S1) Anatomy of the Respiratory System Flashcards
How does the respiratory system develop?
- Develops as a ‘diverticulum’ from the pharynx on the anterior side of the primitive gut tube.
- This elongates, bifurcates and branches to form the respiratory system
Identify 5 functions of the nasal cavity
- Induce turbulent flow (nasal conchae)
- Warm and moisten inspired air
- Recover water from expired air
- Speech production (phonation)
- Olfaction
Briefly describe the purpose of the paranasal sinuses
Complement the function of the nasal cavity
What are the three divisions of the pharynx?
- Nasopharynx
- Oropharynx
- Laryngopharynx
Explain the relationship between the pharynx and larynx
The pharynx and larynx work together to ensure that food and air enter the oesophagus and trachea respectively
How does the larynx protect the airway during swallowing?
The epiglottis is a flap made of elastic cartilage attached to the entrance of the larynx which projects obliquely upwards to prevent the aspiration of food/liquids during swallowing
Identify the 6 structures in the conducting zone of the respiratory system
- Trachea
- Primary (main) bronchi
- Secondary (lobar) bronchi
- Tertiary (segmental) bronchi
- Bronchioles
- Terminal bronchioles
Identify the 3 structures in the respiratory zone of the respiratory system
- Respiratory bronchiole
- Alveolar duct
- Alveolus
Identify 2 functions of the cartilage in the trachea
- Keeps airway open (patency)
- Enables movement during breathing
Why is the tracheal cartilage C-shaped?
The cartilage opens at the esophagus and is replaced by connective tissue and muscle allowing the bolus to press against the trachea and be swallowed easily
Which parts of the body do the superior and inferior thoracic aperture communicate with respectively?
- Superior thoracic aperture communicates with the neck
- Inferior thoracic aperture communicates with the abdomen
Which specific nerves innervate the diaphragm?
Left and right phrenic nerves
Which segment of the nervous system innervates the diaphragm?
The diaphragm is a somatically innervated skeletal muscle (voluntary control)
How do we ventilate the lungs?
- Increase the volume of the thoracic cavity
- Reducing the alveolar pressure
What are the three layers of intercostal muscles connecting the ribs together?
- External intercostal muscle
- Internal intercostal muscle
- Innermost intercostal muscle
What is the primary function of the external intercostals?
Assist inhalation
Internal intercostals are antagonists to external intercostals.
Thus, state their function
Assists exhalation (especially forced exhalation)
What is the location of the main neurovascular bundle for the intercostals?
Below the rib, hence entry during pleural aspiration or insertion of chest drain is always made above the rib
Which three structures pass through the diaphragm?
- Vena Cava
- Oesophagus
- Aorta
At what vertebral levels do the three structures pass through the diaphragm?
- Vena cava (T8)
- Aortic hiatus (T12)
- Oesophagus (T10)
Levels correspond to the number of letters in each structure
What are the components of the intercostal neurovascular bundle?
- Intercostal nerve
- Intercostal vein
- Intercostal artery
What is the azygos vein and what does it do?
The azygos vein is a vein running up the side of the thoracic vertebral column draining itself towards the superior vena cava.
What are the articulating points of the rib cage?
- The ribs articulate with the vertebral column posteriorly
- The ribs terminate anteriorly as cartilage (costal cartilage)
The typical rib consists of three components.
Identify them
- Head
- Neck
- Body
Describe the shape of the head of a typical rib
The head is wedge shaped and has two articular facets separated by a wedge of bone
Identify the different articulation points of the head of the rib
- One facet articulates with the numerically corresponding vertebrae
- The other articulates with the vertebrae above
Describe the articulation points of the neck of a typical rib
Where the neck meets the body there is a roughed tubercle which articulates with the transverse process of corresponding vertebrae
Describe the structure and function of the body/shaft of the rib
- Structure: flat and curved
- Function: internal surface of the shaft has a groove for the neurovascular supply of the thorax, protecting them from damage
What are the four characteristic features of the thoracic vertebrae?
- Vertebral body is heart shaped
- Demi-facets on each side of vertebral body
- Costal-facets on transverse process
- Spinous processes are long and slanted inferiorly
Explain why hoarseness of the voice may be a sign of intrathoracic disease
- Hoarseness is a symptom not a disease
- It is related to swelling, inflammation and an upper respiratory tract infection
Describe the rib movements during inhalation and exhalation
- Inhalation
I. Chest cavity enlarges
II. Rib cage moves upward and outward
- Exhalation
I. Chest cavity reduces
II. Rib cage moves downward and inward
Describe the anatomical position of the lungs
- The lungs lie on either side of the mediastinum, within the thoracic cavity
- Each lung is surrounded by a pleural cavity
Which 4 structures does the mediastinal surface of the left lung lie in close proximity to?
