ANA 202 Lungs and Lower Respiratory Tract

Question 1

What is pleura?

Answer 1

It is large, thin sheet/ sac that invest (wrap) the outside of the lungs and lines the inside of the chest

Question 2

Types of pleura

Answer 2

Parietal pleura (lines the thoracic wall/chest, mediastinum, and diaphragm) and thicker than visceral pleura

*Viscera pleura (adheres to and covers the lung)

Question 3

Describe the pleural cavity

Answer 3

In between these membranes is a potential space called the pleural cavity
•This pleural cavity is filled with serous fluid
•This fluid lubricates the pleural surfaces and allows the layers of pleura to slide smoothly over each other during respiration
●Note
The pleura cavity superiorly, extends above rib I into the root of the neck

Question 4

What are the parts of the parietal pleura?

Answer 4

• Costal part
• mediastinal part
•Diaphragmatic part
•cervical pleura

Question 5

Discuss the costal part of the parietal pleura

Answer 5

Costal part
●This is the part of the pleura that covers the internal part of the thoracic wall
●It is separated from the internal surface of the thoracic wall, intercostal muscles and membranes, and sides of thoracic vertebrae by the endothoracic fascia

Question 6

Discuss the diaphragmatic part of the parietal pleura

Answer 6

Diaphragmatic part
●It is the part of the pleura covering the diaphragm
●This part of the pleural is connected with the diaphragm by the phrenicopleural fascia
●The phrenicopleural fascia is a thin elastic layer of endothoracic fascia

Question 7

Discuss the mediastinal parts of the parietal pleura

Answer 7

Mediastinal part
●The part of the pleura covering the lateral aspect of the mediastinum

Question 8

Discuss the cervical part of the parietal pleura

Answer 8

Cervical pleura
●It covers the apex of the lung (the part of the lung extending superiorly through the superior thoracic aperture into the root of the neck
●forms a cup-like dome called the pleural cupula over the apex of the lungs
●It is reinforced by a fibrous extension of the endothoracic fascia
●This fibrous extension is called the suprapleural membrane/Sibson fascia
● The suprapleural membrane attaches to the internal border of the 1st rib to the transverse process of C7

Question 9

What is the relationship between the Visceral on the parietal pleura?

Answer 9

The visceral pleura is continuous with parietal pleura at the hilum of each lung where structures enter and leave the organ

Question 10

What is a pleural recess?

Answer 10

Pleural recesses
•These are potential spaces within the thoracic cavity where the visceral and parietal pleura are relatively distant, particularly during expiration

Question 11

What are the types of pleural recess?

Answer 11

•There are 2 types;
•Costodiaphragmatic recess
•Costomediastinal recess

Question 12

Describe the Costodiaphragmatic recess

Answer 12

Costodiaphragmatic recess
•also called the phrenicocostal sinus
• a potential space at the posteriormost tips of the cavity
•located at the junction of the costal pleura and diaphragmatic pleura
• measures approximately 5 cm vertically
• extends from the 8-10th rib along the mid-axillary line

Question 13

Function of the costodiaphragmatic recess

Answer 13

Function
•The lungs expand into this recess during forced inspiration, however the recess never fills completely
• During expiration, it contains no lung tissue, only pleural fluid

Question 14

Clinical significance of the of the costodiaphragmatic recess

Answer 14

Clinical significance
1.Pleural effusions collect in the costodiaphragmatic recess when in standing position
●Note
● pleural effusions are excess fluid that accumulates between the two pleural layers
● Excessive amounts of such fluid can impair breathing by limiting the expansion of the lungs during ventilation
II. A thoracocentesis (pleural tap/ removal of fluid or air )

Question 15

Why is A thoracocentesis performed with the lungs are in full expiration?

