1.
Introduction:
The trachea is also called it as “WINDPIPE”.
2.
Situation:
It is situated at the level of 5th
thoracic vertebra where it divides at the carina into the right and left primary
bronchi, one bronchous going to each lung.
3. Measurments:
v
Length approximately 10-11cm long
v SHAPE: WIND
PIPE.
4. Structures
associated with the trachea
v
SUPERIORLY:
the larynx
v
INFERIORLY: the
right and left bronchi
v
Anteriorly:
Upper part: the isthmus of the thyroid
gland .
§ Lower part: the arch of the aorta and
the sternum.
v
POSTERIORLY: The oesophagus separates the trachea from the
vertebral column.
v
Laterally
: The lungs and the lobes of the thyroid gland.
5. Structure :
v
Trachea is composed of 3 layers of tissue
(C-shape) rings of hyaline cartilage lying one above another.
v
The rings are incomplete posteriorly.
v
Connective tissue and involuntary muscle join
the cartilages and form the posterior wall where the rings are incomplete.
v
The soft tissue posterior wall is in contact
with the oesophagus .
Three layers of
tissue “CLOTHE” the cartilages of
the trachea.
1.
The outer layer consists of fibrous and elastic
tissue and encloses the cartilages.
2.
The middle layer consists og cartilages and
bands of smooth muscle that wind round the trachea in a helical arrangement.
3.
The inner lining consists of ciliated columnar epithelium,
containing mucus-secreting goblet cells.
6. Blood supply
v
Arterial Supply
: The inferior thyroid and bronchial arteries.
v
Venous
drainage: Inferior thyroid veins
into the brachiocephalic veins.
7. Nerve supply
Para
sympathetic nerve supply :
v
The recurrent laryngeal nerves and other branches
of the vagi.
v
Para sympathetic stimulation constricts the trachea.
Sympathetic nerve supply:
v
Nerve supply from the sympathetic ganglia.
v
Sympathetic stimulation dilates the trachea.
8. Lymphatic
supply:
v
Lymph from the respiratory passages drains
through lymph nodes situated round the trachea and in the carina.
v
The area where it divides into two bronchi.
9. Functions
1. SUPPORT AND
PATENCY :
v
The arrangement of cartilage and elastic tissue
prevents kinking and obstruction of the airways as the head and neck move.
2. MUCOCILIARY
ESCALATOR:
v
This is the synchronous and regular beating of
the cilia of the mucous membrane lining that wafts mucus with adherent
particles upwards towards the larynx, where it is either swallowed or coughed
up.
3. COUGH REFLEX.
v
Nerve endings in the larynx, trachea and bronchi
are sensitive to irritation, which generates nerve impulses conducted by the
vagus nerves to the respiratory centre in the brain stem.
4. WARMING,
HUMIDIFYING AND FILTERING.
v
These continue as in the nose, although air is
normally saturated and at body temperature when it reaches the trachea.
10. Applied
anatomy:
TRACHEITIS: Inflammation
of the trachea.
v
The infection may occur especially in tobacco
smokers and people who live or work in a polluted atmosphere.
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