Download NB - 4Drs

Trachea:
 It is a mobile tube.
 Extends from the lower border of cricoid cartilage to the sternal
angle(angle of lewis) at the level of T4.
 Trachea bifurcates to right and left main bronchi.
 The length of trachea is 5 inches = 13cm. The diameter of trachea is
approximately equal to the diameter of your index (in children the
trachea is very narrow with a diameter about the diameter of a pencil
and so it is very difficult to deal with it surgically).
 It contains 16-20 C shaped cartilages. The cartilage is absent posteriorly
and replaced by trachealis muscle which is composed of smooth muscle
that is innervated by autonomic nervous system.
 It has two dilatations, one at the middle and the other at the end of the
trachea. The latter is called carina from the inside.
N.B.: the histology of the main bronchus is the same as the
trachea except that in the bronchus, the C shaped cartilage which
is replaced by plates of cartilage and the amount of smooth
muscles is more abundant.
 The main bronchus gives secondary bronchi and each secondary
bronchus will give tertiary bronchi. Each pulmonary segment will have
only one tertiary bronchus.
 The right lung has three lobes so it will have three secondary bronchi.
The left lung has two lobes and two secondary bronchi.
 In the right lung: The secondary bronchus that goes to the upper lobe
will give 3 tertiary bronchi (apical, anterior and posterior). The one that
goes to the middle lobe will give 2 tertiary bronchi (medial and lateral).
The one to the lower lobe will give 5 tertiary bronchi to 5 pulmonary
segments :
1. Apicobasal.
2. Anterobasal.
3. Posterobasal.
4. Medialbasal.
5. Lateralbasal.
 The right main bronchus is shorter, wider, and more vertical than the
left. Because of this we expect that any foreign body will go to the right
bronchus so we should look for it in the right side by the bronchoscope
before looking in the left side.
Trachea relations:
Anterior: (the structures from superficial to deep)
1. Sternum.
2. Remnant of the thymus in adults (in children the thymus is still
present).
3. Left brachiocephalic vein.
4. Arch of the aorta and its branches (left common carotid and
brachiocephalic).
Posterior:
1. Esophagus.
2. Left recurrent laryngeal nerve.
At the right side:
1. Azygos vein.
2. Right vagus nerve.
3. Right pleura and lung.
At the left side:
1.
2.
3.
4.
5.
Arch of the aorta (over the left main bronchus).
Left common carotid and the left subclavian arteries.
Left vagus nerve.
Left phrenic nerve.
Left pleura and lung.
Carina
Carina: is a fold of mucosa at the bifurcation of the trachea from inside and
becomes more prominent at the beginning of the lumen of the right bronchus
since it is more vertical.
The carina is located at the level of T4. During inspiration it descends
downward to reach the level of T6.
Nerve supply to the trachea:
The trachea innervated by the autonomic nervous system.
Parasympathetic from:
1. Vagus nerve.
2. Recurrent laryngeal nerve.
Sympathetic innervations are from the pulmonary plexus from the cervical
ganglia.
N.B.: the left recurrent laryngeal nerve turns from below the arch of
the aorta and ascends between the trachea and the esophagus,
however, the right turns from below the subclavian and ascends
upward. Because of this at the upper part of the trachea the two
nerves will appear lateral to it but at the lower part only the left will
appear.
------------------------------------------------------------------------------------------------The thorax is a space that contains the two lungs and the heart. The heart is
located in the mediastinum. The mediastinum is divided into 2 parts: superior
and inferior. The inferior itself is divided into 3 parts: anterior, middle and
posterior.
On both sides of the mediastinum there is a lung which is covered by pleura.
Pleura:
Pleura consists of two parts:
1. Visceral which is adherent to the lung tissue.
2. Parietal which lines the inner surface of the thoracic wall.
Between these two layers is a potential space in which a fluid for
lubrication is vital during the respiration process.
At the apex of the pleura we have the suprapleural membrane which is
above both visceral and parietal pleura.
 Laterally the membrane is attached to the medial border of the 1st rib
and coastal cartilage.
 Medially blends with the fascia investing the structures that descend
from the neck to the thorax.
 The apex attaches to the tip of the transverse process of the 7th
cervical vertebra.
 At this part there is no space between visceral and parietal pleura.
The action of this membrane:
1. Protection of the pleura and the lung.
2. Maintenance of the intrapleural pressure.
Each lung has the following parts:
1.
2.
3.
4.
Apex: reaches above the clavicle.
Base: over the copula of the diaphragm.
Coastal surface.
Mediastinal surface.
The root (hilum) of the lung:
The root of the lung lies at the level between T5 and T7. At the hilum the two
layers of pleura are adherent to each other forming a cuff around the
pulmonary vessels. Below the hilum, together they form the inferior
pulmonary ligament.
The hilum contains:
I.
II.
III.
Main bronchus.
Pulmonary artery.
Nerves and lymphatic vessels.
N.B.: there are two places where there are no spaces between the
visceral and parietal pleura, at the hilum and at the apex of the lung.
Surface anatomy of the lung:
The apex:




