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.
Costophrenic angle
Point made by lateral lung
Meant to be sharp
Pleural effusion - fluidly likely to collect in costophrenic angle - angle blunting
Describe accessory muscles
Trapezius
Sternocleidomastoid - elevates thoracic cage, promoting inhalation
Scalene - elevates the thoracic cage, promoting inhalation
Also abdominal muscles - reduce volume of thoracic cavity, promoting exhalation
Usually expiration is passive - may become more active
Discuss layers of pleura
Visceral (covers lungs) and parietal (covers internal thoracic cavity)
- Parietal is thicker
- Cervical (dome) - goes through superior thoracic apeture into root of neck
- Costal part - ribes
- Mediastinal
- Diaphragmatic
- Innervated by intercostal nerves (costal and peripheral diaphragmatic) and phrenic nerves (mediastinal)
- Visceral is more delicate
- Extends into horizontal and oblique fissure
- Innervated by autonomic nerves - pulmonary plexus
- Each layer is a single layer of mesothelial cells and supporting connective tissue, BVs and lymph
Continuous at the hilum of the lung
There is a potential space between the viscera and parietal pleura, known as the pleural cavity.
Means that usually there is no space present
Contains a small volume of serous fluid
Visceral surface does not have pain fibres
Parietal is very heavily innervated
When you have pneumonia - not painful until impacts parietal
Which pleural space is smaller?
Left, because of heart
Discuss positioning of the pleura
- Runs down sternum to 4 costal cartilage
Neurovascular supply of pleura
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.
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 arteries (branches of the descending aorta), which also supply the parenchyma of the lungs.
Discss suprapleural membrane
The suprapleural membrane, also known as Sibson fascia is a strong fascial connective tissue layer above the superior thoracic inlet on each side, placed on top of the tips of the lungs.
The structure fastens itself towards the internal margin of the first rib along with the transverse processes of vertebra C7. It spreads approximately 1 inch more superior towards the superior thoracic aperture.
Its superior surface is associated with the subclavian vessels and its inferior surface is related to cervical pleura, covering the apex of the lung.
- It protects the underlying cervical pleura, beneath which is located the apex of the lung.
- It resists the intrathoracic pressure at the time of respiration. Consequently, the root of neck is not puffed up and down during respiration.
- Apical reinforces for the pleural cavity in the root of the neck are provided is provided by the suprapleural membrane.
What does intercostal neurovascular bundle contain?
intercostal artery, vein and nerve
Between internal and innermost layers
Vein = superior, then artery and then nerve
When do the posterior and anterior intercostal arteries from?
Posterior = thoracic aorta
Anterior = internal thoracic artery
Discuss costophrenic recess
located between the costal and diaphragmatic pleura of right and left pleural cavities
Where costal and diaphragmatic pleura become continuous
Discuss negative pressure ventilation
Applies negative air pressure to body
In most NPVs (such as the iron lung in the diagram), the negative pressure is applied to the patient’s torso, or entire body below the neck, to cause their chest to expand, expanding their lungs, drawing air into the patient’s lungs through their airway, assisting (or forcing) inhalation. When negative pressure is released, the chest naturally contracts, compressing the lungs, causing exhalation. In some cases, positive external pressure may be applied to the torso to further stimulate exhalation
Basically helps lungs suck gas in
Positive pressure ventilation
Pushing gas into lungs
When they take a breath in, they give extra oomph to breath in
Can be passive or invasive (tracheal intubation)
Discuss pneumothorax
Gas in pleural cavity - leads to collapse on lung on affected side
Pts have chest pain and shortness of breath
Simple pneumothorax - non-expanding collection of air
Tension - one-way valve within lung tissue, allowing gas to escape from the lung into the pleural cavity but preventing it from returning back into the lung
Treated via intercostal chest drain
What may occur following tension pneumothorax?
Mediastinal shift - trachea, apex beat
Discuss rib fractures
First rib rarely fractured
Heavy breathing, coughing, sneezing
Can compromise ventilation a lot - v painful
Multiple fractures in similar area - flail chest - floating around
You get paradoxical movement of flail segment inwards upon inspiration
Discuss vascular supply
(?) - add
bronchial arteries are at systemic pressures - if you see pt coughing up blood - worry about bronchial arteries - could be bleeding
Discuss hilum of lungs
Pulmonary artery – carries de-oxygenated blood from the pulmonary trunk to the lungs.
Pulmonary veins – variable in number (1-4), responsible for carrying newly oxygenated blood to the left atrium of the heart for systemic circulation.
Bronchial arteries – arise from the thoracic aorta, passing along the posterior aspect of the main bronchi, to supply the lung parenchyma.
