1
Q
Which modalities are used to image the thorax (chest) and its contents?
A
- CXR
- CT
- MRI
- Ultrasound
2
Q
What is required when Generating a Radiograph?
A
- X-ray Source (generator)
- Patient
- Detector (film or more commonly electronic)
- Can be A-P / P-A XR
3
Q
Why are most thoracic radiographs PA?
A
- Want heart to appear as close to life-size as possible.
- Commonly used x-ray sources use a divergent light beam, beam outwards so will project larger onto the detector. Thus P-A perspective heart is close to the detector/wall and projection will be shown closer to life-size
4
Q
What is the Mach Effect?
A
Edges of darker objects located adjacent to light ones appear darker (and vice versa)
5
Q
Outline the Systematic Approach to Reading Chest Images
A
- Demographics
- RIP - Rotation, Inspiration, Penetration
- ABCDE
- Airway - Tracheal position
- Breathing - Hilum, lung fields
- Cardiac - Cardiothoracic ratio
- Diaphragm - Shape & Air underneath
- Everything else - Bones, Peripheries, etc
6
Q
On a Chest XR, why is posterior part of rib normally more visible than the anterior part of a radiograph?
A
Anterior part is made from cartilage connecting to sternum. Posterior part is made from bone.
7
Q
What are the medial ends of the clavicle called?
A
Sternal ends of the Clavicles
8
Q
What can Lymphadenopathy of the hilar regions of lungs/ lateral aspects of mediastinum cause?
A
Oesophageal , tracheal, or superior vena cava compression
9
Q
What is the costodiaphragmatic recess?
A
Parietal pleura lined region between thoracic wall and diaphragm - Forms ‘V’ shape
10
Q
What is the Thorax, what are its openings called? What are the functions of these structures?
A
- Thorax - Irregular cylindrical cavity with Superior Thoracic Aperture and Inferior Thoracic Aperture openings
- Allow for passageway between abdomen * neck/upper limbs
- Protection, breathing
11
Q
What may cause injury to the vessels/nerves exiting the Superior Thoracic Aperture?
A
- Trauma
- Tumour growth compressing vessels/nerves
- An extra cervical rib above rib 1
12
Q
What are the relations of the Superior Thoracic Aperture
A
- Body of T1 vertebrae posteriorly
- Medial margins of rib 1 on each side
- Manubrium anteriorly (top of sternum)
13
Q
What structures exit laterally from the Superior Thoracic Aperture?
A
- Part of Brachial Plexus
- Subclavian artery
- Subclavian vein
14
Q
What occurs when there is deflated appearance of the 1st dorsal webspace?
A
- Compression of C6/C7 nerves exiting at Superior Thoracic Aperture due to tumour or extra rib
- Supplies nervous innervation to muscles in this area
- Resultant muscle atrophy due to loss of nerve supply. Deflated appearance
15
Q
Why do hiccups occur?
A
- Due to irritation of diaphragm
- Causes involuntary diaphragmatic contractions
16
Q
What are the margins of the diaphragm?
A
- Costal cartilages and bony ribs
- Posteriorly - Ligaments of diaphragmatic crura + lumbar vertebra
17
Q
Describe the motor and sensory innervation of the diaphragm
A
- Motor innervation - Solely left and right phrenic nerves
- Sensory Innervation - Left and Right Phrenic Nerves + Additional peripheral innervation from intercostal nerves
18
Q
What happens if there is unilateral phrenic nerve damage on the right side?
A
- Right hemidiaphragmatic palsy - Paralysis of side affected
19
Q
How is Pain felt in the Diaphragm?
A
- Phrenic nerve + Peripheral Intercostal nerve = Sensory supply
- Inflammation of gallbladder - Tip of Shoulder pain or regional pain in Right Hypochondrium (intercostal Neve)
- Can get inflammation of diaphragm e.g. basal pneumonia, irritation of subphrenic area, malignant disease, pleural effusions
20
Q
What are pericardial branches?
