Lecture 1 and 2 - Anatomy Flashcards
Contents of the upper respiratory tract
Nose
Paranasal air sinuses
Pharynx
Larynx - lower border of the cricoid cartilage
How does the respiratory system develop?
Develops as a diverticulum from the pharynx from the primitive gut tube
It then branches
What is the purpose of the nasal cavity? (5)
- Olfaction
- Produce turbulent air flow via conchae - slows speed of air entry so it can be warmed and moistened
- Warms and moistens inspired air (by transudation of mucous secretions)
- Recovers water from expired air
- Speech production
What divides the left and right nasal cavities
Median nasal septum
Transudation
Passage of substance through a membrane due to its hydrostatic pressure gradient
What is each nostril lined by?
Course hairs
Mucous secreting goblet cells - trap large particles in inhaled air
Cilia - waft mucous to the oropharynx where it can be swallowed
Which plane is the nasal cavity floor in
Horizontal
What does the pharynx and larynx do
Ensures food and air enter the oesophagus and trachea respectively
Aspiration
Inhalation
Of food particles and liquids which can cause aspiration pneumonia
Why can aspiration occur
The trachea and oesophagus crossover
4 Paranasal air sinuses
Ethmoidal
Frontal
Maxillary
Sphenoidal
Paranasal air sinuses
Air-filled spaces in the head which reduces the weight of the skull
What are paranasal air sinuses lined by?
Respiratory epithelium - pseudostratified ciliated columnar epithelium
What are conchae/turbinates?
3 bony projections on the lateral wall of the nasal cavity
Larynx
Links the pharynx to the trachea
Contains the vocal cords - guards tracheal inlet
Prevents aspiration
Cough reflex
Glottis
Vocal cords and aperture between the cords
What happens to the larynx during swallowing?
- Laryngeal inlet narrows
- Epiglottis folds down over the laryngeal inlet
- Vocal cords adduct - closing the laryngeal inlet
What adducts the vocal cords?
Intrinsic laryngeal muscles
Supplied by the recurrent laryngeal nerve
What can damage the left recurrent laryngeal nerve?
Aortic aneurysm
Pancoast tumour
- Presents with a hoarse voice as the left vocal cord is paralysed
Cough reflex
Vocal cords close - increased intrathoracic pressure in early stage of cough reflex
Sudden opening of the vocal cords causes air to be expelled at a high velocity
Conducting airways
Do not take part in gas exchange
Trachea Primary bronchi - main Secondary bronchi - lobar Tertiary bronchi - segmental Bronchioles Terminal bronchioles
1- 16 divisions
Why is the trachea horseshoe shaped?
Prevents compression of the oesophagus
Allows the oesophagus to bulge during the passage of a bolus
How many secondary bronchioles does the right and left lung have?
Right - 3
Left - 2
What do the ribs articulate with?
Anteriorly - costal cartilage
Posteriorly - vertebral column
Sternal angle
Transverse ridge on palpation
Between the manubrium and sternal body
Indicates 2nd rib
What does the tubercle of the rib articulate with?
Transverse process of corresponding vertebrae
Describe the head of the ribs T3-9
They have 2 articular facets
Articulate with the corresponding and above vertebrae
e.g third rib articulates with T2 and T3
Bony thorax
Sternum
Ribs
Thoracic vertebrae
Costovertebral joints
Describe the structure of a rib
Head with 2 facets articulates with the vertebrae
Neck connects head and shaft
Tubercle articulates with the transverse process of vertebrae
Shaft - external surface
The internal surface contains a costal groove
Costal cartilage
Describe the thoracic vertebrae
Superior articular facets (2) Inferior articular facets (2) Superior costal facet (2) [demifacet] Inferior costal facet (2) [demifacet] Transvere costal facet (2)
Heart shaped vertebral body
Inferiorly slanted spinous processes
Mediastinum
Midline structure that separates the lungs
The sternal angle T4/ T5 separates the superior and inferior mediastinum
What nerve innervates the intercostal muscles
Intercostal nerve
External intercostal muscle
Most superficial
30% of chest expansion during quiet inspiration
Contraction elevates the ribs in a bucket handle type motion
Increases thoracic volume and decreases pressure
Internal intercostal muscles
Muscle fibres are perpendicular to the external intercostal muscles
Pulls ribs down from chest expansion during FORCED expiration
Quiet expiration
Passive process
Due to the elastic recoil of the alveoli
Innermost intercostal muscles
Less well developed
Support inner intercostal muscles
The costotransverse ligament
Connects the anterior surface of the transverse ligament to the neck of the rib
Lateral costotransverse ligament connects the tip of the transverse process to the tubercle of the rib
Movement of chest wall during inspiration
RIbs move laterally up and out
Sternum moves forward due to rib elevation
Diaphragm
70% of chest expansion during quiet inspiration
Dome shape
Bulges into the thorax
Origin: lower margin of thoracic cavity
Insertion: Central tendon
Innervation: C3,4,5
Action: Contract moving the diaphragm down to decrease pressure in the thoracic cavity
Relaxation on exhalation moves the diaphragm up by 2 intercostal spaces
Damage to phrenic nerves
C3,4,5,
Paralysis of the diaphragm on the affected side
Elevated hemidiaphragm on CXR
- Breathless
Openings to the diaphragm
Vena cava T8
Oesophagus T10
Aortic hiatus T12
Which diaphragmatic dome is higher?