Discuss lung lobes and segments
Right - 3 lobes - upper, lower, middle
Left - 2 lobes - upper and lower, no middle but have lingula which is part of upper
Discuss fissures in lung
Each lung has oblique - from spinous T3 to 6th costal cartilage
Horizontal fissue in right - above oblique - midaxillary line to level of 4th intercostal cartilage
Discuss trachea.
Which side is soft?
Where does it travel in relation to the oesophagus?
Softer posteriorly
Anteriorly to oesphagus
Where does the trachea bifurcate?
Level of sternal angle - T4
Discuss bronchi angles
The right main bronchus is much straighter with respect to the trachea
You’re much more likely to inhale into the right lung
Discuss right bronchus
Produces a superior lobar bronchus before entering the right lung at the hilum
What are both bronchi supported by?
hyaline cartilage, which forms an incomplete ring.
What marks transition from bronchi to bronchioles?
Loss of cartilage
Discuss lymph drainage
The lymph from the lung parenchyma drains to the lymph nodes within the lung hila.These nodes subsequently drain to the tracheobronchial nodes, before reaching the venous circulation. Diseases of the lungs, including lung cancer and tuberculosis, can cause lymphadenopathy, which may be sufficiently large to cause an obstruction of the bronchus at the hilum and ultimately lobe collapse.
All goes up into the thoracic duct. If this is damaged - accumulation of lymph in the chest = chylothorax = white fluid coming out of chest
enlarged lymph nodes = cancer
Discuss sympathetic chain
Runs down back of lungs
Tumour at top of lungs - can damage sympathetic structures - Horners syndrome
Horner syndrome is a rare condition classically presenting with partial ptosis (drooping or falling of the upper eyelid), miosis (constricted pupil), and facial anhidrosis (absence of sweating) due to a disruption in the sympathetic nerve supply.
Why percuss chest?
Detect resonance of air-filled cavity
Crackles = pneumonia
Could also detect cardiac and liver dullness
Cardiac = right ventricular dilation
Liver dullness = enlarged liver
Discuss thoracic dermatomes
Dermatome of sternal angle = T2
Nipples = T4
Xiphoid T6
Discuss chest drains
Whenever inserting a needle into the intercostal space, it is important to appreciate the anatomy. Needles should always be inserted immediately above the inferior rib of a space, in order to avoid damage to the neurovascular bundle within the costal groove of the superior rib. Damage to the intercostal artery can cause significant haemorrhage, whilst damage to the intercostal nerve can cause intercostal muscle paralysis and chest wall paraesthesia.
Discuss lympathic drainage of chest wall
The parasternal lymph nodes, located along the course of the internal thoracic artery, drain lymph from the medial part of the breast tissue, intercostal spaces and diaphragm.These nodes ultimately return lymph to the systemic circulation, at the junction of the internal jugular and subclavian veins.
Lymph from the more lateral parts of breast tissue (75% of total) drain to the anterior axillary and pectoral groups of lymph nodes. Understanding this lymphatic drainage is critical for understanding lymphatic spread of metastatic breast cancer.
Discuss pleural effusions
A significant increase in the volume of fluid in the pleural cavity is called a pleural effusion.The fluid may cause shortness of breath, cough and pleuritic chest pain.
There are a range of causes, including pulmonary (such as pneumonia, lung cancer), pleural (such as mesothelioma) and extra-pulmonary (such as heart failure, cirrhosis) causes.
If the cause is not clear on examination alone, the fluid can be sampled and classified as either a transudate or exudate (based on relative protein content).This can narrow the differential diagnosis.
Breath sounds are diminished or absent over pleural effusions on auscultation, whilst the lungs are dull on percussion. Effusions can be seen as a blunting of the costophrenic angle on a chest X-ray if small, and a fluid level with a meniscus obliterating the lung markings if larger.
What can each lobe be further divided into? What can blockage of these cause?
Bronchopulmonary segments - each supplied by segmental bronchis
Segments = pyramidal
Blockage of the segmental bronchus supplying a segment can result in collapse of that lung segment (at- electasis). Obstruction may be caused by inhaled foreign objects, lung tumours and cystic fibrosis. This causes difficulty breathing, rapid breathing and coughing. On X-ray, the appearance can vary from a thin linear opacity to a large wedge-shaped opacity.
Discuss innervation of lung parenchyma
The lung parenchyma is under autonomic nervous system control, derived from the pulmonary plexus of nerves around the lung hilum. Bronchial smooth muscle contracts and mucous glands secrete under Vagal stimulation, whilst other glands and blood vessels are controlled by sympathetic fibres originating from T1-T5 spinal levels.
Describe lobar collapse
Atelectasis
What does pulmonary oedema look like on xray?
What does hilar node enlargement look like on xray?