A
- Each phrenic nerve supplying the diaphragm (left and right) also give sensory supply to branches of mediastinal pleura + Pericardium of heart
21
Q
What is meant by Flail Chest?
A
- Rib fractures can lead to paradoxical movement of the thoracic wall segment affected.
- On inspiration will fall inward as rest of thoracic wall moves outward
22
Q
What is the Sternum composed of?
A
- Manubrium
- Body
- Xiphoid Process
- Ossify together with age
22
Q
What is the Sternum composed of?
A
- Manubrium
- Body
- Xiphoid Process
- Ossify together with age
23
Q
What is the significance of the Sternal Angle / Manubiosternal Joint?
A
- Major Surface Anatomy Landmark
- 2nd Costal cartilage is lateral
- If trace around body = Sternal plane = T4-T5 IV disc
- Divides Mediastinum into Superior & Inferior Parts
24
What is the Jugular (Suprasternal) Notch
Palpatable region at top of sternum
25
Describe the Costal Grooves of the Ribs
- On inferior margin of each rib
| - Where neurovascular bundle runs
26
Describe the ribs and its general attachments
- 12 pairs of ribs
- Articulate with thoracic vertebrae posteriorly and costal cartilages anteriorly which attach to the sternum
- Consist of Head, Neck, Angle, and Body regions of bony rib from posterior to anterior aspects.
27
What is an intercostal nerve block? What is its relevance to the ribs?
- Nerve block delivered around intercostal nerve in space + fascial plane surrounding area.
- Anaesthetists use the angles of the ribs to mark pt and localise most advantageous position for delivery
- Used in cases of trauma - Anaesthesia / Post-operative pain relief
28
What type of joints are found between ribs and + vertebra?
Synovial joints - Allows for movement
29
Describe the Articulations of the Ribs
- Head of most ribs articulate with Body + Transverse process of their OWN Vertebra
- AND with vertebral body of the vertebra above
- Joined via synovial joints
30
State the 3 Rib Classifications
- Vertebrosternal (Ribs 1-7)
- Vertebrocostal (Ribs 8-10)
- Floating (Ribs 11 & 12)
31
Where do the Neuromuscular bundles that supply the intercostal spaces + tissues sit?
- Main Neuromuscular bundle runs within costal groove Superiorly between internal & innermost intercostal muscles
- Also have Collateral/Accessory Neuromuscular bundle - Less important
- These supply Vein, Artery, and Nerve
32
Describe a Chest drain
- Performed using Tube Thoracostomy unit/ Chest tube/ Intercostal catheter to drain fluid from pleural or thoracic cavity
- Should be inserted in the inferior part of the intercostal spaces to avoid damaging the main neurovascular bundle
33
Describe the Sensory and Motor Supply to the Ribs
- Intercostal nerves (Ventral Rami of Spinal Nerves) provide both Sensory + Motor to:
- Intercostal space, Overlying tissues (skin, cartilage, bone, muscle, parietal pleura)
- In a dermatomal arrangement
- Pleuritic pain can refer to a dermatome
- Shingles can distribute to a dermatome
34
What is the blood supply to the ribs?
- Anterior Intercostal Artery - arises from Internal Thoracic & Musculophrenic Arteries
- Posterior Intercostal Arteries - arises from Descending Aorta
- Form an anastomosis - Collateral circulation for potential bypass if have an Aortic Coarctation (Narrowing)
35
What Causes Rib Notching (wavy appearance)?
- Increased volume of blood in intercostal arteries that become big, waxy, tortuous.
- Causes bone that it sits in to remodel
- Would be a sign to investigate aorta for possible Aortic Coarctation
36
Describe the Venous Drainage of the Thoracic Wall
- Via UNPAIRED Azygous System
- Right sided structures - Into Azygous vein --> SVC
- Left sided structures - Into Accessory Azygous Vein / Hemizygous Vein --> Cross midline into Azygous --> SVC
- Upper spaces above this system drain directly into left or right Brachiocephalic veins which join to form Superior Vena Cava.
37
Along which vertebra do the Sympathetic chain run?
