Trachea and esophagus are the tubular structures located in the neck region according to human anatomy. They are close to each other but their function stands out. The trachea is a respiratory structure that transfers air entering the nose from the environment to lungs whereas the esophagus belongs to the digestive system which is called ‘Gastrointestinal tract’ and it passes food and water to stomach. Both the trachea and esophagus are significant structures that may stop working normally due to several conditions ranging from infections to cancers. Following article discusses the main difference between the two

Trachea

The trachea is a tube-shaped structure that is a part of the respiratory system. It is present in the lower part of the neck which is slightly deviated to the right side towards the end. It starts from below the larynx and bifurcates at the carina into right and left bronchi on entering the chest. Its length is 12 to 15 cm and the diameter is 2cm in males and about 1.5 cm in females. The lumen is narrower in children.

Esophagus

It is a narrow tube made up of muscles that form a path for passage of food and liquids from the pharynx to the stomach through the peristaltic movement during the third stage of deglutination. It starts at the lower part of the neck and ends in the abdomen. Its length is 25cm. the esophagus is normally in a collapsed state which does not allow passage of food through it. It becomes open only when food bolus enters it. In general, the esophagus is vertical but it has minute curvatures at two sites; one at the root of the neck, second at the level of T7 vertebra.

Trachea VS Esophagus

Location:

The trachea is located in the lower part of the neck, beginning at the lower border of the cricoid cartilage (C6).

The esophagus is also located in the neck but it starts at the lower end of the pharynx.

Length:

The trachea is 12 to 15 cm in length.

The esophagus is 25 cm in length.

Relation:

The trachea is located anterior to the esophagus.

The esophagus is located posterior to the trachea.

Upper end:

The trachea has larynx at its upper end.

The esophagus has pharynx at its upper end.

Lower end:

The trachea is divided into right and left halves and then into bronchi at its lower ends.

The esophagus ends at the upper part of the stomach.

Divisions:

The trachea is divided into 2 segments i.e cervical and thoracic. The cervical region is located in the anterior neck whereas the thoracic part is found in the thorax.

The esophagus is divided into 3 segments i.e cervical, thoracic, and abdominal.

Constrictions:

The trachea has no constrictions along its path.

The esophagus has three constrictions.

The first is at the junction with the pharynx.

The second is at the crossing with the aortic arch and the left main bronchus.

The third is at the junction with the stomach after it pierces the diaphragm.

Structure:

The trachea has 16 to 20 C-shaped rings.

The esophagus does not have rings but it’s muscular.

X-ray appearance:

The trachea is seen as a vertical shadow in the radiograph due to the presence of air in it.

The esophagus is not visible on the X-ray as it does not contain air in it.

Musculature:

The trachealis muscle is a smooth muscle located on the posterior wall of the trachea that connects the gaps between the C-shaped cartilages.

The cervical part mainly consists of striated muscle, the abdominal part consists of smooth muscle and the thoracic part is mixed. Arrangement of the muscular coat of the esophagus consists of an outer longitudinal and inner circular layer.

Mucous membrane:

The trachea is lined by pseudostratified ciliated columnar epithelium and contains goblet cells and mucous glands.

Nonkeratinized stratified squamous epithelium covers the entire esophageal lumen

 Blood supply:

The upper two-thirds of the trachea is supplied by inferior thyroid arteries and the lower third is supplied by the bronchial arteries.

Esophagus: the upper third is supplied by the inferior thyroid artery.

Middle third is supplied by the branches from the middle thoracic aorta

The lower third is supplied by the left gastric artery.

Function:

Trachea carries the air along its path down to the lungs.

The esophagus carries food down the GIT for digestion.

Conclusion

Trachea and esophagus are two important structures of the human body that have individual importance owing to their location and function.

References:

https://www.scribd.com/presentation/54109263/Thorax-2

https://studyres.com/doc/1305777/l1–esophagus-and-stomach-final2014-11-16-06

https://teachmeanatomy.info/abdomen/gi-tract/oesophagus/

https://www.intechopen.com/books/esophageal-abnormalities/anatomy-of-esophagus

https://teachmeanatomy.info/thorax/organs/tracheobronchial-tree/