Anatomy: Lungs and the Thorax Flashcards
What 2 distinct clinical and anatomical regions can the airway be split into?
The upper and lower airway
What are the major structures of the upper airway?
Nasal cavity Oral cavity Nasopharynx Oropharynx Laryngopharynx Larynx (also the sinuses which cannot all be seen)
What are the major structures of the lower airway?
Trachea
Left main bronchus
Right main bronchus
(and the smaller bronchi, bronchioles and alveoli which cannot be seen)
What are the two entrances for air into the pharynx?
Nasal cavity
Oral cavity
What are the three divisions of the pharynx?
The nasopharynx is most superior division, lying behind the nasal cavity.
The oropharynx lies posteriorly to the oral cavity.
The most inferior part of the pharynx is the laryngopharynx (also hypopharynx).
Where does air exit the pharynx? What about food?
Air exits via the larynx
Food exits via the oesophagus
What is the trachea and where is it situated?
The trachea (or windpipe) is a flexible tube arising from the inferior end of the larynx at the level of the 6th cervical vertebra (C6). The trachea is approximately 10 cm long and ends at the level of the sternal angle (T4/5 intervertebral disc) where it divides into left and right main bronchi, one for each lung. This is the level of the transthoracic plane.
What are the tracheal rings?
These are C-shaped rings of fibrocartilage which are deficient posteriorly where the trachea is adjacent to the oesophagus.
What does the flexibility of the trachea allow for?
The flexibility of the trachea allows the upper end to move with the larynx, for example on swallowing. The lower end moves with the diaphragm as it is lowered and raised in respiration.
What is located on either side of the trachea?
On either side of the trachea are the common carotid arteries taking blood to the head and, in front of it, lies the thyroid gland at the level of C5-T1.
What main bronchus are aspirated foreign bodies most likely to end up in?
The right main bronchus is the site aspirated structures tend to lodge due to its wider and more vertical structure
What are the features of the main bronchi?
Notice that the right main bronchus is wider and shorter (2.5cm) than the left (5cm) and passes directly to the hilum of the lung. Because it is wider and more vertical than the left main bronchus, foreign objects inhaled by small children lodge more frequently in the right main bronchus than the left.
What are the lobar and segmental bronchi?
Within the lung the main bronchi divide into lobar bronchi each supplying one lobe of a lung with air. The left lung has two lobes while the right lung has three so there are two lobar bronchi on the left and three on the right. Each lobar bronchus divides into several segmental bronchi each going to one bronchopulmonary segment (see below). These airways then subdivide many times, the branches becoming smaller on each division.
What are the bronchioles and what are their features?
The smallest branches are called bronchioles. These do not have any cartilage in their walls but do have large amounts of smooth muscle so that these airways, by constricting or relaxing, control the flow of air into the air sacs or alveoli, where gaseous exchange takes place.
What structures have a complete ring of cartilage?
Cricoid
What structures have a C-shaped ring of cartilage?
Trachea
Main bronchi
What structures have plates or crescents of cartilage?
Small bronchi
What structures have no cartilage?
Bronchioles
What is the carina?
Where the trachea splits into the left and right bronchi
What is the diaphragm? Which parts are muscular/fibrous? What is its function?
The diaphragm forms a partition between the abdomen and the thorax. The outer part is muscular while the inner part, the central tendon, is fibrous and is firmly attached to the pericardium, the fibrous sac containing the heart. The diaphragm is the main muscle of ventilation, descending into the abdomen on inspiration (breathing in).
What are the three parts of the diaphragm that attach the bony skeleton of the thorax?
The sternal part is attached to the posterior aspect of the xiphoid process.
The costal part is attached to internal surfaces of the lower six ribs & costal cartilages.
The lumbar part attaches to the first 3 lumbar vertebrae posteriorly (around the aorta).
How high up is the diaphragm in relation to the sternum?
The right dome of the diaphragm reaches as high as the upper border of the 5th rib, and the left dome reaches the lower border of the 5th rib (NB the height of the nipple is 4th intercostal space so domes of diaphragm just below this level). This is always higher than students think.
At what vertebral levels do the oesophagus, aorta and inferior vena cava pass through the diaphragm?
IVC = T8 Oesophagus = T10 Aorta = T12
What is the pleura
A serous 2-layered membrane covering each lung
What is the visceral pleura, parietal pleura and pleural cavity?
The visceral pleura covers the surface of each lung. The outer layer is the parietal pleura which lines the inside of the thoracic cavity. Between the two layers is the pleural cavity, a potential space (i.e. usually shouldn’t be a big space), which contains a very thin layer of fluid – the pleural fluid which allows the layers of pleura to slide smoothly over each other during respiration.
What does the visceral pleura cover?
Just the lungs
What can the parietal pleura be subdivided into (based on what it covers)?
The pleural lining extends above the first rib into the neck forming the cervical pleura.
The mediastinal pleura cover the lateral surface of the mediastinum (in green).
The diaphragmatic pleura cover the superior surface of the diaphragm on each side of the heart.
The costal pleura covers the thoracic wall.
Physiologically and pathologically, when might there be a pleural space?
The costal and diaphragmatic pleurae usually lie in opposition to (touching) the visceral pleura. However a (pleural) space may be generated between them:
Physiologically: In deep inspiration, the diaphragm (and therefore the lung base) descends and the costal and diaphragmatic pleurae can separate. This lower area of the pleural cavity into which the lung expands is called the costodiaphragmatic recess – this is also known as the costophrenic recess.
Pathologically: If fluid (transudate, pus, blood, chyle) or gas (air) collects in the space.
What is the lowest point of the pleural cavity?
The costophrenic recess is the lowest point of the pleural cavity. If there is excess fluid in the pleural cavity (such as blood or pus) this is where it will collect.
Where might the following substances collecting pathologically in the pleural cavity - blood, pus, serous fluid, urine, lymphatic fluid and air?
Blood = haemothorax Pus = pyothorax (empyema) Serous fluid = hydrothorax Urine = urinothorax Lymphatic fluid = chylothorax Air = pneumothorax