Answer 15

is often performed here while a patient is in full expiration because of less risk of puncturing the lungs and thereby causing pneumothorax

Question 16

Describe the costomediastinal recess & where is it most obvious

Answer 16

•is a potential space at the border of the mediastinal pleura and the costal pleura
• It helps the lungs to expand during deep inspiration, although its role isn’t as significant as the costodiaphragmatic recess, which has more volume

The costomediastinal recess is most obvious in the cardiac notch of the left lung

Question 17

Describe the trachea

Answer 17

•The trachea is about 4.5In (11.5cm) in length and nearly 1 In (2.5cm) in diameter.

•It commences at the lower border of the cricoid cartilage (C6) and terminates by bifurcating at the level of the sternal angle of Louis (T4/5) to form the right and left main bronchi.

•(In the living subject, the level of bifurcation varies slightly with the phase of respiration; in deep inspiration is descends to T6 and in expiration it rises to T4.)

Question 18

Discuss the cervical relations of the trachea

Answer 18

Cervical
•Anteriorly— the isthmus of thyroid gland, inferior thyroid veins, sternohyoid and sternothyroid muscles;
•Laterally—the lobes of thyroid gland and the common carotid artery;
•Posteriorly—the oesophagus with the recurrent laryngeal nerve lying in the groove between oesophagus and trachea.

Question 19

Discuss the thoracic relations of the trachea

Answer 19

Thoracic
•In the superior mediastinum its relations are:
•Anteriorly—commencement of the brachiocephalic (innominate) artery and left carotid artery, both arising from the arch of the aorta, the left brachiocephalic (innominate) vein, and the thymus;
•Posteriorly—oesophagus and left recurrent laryngeal nerve;
•The left— arch of the aorta, left common carotid and left subclavian arteries, left recurrent laryngeal nerve and pleura;
•To the right—vagus, azygos vein and pleura.

Question 20

Describe the structure of the trachea

Answer 20

The patency of the trachea is maintained by a series of 15–20 U-shaped cartilages.

•Posteriorly, where the cartilage is deficient, the trachea is flattened and its wall completed by fibrous tissue and a sheet of smooth muscle (the trachealis).

Question 21

Epithelial lining of the trachea

Answer 21

Within, it is lined by a ciliated pseudostratified columnar epithelium with many goblet cells.

Question 22

Describe the pathway of the main bronchi

Answer 22

The main bronchi (primary bronchi), one to each lung, pass inferolaterally from the bifurcation of the trachea at the level of the sternal angle to the hila (plural of hilum) of the lungs.

The main bronchi enter the hila of the lungs and branch in a constant fashion within the lungs to form the bronchial tree.
•Each main bronchus divides into lobar bronchi (secondary bronchi), two on the left and three on the right, each of which supplies a lobe of the lung.
•Each lobar bronchus divides into several segmental bronchi (tertiary bronchi) that supply the bronchopulmonary segments.

Question 23

Describe the right main bronchus. What are its relations?

Answer 23

The right main bronchus is wider, shorter and more vertical than the left.
•It is about 1 in (2.5cm) long and passes directly to the root of the lung at T5.

•Before joining the lung it gives off its upper lobe branch, and then passes below the pulmonary artery to enter the hilum of the lung.

•It has two important relations: the azygos vein which arches over it from behind to reach the superior vena cava, and the pulmonary artery which lies first below and then anterior to it.

Question 24

Describe the left main bronchus

Answer 24

The left main bronchus is nearly 2 in (5cm) long and passes downwards and outwards below the arch of the aorta, in front of the oesophagus and descending aorta.
•Unlike the right, it gives off no branches until it enters the hilum of the lung, which it reaches opposite T6.
•The pulmonary artery spirals over the bronchus, lying first anteriorly and then above it

Question 25

What are the bronchopulmonary segments?

Answer 25

A bronchopulmonary segment is a portion of lung supplied by a specific segmental bronchus and its vessels.

