TRACHEA AND LUNGS ANATOMY

By:Dr Mohammed Faez

Trachea

The trachea is a cartilaginous and membranous tube, extending from the cricoid cartilage of the larynx, on a level with C6 vertebra, to the level of the angle of Louis (T4/5) vertebra, where it divides into the two bronchi, one for each lung.

Trachea

• Structure: The trachea is a rigid fibroelastic structure. Incomplete rings of hyaline cartilage continuously maintain the patency of the lumen.

• The trachea is lined internally with ciliated columnar epithelium.

Trachea

Trachea

• It measures about 11 cm. In length.

• Its diameter, from side to side, is from 2 to 2.5 cm.

• It has 18-22 cartilaginous rings

• It is greater in the male than in the female.

TracheaRelations:Anteriorly:

Neck:• The isthmus of the thyroid gland (2nd,

3rd and 4th tracheal rings )• The inferior thyroid veins• The sternothyroid and sternohyoid

muscles• The cervical fascia

Thorax: • The manubrium sterni • The remains of the thymus• The left innominate vein• The aortic arch• Left common carotid arteries• The deep cardiac plexus.

Trachea

Relations:Posteriorly : the esophagusLaterally:Neck:

• Common carotid arteries• Right and left lobes of the

thyroid gland• Inferior thyroid arteries• The recurrent nerves

TracheaRelations:

Laterally:Thorax: it lies in the superior mediastinum.Right

• The pleura • Right vagus, • The innominate artery

Left • Left recurrent nerve• The aortic arch• The left common carotid • Subclavian arteries

Inferior thyroid a.

Recurrent laryngeal n. Thoracic duct

Vagus n.

Sympathetic trunk

Trachea

Trachea

• The trachea divides into two main bronchi : the left and the right bronchi, at the level of the sternal angle at the anatomical point known as the carina.

Bronchi

The right bronchus:• Wider, shorter, and

more vertical in direction than the left.

• It is about 2.5 cm. Long, • It enters the right lung

nearly opposite the T5 vertebra.

Bronchi

The Left Bronchus • It is smaller in caliber

but longer than the right

• It is about 5 cm. long.• It enters the root of the

left lung opposite the T6 vertebra.

trachea

Left primary bronchus

Right Primary Bronchus

Wider, shorter, and more vertical than the left

Bronchi

• The primary bronchi divide to form Secondary Bronchi (lobar bronchi).

• There is one secondary bronchus for each lobe of the lungs.

• There are 2 lobes on the left lung.

• There are 3 lobes on the right lung.

Bronchi

• The left main bronchus enters the hilum and divides into a superior and inferior lobar bronchus.

• The right main bronchus gives off the bronchus to the upper lobe prior to entering the hilum (superior lobar bronchus) and once into the hilum divides into middle and inferior lobar bronchi.

Bronchi

• Each lobar bronchus divides within the lobe into(Tertiary Bronchi) segmental bronchi.

• Each segmental bronchus enters a bronchopulmonary segment.

• Each bronchopulmonary segment is pyramidal in shape with its apex directed towards the hilum.

Bronchi

• Each bronchopulmonary segment has its own segmental bronchus, artery and lymphatics.

• The veins draining each segment are intersegmental.

Bronchi

Trachea blood supply

• the trachea receives its blood supply from branches of the inferior thyroid and bronchial arteries.

Lungs

• The two lungs are organs of respiration and lie on either side of the mediastinum surrounded by the right and left pleural cavities.

• Right and left lungs.

Lungs

• The right lung is normally a little larger than the left lung because the middle mediastinum, containing the heart, bulges more to the left than to the right.

Lungs

Each lung has a half-cone shape, with a base, apex, two surfaces and three borders:

• The base sits on the diaphragm.

• The apex projects above 1st rib and into the root of the neck.

Lungs• The two surfaces-the costal

surface lies immediately adjacent to the ribs and intercostal spaces of the thoracic wall.

• The mediastinal surface lies against the mediastinum anteriorly and the vertebral column posteriorly and contains the comma-shaped hilum of the lung through which structures enter and leave.

Lungs

• The three borders-the inferior border of the lung is sharp and separates the base from the costal surface. The anterior and posterior borders separate the costal surface from the medial surface.

• Unlike the anterior and inferior borders, which are sharp, the posterior border is smooth and rounded.

Lungs

Root and hilum of lung:• The root of each lung is

a short tubular collection of structures that together attach the lung to structures in the mediastinum .

• The hilum, where structures enter and leave.

Lungs

Structures within each root and located in the hilum:

• A pulmonary artery • Two pulmonary veins• A main bronchus• Bronchial vessel • Nerves• Lymphatics

Lungs

Structurethe right lung:

• It is divided into upper, middle and lower lobes by oblique and horizontal fissures.The left lung:

• It has two lobes, upper and lower lobes. They are separated by the oblique fissure.

Lungs

Read about right and left lungs relations and lungs impressions.

Bronchial Tree• The trachea is divided into 2

bronchi• The main bronchus divides within

the lung into lobar bronchi.• The lobar bronchi divide into

segmental bronchi which supply bronchopulmonary segments.

• Each bronchopulmonary segment, the segmental bronchi divide into bronchioles, which further subdivide and supply the respiratory surfaces.

Bronchopulmonary Segment

• There are ten bronchopulmonary segments in each lung

• Each bronchopulmonary segment is shaped like an irregular cone with the apex at the origin of the segmental bronchus and the base projected peripherally onto the surface of the lung.

Bronchopulmonary Segment

• A bronchopulmonary segment is the smallest, functionally independent region of a lung and the smallest area of lung that can be isolated and removed without affecting adjacent regions.

Blood supply of the lung

• The bronchi and parenchymal tissue of the lungs are supplied by bronchial arteries a branches of the descending thoracic aorta.

• Bronchial veins, which also communicate with pulmonary veins, drain into the azygos and hemiazygos.

Lymphatic drainage of the lungs

• lymph returns from the periphery towards the hilar tracheobronchial groups of nodes and from here to mediastinal lymph trunks.

Nerve supply of the lungs

• A pulmonary plexus is located at the root of each lung.

• The plexus is composed of sympathetic fibres (from the sympathetic trunk) and parasympathetic fibres (from the vagus).

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