Trachea

The windpipe is a tube in your neck.

It carries air to your lungs. It stays open with hard rings. These rings are shaped like the letter C.

Inside, the tube has tiny hairs. These hairs move a sticky liquid. This liquid traps dust and dirt. The hairs push the dirt away. This keeps your lungs clean. It is a very busy tube!

The trachea is a tube in your neck. Most people call it the windpipe.

Its main job is to carry air to your lungs. It also helps warm and clean the air you breathe.

The trachea stays open using many hard rings. These are called rings of hyaline cartilage.

The rings are shaped like the letter C. They are about 4 millimeters high. A muscle called the trachealis connects the ends of these rings. This helps the tube work when you cough.

Inside, the tube has a special lining. It has tiny hairs called cilia.

There are also cells called goblet cells. These cells make a sticky liquid called mucin. This liquid makes mucus. The mucus traps dust and dirt. Then, the cilia move the mucus up and out. This keeps your airways clear.

Sometimes, germs cause an infection in the trachea. This can make the tube swell. If the tube gets too narrow, it can make a harsh sound. This sound is called stridor.

This sound happens when air struggles to pass through.

The trachea is a very important tube in your body. Most people call it the windpipe.

It connects your larynx, which is your voice box, to your lungs. This tube allows air to pass in and out of your body. Almost all land animals with lungs have a trachea. It is a vital part of the respiratory tract. Without it, air could not reach the lungs to keep you alive.

The trachea works by staying open and cleaning the air.

It is made of 16 to 20 C-shaped rings of hyaline cartilage. These rings are about 4 millimeters high. They act like a sturdy frame to prevent the tube from collapsing. A muscle called the trachealis connects the ends of these rings. This muscle can contract when you cough to change the tube's size. Inside, tiny hairs called cilia move mucus up and out.

This process is called mucociliary clearance.

Scientists and doctors have studied the trachea for a long time. We know it starts to form very early in life. During the second month of embryo development, the trachea begins to grow. It starts as a small bud in the respiratory system. By the fifth week, the main branches called bronchi begin to form. In the first year of life, the trachea is only 4 millimeters wide. By late childhood, it grows to about 2 centimeters in diameter.

There are many specific facts about how the trachea is built.

An adult trachea is wider in males than in females. It starts at the level of the sixth cervical vertebra. It ends at the carina, where it splits into two bronchi. The carina is at the level of the fourth thoracic vertebra. The trachea is also surrounded by many other parts. The thyroid gland sits across the upper part of the tube. Nearby, large blood vessels like the aortic arch pass close by.

Learning about the trachea helps us understand how we breathe every day. If the tube gets too narrow, it makes a loud sound.

This sound is called stridor. It can happen if there is an infection or swelling. You might also see different types of tracheae in nature. For example, insects use a very different system to breathe. They use tiny tubes called tracheae and spiracles to move gases. This shows how different living things solve the same big problem.

The trachea, often called the windpipe, is a vital cartilaginous tube in the respiratory tract.

It serves as the main passageway for air traveling between the larynx and the lungs. In almost all land vertebrate animals, this structure is essential for breathing. It connects the larynx, or voice box, to the two primary bronchi of the lungs. Without a functional trachea, oxygen could not reach the lungs to sustain life.

To function effectively, the trachea must remain open while also being able to move. It is constructed from 16 to 20 C-shaped rings of hyaline cartilage. These rings are approximately 4 millimeters high in adults. Because the rings are incomplete and C-shaped, they do not form a solid circle. Instead, the open ends are joined vertically by overlying ligaments and the trachealis muscle. The trachealis muscle runs along the back wall of the trachea. This muscle can contract during a cough to reduce the size of the lumen, which is the inner space of the tube. Additionally, an outer layer of connective tissue called adventitia allows the trachea to bend and stretch during body movements.

The internal environment of the trachea is highly specialized for protection. The trachea is lined with an epithelium of column-shaped cells. These cells feature tiny, hair-like extensions known as cilia. Scattered among these are goblet cells, which are glandular cells that produce mucins. Mucins are the main components of mucus. This mucus works to moisten and protect the airways by trapping inhaled dust and foreign particles. The cilia then perform a process called mucociliary clearance. They waft the mucus and trapped particles upward toward the larynx and pharynx. From there, the material is either swallowed or expelled as phlegm.

Development of the trachea begins very early in the human life cycle. During the fourth week of embryo development, the respiratory bud grows and the trachea begins to separate from the foregut. This separation is caused by the formation of ridges known as the tracheoesophageal septum. By the fifth week, the left and right main bronchi begin to form as buds at the end of the trachea. In the first year of life, the trachea is quite small, measuring no more than 4 millimeters in diameter. By late childhood, it expands to an adult diameter of approximately 2 centimeters. In children, the trachea is generally more circular and vertical than in adults.

An adult trachea has specific anatomical landmarks and dimensions. It begins at the lower edge of the cricoid cartilage of the larynx at the level of the sixth cervical vertebra (C6). It ends at the carina, which is the specific point where the trachea branches into the left and right main bronchi. This branching occurs at the level of the fourth thoracic vertebra (T4). While the trachea is a midline structure, its position can change with breathing. It may also be displaced to the right by the aortic arch. In adults, the trachea is also wider in males than in females.

The trachea is surrounded by many critical structures in the neck and chest.

The thyroid gland stretches across the upper trachea, with its isthmus overlying the second to fourth rings. Nearby, the aortic arch and the left common carotid artery pass close to the lower trachea. Behind the trachea sits the esophagus, followed by the vertebral column. Blood is supplied to the trachea through small branches from the inferior thyroid arteries and the bronchial arteries. These arteries split into superior and inferior branches to supply the anterior and posterior parts of the tube. The lymphatic system also serves the area, draining into the pretracheal and paratracheal lymph nodes.

Medical issues can significantly impact tracheal function. Inflammation of the trachea is called tracheitis. This is often caused by viral infections, such as parainfluenza or influenza viruses. Bacterial infections, which can be caused by *Staphylococcus aureus* or *Streptococcus pneumoniae*, can also cause tracheitis. These infections may lead to swelling that narrows the airway. This narrowing often produces a harsh breathing sound called stridor.

If the trachea becomes completely obstructed, a tracheostomy may be required. During surgery, doctors may perform tracheal intubation, which involves inserting a tube into the trachea to assist with mechanical ventilation.

It is interesting to note that the term "trachea" describes different structures in different animals. In insects, the trachea is part of a completely different respiratory system.

Instead of using lungs, insects use a system of spiracles, tracheae, and tracheoles. This system transports metabolic gases directly to and from their tissues. This highlights how evolution has developed various ways to solve the challenge of gas exchange across the animal kingdom.