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==Introduction==

==Introduction==

The trachea is the tube linking the cricoid [[Bones and Cartilage - Anatomy & Physiology#Types of Cartilage|cartilage]] of the [[Larynx - Anatomy & Physiology |larynx]] to the [[Bronchi and bronchioles - Anatomy & Physiology|bronchi]], forming part of the conducting system which transports air from the external environment to the [[Lungs - Anatomy & Physiology|lungs]]. The [[Oesophagus - Anatomy & Physiology|oesophagus]] lies dorsally to the trachea.  

The trachea is the tube linking the cricoid [[Cartilage - Anatomy & Physiology#Types of Cartilage|cartilage]] of the [[Larynx - Anatomy & Physiology |larynx]] to the [[Bronchi and Bronchioles - Anatomy & Physiology|bronchi]], forming part of the conducting system which transports air from the external environment to the [[Lungs - Anatomy & Physiology|lungs]]. The [[Oesophagus - Anatomy & Physiology|oesophagus]] lies dorsally to the trachea. The cervical part of the trachea lies generally in the median position, although this varies slightly depending on the position of the head. The thoracic part of the trachea crosses the aortic arch, thus its positioning is moved slightly to the right at this level. The trachea bifurcates to form the two [[Bronchi and Bronchioles - Anatomy & Physiology|bronchi]] at the level of the 4th-6th intercostal space.

The cervical part of the trachea lies generally in the median position, although this varies slightly depending on the position of the head.  

The thoracic part of the trachea crosses the aortic arch, thus it's positioning is moved slightly to the right at this level.

 

The trachea bifurcates to form the two [[Bronchi and bronchioles - Anatomy & Physiology|bronchi]] at the level of the 4th-6th inter[[Ribs and Sternum - Anatomy & Physiology#Costae|costal]] space.

==Structure==

==Structure==

*The trachea contains numerous rings of [[Bones and Cartilage - Anatomy & Physiology#Hyaline Cartilage|hyaline cartilage]] which are C-shaped, being dorsally incomplete, connected to each other by elastic connective tissue. The ends of the incomplete rings are joined by smooth muscle - ''Trachealis'' muscle.

The trachea contains numerous rings of [[Cartilage - Anatomy & Physiology#Hyaline Cartilage|hyaline cartilage]] which are C-shaped, being dorsally incomplete, connected to each other by elastic connective tissue. The ends of the incomplete rings are joined by the smooth ''trachealis'' muscle. The structural conformation of the trachea prevents collapse due to traction forces, whilst allowing it to adjust in length and diameter, as the neck moves and the [[Diaphragm - Anatomy & Physiology|diaphragm]] contracts. The trachea's walls are made up of a number of layers including the inner mucosa, fibrocartilaginous middle layer, and adventitia (in the neck) or serosa (in the thorax). The inner mucosa contains glands which produce mucus. This mucus traps debris and is constantly moved upwards towards the [[Oropharynx - Anatomy & Physiology|oropharynx]] where it is swallowed. This mechanism is known as the [[Respiratory Epithelium - Anatomy & Physiology#Mucociliary Escalator|'''Muco-Ciliary escalator''']].

**The structural conformation of the trachea prevents collapse due to traction forces, whilst allowing it to adjust in length and diameter as the neck moves and the [[Diaphragm - Anatomy & Physiology|diaphragm]] contracts.  

*The trachea's walls are made up of a number of layers: Inner Mucosa, Fibrocartilaginous middle layer, and adventitia (in the neck) or serosa (in the thorax).

*The inner mucosa contains glands which produce mucus. This mucus traps debris and is constantly moved upwards towards the [[Oral Cavity - Oropharynx - Anatomy & Physiology|oropharynx]] where it is swallowed. This mechanism is known as the [[Respiratory Epithelium - Anatomy & Physiology#Mucociliary Escalator|''Muco-Ciliary escalator'']].

==Function==

==Function==

*Transporting air for respiration from the [[Larynx - Anatomy & Physiology|larynx]] to the [[Bronchi and bronchioles - Anatomy & Physiology|bronchi]].

The trachea is responsible for transporting air for respiration from the [[Larynx - Anatomy & Physiology|larynx]] to the [[Bronchi and Bronchioles - Anatomy & Physiology|bronchi]].

==Species Differences==

==Species Differences==

*In the '''Dog and Cat''' the C-Shaped rings are joined by muscle which is placed externally, rather than internally as is normal for the other species.

In the '''dog and cat''' the C-Shaped rings are joined by muscle which is placed externally, rather than internally as is normal for the other species. In [[Avian Respiration - Anatomy & Physiology|'''avian]] species''' the trachea is composed of tightly stacked rings of [[Cartilage - Anatomy & Physiology#Types of Cartilage|cartilage]], which are complete with no dorsal space. They overlap considerably. The [[Respiration in Non-Homeotherms - Anatomy & Physiology|respiratory systems of '''non-homeotherms''']] are also very different to that of mammals.

*In [[Avian Respiration - Anatomy & Physiology|'''avian]] species''' the trachea is composed of tightly stacked rings of [[Bones and Cartilage - Anatomy & Physiology#Types of Cartilage|cartilage]], which are complete with no dorsal space. They overlap considerably.

*The [[Respiration in Non-Homeotherms - Anatomy & Physiology|Respiratory Systems of non-Homeotherms]] are also very different to that of mammals.

==Histology==

==Histology==

==Links==

==Links==

*[[Trachea - Pathology]]

Click here for information on [[:Category:Trachea - Pathology|trachea pathology]].

==References==

{{citation|initiallast = Dyce|initialfirst = K.M|2last = Sack|2first = W.O|finallast = Wensing|finalfirst = C.J.G|year = 2002|title = Textbook of Veterinary Anatomy|ed =3rd|city = Philadelphia|pub = Saunders}}

*{{citation|initiallast = Dyce|initialfirst = K.M|2last = Sack|2first = W.O|finallast = Wensing|finalfirst = C.J.G|year = 2002|title = Textbook of Veterinary Anatomy|ed =3rd|city = Philadelphia|pub = Saunders}}

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