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1. TRACHEA
Position, length, Anatomical Relations, Structure, Functions, Disorders

4. FRONT VIEW

5. SIDE VIEW

6. BACK VIEW

7. INTRODUCTION
◦ The trachea is a hollow, tube-like structure .
◦ The trachea, also known as the windpipe, is a U-shaped tube
that connects the voice box (larynx) to the lungs. It’s a key part
of the respiratory system, allowing air to pass from the nose or
mouth to the lungs.
◦ The average length of the trachea is about 11.8 centimeters ,
and a male’s trachea is typically longer than a female’s.
◦ A mucous membrane, similar to those in the nasal cavity, lines
the interior of the trachea. Cells in this membrane, called
goblet cells, release mucus to help prevent microorganisms
and debris from entering the lungs.

8. The trachea is also lined with tiny hair-like structures called cilia.
These help push mucus that contains debris or pathogens out
of the trachea. A person then either swallows or spits out the
mucus.
Soft tissue makes up most of the trachea, and cartilage
provides extra support.
The trachea runs parallel to the esophagus and lies just in front
of it. The back of the trachea is softer to allow the esophagus to
expand when a person is eating.
◦ Due to their proximity, a small piece of cartilage in the larynx
automatically covers the opening of the trachea to prevent
food or drink from getting into it when the person is eating.

9. ◦If food or drink do get into the trachea, this typically
causes the person to cough. If a piece of food is
particularly large, it could become trapped in the
trachea and obstruct breathing.

10. LOCATION AND POSITION
The trachea is located in the lower neck and upper chest, between the
collarbones and behind the notch at the base of the throat. It’s a midline
structure that runs in front of the esophagus and between the top lobes
of the lungs.
◦ The trachea starts at the bottom of the larynx, at the level of the sixth
cervical vertebra. It ends at the carina, where it splits into the left and
right main bronchi, at the level of the fourth thoracic vertebra.
◦ The trachea extends from the inferior margin of the cricoid cartilage
(C6) and branches into the right and left main bronchi at the carina,
located at the T4 vertebral body level, in the plane of Ludwig. It is
usually situated in a midline position and can be displaced slightly to
the right at the arch of the aorta.

11. STRUCTURE OF TRACHEA
Cartilage rings
The trachea is made up of 16–20 C-shaped
cartilage rings that support the trachea and
allow it to move and flex when you breathe.
The rings are separated by a thin membrane,
and the free ends of the rings are connected by
muscle bands.
Mucosa
A moist tissue that lines each ring of cartilage.
The mucosa contains goblet cells, which produce
mucus that traps dust and other debris.

12. Cilia
Small, hair-like structures in the inner layer of the
trachea that move in rhythm to push mucus
out of the trachea.
Trachealis muscle
A muscle located between each ring of cartilage.
When you cough, the trachealis muscle contracts
to help expel air more forcefully.
Blood and lymphatic vessels
A complex network of tissue in the base of the mucous membrane that includes
blood vessels and lymphatic vessels. The blood vessels control cellular maintenance
and heat exchange, while the lymphatic vessels remove foreign particles.

13. ◦ The trachea consists of four histological layers. The mucosa represents the
innermost layer and it is lined with pseudo stratified ciliated columnar
epithelium. The second histological layer is the submucosa. It consists of
connective tissue that contains mucus glands, smooth muscle, vessels,
nerves and lymphatics. The third layer is the musculocartilaginous layer
which is represented by the cartilaginous rings and intervening smooth
muscle. Lastly, the most external layer is provided by the fibroelastic
adventitia.
◦ Trachea or windpipe is lined by pseudo stratified ciliated epithelium.
◦ Outside is C shaped cartilaginous rings . These rings prevent collapse of
trachea during expiration.
◦ Trachea bifurcate at 5th
thoracic vertebrae T5

