Session 1

Question 1

Describe the development of the respiratory system.

Answer 1

The respiratory system develops as a ‘diverticulum’ from the pharynx (gut tube) and so is derived from endoderm. Abnormal formation can lead to defects such as fistulae.

Question 2

Describe the nasal cavity and its functions

Answer 2

Floor of nasal cavity is in horizontal plane.

• Induce turbulent flow (nasal conchae)
• Warm and moisten inspired air - cold air can be an irritant - moist air allows more efficient for gas exchange
• Recover water from expired air
• Speech production (phonation)
• Olfaction

Most functions are reliant on a large surface which turbinates on the lateral walls provide

Question 3

Role of the pharynx and larynx?

Answer 3

The pharynx and larynx work together to ensure that food and air enter the oesophagus and trachea respectively

Nasopharynx

Oropharynx

Laryngopharynx

Air comes in through the mouth and nose and runs anteriorly through the pharynx and into the trachea. Food comes in through the mouth and runs posteriorly through the pharynx and down the oesophagus. Therefore the paths of food and air cross which is not good as it makes us susceptible to aspiration. Good coordination in the area prevents this.

Question 4

What are the paranasal sinuses?

Answer 4

Thin air filled bones in the skull to allow extra space. Also helps to minimise the weight of the head

Question 5

The larynx

Answer 5

The larynx has important roles in speech, prevention of aspiration through use of the epiglottis and coughing

Question 6

Describe the conducting portion of the airways

Answer 6

• Trachea - composed of horseshoe shaped cartilage and originates from the primitive gut tube. Not a complete ring as allows expansion of oesophagus as bolus travels through it.
• Primary (main) bronchi
• Secondary (lobar) bronchi (right has 3 lobes (superior, middle and inferior) whereas left has only 2 (superior and inferior)). Left only has two has heart indents into that region so not enough space. The lingula is there instead.
• Tertiary (segmental) bronchi - these go to individual pulmonary segments.
• Bronchioles
• Terminal bronchioles

Question 7

Bones that form the thoracic cavity

Answer 7

Walls of thoracic cavity composed primarily of ribs laterally, the vertebral column posteriorly and the sternum anteriorly. Bony walls.

Roof - no real roof, insead theres an opening called the superior thoracic aperture. Considered thoracic inlet and/outlet.

Floor of thoracic cavity is the diaphragm. Underneath that is the inferior thoracic aperture

Ribs - Has a head, a neck, a body which sweeps around from posterior to anterior and articulur facets. Rib has to articulate with the thoracic vertebrae posteriorly and the sternum anteriorly. 3 points of articulation posteriorly - articular facets articulate with facets on the body of the vertebrae and the transverse processes.

Each thoracic vertebrae has 4 joints on body which articluate with ribs, 4 facet joints, 2 joints on the transverse processes and one facet on the adjacent vertebra.

Question 8

Describe the movements of the thorax and the mechanics of ventilation

Answer 8

Head of each rib articulates with two thoracic verebrae via the two hemifacets and additionally there’s a joint between the rib and the transverse process. Movement of these joints allows ventilatory movement.

Chest wall during breathing has a bucket handle movement. To get air in we need to decrease thoracic pressure and this is done by increasing volume. Firstly by increasing the lateral aspect of our chest, this is done due to the bucket handle movemnt of the ribs. Second movement is a pump handle movement as the chest moves upwards and anteriorly. This increases anteroposterior portion of the chest. Third movement is from diaphragm which descends and flattens during inspiration.

Question 9

What is the diapragm and what innervates it? Describe the costal muscle layers and their neurovasculature.

Answer 9

Diaphragm is a dome shaped muscular structure and is attached entriely to the edge of the inferior thoracic aperture. Left and right phrenic nerves (c3 c4 c5) innervate the diaphragm. Both motor and sensory function of diaphragm. Also sensory to pericardium. Innervation from cervical region as diaphragm evelopes high then descends.

From superficial to deep: External intercostal muscle (fibres run in antero-inferior direction), internal intercostal muscle (fibres run peropendicular to the external costal muscles), innermost intercostal muscle (fibres run in the same direction as internal intercostal muscles) then endothoracic fascia.

Neurovascular supply exists between internal and innermost intercostal muscles. It’s arranged as a major bundle (intercostal vein, intercostal artery and intercostal nerve run) which sits beneath each rib in the costal groove and a minor bundle (called collateral branches) run just above each rib.

Dual blood supply so risk of haemhorrage One from aorta at back and one from internal thoracic arteries. These internal thoracic artreies can also be used to graft on heart.

Intercostal muscles are less significant in quiet breathing in comparison to the diaphragm but have abigger role in forced ventilation e.g through exercise.

Question 10

At what vertebral levels do the vena cava, oesophagus and aorta (aortic hiatus) pass through the diaphragm?

Answer 10

Vena cava t8

Oesophagus t10

Aortic hiatus t12

Question 11

Accessory muscles in respiration

Answer 11

Pectoral muscles used in aid to respiration to force out air. Fix arms to reverse chest orign/insertion.