- Posterior thoracic wall T1-L2
38
Describe Pancoast Tumour and Associated Horner Syndrome
- Pancoast tumour - Apical Lung tumour
- Compression in the apical region can lead to unilateral compression of sympathetic chain at this point which supply head+neck
- Can lead to Horner Syndrome - Ptosis (droopy eyelid) due to paralysis of Superior Tarsal Muscle, Miosis (Constricted Pupil), and Loss of Hemi-fascial sweating
39
Where does the Respiratory System develop from?
- Develops as an outgrowth of the gut tube
- Appears at 4 weeks as a Diverticulum
- Develops into Lung/Bronchial buds --> Grow into splanchno-pleuric Mesoderm (wk 5)
40
How does the Oesophagus and Trachea develop into separate structures?
- Via formation of a septum (tissue that grows between oesophagus + trachea
- Wk 4/5
41
What can occur if Oesophagus and Trachea do not separate correctly?
- Proximal atresia - Oesophagus ends in a blind-ended sac early in tube
- Distal Fistula / Fistula - Communication with the Trachea either with Proximal Atresia or without.
- Must be corrected early in life
42
Describe the Branching/Development of Lung buds
- 2 lung/bronchial buds develop
- Branch into 3 segmental/secondary bronchi on the right and 2 segmental bronchi on the left
- Segmental bronchi develop to give 3 lung tissue lobes on right and 2 on left + Mesoderm divides with segmental bronchi
- Week 26 - Respiratory epithelia begins developing. Can take up to 10 years to full maturation
- Week 16 - All major lung parts are developed (just not gas exchange)
43
Why might a premature baby have very little chance of survival before 26 weeks?
- Lack Respiratory epithelium needed for gas exchange even with ventilation very hard to perfuse tissues.
44
What is atelectasis of the lung?
Collapse/closure of a lung resulting in reduced or completely absent gas exchange
45
What is the oblique fissure?
- Found on both lungs
| - Lines which indicate the borders of the superior and inferior lobes
46
What is the Horizontal fissure?
- Only found on Right lung due to 3 lobes
| - Fissure between superior lobe and middle lobe
47
What functional relevance does the existence of lobes in the lungs present?
- Disease, collapse, oedema, atelectasis can affect lobes independently
- Other lobes will remain functional and unaffected
48
Describe the structures going to and from lungs throughout the hilum (root of the lung)
- Bronchi - Typically enter most superior
- Pulmonary artery w/deoxygenated blood
- Pulmonary vein w/oxygenated blood - Most Inferior
- Phrenic nerve passes anteriorly to hilum of each lung
49
What is the Point of Pleural Reflection? And the Resultant Pulmonary Ligament?
- Where visceral pleura around lung reflects off at hilum of lung to become parietal pleura to line the thoracic cavity
- Pulmonary Ligament is the fold of parietal pleura below the hilum
50
Describe the structures related to the Mediastinal surfaces of lungs that may be damaged by lung pathology
- Phrenic nerves - Pass ANTERIOR to hilum
- Vagus nerves - Pass POSTERIOR to hilum. Recurrent Laryngeal Nerves (RLN), branch off Vagus enter the thorax -
- Right RLN - Recurs at right lung apex under right subclavian vein
- Left RLN - Recurs at aortic arch
51
What might happen in a patient with an aortic arch aneurysm in regards to the nerves?
- Could damage Left Recurrent Laryngeal Nerve + Paralyse left side of the Larynx - Right side unaffected
52
What is a Pneumothorax
Air in Pleural Cavity
53
What is a Haemothorax
- Blood in pleural cavity
54
What is Chylothorax
Lymphatic fluid in pleural cavity
55
What is Effusion
- Excess fluid leaking out of lung into pleural cavity
56
What is a Tension Pneumothorax
- Medical Emergency
- Occurs when there is a penetrating injury, causing progressive loss of air into the pleural cavity - Acts as a one-way valve so that air escapes from the lung into pleural cavity, building up and collapsing the lung
- Get: Mediastinal shift, Tracheal Deviation, Diaphragmatic depression, Unilateral hyperinflation
- Increased intercostal space size
- Emergency as compromised not only lung function but have decreased venous return to heart + decreased cardiac output as result.
