Thoracic wall & pleura Flashcards
Where are the apices of the lung?
Extend around 3cm above the medial third of the clavicles.
Discuss elements of thoracic skeleton
12 pairs of ribs and costal carilages
12 thoracic vertebrae
Sternum
Which ribs have no anterior attachment?
11-12
Where do ribs 1-7 attach?
Sternum via costal cartilage
Where do ribs 8-10 attach?
Costal cartilage of rib above them
What about ribs 11-12
Do not connect to sternum - floating
Which side of diaphragm is higher?
Right, because of liver
How is the first rib specialised?
Widest, shortest
Head articulates with T1 - only one articulatory surface - while others have two (at costal hemifacets)
The superior surface is unique in that it is marked by two grooves that allow passage of the subclavian vessels.
These grooves are separated by the scalene tubercle – to which the anterior scalene muscle attaches.
Attach photo
What is the costal groove? What are the implications of this clinically?
Where neuromuscular bundle runs of ribs
Runs just under the rib
Where we want to access the pleural space
You want to do this over the top of the lower rib rather than the upper lib so you dont damage
Discuss muscle layers
3 layers - intercostals
1. External intercostal muscle - hands in pockets
- fibres run inferomedially rib above to below. Most active on inspiration
2. Internal intercostal muscle - fibres run inferolaterally rib above to below. Most active on expiration
3. Innermost intercostal muscle - similar to internal intercostals but separated from middle layer by intercostal nerves and vessels
Help to move ribs and ventilate the lung
Discuss movement of ribs
Superior and anterior movement = pump handle
- Movement of 2nd-6th ribs at costovertebral joints
Elevation of lateral shaft of the rib - bucket handle movement
Discuss attachments of ribs to vertebrae
2 areas
1 - head of rib to costal hemifacet on the body
2- articular part of tubercle to vertebral transverse process
Discuss costal cartilage
Articulate with medial ribe and lateral sternum
Provide elasticity
Inferiorly the fusion of multiple costal cartilages = costal margin
Describe xiphoid process
Cartilaginous in young people, ossified by 40
Discuss forced vital capacity
Reduced in supine posture (sitting patients up = helpful)
Reduced in kyphoscolosis - makes it very difficult for them to increase the volume of their thoracic cavity
What time of day do patients struggle with ventilation the most?
Nightime - more tired in the morning, headaches, etc
What is the most common reason for people going into ventilatory failure overnight?
Obesity hypoventilation - issue there is there it makes harder for the diaphragm to push down as abdominal contents push up
Where does diaphragm attach?
anteriorly to the xiphoid process and costal margin, laterally to the 11th and 12th ribs, and posteriorly to the lumbar vertebrae.
What passes through diaphragm
Draw diaphragm openings
What innervates diaphragm?
C345 keeps diaphragm alive
Mainly phrenic nerve (formed by these roots)
Sensory
- Central part = phrenic
- Periphrally = intercostal nerves
Discuss anatomical course of phrenic nerve
Long course
C4 is main contribution (from C345)
Arises at lateral border of scalene → anterior to scalene → runs posterior to subclavian vein → then left and right differ
Right
Passes anteriorly over the lateral part of the right subclavian artery.
Enters the thorax via the superior thoracic aperture.
Descends anteriorly along the right lung root.
Courses along the pericardium of the right atrium of the heart.
Pierces the diaphragm at the inferior vena cava opening.
Innervates the inferior surface of the diaphragm.
Left
Passes anteriorly over the medial part of the left subclavian artery.
Enters the thorax via the superior thoracic aperture.
Descends anterior to the left lung root.
Crosses the aortic arch and bypasses the vagus nerve.
Courses along the pericardium of the left ventricle.
Pierces and innervates the inferior surface of the diaphragm.
Discuss motor and sensory phrenic
Motor - ipsilateral diaphragm
Sensory fibres from the phrenic nerve supply the central part of the diaphragm, including the surrounding pleura and peritoneum. The nerve also supplies sensation to the mediastinal pleura and the pericardium.
Discuss diaphragmatic paralysis
Mechanical trauma – ligation or damage to the nerve during surgery.
Compression – due to a tumour within the chest cavity.
Neuropathies – such diabetic neuropathy.
Paralysis of the diaphragm produces a paradoxical movement. The affected side of the diaphragm moves upwards during inspiration, and downwards during expiration.
A unilateral diaphragmatic paralysis is usually asymptomatic and is most often an incidental finding on x-ray.
If both sides are paralysed, the patient may experience poor exercise tolerance, orthopnoea (harder to breath when lying down) and fatigue.