Flashcards in Lungs and thoracic walls Deck (31)
What is the composition of the thoracic walls?
- Posterior: 12 thoracic vertebrae
- Lateral: 12 ribs and 11 intercostal spaces and all of their contents
- Anterior: Sternum and costal cartilages
What are the contents of the intercostal spaces?
- External intercostal muscles (fibres running forwards and downwards) and becomes membranous sheath between costal cartilages
- Internal intercostal muscles (fibres running backwards and upwards) and become posterior intercostal membranes posteriorly
- Innermost intercostal muscles (fibres running backwards and upwards)
- Subcostalis (posterior, spanning multiple ribs and in the same plane as innermost)
- Transversus thoracis (Arises from posterior sternum, crosses 2 or more ribs and attaches to 3rd-6th costal cartilages)
- Intercostal neurovascular bundle
What are the contents of the intercostal neurovascular bundle (from superior to inferior)?
- Intercostal Veins: Draining into the internal thoracic veins (anterior) and azygos/hemiazygos veins (posterior).
- Intercostal Arteries: Originating from the internal thoracic artery (anterior) and the descending aorta (posterior).
- Intercostal Nerves (arising from associated spinal levels separately).
Where is the intercostal neurovascular bundle?
Between internal and innermost intercostal muscles
What is the structure of a rib?
- Costal groove (inferior)
What is significant about the structure of a rib?
The angle is the most vulnerable point on a rib.
What is the general structure of the chondrosternal joint?
- The ribs articulate with their costal cartilage via a primary cartilaginous joint.
- The costal cartilages usually articulate with the sternum via synovial joint (atypical as contains fibrocartilage).
What are the types of ribs in the thoracic wall?
- First 7 ribs are 'true' ribs as they articulate with the sternum individually.
- The last 5 ribs are false ribs:
1. Ribs 8-10 have costal cartilages fused with the one above (forming costal margin)
2. Ribs 11 and 12 don't articulate with the sternum, so are floating ribs.
What is significant about rib 1, 11 and 12?
They articulate with their own vertebral bodies only, whereas other ribs articulate with their own vertebral bodies of the vertebrae above. The 11th and 12th rib are tethered to transverse processes of own vertebrae but don't form joints.
What are the movements associated with the thoracic wall?
- Pump handle movement: Upper 7 ribs rotate about the vertebral joints superiorly, leading to anterior expansion of the thoracic cavity.
- Bucket handle movement: Ribs 7-10 lifted laterally by diaphragm, leading to lateral expansion of the thoracic cavity.
- Ribs 5-9 able to carry out combination of both types of movements.
What are the accessory inspiratory muscles?
- Pectoralis major
- Pectoralis minor
- External intercostal muscles
What are the accessory expiratory muscles?
- Latissimus dorsi
- Anterior abdominal wall muscles
What is the structure of the pleura?
- The pleura consists of 2 layers:
1. Parietal pleura
2. Visceral pleura
- Between the parietal pleura and the visceral pleura is the pleural cavity, containing small amount of serous fluid.
- The 2 layers are continuous with each other at the hila of the lungs.
What structures are lined by parietal pleura?
- Cervical part: Covers the apex of the lungs (beyond thoracic inlet)
- Costal part: Covers inside of thoracic wall
- Mediastinal part: Covers the fibrous pericardium
- Diaphragmatic part: Covers superior surface of diaphragm
What structures are lined by the visceral pleura?
External surface of the lungs
What is the innervation of the pleura?
- Costal part of parietal pleura innervated by the intercostal nerves.
- Diaphragmatic part of parietal pleura innervated by the phrenic nerves.
- Visceral pleura is insensitive.
What is the costodiaphragmatic recess?
- Space between the costal part and the diaphragmatic part of the parietal pleura.
- Deepest in full expiration.
What is the structure of the the lungs?
- The left lung is divided into an superior and inferior lobe by the oblique fissure.
- The right lung is divided into the superior, middle and inferior lobes by the horizontal and oblique fissures respectively.
- The right lung is much shorter and broader than the left lung due to the liver. Overall, the left lung is smaller than the right lung due to heart.
What is the structure of the bronchial tree?
- The trachea is the biggest segment of the bronchial tree, extending from the larynx to its bifurcation at level T4/5 into the main bronchi. The cartilage at the tracheal bifurcation is called the carina.
- The right main bronchus is much shorter and more vertical than the left main bronchus.
- The main bronchi then divide into lobular bronchi, and then into terminal bronchi.
- Each terminal bronchus supplies a separate bronchopulmonary segment, which is considered the smallest independent segment of the lungs.
What is the vascular supply to bronchopulmonary segments?
- Each segment is supplied by a separate branch of the pulmonary artery.
- Each segment is drained by an intersegmental vein, located between segments to avoid compression during inspiration.
- Each segment is drained by lymphatic vessels that drain into into the tracheobronchial nodes.
What are the bronchiopulmonary segments of the right lung?
What are the bronchiopulmonary segments of the left lung?
What are the surface markings of the pleura?
- The apex is located 2.5cm above the medial 1/3 of the clavicle.
- The 2 pleura meet at the angle of louis (manubriosternal joint)
- The right pleura extends to the level of 6th costal cartilage and deviates laterally.
- The left pleura extends to the level of the 4th costal cartilage and deviates laterally (due to heart).
- Both pleura reach level of 8th costal cartilage at the mid-clavicular line.
- Both pleura meet the level of 10th costal cartilage at mid-axillary line.
- Both pleura extend posteriorly to just below neck of 12th rib.
What are the surface markings of the lungs?
- -2 rule.
- Both lungs reach level of 6th costal cartilage at the mid-clavicular line.
- Both lungs meet the level of 8th costal cartilage at mid-axillary line.
- Both lungs extend posteriorly to just below neck of 10th rib.
What are the surface markings of the fissures?
- The oblique fissures begin at the level of spine of T3 vertebrae posteriorly and follows contour of medial border of scapula when arm is fully abducted. It ends at the level of the 6th costal cartilage.
- The transverse fissure begin anteriorly at the level of the 4th costal cartilage and meets the oblique fissure at the mid-axillary line at the level of the 5th costal cartilage.
What are the relations of the left lung?
- Thoracic wall
- Left ventricle
- Arch of aorta
- Descending aorta
- Oesophagus (inferiorly)
- Left subclavian artery
What are the relations of the right lung?
- Thoracic wall
- Right atrium
- Arch of azygos vein
- Brachiocephalic trunk
What are the structures at the hila of the lungs?
- Pulmonary artery
- Pulmonary vein
- Bronchial arteries
- Nerves of pulmonary plexus
What are the relations of the structures at the hila of the lungs?
- The bronchi are always situated posteriorly
- The pulmonary arteries are always situated anterosuperiorly
- The pulmonary veins are always situated anteroinferiorly
What are the innervations of the lungs and their locations?
- The lungs are supplied by parasympathetic fibres (bronchoconstriction) from the vagus nerve.
- The lungs are supplied by sympathetic fibres (bronchodilation) from the sympathetic chain.
- These fibres originate from the anterior (to trachea) and posterior pulmonary plexuses.