Anatomy of the Thorax Flashcards
Over what muscle does the long thoracic nerve run?
Serratus anterior
What is the innervation to the intercostal muscles?
Innervated by the anterior rami of the thoracic spinal nerves
Between which muscles do the neuromuscular bundles run in the intercostal margin?
Between the internal intercostal and the innermost intercostal muscles
Describe the procedure of thoracocentesis
Where a needle is inserted just superior to the rib in the mid-axillary line of the 9th rice to avoid the inferior border of the lung and sample the pleural fluid
What is thoracocentesis?
Where a sample of pleural fluid is taken using a needle
Describe the procedure of chest drain insertion
A chest drain is inserted into the 5th intercostal space in the mid-axillary line in the ‘safe triangle’
What is the ‘safe triangle’ formed by?
Medially: the lateral border of pectorals major
Laterally: anterior border of latissimus dorsi
Inferiorly: level of the nipple
Superiorly: apex is just below the axilla
What muscles are involved in quiet inspiration?
Contraction of the diaphragm, external intercostals and the interchondral part of the internal intercostal
What muscles are involved in deep inspiration?
Contraction of the diaphragm, external intercostals and the interchondral part of the internal intercostal as normal, with the addition of accessory muscles of respiration: sternocleidomastoid and scalene muscle contraction
What muscles are involved in quiet expiration?
Elastic recoil of the diaphragm, external intercostals and interchondral part of internal intercostals
What muscles are involved in forced expiration?
Elastic recoil of the diaphragm, external intercostals and interchondral part of internal intercostals alongside contraction of the internal intercostal muscle (except for interchondral aspect) and contraction of abdominal muscles
What is fluid in the pleural cavity known as?
Pleural effusion
How could you diagnose pleural effusion from a chest x-ray?
Severe blunting of the costophrenic recess and white at the base of the lungs
Which type of pleura produces pleural fluid?
The parietal pleura, and this fills the pleural cavity
What structures are covered by the parietal pleura?
Thoracic wall and superior surface of diaphragm
What structures are covered by the visceral pleura?
External lung surface
What is the neuromuscular supply to the parietal pleura?
The parietal pleura is sensitive to pressure, pain, and temperature. It produces a well localised pain, and is innervated by the phrenic and intercostal nerves.
The blood supply is derived from the intercostal arteries.
What is the neuromuscular supply to the visceral pleura?
The visceral pleura is not sensitive to pain, temperature or touch. Its sensory fibres only detect stretch. It also receives autonomic innervation from the pulmonary plexus (a network of nerves derived from the sympathetic trunk and vagus nerve).
Arterial supply is via the bronchial circulation (internal thoracic arteries), which also supplies the parenchyma of the lungs.
What is the difference in blood supply to the parietal and visceral pleura?
Visceral pleura is supplied by the bronchial circulation (internal thoracic artery) whereas the parietal pleura is supplied by the intercostal arteries
Why may a lung tumour not cause any pain until it is very large?
As the visceral pleura doesn’t have sensory nerve fibres for pain, and therefore it is only when the tumour grows large enough to distort the parietal pleura that it will trigger referred pain via the phrenic or intercostal nerves
Where is the apex of the lung located from surface anatomy?
About 2cm above the clavicle
Where is the cardiac notch approximately located from surface anatomy?
Approximately at the 4th rib
How would COPD/emphysema appear on chest x-ray?
Lung hyper expansion (can see more than 8 ribs)
How many lobes are there in the left lung?
Two, superior and inferior