing).

Tracheomalacia can also affect babies if they are born with weakness of tracheal cartilage (congenital). Symptoms include stridor, rattling breath sounds, and cyanosis.

  • Acquired tracheomalacia may need surgery to correct and support the weakened airway.
  • Congenital tracheomalacia rarely needs surgery and usually gets better on its own by the time the child is 2 years old.

Tracheal Cancer

Tracheal cancer is extremely rare, occurring in only about one in every 500,000 people. Most cases are squamous cell carcinomas that are caused by cigarette smoking. Cancers that start in nearby structures, such as the lungs, esophagus, or thyroid gland, can sometimes spread (metastasize) to the trachea.

Tumors that are not cancer (benign)—like chondromas and papillomas—can also form in the trachea. Though they are benign, the tumors can block the airway and affect breathing, as well as trigger stenosis.

The surgical removal of a tracheal tumor is the preferred method of treatment (with or without radiation therapy). Some people with tracheal cancer can be treated with radiation alone. Chemotherapy with radiation often is used if a tumor cannot be taken out.

Treatment and Rehabilitation

Injuries, infections, and diseases of the trachea can cause damage to the airway, and it can’t always be fixed or healed. Tracheal stenosis is one example. In this case, the scars that form are usually permanent. Once the cause of a tracheal injury is treated, efforts can be made to repair the trachea or at least support its function.

Chest Physical Therapy

Since most children with tracheomalacia outgrow the condition by the age of 3, treatment is usually only supportive. Chest physical therapy (CPT) to help with breathing and making sure the airway stays clear can be helpful. 

Chest percussion, vibration/oscillation, deep breathing, and controlled coughing are examples of techniques that can be used. A humidifier and continuous positive airway pressure (CPAP) device might also be recommended.

CPT is sometimes recommended for adults with tracheomalacia or chronic airway obstruction or restriction. Regular exercise, 20 to 30 minutes five times weekly, can also help.

Tracheal Dilation and Stent Placement

In some cases of tracheal stenosis, a flexible, tube-like instrument called a bougienage can be put into the trachea during a bronchoscopy and expanded with a balloon to open up (dilate) the airway. A rigid silicone or metal sleeve (stent) is then put in to hold the trachea open.

Tracheal dilation and stent placement are typically only used when surgery is not possible. Most procedures can be done on an outpatient basis and only require a short-acting anesthetic like propofol.

Ablation Therapy

Stenosis can often be treated by getting rid of any retracted scar tissue that is narrowing the airway. The procedure, called ablation, can release the retracted tissue and help a person breathe better.

Ablative techniques include laser therapy (using a narrow beam of light), electrocautery (using electricity), cryotherapy (using cold), brachytherapy (using radiation), and argon plasma (using argon gas).

Ablation therapies usually can be done on an outpatient basis with a mild, short-acting sedative and tend to be successful. However, possible side effects include pain, cough, and infection.

Fistula Repair

Tracheoesophageal fistulas almost always need to be fixed with surgery to close the hole between the trachea and the esophagus. Although tracheal stenting is sometimes used to plug the gap, a stent can slip and would need repositioning or replacement.

Surgery is a more permanent solution. Once the hole is repaired with sutures, a full-thickness skin graft or muscle graft can be added to prevent the fistula from opening up again. 

The rate of complications after fistula repair surgery is high—between 32% and 56%. Pneumonia, airway obstruction, wound infection, and reopening of the fistula are the most common complications.

Tracheal Resection

Tracheal resection and reconstruction (TRR) is an open surgical procedure used to remove tracheal tumors and treat severe post-intubation stenosis or fistulas.

This procedure involves the removal of a section of the airway, the cut ends of which are then stitched together with sutures. Reconstruction involves the placement of a small piece of cartilage (taken from another part of the body) to rebuild the trachea and keep it well-supported.

TRR is considered major surgery and typically requires two to three weeks of recovery. Complications include post-operative stenosis or fistula as well as vocal cord dysfunction.

Tracheal Reconstruction

Techniques such as the Maddern procedure and the REACHER technique are sometimes used to treat stenosis in the upper part of the trachea near the larynx.

These procedures involve removing diseased tissue and putting in a full-thickness skin graft from the thigh.

  • The Maddern procedure can be performed through the mouth.
  • The REACHER procedure requires a cervicotomy, is faster than a resection, and has a far shorter recovery time.

You may need to find a specialist ENT-otolaryngologist who can use these techniques to treat the condition if they are recommended for your condition. 

Tracheostomy

Tracheostomy and tracheotomy are surgical procedures where a breathing tube is put into the trachea through an incision in the throat.

  1. A tracheostomy is a permanent opening in the trachea. It can be used for laryngectomy patients, laryngeal stenosis, and crushing laryngeal injuries. It also might be needed for people with a major spinal cord injury who cannot breathe well enough on their own or people with end-stage lung disease.
  2. Tracheotomy is a temporary opening into the trachea. A traumatic chest wall injury or epiglottitis may need an emergency tracheotomy. This can also be necessary for head and neck cancer patients having radical resections and reconstructions.

These procedures are also used when intubation through the nose or mouth is not possible or when long-term ventilator support is needed.

Summary

The main function of the trachea is to bring air to your lungs. There are many conditions that can affect the trachea. These disorders don’t always cause symptoms, but people may have breathing trouble or difficulty swallowing if there is something wrong with their trachea. Diagnosing tracheal disorders usually requires seeing a provider who specializes in them and can recommend the best treatment. 

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By Lynne Eldridge, MD
 Lynne Eldrige, MD, is a lung cancer physician, patient advocate, and award-winning author of "Avoiding Cancer One Day at a Time."