Sternocleidomastoid used to elevate ribs

Question 12

What is the azygous system?

Answer 12

Left inntercostal veins drain into the hemiazygous vein (inferior) and accessory azygous vein (superior) drain into the azygous vein (right side drains directly into azygous vein) which drains into superior vena cava. This system also allows drainage of heart . There’s no azygous artery.

Question 13

Thoracic topography

Answer 13

Lobes of lung separated by fissures (oblique (separaing middle and lower lobe) and transverse(depearting middle and superior)). When looking at the lungs posteriorly most of it is the inferior lobe so when auscultating the from the back, we’re mainly listening to the inferior lobe. Transverse fissure can fill with fluid.

Left lung only has two lobes as there’s not enough space for three due to indentation of the heart. Right main bronchus sits at a more straight angle in comparison to the left. It is also wider and flatter these factors make it more likely to get obstructed.

Question 14

The pleura and pleural cavity

Answer 14

Few ml of pleural fluid in pleural space. Two layers, visceral pleura (no pain) and parietal pleura (pain as it has somatic innervation from intercostal nerves). Surface tension of pleural fluid transmits force to lungs from intercostal muscles. Area at base of each lung is called costophrenic recess. There’s space under each lung so that the lungs can expand during inhalation. Top of pleura extends right up into the supraclavicular fossae.

Question 15

Risk to lung during heart surgery

Answer 15

Pleura go very close to midline so a risk of damage causing pneumothorax.

Pneumothorax - air in pleural space which causes lung to collapse

Question 16

Pulmonary blood supply

Answer 16

Blood leaves heart via pulmonary trunk and that splits into right and left pulmonary arteries. Blood leaves lungs via pulmonary veins. Lungs also supplied via bronchial arteries which branch from intercostal arteries.

Question 17

Why is diaphragm higher on right side?

Answer 17

Diphragm can extend up to T4 centrally (dome shaped). Liver pushes left hemidiaphragm superiorly

Question 18

Explain why pain arising from inflammation of the parietal pleura lining the diaphragm can be referred to the shoulder tip.

Answer 18

This is due to referred pain. The phrenic nerve is sensory to the diaphragmatic (parietal) pleura.  Pain impulses travelling in the phrenic nerve enter the spinal cord at C3, C4 and C5 spinal levels (the nerve roots of the phrenic nerve). The body may perceive the pain as arising from the shoulder tip area because the somatic sensory nerves which bring impulses from this area also enter the spinal cord at the same levels.

Question 19

Where would pain arising from inflammation of the costal pleura be felt in a patient with a right middle lobar pneumonia? Which nerves are responsible?

Answer 19

Each intercostal nerve is sensory to the strip of parietal pleura lining the intercostal space (ICS) and the strip of skin overlying the ICS, (with some overlap of adjacent ICSs as well). This is responsible for the dermatomal pattern of sensation on the trunk.  Inflammation of the costal (parietal) pleura by the pneumonia is therefore localised to the overlying skin, as sensory fibres from the pleura and the skin travel in the same intercostal nerve to enter the spinal cord at the same level.

Question 20

From your knowledge of anatomy, what clinical signs would you expect if the superior vena cava was compressed by local spread of a lung tumour?

Answer 20

o Swelling of the arms, face and neck, o Plethoric face, o Dilated veins over the arms and chest, o Elevated Jugular venous pressure, o papilloedema

Question 21

Identify the trachea, oesophagus, phrenic and vagus nerves, the sympathetic trunk and the hilum of the lung.

Answer 21

Note: Phrenic nerve lies anterior to the hilum on the fibrous pericardium; vagus passes posterior to the hilum

Question 22

The image shows a lung, which has been removed from the thoracic cavity.

Is this the right lung or the left lung?

Identify the costal, diaphragmatic and mediastinal surfaces of the right lung

Identify the lobes of the lung

Label the fissures

Answer 22

2.1 The right lung – It has 3 lobes insert images from self study

Question 23

State the surface marking of the oblique fissure

Answer 23

On either side, the oblique fissure extends from the tip of the spinous process of T2 vertebra posteriorly to the 6th costal cartilage anteriorly. If a patient abducts his arms to place his hands on his head, then the medial border of the scapula corresponds roughly to the oblique fissure posteriorly.

Question 24

Why do objects such as nuts and other foreign bodies frequently pass into the right lung?

Answer 24

The right main bronchus is wider and more vertical; hence it is more in line with the trachea, making it likely that a foreign body will go down it. Left main bronchus is more horizontal, hence a foreign body is less likely pass into it.

Question 25

A child inhales a peanut and goes to A and E. Why would a doctor find poor expansion of the right chest? Why was there reduced air entry (reduced breath sounds) over the right side of the chest?

Answer 25

The nut (foreign body) was obstructing the right main bronchus, preventing air from entering the right lung during inspiration. This results in in poor inspiratory expansion of the right side of the chest, and reduced breath sounds over the right lung on auscultation with a stethoscope.

Question 26

What would happen if a nut had become stuck fast in the larynx and what could you do?