- Can remove air build up via needle decompression
57
What is a Pleural Catch?
- Prolonged leaning on one side of thorax, Serous fluid can be pushed out of portion of cavity
- Then take deep breath/change positions - 2 layers of pleura stick together briefly and pulled due to loss of normal frictionless interface
- Experience sharp-shooting pain
- Rebalances shortly with movement
58
What is a Needle Decompression?
- Used to release air from lungs/thorax
| - Wide bore needle stuck into 2nd intercostal space at midclavicular line
59
Describe the Costodiaphragmatic Recess
- Where parietal pleura reflects and forms a recess between the thoracic wall and diaphragm.
- Lung can expand into during deep inspiration
- Region for potential fluid accumulation (Pleural Effusion)
60
Why would you want patient to exhale immediately prior to a procedure e.g. renal biopsy/sample costodiaphragmatic recess?
- Helps ensure you have removed lung tissue out of the costodiaphragmatic recess
- Reduces risk of lung puncture + collapse
61
What surface markings can you use to find the inferior edges of the lung tissue of the right lung?
* 6 - 7 - 8 - 10 - As lung goes anterior to lateral to posterior
62
What surface markings can you use to find the inferior edges of the lung tissue of the left lung?
* 5 - 5 - 8 - 10 - As lung goes anterior to lateral to posterior
63
How do you auscultate/locate the Middle lobe of the right lung?
- 4th Intercostal space on anterior axillary line
64
How do you locate the Oblique fissure of the right lung, thus the inferior and superior lobes of the lungs?
- On posterior side of pt - Ask them to abduct upper limbs above their head
- Oblique fissure approx. follows the medial border of scapula
65
How do you locate the Apex of the lungs?
- Apex sits behind (& up to 2cm superior to) the medial 1/3 of clavicle
66
Thoracostomy Insertion Triangle is:
- Chest drain
- lower part of 4th intercostal space
- Anterior to midaxillary line
- Posterior to anterior axillary fold
67
What is the Carina? When might the SHARP Carina divide become more rounded and bulbous?
- Keel-shaped fork of the bifurcation of trachea into main bronchi.
- Many lymph nodes inferior to it
- Subcarinal lymph nodes in this region may become enlarged - Can be indicative of lung cancer which has metastasised to the nodes
68
Why is the Right main bronchus wider and more vertical than left Important?
- Aspirated objects are more likely to pass into right main bronchus
- First place to look upon scoping for aspirated object
69
Describe Bronchopulmonary segments
- Functionally independent wedge-shaped parts of lung supplied by a segmental bronchus and its accompanying pulmonary artery branch.
- Right lung - Normally 10 segments
- Left lung - Normally 8-9 segments
- Pulmonary arteries run with bronchi
- Pulmonary veins run between segments
70
How does gravity affect drainage of bronchopulmonary segments
When pt supine, the superior segment of lower lobe is most inferior
71
What is Pneumonectomy
Removal of whole lung
72
What is Lobectomy
Removal of whole lobe of lung
73
What is Segmentectomy
- AKA - Wedge Resection
| - Removal of Segment of lung
74
Contrast Bronchi and Bronchiole structure
- Bronchi contain cartilage, smooth muscle, & elastic fibres in their walls
- Bronchioles have no cartilage & their walls are mainly smooth muscle & elastic fibres
74
Contrast Bronchi and Bronchiole structure
- Bronchi contain cartilage, smooth muscle, & elastic fibres in their walls
- Bronchioles have no cartilage & their walls are mainly smooth muscle & elastic fibres
75
What provides blood supply to the lung tissue itself?