15. ANATOMICAL RELATIONS OF TRACHEA
Anterior
The sternum, strap muscles, thyroid isthmus, ascending aorta, brachiocephalic artery, right common
carotid artery, superior vena cava, and inferior thyroid veins
Posterior
The esophagus
Lateral
The lateral walls of the thyroid gland, left common carotid artery, arch of the azygos vein, right and
left recurrent laryngeal nerves, and right and left vagus nerves
Right side
The pleura, right vagus, brachiocephalic trunk, right lung, right brachiocephalic vein, superior vena
cava, and azygos vein
Left side
The left recurrent nerve, aortic arch, left common carotid and subclavian arteries, and left subclavian
artery

16. ◦ The right and left lobes of the thyroid gland sit
anterolateral to the proximal cervical trachea and the
isthmus connecting the two lobes tends to cross the
anterior trachea at the 2nd
or 3rd
tracheal ring . In addition
to the proximal trachea, the inferior thyroid artery provides
blood to the inferior thyroid gland.
◦ The esophagus has an intimate relationship with the
trachea along its course). The esophagus begins at the
level of the cricoid cartilage and runs toward the
gastroesophageal junction along the left posterior border
of the trachea. Fibroelastic membranes and rare muscle
fibers lie between the longitudinal muscle of the outer
esophagus and the trachealis muscle. The right posterior
border of the trachea runs along the anterior aspect of
the vertebral bodies. Occasionally, the esophagus may
be found more laterally on the left side making it prone to
injury during mediastinoscopy.

17. ◦ There are a number of large blood vessels lying in close proximity to
the trachea that must be respected during tracheal operations. The
brachiocephalic, or innominate, artery is the first branch of the aortic
arch. It originates at the right anterior aspect of the trachea and runs
superiorly from left-to-right over the right anterolateral portion of the
distal and mid trachea. The left common carotid artery is the next
branch of the aorta. It takes off just to the left of the trachea’s midline
and runs superiorly from right-to-left over the left anterolateral
trachea. The superior vena cava courses toward the right atrium
along the right anterior aspect of the trachea. The azygous vein,
coursing superiorly along the right side of the thoracic vertebral
column before bending anteriorly, joins the superior vena cava lateral
and just superior to the right tracheobronchial angle. Care must be
taken during mediastinoscopy to anticipate this landmark so as to
avoid mistaking the azygos vein for a lymph node during biopsy.

18. The main pulmonary artery, or
pulmonary trunk, lies anterior and
to the left of the carina . Its
branches, the right and left
pulmonary artery, run laterally and
anterior to their corresponding
main stem bronchi before
branching into the lobar arteries of
the right and left lungs.

19. BLOOD SUPPLY
The trachea’s blood supply comes from multiple sources, including:
Inferior thyroid arteries: The upper trachea receives blood from the tracheoesophageal
branches of the inferior thyroid arteries. These branches originate from the right and left
thyrocervical trunks, which branch off the subclavian arteries.
Bronchial arteries: The lower trachea, carina, and bronchi receive blood from the
bronchial arteries, which usually come from the proximal descending aorta.
Subclavian, internal mammary, and innominate arteries: Small branches from these
arteries also supply the trachea.
◦ The trachea’s blood vessels branch out from the sides and enter the trachea over its
lateral wall. As the branches approach the trachea’s wall, they split into superior and
inferior branches. These branches join with the branches of the arteries above and
below, and then split into branches that supply the anterior and posterior parts of the
trachea.

20. Venous drainage
◦ The trachea's venous drainage is via the brachiocephalic,
azygos, and accessory hemiazygos veins. The inferior
thyroid venous plexus receives drainage from the trachea,
and then empties into the brachiocephalic veins.
Arterial supply
◦ The trachea receives arterial blood from the tracheal
branches of the inferior thyroid artery.

21. DEVELOPMENT OF TRACHEA
In the fourth week of development of the human embryo as the respiratory
bud grows, the trachea separates from the foregut through the formation
of ridges which eventually separate the trachea from the esophagus, the
tracheoesophageal septum. This separates the future trachea from the
esophagus and divides the foregut tube into the laryngotracheal tube. By
the start of the fifth week, the left and right main bronchi have begun to
form, initially as buds at the terminal end of the trachea.
The trachea is no more than 4 mm in diameter during the first year of life,
expanding to its adult diameter of approximately 2 cm by late childhood.
The trachea is more circular and more vertical in children compared to
adults, varies more in size, and also varies more in its position in relation to
its surrounding structures.