- Heart
- Arch of aorta
- Thoracic aorta
- Oesophagus
Which 5 structures does the mediastinal surface of the right lung lie in close proximity to?
- Oesophagus
- Heart
- Inferior vena cava
- Superior vena cava
- Azygos vein
Briefly describe the structure of the lungs
Each lung consists of:
- An apex
- Base
- Lobes
- Three surfaces
- Three borders
What are the three surfaces of the lungs?
- Costal (faces internal surface of chest wall, smooth)
- Mediastinal (lateral aspect of middle mediastinum)
- Diaphragmatic (concave)
Which lung is smaller?
The left lung is slightly smaller than the right due to the presence of the heart
Distinguish the lobular structure of the left and right lungs
- The right lung has three lobes (superior, middle and inferior) separated by oblique and horizontal fissures
- The left lung has two lobes (superior and inferior) separated by a similar oblique fissure
What is the lung root?
The lung root is a collection of structures that suspends the lung from the mediastinum
Identify the contents of each lung root
- Bronchus
- Pulmonary artery
- 2 pulmonary veins
- Lymphatic vessels
- Pulmonary plexus of nerves
All the structures in the lung root enter/leave via the hilum.
What is this?
The hilum is a wedge shaped area on the mediastinal surface of the lung
Briefly describe the arterial supply and venous drainage of the lungs
- The lungs are supplied with deoxygenated blood by the paired pulmonary arteries
- Once the blood receives oxygenation, it leaves the lungs via the four pulmonary veins
Describe the venous drainage and arterial supply of the bronchi, lung roots and visceral pleura
- Arterial supply via the bronchial arteries which arise from the descending aorta
- Venous drainage via the bronchial veins:
I. Right - drains into azygos vein
II. Left - drains into accessory hemiazygos vein
The nerves of the lungs are derived from pulmonary plexuses.
Describe the parasympathetic and sympathetic supply of the lungs
- Parasympathetic: derived from the vagus nerve
- Sympathetic: derived from the sympathetic trunks
There are two pleurae in the body, consisting of a serous membrane.
How can the pleura be divided into two parts?
- Visceral pleura which covers the lungs
- Parietal pleura which covers the internal surface of the thoracic cavity
The parietal pleura is the thicker pleura and can be subdivided into 4 parts.
Identify and describe these
- Mediastinal pleura lines lateral aspect of mediastinum
- Cervical pleura lines neck extension of pleural cavity
- Costal pleura covers inner aspect of ribs, etc
- Diaphragmatic pleura covers surface of diaphragm
Describe the structure of the visceral pleura
- Covers outer surface of lungs
- Extends into interlobar fissures
- Continuous with the parietal pleura at hilum of each lung
What is the pleural cavity?
The pleural cavity is a potential space between the parietal and visceral pleura which contains a small volume of serous fluid
What are the two functions of the parietal pleura?
- Lubricates the pleural surfaces, allowing friction-free movement
- Produces surface tension, pulling the pleurae together and ensuring the lungs expand during inspiration
What are recesses?
- The pleural cavity is not completely filled by the lungs anteriorly and posteroinferiorly.
- It gives rise to recesses, which are potential spaces where opposing surfaces of the parietal pleura touch
There are two recesses in each pleural cavity.
Identify and describe their location
- Costodiaphragmatic: located between the costal pleurae and the diaphragmatic pleura
- Costomediastinal: located between the costal pleurae and the mediastinal pleurae, behind the sternum
What happens when fluid collects in the pleural recesses?
Compare and contrast the vascular supply of the parietal and visceral pleura
- Parietal: intercostal arteries
- Visceral: internal thoracic arteries
Compare and contrast the innervation of the visceral and parietal pleura
- Visceral: pulmonary plexus – sensitive to distension only
- Parietal: phrenic and intercostal nerves – sensitive to pressure, pain and temperature
What is pneumothorax?
- Pneumothorax is a condition which occurs when air or gas is present within the pleural space
- This removes surface tension of the serous fluid in the space and reduces lung extension
What is the sternal angle?
The sternal angle is a joint formed by the articulation of the manubrium and the body of the sternum
How can one find the sternal angle?
- Find the sternal notch
- Walk your fingers down the manubrium a few centimetres
- Feel for a distinct bony ridge
The costal cartilages of which rib articulate with the sternum at the level of the sternal angle?
The second rib
