Bronchi, lungs, pleura and diaphragm

Question 1

Where should the trachea be located

Answer 1

Central
If not- indication of pathology
Swallowing and breathing can also cause positional shifts.

Question 2

Describe the trachea

Answer 2

Extends from vertebral level C6 to T4/5
Held open by C-shaped cartilage rings
Lowest ring has a hook – carina (keel of ship)
The oesophagus continues into the posterior mediastinum

Question 3

Describe the relations of the trachea to other structures

Answer 3

As the trachea passes through the superior mediastinum, they are crossed laterally by the azygos vein (right) and arch of aorta (left)

Question 4

Describe the primary bronchi

Answer 4

formed at T4/5, with the right wider and more vertical (STERNAL ANGLE) - inhaled objects likely to enter right lung as more vertical and wider.

Question 5

Describe the lobar (secondary bronchi)

Answer 5

formed within lungs to supply lobes (2 on left, 3 on right)

Supply the lobes

Question 6

Describe the segmental bronchi

Answer 6

supply the bronchopulmonary segments (further subdivisions to supply independent units of lung tissues known as bronchopulmonary segments)

Question 7

Describe the bronchial tree

Answer 7

Trachea divides into two main bronchi at vertebral level T4/5:

Right and left main (primary) bronchi divide into:

Lobar (secondary) bronchi - supplying the lobes (2 left, 3 right)

The lobar bronchi further subdivide into segmental (tertiary) bronchi supplying self-contained independent units of lung tissue named bronchopulmonary segments

Question 8

What is meant by the bronchial tree

Answer 8

Branching pattern of trachea into main, lobar and segmental bronchi

Question 9

What is C7

Answer 9

Prominent vertebrae- can be palpated

Question 10

What happens to the segmental bronchi

Answer 10

The segmental bronchi give rise to multiple generations, ultimately bronchioles, which further subdivide and supply the respiratory surfaces.
The walls of the bronchi are held open by discontinuous elongated plates of cartilage, but these are not present in bronchioles

Question 11

Why is the trachea open posteriorly

Answer 11

To allow the oesophagus to expand (e.g when eating)

Question 12

What is meant by a bronchopulmonary segment

Answer 12

smallest functionally independent region of the lung so can remove one without affecting others/upstream
Has its own blood supply (pulmonary artery), innervation and airway
Tributaries of the pulmonary vein tend to pass intersegmentally around the margins of the segment..

Question 13

How many bronchopulmonary segments are there

Answer 13

10 in each lung- however some fuse in the left lung

Question 14

Describe the lungs

Answer 14

essential respiration organs situated in thorax and separated by mediastinum; each lies freely in pleural cavity (lined by pleural membranes held together by tension of fluid) apart from attachment to heart via pulmonary vessels and trachea and lung room (hilum)

Question 15

Describe the shape of the lungs

Answer 15

The lungs are conical in shape

Question 16

Describe the base of the lungs

Answer 16

concave

rests on convex surface of diaphragm

Question 17

Describe the apex of the lungs

Answer 17

thoracic inlet oblique - apex rises 3-4 cm above

level of first costal cartilage- into root of neck.

Question 18

Describe the surfaces of the lungs

Answer 18

The surfaces of the lungs relate to the structures that the lungs are sat in.
Costal- lies immediately adjacent to the ribs and intercostal spaces
Mediastinal surface- lies against the mediastinum anteriorly and vertebral column posteriorly- contains hilum
Inferior- diaphragm

Question 19

Describe the borders (edges) of the lungs

Answer 19

Inferior border- sharp, separates base from the costal surface
Anterior and posterior- separate costal surfaces from the medial surface- smooth and rounded.

Question 20

What does the diaphragm separate

Answer 20

right lung from right lobe of liver

left lung from left lobe of the liver, stomach & spleen

Question 21

Describe the anterior part of the mediastinal surface of the lung

Answer 21

deeply concave - accommodates the heart - cardiac impression larger on L than R because of position of heart

Question 22

What is found above and behind the cardiac impression of the lungs

Answer 22

Above and behind cardiac impression - hilum of the lung where vessels, bronchi & nerves enter & leave the mediastinum

Question 23

Which structures indent the costal surfaces of the lungs

Answer 23

The ribs

Question 24

Describes the lobes of the left lung

Answer 24

Oblique fissure separates the superior and inferior lobes

Superior lobe lies above the fissure – includes:
Apex
Most of anterior part of lung
The inferior lobe is in contact with posterior and inferior borders

Question 25

Describe the other key features of the left lung

Answer 25

The inferior portion of the medial surface is notched because of the heart's projection into the left pleural cavity from the middle mediastinum. From the anterior border of the lower part of the superior lobe a tounge-like extension (lingula) projects over the heart bulge. Groove for aorta Cardiac impression Groove for left subclavian artery Groove for the left brachiocephalic vein ( second groove).

Question 26

Describe the lobes of the right lung

Answer 26

The right lung has three lobes and two fissures Normally, these lobes are freely moveable against each other because they are separated, to the hilum, by invaginations of the visceral pleura. Oblique fissures- separate the inferior lobe from the superior and middle lobes Horizontal fissure- separates superior from the middle lobe.