22. ◦ The trachea is surrounded by 16 to 20 rings of hyaline cartilage; these
‘rings’ are incomplete and C-shaped. Two or more of the cartilages
often unite, partially or completely, and they are sometimes bifurcated
at their extremities. The rings are generally highly elastic but they may
calcify with age.

23. FUNCTIONS OF TRACHEA
◦ 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).

24. In addition to delivering air, the trachea aids in disease defense.
Mucus in the trachea aids in the capture of germs such as viruses
and pathogenic bacteria before they enter the lungs.
The trachea also serves to control the temperature of the air that
enters and exits the lungs.
On chilly days, the trachea warms and humidifies the air before it
reaches the lungs.
◦ On hot days, the trachea aids in the cooling of the air through
evaporation.
◦ The trachealis muscle that joins the two ends of the tracheal ring
can contract thereby constricting the tracheal tube. This is useful
for increasing the pressure during coughing to evacuate any
irritants more effectively.

25. DISORDERS OF TRACHEA
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)

26. Congenital Disorders
These are present at birth and may be due to developmental abnormalities:.
1. Tracheomalacia
Description: Weakness of the tracheal cartilage leads to collapse during breathing.
Symptoms: Stridor, difficulty breathing, recurrent respiratory infections.
Causes: Genetic syndromes, prematurity.
Treatment: Often resolves with age, but severe cases may require surgery or stenting.
2. Tracheoesophageal Fistula (TEF)
Description: Abnormal connection between the trachea and esophagus.
Symptoms: Difficulty feeding, choking, recurrent pneumonia.
Diagnosis: Imaging and bronchoscopy.
Treatment: Surgical repair.

27. 3. Tracheal Stenosis
Description: Narrowing of the trachea due to incomplete cartilage rings.
Symptoms: Stridor, cyanosis, respiratory distress.
Treatment: Surgery (tracheoplasty).
Acquired Disorders
Tracheomalacia (Acquired)
Causes: Chronic inflammation (e.g., COPD), prolonged intubation, external
compression.
Symptoms: Persistent cough, wheezing, dyspnea.
Treatment: Airway stents, CPAP, or surgical intervention.

28. Tracheal Neoplasms
Types:
Benign: Papillomas, hemangiomas.
Malignant: Squamous cell carcinoma, adenoid cystic carcinoma.
Symptoms: Persistent cough, hemoptysis, airway obstruction.
Diagnosis: Bronchoscopy and biopsy.
Treatment: Surgery, radiation, chemotherapy (depending on type and
stage).

29. Infections
Common Causes:
Acute tracheitis (e.g., bacterial tracheitis caused by Staphylococcus aureus).
Chronic infections (e.g., tuberculosis, fungal infections).
Symptoms: Fever, productive cough, difficulty breathing.
Treatment: Antibiotics, antivirals, or antifungals based on the pathogen
Trauma
Causes: Blunt or penetrating neck trauma, intubation injury.
Symptoms: Subcutaneous emphysema, difficulty breathing, voice changes.
Treatment: Airway stabilization and surgical repair.

30. Inflammatory and Autoimmune Disorder
a. Tracheobronchial Inflammation
Causes: Infections, irritants (e.g., smoke, pollutants), allergies.
Symptoms: Cough, wheezing, chest discomfort.
Treatment: Anti-inflammatory agents, bronchodilators, supportive care.
B. Granulomatosis with Polyangiitis
Description: Autoimmune vasculitis affecting the trachea.
Symptoms: Subglottic stenosis, hemoptysis, stridor.
Treatment: Immunosuppressive therapy (e.g., corticosteroids, cyclophosphamide).

31. Functional Disorders
Tracheal Diverticulum
Description: Outpouching of the tracheal wall.
Symptoms: Often asymptomatic, but may cause cough or infections.
Treatment: Monitoring, surgical excision if symptomatic.
Foreign Body Aspiration
Causes: Accidental inhalation (common in children).
Symptoms: Acute onset cough, wheezing, choking.
Treatment: Emergency bronchoscopy.