Right due to the liver (5th rib)
Left dome - lower at the 5th intercostal muscle
How does the movement of the ribs cause movement of air into the lungs?
The ribs move up and out, increasing intrathoracic volume.
Decreases intrathoracic pressure creating negative pressure.
Air is drawn in
Where are the major neurovascular bundles located in the thorax?
Just below the rib at the inferior margin
Therefore when inserting tubes, go superior to the rib
Accessory muscles of inspiration
SCM
Pectoralis major when arms are fixed
Serratous anterior
Scalene muscles
Accessory muscles of expiration:
Internal intercostal muscles
Innermost intercostal muscles
Abdominal muscles - Rectus abdominis + EO + IO
Sternum
Manubrium
Sternal angle
Sternal body
Xiphisternum
Neurovasculature of the thorax
Intercostal artery, vein and nerve
Supply and drain the:
- Intercostal muscles
- Parietal pleura
- Overlying skin
The intercostal arteries are posterior and the internal thoracic arteries are anterior
Specialised draining system of the thorax
Azygous veins - unpaired (no associated artery)
Right - azygous veins - required for intercostal muscles at the level of the heart and drain into the IVC
Left - Accessory hemiazygous vein
Referred pain to shoulder in pericardium defect
The pericardium is supplied by C3, 4 and 5
Therefore pain in the shoulder due to irritation of the pericardium will be referred to the C3,4, 5 dermatome
Liver biopsy
Needle introduced below the 5th intercostal space
Trachea
Commences at the lower margin of the cricoid cartilage of the larynx and terminates by dividing into primary bronchi at the sternal angle
Carina
Angle between the right and left bronchi
Bronchopulmonary segment
Area of the lung supplied by a segmental (tertiary) bronchiole and the accompanying segmental branch of the pulmonary artery.
Drained by a segmental pulmonary vein.
Segments are pyramid-shaped with the apex facing towards the segmental branches and base towards the lung face
Can be isolated and removed with limited bleeding and air leakage during surgery
Why is food more likely to lodge in the right bronchus
Shorter
Wider
More vertical
Respiratory zone
7 divisons 16 - 23
Where gas exchange occurs
Respiratory bronchioles
alveolar sacs
alveolar ducts
Alveoli
3 million
SA = 70m^2
Surrounded by a network of pulmonary capillaries
Thin membrane
Right lung
3 lobes: upper, middle and lower
Horizontal - separates lower lobe from middle
Oblique fissure - seperates upper lobe from middle
Bases- rests on the right hemidiaphragm
Rib 6 MCL
Rib 8 MAL
Rib 10 Scapula line
Apex - extends above the 1st rib level
Horizontal fissure
In the midaxillary line
anterior along 4th rib to edge of lung
Oblique fissure
From spinous process of T2 posteriorly to 6th intercostal cartilage anteriorly
Follows medial border of the scapula
Mediastinal surface of the lungs
Contains the hilum:
- Main bronchi
- lymphatics
- pulmonary veins x 2
- pulmonary artery branches
- pulmonary plexus
What is the right lung adjacent to?
Superior vena cava Azygous veins Right atrium Oesophagus Phrenic nerve Vagus nerve Sympathetic trunk
What is the left lung adjacent to?
Heart Aortic arch Descending aorta Left recurrent laryngeal nerve Phrenic nerve Vagus nerve Sympathetic trunk
Lung pathologies affecting mediastinal surfaces
Phrenic nerve - paralysis of the diaphragm - breathlessness
Left recurrent laryngeal nerve - paralysis of the intrinsic laryngeal muscles - hoarse voice
Superior vena cava - Obstruction - peripheral oedema
Pleural layers
Visceral
Parietal
Visceral pleura
Lines the outside of lungs
Extends into the fissures
Supplied by the pulmonary plexus - sensitive to distention only
Parietal pleura
Lines the inside of the hemi thorax
Continous with the visceral pleura at the hilum of the lungs
Supplied by the phrenic and intercostal nerves
- sensitive to pain, pressure and temperature
Pleural cavity
Potential space between the visceral and parietal pleura which contains a small amount of pleural fluid
Pleural fluid
Surface tension of pleural fluid creates a seal so when the thorax expands the lungs do too.
Costodiaphragmatic angle
Space in which only the parietal pleura extends around the outer edge of the diaphragm
Allows room for expansion
Rib 8 MCL
Rib 10 MAL
Rib 12 Scapular line
Blood supply to the lungs
Dual blood supply:
Pulmonary arteries - Supplies alveoli with deoxygenated blood for gas exchange
Bronchial arteries - supplies parenchyma of lung and visceral pleura with oxygenated blood
Most blood drains via the pulmonary veins
Some blood drains to the azygous vein to SVC
Lymphatic drainage
Hilar node (bronchopulmonary) Efferent lymph nodes - tracheobronchial nodes - enlarged tracheobronchial nodes can widen the carina angle
Nerve supply of the lungs
Right and left vagus nerve
PS efferents - motor to smooth muscle (bronchoconstriction) and secretomotor to mucous glands
afferent - cough reflex and pain
Sympathetic trunk - efferent - bronchodilation
- afferent - vasoconstriction