Bronchial arteries supply bronchi & lung connective tissue arising from the aorta and a number of posterior intercostal arteries
76
Describe the lymphatic drainage from the lungs
- Follows tracheobronchial tree
- Lungs --> Hilar Nodes --> Subcarinal nodes --> Paratracheal nodes
- Most ultimately drain into Right Lymphatic duct (Right Subclavian vein)
- Except Left Superior Lobe - Drains into Thoracic Duct (Left Subclavian vein)
77
Why is the lymphatic drainage of the lungs important?
If suspect a lung cancer has metastasised, will want to check node groups that are next in line not just hilar node groups. To ensure if it has metastasised to hilar nodes, this is the extent of metastasis.
78
What is the Larynx?
- Hollow Musculo-ligamentous structure with cartilaginous framework
- Extends from hyoid bone to the cricoid cartilage
- Continuous with Pharynx and Trachea
- Stretches from C2 - C6/7
79
What is the Adam's apple made up of?
- In men, Thyroid cartilage and Cricoid cartilage come together at a more acute angle
- More prominant
80
What is the Inferior Horn of the Larynx?
- Part of a synovial joint
- Where Thyroid cartilage and Cricoid cartilage articulate
- Allows larynx above cricoid to tilt anteriorly and posteriorly
- Enabling vocal cord tension change - Changing pitch of voice
81
What Components make up the Larynx?
- Hyoid bone
- Cartilage - Superior horn, Lamina, Laryngeal prominence, Inferior horn, Thyroid cartilage, Cricoid cartilage, Arytenoid cartilage (posterior)
- Membranes - Thyrohyoid membrane + Cricothyroid membrane
82
What is the clinical relevance of the Cricothyroid membrane?
- In cannot ventilate/intubate situations
- Life-saving emergency airway is established by performing cricothyroidotomy - Cutting into the membrane for placement of a tracheal cuff and tracheal tube required in order to ventilate pt
83
What does the arytenoid cartilage do?
- Sits on top of cricoid cartilage posteriorly
- Part of synovial joint allows the cartilage to pivot
- Controls how open/closed our vocal cords can be
- Vocal Process - Pointing anteriorly where vocal ligaments arise
- Muscular Process - Pointing laterally where muscles attach which change position of vocal ligaments
84
What is the function of the Larynx?
- To protect the Tracheobronchial tree
- Prevent ingress of fluids or solids into the tracheobronchial tree
- Also enables phonation
85
What does the Larynx allow us to regulate in the thorax and the abdomen?
- Allow us to regulate our intra-thoracic and intra-abdominal pressures
Volsava Manouvre
86
What controls Speech Articulation?
- Pharynx
- Soft Palate
- Tongue
- Lips
87
What role does the larynx play in coughing?
Allows for production of a productive cough to assist mucociliary clearance
88
What is the Cricovocal membrane (elastic)?
- Very elastic membrane passing from cricoid cartilage to vocal processes of arytenoids
- Top of Cricovocal membrane forms the vocal ligaments on both sides
89
What are the vocal ligaments of the Larynx?
- FREE upper thickened edge of cricovocal membrane
- Covered in stratified epithelium to withstand constant collisions between its two sides
- Attaches directly to inside of Thyroid cartilage anteriorly
- Vocal process of Arytenoid cartilages posteriorly
90
What is the Aryepiglotic Membrane of the Larynx?
- Stretches from Apex of Arytenoid Cartilage to epiglottis
| - Its FREE Lower Border = Forms vestibular ligament
91
Describe the Membranes in the Larynx
- Cricovocal membrane - Free upper border forms Vocal Ligament
- Aryepiglotic Membrane - Free lower border forms Vestibular Ligament
- Ventricle & Saccule - Mucosal pouch between vestibular ligament and vocal ligament
- Mostly covered in respiratory mucosa except vocal ligament (stratified squamous to withstand collisions between two sides) = Called Vestibular and Vocal Folds (as covered with mucosa)
92
What is the Roma Glottidis?
Gap between vocal folds
93
What are Vocal Nodules?