Question 26

Features of the bronchopulmonary segment

Answer 26

•Each segment are pyramidal in shape
•They are surrounded by connective tissue
•Separated from adjacent segments by connective tissue septa
•Each segment have their own artery

Question 27

Discuss the clinical significance of the bronchopulmonary segment

Answer 27

each bronchopulmonary segment is a discrete anatomical and functional unit,
•this separation means that a bronchopulmonary segment can be surgically removed without affecting the function of the other segments

Question 28

Vasculature of the bronchopulmonary segments

Answer 28

Each bronchopulmonary segment is supplied by;
•a segmental tertiary bronchus
• and 2 arteries
These 2 arteries are;
• a pulmonary artery
• bronchial artery
•Drained by tributaries of the pulmonary veins that lie in the connective tissue between adjacent bronchopulmonary segment
•Each segment has its own lymphatic vessels and autonomic nerve supply

Question 29

Division of the bronchopulmonary segment

Answer 29

Division of segmental bronchi
•The segmental bronchi divide repeatedly to form terminal bronchioles
•Each terminal bronchiole gives rise to several generations of respiratory bronchioles
•Each respiratory bronchiole gives rise to 2-11 alveolar ducts, each of which gives rise to 5-6 alveolar sacs
•each alveolar sac contains a bunch of alveoli (the balls)
•The total no of alveoli has been estimated to be between 200 - 600 millions

Question 30

Clinicals of the bronchopulmonary segment

Answer 30

1. The greater width and more vertical course of the right bronchus accounts for the greater tendency for foreign bodies and aspirated material to pass into the right bronchus (and thence especially into the middle and lower lobes of the right lung) rather than into the left.
2. The inner aspect of the whole of the trachea, the main and lobar bronchi and the commencement of the first segmental divisions can be seen at bronchoscopy.
3. Widening and distortion of the angle between the bronchi (the carina) as seen at bronchoscopy is a serious prognostic sign, since it usually indicates carcinomatous involvement of the tracheobronchial lymph nodes around the bifurcation of the trachea.

Question 31

Describe the lungs

Answer 31

The lungs are the vital organs of respiration.
•Their main function is to oxygenate the blood by bringing inspired air into close relation with the venous blood in the pulmonary capillaries.
•Although cadaveric lungs may be shrunken, hard to the touch, and discolored in appearance, healthy lungs in living people are normally light, soft, and spongy.
•They are also elastic and recoil to approximately one-third their size when the thoracic cavity is opened .

The lungs are separated from each other by the heart, viscera, and great vessels of the mediastinum.
•The lungs attach to the heart and trachea by structures that comprise the roots of the lungs- formed by structures entering and emerging from the lung at its hilum (hilus)–the bronchus and pulmonary vessels

Question 32

What is the hilum of the lungs?

Answer 32

The hilum is where structures forming the root enter or exit the lungs e.g. like the area of earth where a plant’s roots enter the ground.

Question 33

The structures forming the root of the lungs include

Answer 33

•pulmonary artery
•two pulmonary veins
•a main bronchus
•bronchial vessels
•nerves
•lymphatics

Question 34

pulmonary ligament

Answer 34

A thin blade-like fold of pleura projects inferiorly from the root of the lung and extends from the hilum to the mediastinum

Question 35

Why so the right lungs a little larger than the left?

Answer 35

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.

Question 36

What divide the lungs into lobes?

Answer 36

horizontal and oblique fissures

The right lung has three lobes, the left lung has two

Question 37

Functions of the lungs

Answer 37

Allows air to enters and leave via main bronchi, which are branches of the trachea
•Receives deoxygenated blood from the right ventricle via the pulmonary arteries
•Returns oxygenated blood to the left atrium via the pulmonary vein

Question 38

Parts of the lungs

Answer 38

Each lungs has;
• An apex (projects above rib I and into the root of the neck)
•A base (which sits on the diaphragm)
•2 or 3 lobes, created by one or two fissures
•3 surfaces (costal, medial, and diaphragmatic)
•3 borders (anterior, inferior, and posterior)