Question 27

Describe the other features of the right lung

Answer 27

``` Groove for right subclavian artery Groove for oesophagus Groove for SVC Groove for azygos vein Groove for IVC ```

Question 28

Describe the root (hilum) of the lung

Answer 28

The root of each lung is a tubular collection of structures that together attach the lung to structures in the mediastinum (heart and trachea) It is covered by a sleeve of mediastinal pleura that reflects onto the surface of the lungs as visceral pleura. The region outlined by this pleural reflection on the mediastinal surface is the hilum, where structures can enter and leave The root and hilum are not the same thing. root is inside the hilum. Pleural reflection occurs at the hilum where the pulmonary ligament attaches to lungs

Question 29

What structures are found inside the hilum

Answer 29

Principal (primary) bronchus Pulmonary artery (deoxygenated blood from RV) 2 pulmonary veins (oxygenated blood to LA) Bronchial arteries (oxygenated blood from descending aorta) and veins Pulmonary plexus of nerves (autonomic) Lymph vessels and nodes

Question 30

Describe the positioning of the structures inside the hilum

Answer 30

Generally, the pulmonary artery is superior at the hilum, the pulmonary veins are inferior, and the bronchi are somewhat posterior in position. On the right side, the lobar bronchus to the superior lobe branches from the main bronchi in the root, unlike on the left where it branches within the lung itself and is superior to the pulmonary artery.

Question 31

Which lung is bigger

Answer 31

The right (because the middle mediastinum bulges more to the left).

Question 32

Describe the difference between the pulmonary arteries and veins

Answer 32

Pulmonary arteries- carry deoxygenated blood to the lungs | Pulmonary veins- carry oxygenated blood to the lungs.

Question 33

What is the role of the brachial arteries

Answer 33

systemic- carry oxygenated blood to the lungs.

Question 34

Describe the pulmonary ligament

Answer 34

used to be an open vessel- no longer- just a thickening of tissue- no function- expands as you breathe in.

Question 35

What is meant by the pleura

Answer 35

A thin layer of flattened cells supported by connective tissue that lines each pleural cavity and covers the exterior of the lungs

Question 36

Describe the two pleural layers

Answer 36

2 layers visceral pleura - covers surface lungs and lines fissures between the lobes parietal pleura - lines inner surface of chest walls Visceral and parietal pleura are continuous with each other around the root of the lung – this is the hilum

Question 37

Describe the pleura in health

Answer 37

In health: | Pleural cavity is collapsed, but moist surfaces allow lungs to glide as they expand and collapse

Question 38

Describe pleural origin

Answer 38

Pleural cavities inside chest wall Lined by parietal pleura Lung buds grow into them Within covering of visceral pleura

Question 39

What is meant by the pleural cavity

Answer 39

Is the potential space enclosed between the visceral and parietal pleurae. They normally contain a thin layer of serous fluid. As a result, the visceral pleura directly opposed and freely slides over the parietal pleura attached to the wall.

Question 40

What is meant by the pleural recesses

Answer 40

The lungs do not completely fill the anterior or posterior inferior regions of the pleural cavities. This results in recesses in which two layers of parietal pleura become opposed. Expansion of the lungs into these spaces usually occurs during forced inspiration. These recesses also provide potential regions for fluid to accumulate and be aspirated.

Question 41

Describe the costomediastinal recesses

Answer 41

Anteriorly, a costomediastinal recess occurs on each side where costal pleura is opposed by mediastinal pleura- the largest is on the left side in the region covering the heart

Question 42

Describe the costodiaphragmatic recess

Answer 42

Largest and most clinically important Between costal pleura and diaphragmatic pleura Recess between inferior margin of lungs and inferior margin of pleural cavities Largest after forced expiration, shallowest after forced inspiration.

Question 43

Describe breathing

Answer 43

Controlled by nervous system and produced by skeletal muscle Brings about inhalation and exhalation of air into/out of the lungs, to ventilate the gas exchange areas - alveolar sacs capacity of thoracic cavity can be increased: by movements of the diaphragm by movements of the ribs

Question 44

Describe movements of the pleural cavity in breathing

Answer 44

Pleural cavity is expanded by muscles in walls | Elastic lungs expand with the pleural cavity, sucking air down trachea and bronchi into lungs

Question 45

Describe the role of the diaphragm in inspiration

Answer 45

Contraction of the diaphragm increases the vertical dimension of the thoracic cavity. When it contracts, the diaphragm presses on the abdominal viscera which initially descend (because of relaxation of the abdominal wall during inspiration) Further descent is stopped by the abdominal viscera, so more diaphragm contraction raises the costal margin Increased thoracic capacity produced by diaphragm and rib movements in inspiration, reduces intrapleural pressure, with entry of air through respiratory passages and expansion of the lungs

Question 46

Describe the costal margin

Answer 46

The margin of the diaphragm (black) is attached to the: costal margin (lower border of the rib cage) xiphoid process ends of ribs 11 and 12 lumbar vertebrae

Question 47

Describe the dome of the diaphragm

Answer 47

The dome of the diaphragm (red) bulges high inside the rib cage. So high abdominal organs such as liver are covered by diaphragm, pleura and lung

Question 48

Describe the movements of the ribs in breathing

Answer 48

Ribs elevated - anterior ends thrust forward and upwards - increases antero-posterior dimension of thoracic cavity. At same time ribs are everted, increasing transverse diameter of thoracic cavity Internal and external intercostal muscles stiffen the rib cage to increase efficiency of diaphragm

Question 49

Explain the lateral movement of the ribs

Answer 49

Raising the costal margin widens the pleural cavities by raising drooping lateral parts of ribs

Question 50

Describe the antero-posterior movement of the ribs

Answer 50

Raising the costal margin also raises drooping anterior ends ribs, tilting sternum upwards to increase antero-posterior diameter of pleural cavities

Question 51

Describe expiration

Answer 51

Quiet expiration is a passive activity not requiring muscles It depends on elastic recoil in the elastic tissue throughout the lungs and in the rib cage In deep or forced expiration, this is assisted by the muscles of the abdominal walls that squeeze the abdominal organs against the diaphragm and pull the lower ribs downward