- A form of vocal cord lesion
- Typically benign non-cancerous growths
- Can cause hoarseness, may be associated with vocal overuse/trauma
94
What are possible causes of Vocal Nodules / Polyps
- Singing (professional), Screaming, Excessive talking
- Extra muscle tension when speaking
- Smoking
- Excess alcohol
- Sinusitis
- Allergies
- Rare = Hypothyroidism
95
What is the motor and sensory innervation of the Larynx?
- CN X (Vagus)
- Superior Laryngeal nerve branches into Internal Laryngeal nerve (Sensory supply above Vocal folds) and External Laryngeal nerve (Motor supply to Cricothyroid muscle)
- Recurrent laryngeal nerve - Sensory supply to whole larynx below Vocal folds + Supplies all laryngeal muscles except for Cricothyroid
96
Why is the close relation of the Superior Thyroid a. with the Superior laryngeal n. Important?
- During a thyroidectomy / thyroid surgery Superior Thyroid artery often needs to be ligated
- Thus Superior laryngeal nerve is at risk of damage - Would result in loss of pitch - Monotone voice
97
What is the role of the Cricothyroid muscle?
- Pulls thyroid cartilage forwards + down
- Lengthens and tightens vocal cords
- Sole muscle that is responsible for raising the pitch of the voice
98
What are the roles of the Lateral Cricoarytenoid Muscles and the Posterior Cricoarytenoid Muscles?
- Lateral Cricoarytenoid Muscles - Adduct vocal ligaments and narrow Rima Glottidis
- Posterior Cricoarytenoid Muscles - Abduct vocal ligaments and widen Rima Glottidis
99
What is the role of the Thyroarytenoid & Vocalis muscle?
- Pull arytenoid cartilage anteriorly + Thyroid cartilage posteriorly and superiorly
- Relaxes vocal fold (parts of it) and lowers pitch of voice
100
What can occur in Unilateral injury of the Right Recurrent Laryngeal Nerve (RLN)
- Hoarse/altered/weakened voice due to vocal fold paralysis of one side
101
What can occur in Unilateral injury of the Right Recurrent Laryngeal Nerve (RLN)
- Hoarse/altered/weakened voice due to vocal fold paralysis of one side
- At risk in surgery on: Thyroid, Anterior Neck and Thorax
- Can be compressed by mediastinal tumours
102
What can occur in Bilateral injury of the Recurrent Laryngeal Nerves (RLN)
- Cords Paralysed due in mid-abduction-adduction position
- Voice initially absent and later weak
- Floppy cords can stick together and block the respiratory tract = Medical emergency
- At risk in surgery on: Thyroid, Anterior Neck and Thorax
- Can be compressed by mediastinal tumours
103
Why would losing Superior Laryngeal Nerve be exceptionally dangerous?
- Loss of sensation of upper Larynx above vocal fold
- Cannot sense if something is there to cough to remove it and protect airways
- High risk of aspiration
104
What can occur in Superior Laryngeal Nerve Damage?
- External branch is particularly at risk in thyroid surgery during superior thyroid artery ligation
- Damage - Paralysis of cricothyroid & monotonous voice
- Loss of sensation - risk of aspiration
105
Explain the principles underlying the alveolar – arterial oxygen difference.
- Difference between mean Calculated Alveolar PAO2 (alveolar gas equation) and Systemic Arterial PO2 (PaO2) - Slightly lower.
- Due to Physiological shunt - blood that bypasses the alveoli and does not participate in gas exchange.
- Anatomical shunt - bronchial circulation + thebesian veins / Functional shunt - Local V/Q mismatch e.g. base of lungs
- Normally A-a gradient <1.5kPA in young healthy adults
106
Describe Oxygen Delivery to tissues
- CaO2 = [bound O2] + [dissolved O2]
- Oxygen delivery = Cardiac output x CaO2
- Not all to do with the lungs,
- For cells to utilise O2 for aerobic respiration there must be adequate:
- PaO2
- O2- Carrying capacity - Hb Concentration
- Cardiac output and arterial flow
- Mitochondrial function
107
What size should the heart be on a radiograph?
- A normal sized heart should occupy
Block 2
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