Note: the medial surface is divided into
•vertebral part
• mediastinal part ( related to the mediastinal

Question 39

Describe the apex of the lungs

Answer 39

The Apex of the Lung
•The rounded, tapered superior end or apex of the lung extends through the superior thoracic aperture into the root of the neck
•Here, it lies in close contact to the dome or the cupula of the pleura
•The apex of the lung is crossed by the subclavian artery, which produces a groove in the mediastinal surface
•The artery, however, is separated from the cupula by the suprapleural membrane

Question 40

Describe The Base of the Lung

Answer 40

•This is the concave diaphragmatic surface of the lung, which is related to the dome of the diaphragm
•The base of the right lung is deeper because the right dome rises to a more superior level
•Its inferior border is thin and sharp where it enters the costodiaphragmatic recess

Question 41

List The Main Differences Between the Right and Left Lungs

Answer 41

•The right lung has 3 lobes while the left has 2 lobes
•Right lungs has 2 fissure, left lungs has one
•The right lung is larger and heavier than the left lung
(right lung weighs about 700g, left lung weighs about 600g)
• it is shorter and wider because the right dome of the diaphragm is higher and the heart and pericardium bulge more to the left
•The anterior margin of the right lung is straight, whereas the margin of the left lung has a deep cardiac notch
•Right lung is shorter, wider and more in line with the trachea than the left principal bronchus. Inhaled particles pass more frequently to the right lung as a result of this compared to the left lung

Question 42

The medial surface of the right lung lies adjacent to a number of important structures in the mediastinum and the root of the neck
These include;

Answer 42

•heart
•inferior vena cava
•superior vena cava
•azygos vein
•Esophagus
•Trachea
•Right vagus nerve
•Right phrenic nerve
•The right subclavian artery and vein arch over and are related to the superior lobe of the right lung as they pass over the dome of cervical pleura and into the axilla.

Question 43

The medial surface of the left lung lies adjacent to a number of important structures in the mediastinum and root of the neck
These include

Answer 43

•heart,
• arch of aorta
•Descending thoracic aorta

Esophagus
•Thoracic duct
•Pulmonary trunk
•Left vagus nerve
•Left phrenic nerve
•The left subclavian artery and vein arch over and are related to the superior lobe of the left lung as they pass over the dome of cervical pleura and into the axilla

Question 44

Arterial supply of the lungs

Answer 44

•right and left pulmonary arteries
•Bronchial arteries

Question 45

Venous drainage of lungs

Answer 45

•Pulmonary veins
•Bronchial veins:
•Right bronchial veins drain into the azygos vein
•Left bronchial vein drains into the hemi azygos vein

Question 46

Lymphatics of the lungs

Answer 46

lymphatics
•Superficial and deep plexus drain into the bronchopulmonary lymph nodes in the region of the lung hilum
•All the lymph from the lung leaves the hilum and drains into the tracheobronchial nodes and then into the bronchomediastinal lymph trunks
Innervation:

Question 47

Innervation of the lungs

Answer 47

Innervation:
•Anterior and posterior pulmonary plexus
•Vagus nerve (parasymphathetic) constrict the bronchioles
•2nd -5th spinal segments (symphathetic) dilate the bronchioles

Question 48

Clinical anatomy of the lungs

Answer 48

Pneumothorax
•Entry of air into the pleural cavity (pneumothorax), resulting from a penetrating wound of the parietal pleura from a bullet
•Fractured ribs may also tear the visceral pleura and lung, thus producing pneumothorax
Hydrothorax
•The accumulation of a significant amount of fluid in the pleural cavity (hydrothorax) may result from pleural effusion (escape of fluid into the pleural cavity)
Haemothorax
•With a chest wound, blood may also enter the pleural cavity (hemothorax)
• Hemothorax results more commonly from injury to a major intercostal or internal thoracic vessel than from laceration of a lung