Answer 26

o It would cause severe airway obstruction and asphyxia. o Lean the child forwards and carry out up to 5 back blows; if not successful try abdominal thrusts (the Heimlich manoeuvre). o Call an ambulance.

Question 27

A 60 year old man see his doctor for weight loss, a cough of 2 months duration and pain and tingling of the medial aspect of his right arm for 2 weeks. On examination the doctor notes wasting of the small muscles of the right hand. Following investigation, he is diagnosed with an advanced lung cancer involving the apex of the right lung. Explain the anatomical basis for the symptoms and signs in his right upper limb.

Answer 27

The apex of the lung extends about 2 cm above the clavicle into the root of the neck. A carcinoma of the apex of the right lung can therefore spread to involve the lower part of the brachial plexus. In this case, the T1 root of the brachial plexus has been involved. Hence there is sensory loss in the T1 dermatome area of the right arm. The T1 root also supplies the intrinsic muscles of the hand (via the ulnar and median nerves), hence the wasting of these muscles of the right hand.

Question 28

What is the sternal angle and how do you find it?

Answer 28

The junction of the manubrium & body of the sternum is known as the sternal angle. It can be identified by drawing the finger down the sternum in the midline, from the supra-sternal notch towards the xiphisternum. The sternal angle can be felt as a transverse ridge about one third of the way down.

Question 29

Which costal cartilages articulate with sternum at the level of the sternal angle?

Answer 29

The second costal cartilage. Finding the sternal angle enables you to identify the 2nd rib, and count downwards to identify the other ribs.

Question 30

Which parts of the respiratory tract are the conducing portion, which parts form the respiratory portion, where does gas exchange occur and what cell type lines he airways from the nasal cavity to the largest bronchioles?

Answer 30

1. The conducting portion of the airways extend from the nostrils to the Terminal bronchioles 2. The respiratory portion of the airways extend from the Respiratory bronchioles to the alveoli. 3. Gas exchange only occurs in the Respiratory portion of the airways 4. Pseudostratified ciliated columnar epithelium lines the airways from the nasal cavity to the largest bronchioles.

Question 31

What portions of the respiratory tract contain goblet cells and submucous glands? What is their protective function?

Answer 31

The bronchi comprising of the main bronchi (generations 1-4) and small bronchi (generation 5-8) contain goblet cells and submucous glands. They secrete mucus; Inhaled particles (between about 5 – 8 µm) are deposited on the mucus layer and are swept up by the cilia (the mucociliary escalator) to the oropharynx where they are swallowed. Also, the viscous mucus layer provides a physical barrier to chemical damage of the epithelium NB: Larger Particles (>8 µm or so) are deposited on the mucus layer lining the nose and pharyngeal walls; these are swept to the oropharynx where they are swallowed. Smaller particles (< 5 µm or so) reach the respiratory bronchioles and alveoli where they are deposited and then removed by alveolar macrophages. Note: The particles sizes as stated in different books and articles vary somewhat (eg 10 µm instead of 8 µm). The important point is that the large particles are deposited in the nose and pharynx, while very small particles reach the alveoli; the rest are dealt with by the mucociliary escalator.

Question 32

What parts of the respiratory tract contain Club (Clara) cells? What is their function?

Answer 32

Bronchioles. Note: Clara cells are now also known as ‘Club cells’ They secrete a number of substances including a surfactant lipoprotein, which prevents the bronchiolar walls sticking together during expiration. They produce proteins which play an important role in protecting the lungs from inhaled toxins.

Question 33

How are the bronchioles kept open?

Answer 33

The bronchioles are embedded in the lung parenchyma, and the walls of the adjacent alveoli are attached to the walls of the bronchioles. Elastin in the walls of adjacent alveoli exert traction (a tugging action) on the walls of the bronchioles which keep them open. This is known as radial traction

Question 34

What type of connective tissue fibres lie on the walls of the alveoli?

Answer 34

Elastin fibres, collagen fibres

Question 35

Name the substance produced by type II Pneumocytes in the alveoli. What is the function of this substance?

Answer 35

Type II Pneumocytes secrete Surfactant, which reduces the surface tension of the film of fluid lining the alveoli, making the alveoli easier to expand

Question 36

What is the mediastinum?

Answer 36

Lungs are separated by heart and other structures in the midline. Midline structure containing these separating structures is called the mediastinum.

Superior and inferior is subdvided by plane that passes through angle of Louis between manubrium and body of sternum.and corresponds with level of t4 and t5 vertebral disks. Superior communicates with the neck and contains great vesssels, trachea and oesophagus along ith nerves.

Inferior has three subdivisions in itself, anterior, middle and posterior. Middle contains heart. Anterior is mostly fat and in children contains the thymus. Posterior has structures that communicate with abdomen.

Question 37

Hialum of the lung

Answer 37

Hialum is where we have vessels coming in and out. Three major structures in hialum of lung: pulmonary vein, pulmonary artery and bronchi. Bronchi are represented posterior and superior, pulmonary artery reprsented superiorly but a little more anterior, pulmonary veins are represented inferiorly. Hialum at level T5,6 and 7 vertebrae