Respiratory system anatomy Flashcards
At what level does the trachea originate?
C6 (larynx C3 - C6)
At what level is the tracheal bifurcation (carina)
T5 - T6
How long is the trachea in adults and what is its length above the suprasternal notch?
15cm long
5cm of trachea above the suprasternal notch
8 cm of trachea above the suprasternal notch when neck is in full extension
What is the diameter of the trachea?
Its about the width of the base of the patients index finger
What makes up the anterior and posterior aspects of the trachea
Anteriorly - C-shaped cartilage rings
Posteriorly - Trachealis muscle
Which tracheal rings are covered by the thyroid isthmus?
2nd to the 4th tracheal ring (percutaneous tracheostomy tube sited in the space between the 2nd and 3rd tracheal ring)
What type of cartilaginous rings are contained within the bronchi?
Complete cartilaginous rings
Describe the right main bronchus compared to the left main bronchus
Shorter wider and more vertically positioned
How far from the origin of the bronchi do the left and right upper lobe bronchi originate from the left main bronchi and right main bronchi respectively
Right upper lobe bronchi originates 2.5 cmm from the carina
The left upper lobe bronchi originates > 5 cm from carina
Clinically implications for one lung intubation/ventilation
How many lobes in the right and left lung?
Right lung: 3 lobes (upper, middle, lower)
Left lung: 2 lobes plus lingula
During which common procedures may the pleural cavity be inadvertently opened to cause a pneumothorax?
CVL insertion
Supraclavicular brachial plexus block
Intercostal nerve block
Surgery on the kidney/adrenal gland
How many functionally separate bronchopulmonary segments does each main bronchus divide into and what is the clinical relevance of these bronchopulmonary segments?
10
Relevant for the surgeon in lung resection surgery as each bronchopulmonary segment has its own bronchus, blood supply and distinct lung parenchyma.
Name the bronchopulmonary segments
Both lungs
Upper lobe
- Apical
- Posterior
- Anterior
Middle Lobe
- Medial (in the left lung this is the superior lingular)
- lateral (in the left lung this is inferior lingula)
Lower lobe
- Apical
- Medial basal
- Lateral basal
- Posterior basal
- Anterior basal
Which lung segment is most commonly affected by aspiration during anaesthesia
Right lower lobe apical segment is the first segmental bronchus to arise posteriorly and is the most commonly affected in the supine patient.
What is a primary lung lobule?
Each bronchiole with its further subdivision (into respiratory bronchioles, alveolar ducts and alveoli) is called a primary lung lobule
What is contained within the bronchiolar wall
No cartilage
Smooth muscle
ciliated cuboidal epithelium
Describe the cells in the alveoli
Type 1 pneumocytes - specialised squamous epithelium seperated from surounding endothelium of the blood capillary network by the thin basement membrane
Type 2 pneumocytes - produce surfactant to counter surface tension and atelectasis
Define and describe the mediastinum
The space between the two plural cavities consisting of 4 compartments
SUPERIOR MEDIASTINUM
Superior mediastinum
INFERIOR MEDIASTINUM
Anterior inferior mediastinum (mass here is significant anaesthetic risk due to potential compression of heart, great vessels, major airways especially when muscle tone is lost in anaesthesia)
Posterior inferior mediastinum
Middle inferior mediastinum (containing the pericardium)
Name the spinal levels that permit function of the diaphragm
C3 4 and 5 keep the diaphragm alive –> via the phrenic nerve
Which muscles contributes to the lower oesophageal sphincter mechanism?
Diaphragm - mechanism disrupted in patients with a hiatus hernia –> GORD - risk for aspiration
What is the range of diaphragm movement?
1.5 cm during quiet breathing
13 cm during deep breathing
When can the phrenic nerve be damaged?
During cardiac surgery
What effect does a damaged phrenic nerve have on the diaphragm
Paradoxical movement of the diaphragm on the affected side during inspiration diagnosed by fluoroscopy
What conditions may limit diaphragm movement
- Pregnancy (Fetus)
- Obesity (Fat)
- Ascites (Fluid)
- Large abdominal tumours (Fucking cancer)
- Pneumoperitoneum (Flatus) – Diaphragmatic impairment caused by gastric distension following BVM can be a particular problem in children
Describe the orientation and function of the external intercostal muscles
Slope downward and forward –> contraction leads toupward and outward movement increasing the AP diameter of the thorax
Describe the orientation and function of the internal intercostals
Slope downward and backward –> contraction leads to downward and inward movement of the ribs to decrease the volume of the thoracic cavity during forced expiration.
What is the function of the innermost intercostal muscles?
Link ribs together and stabilize chest wall
What is the nerve supply to the intercostal muscles and what is the effects of intercostal nerve blocks (Spinal/epidural anaesthesia for abdominal surgery) on respiration
Intercostal nerves T1 -T11
Minimal effects on respiration as the diaphragm is the more important muscle of respiration
Name the four accessory respiratory muscles
Scalene
Sternomastoids
Alae nasi
Small muscles of the head and neck
Name the scalene muscles and their function
Medial and anterior Scalene muscles - elevate the first 2 ribs
Sternocleidomastoid muscle function?
Elevate the sternum (multiple movements of the head - flex, rotate)
Alae nasi function?
Flare nostrils
Small muscles of head and neck function?
‘Head bobbing’ in infants
What is the ideal placement of the ETT
cuff inflated just beyond the vocal cords in the immediate sub-glottic area with the tip of the tube midway between the vocal cords and the carina.
Males - 23 cm at the lips
Females - 21 cm at the lips
ETT too far –> which areas of the lung are prone to collapse
The left lung and the right upper lobe
On a CXR which spinous process is visible directly between the clavicles
T4
What is the correct site for emergency needle thoracocentesis in tension pneumothorax
2nd ICS MCL
What is the correct site for the insertion of an ICD
5th intercostal space MAL in the safe triangle (Bordered by lat, pec major and axilla)
What are the vertebral levels for the diaphragmatic hiatuses?
The word vena cava has 8 letters - T8
Oesophagus has 10 letters - T10
Aortic hiatus has 12 letters - T12
Summarizes the course of the left and right phrenic nerve
Originates: C3, C4, C5
Emerge and pass over the anterior scalene muscles
Descend through the thorax over the heart
Left through aortic hiatus but motor innervation to superior and inferior surfaces
Right goes through vena cava hiatus
