Trachea, bronchi, pleura and lungs Flashcards
What is the histology of the trachea from inner to outer?
- Goblet cells (mucous)
- Pseudostratified ciliated columnar epithelium
- Fibro-elastic support
- Submucosal glands
- Smooth muscle to control diameter (trachealis)
- Cartilage C-rings hold trachea open
What is the tracheal neurovascular supply?
Arteries - inf thyroid and bronchial
Veins - inf thyroid
Lymph - pre and para tracheal
Nerves - vagi, recurrent laryngeal, symp trunks
What is parietal pleura attached firmly to?
- Thoracic wall (costal pleura)
- Fascia at thoracic inlet at 1st rib and T1 (cervical pleura)
- Fibrous pericardium and other mediastinal structures (mediastinal pleura)
- Diaphragm - diaphragmatic pleura
Name the recesses
The lungs do not entirely fill the pleural cavities.
Costodiaphragmatic recess is potential space inferiorly around the periphery of diaphragm
Costomediastinal recess is potential space anteriorly where the pleurae wrap around the mediastinum - larger on left
SItes of fluid accumulation
What is function of pleural membrane and pneumothorax
Surface tension between parietal and visceral pulls visceral layer (and lung) with the movements of thoracic wall Elastic recoil of lung tissue means that lungs are tending to deflate. The surface tension creates a slight -ve pressure that maintains the lung in slight inflation even at the end of expiration.
If air enters the pleural cavity the surface tension and -ve pressure lost and lung collapses. If severe the infected side shows no thoracic movement, elevated hemi-diaphragm, shift of mediastinum to affected side (in pneumothorax, not tension pneumothorax)
What are borders, surfaces and fissures of lungs?
3 borders - anterior, posterior, inferior (diaphragmatic)
3 surfaces - costal, diaphragmatic, mediastinal
Fissures - oblique, both lungs (spine of T4 to 6th rib), horizontal - right lung only (rib 4 or 5)
Lung lobes
Left lung has two lobes (therefore two lobar bronchi) and the right has 3 lobes (3 lobar bronchi). The right main bronchus is slightly more vertical, shorter and wider than left. Foreign bodies may be more likely to enter the right lung
What are auscultations of lung?
Right lung Upper lobe (above horizontal fissure) - ant wall of thorax Middle lobe (between horizontal and oblique fissure) - side of thorax, low axilla Lower lobe (inf to oblique fissure) - extends much higher on post surface of lung so auscultate on post thoracic wall
Left lung
Upper lobe - above oblique fissure anteriorly
Lower lobe - inf to oblique fissure - post thoracic wall
What are divisions of bronchi called?
1y - main
2y - lobar
3y - segmental
Each 3y bronchus passes to a broncho-pulmonary segment
Discuss these broncho-pulmonary segments
Pyramid with its base on surface of lung, apex pointing towards hilium
10 in each lung, but on left some may fuse (=8-10)
Separated from each other by connective tissue
Disease may be confined within a segment - can be removed surgically
What differences are observable at the bronchial stage?
Cartilage and mucous cells go, epithelium flattens from pseudostratified columnar to cuboidal and eventually squamous in alveoli…and there is a high proportion of elastic tissue
Blood supply to the lungs
Bronchial arteries supply lung tissue - walls of bronchi and support tissues
Single right bronchial artery arises from 3rd posterior intercostal artery
Two left bronchial arteries usually arise from aorta directly
Bronchial arteries may anastomose with pulmonary arteries in walls of bronchioles therefore some blood supplied by bronchial arteries drains into the pulmonary veins. Bronchial veins themselves drain into the azygos system.