An arch ascends from the lateral side of the medial third of the clavicle.
It ascends about one inch at the root of the neck.
Then it descends downward to the sternoclavicular junction.
This means that the apex is located one inch above the medial third of
the clavicle.
N.B.: at the apex of the lung there is no space between the parietal
and the visceral pleurae. Consequently, the surface anatomy of
the lung and the pleura is considered as one.
N.B.: the absence of pleural cavity at the apex makes it a very
dangerous area. If there is any injury it can easily reach the lung
and that’s why in hospitals after they put the CVP (central venous
pressure) line in the subclavian they make a chest X-ray for the
patient to check if there is any injury.
The anterior border:
 The two lungs are different in their anterior border.
 The anterior border of the right lung extends from the sternoclavicular
joint to the mid of sternal angle and terminates at the xiphisternal joint.
 The anterior border of the left lung has a notch which is called cardiac
notch and it is located between the 4th and the 6th coastal cartilages. This
notch originates as a result of the pushing by the heart on the left lung
during embryonic life. This notch ranges from ½ -1 inch.
The base: is the most important, why? During deep inspiration, the lung
grows larger mainly downwards.
 There are three lines that have specific relations with the lung
1. Midaxillary line intersects with the 6th rib.
2. Midclavicular line intersects with the 8th rib.
3. Midscapular line (posterior line which extends from the inferior
angle of the scapula) intersects with the 10th rib.
The posterior border of the lung:
 Extends from the apex to the 10th rib posterior to the erector spinae
muscle.
Surface anatomy of the pleura:
The apex is precisely that of the lung.
As for the anterior border, the same story.
N.B.: some anatomists say that the pleura reach the 6th rib, others say that
it reaches the 7th rib.
The base has the relations with the three lines:
1. Midaxillary line intersects with the 8th rib.
2. Midclavicular line intersects with the 10th rib.
3. Midscapular line (posterior line which extends from the inferior
angle of the scapula) intersects with the 12th rib.
And so the pleura descend 2 spaces below the lung and during inspiration the
lung descends downward and fills these spaces.
The surface anatomy of the fissures:
 The right lung has 2 fissures which divides the lung into 3 lobes: upper,
middle and lower. The left lung has only one fissure which divides the
lung into two lobes: upper and lower.
 The transverse fissure present in the right lung only but the oblique
fissure is present in both lungs.
 The oblique fissure is a line that begins posteriorly 3 cm away from the
dorsal spine of the 3rd thoracic vertebra and descends obliquely with the
6th rib till the costochondral junction.
 The horizontal line in the right lung separates the upper lobe from the
middle lobe. It begins anteriorly at the level of the 4th coastal cartilage
and goes horizontally until it reaches the 6th rib.
The parietal pleura has:




Cervical pleura which is above the clavicle at the root of the neck.
Costal pleura that is related to the costal cartilage.
Mediastinal pleura.
Diaphragmatic pleura over the copula of the diaphragm.
Costodiaphragmatic recess is an angle of the reflection of pleura when
the diaphragmatic and costal pleura blend together.
The costodiaphragmatic recess:
i.
ii.
iii.
3 inches in the midaxillary line.
2 inches in the scapular line.
1 inch in the midclavicular line.
N.B.: when you insert a tube in the pleural cavity it is best to
insert it in the midaxillary line because it is the longest.
Mediastinodiaphragmatic recess is a recess that is located between the
mediastinal and the diaphragmatic pleura.
Nerve supply to the pleura:
 Parietal pleura innervation:
i. Costal surface is innervated by intercostal nerves segmentally. For
example the 5th intercostal space is supplied by the 5th intercostal
nerve.
ii. Diaphragmatic and mediasinal surfaces are innervated by phrenic
nerve.
N.B.: the parietal pleura is sensitive to pain, temperature,
touch and pressure.
N.B.: the phrenic nerve contains both sensory fibers to the
pleura and motor fibers to the diaphragm.
Visceral pleura is innervated by the autonomic nervous system from
the pulmonary plexus (sympathetic) and parasympathetic from the
vagus nerve.
Clinical notes:
1. Pneumothorax: accidents, stab wounds…etc. can permit air entry
into the pleural cavity. When we do a chest X-ray for the patient we
will find that one lung is inflated and the other is black. The black
color is due to the air that fills the pleural cavity.
2. Heamothorax: blood in the pleural cavity.
3. Empynema: pus in the pleural cavity.
4. Pleural effusion: fluid in the pleural cavity due to congestion of the
lungs.
We treat all these problems by the insertion of tube under water seal.
Where should the tube be inserted?
We should insert this tube under the base of the lung and above the pleura. So
it is put in the 9th intercostal space in the midaxillary line and in the 7th
intercostal space in the midclavicular line.
N.B.: we insert the tube (the needle) at the upper border of the rib
not at lower border, because we have V.A.N. (vein, artery and nerve
respectively) in the costal groove.
Pleuritis is an inflammation of the parietal pleura which is very painful
especially during inspiration.
The end