Thorax 2

Part 1 of 4

Learning Checklist

  • Thoracic skeleton: Describe the main features of thoracic vertebrae, ribs, sternum and the joints between them. Demonstrate the palpable anatomical landmarks on the chest.

  • Thoracic inlet and outlet: Describe the boundaries of the thoracic inlet and outlet and list the structures that pass through them and their relations.

  • Intercostal muscles and spaces: Describe the anatomy of intercostal muscles and its neurovascular bundle. Demonstrate surface marking of ribs and intercostal spaces and safe location for insertion of chest drain.

  • Lungs & pleura: Describe the anatomy of the lungs, bronchial tree, bronchopulmonary segments, hilar structures and explain their functional and clinical significance. Demonstrate the surface markings of the pleura, lung lobes, fissures, and perform auscultation and percussion of the chest.

  • Diaphragm & Ventilation:Describe the anatomy of the diaphragm, its movements in ventilation, and its related structures. Demonstrate assessment of respiratory rate, pattern and chest expansion.


  • Diagnostic Imaging of the Chest:Identify major thoracic structures on standard diagnostic images e.g. CT, MRI, X-ray and ultrasound.


Divisions of the Respiratory Tract

  • Divided into the upper and lower respiratory tract

Upper Respiratory Tract

  • Consists of nasal cavity, nasopharynx, oropharynx and larynx

  • These structures are part of the conducting system as they are responsible for taking air from the external environment down to the trachea

  • They filter the air for particulates, pollutants and pathogens

  • They humidify the air - add moisture and warm the air

  • This is so that the air will not irritate the lower respiratory tract when it gets there.

  • Ensures air is optimum for exchange in the lower respiratory tract

  • Larynx is important for ensuring that only air passes into the trachea

    • Has a number of structures that prevent solids passing through

    • Epiglottis - close over laryngeal inlet when swallowing food or water

    • Vocal cords, vocal folds and vestibular folds, which also close and are completely adducted to close off the laryngeal inlet to prevent solids passing into the trachea

  • Border between the upper and lower respiratory tract is the inferior border of the cricoid cartilage


Lower Respiratory Tract

  • Consists of the trachea, the main bronchi and the bronchiole tree (where the bronchi continue to divide, until they become microscopic and open into alveolar sacs)

  • Alveoli form the parenchyma (lung tissue)

  • Most of the lower respiratory tract conducts air, apart from the terminal and respiratory bronchioles and the alveoli

  • Alveoli, respiratory and terminal bronchi are part of the respiratory system (which is where the gas exchange occurs)

  • Upper sits in head and neck, lower respiratory system sits in the thorax

    • Namely in the lower part of trachea, bronchiole tree and lung tissue itself


Trachea, Bronchopulmonary Segments and Lungs

  • Trachea is the first structure of the lower respiratory tract

  • Carilaginous and tendinous tube which transmits air from larynx to bronchi

  • Bronchi arise at the level of sternal angle as the trachea bifurcates

  • Bronchi enter the lung via the hilum and then they commence to divid drutehr and further into smaller and smaller tubes - bronchioles

  • Bronchiles eventually becomes the alveolie which are the main site for gaseous exchange in the lungs.

Trachea

  • First structure with lower respiratory tract

  • Level with the tracheal ring which is in line with 6th cervical vertebrae

  • Continuous with the larynx

  • Lower board of cricoid cartilage is the true demarcation between upper and lower respiratory tracts

  • Predominantly a cartilaginous structure

    • Tracheal cartilage structures are not true rings (C-shaped)

    • Allows oesophagus to fill with a bolus and allow the bolus to move down the neck and into the thorax without getting compressed

  • For a short portion is found in the neck

    • Can be palpated just above the jugular notch

  • Trachea classed as thoracic structure once it moves behind the menubrium of the sternum and through the superior thoracic aperture

  • Approximately 10cm in length and 3cm in diameter

  • Terminates at the bifurcation into the right and left main bronchi

    • Bifuration occurs at the sternal angle

    • In lilne with the 4th thoracic vertebrae

  • At the bifurcation is the Carina → cartilaginous structure that separates the right and leftt main bronchi

  • Right and left main bronchi are found at the hilum

  • Hilum is the site of the mediastinal surface of the lung where a number of structures enter and leave

    • Main bronchi, pulmonary arteries and veins

Bronchi

  • Main bronchi are for supplying an entire lung with air

  • Right main bronchus is shorter, wider and more vertical than left main

    • Right main bronchus is the site where a foreign object is more likely to get lodged (it is more continuous with trachea)

  • Right main bronchus divides into superior lobar bronchus and bronchus intermedius

  • Bronchus intermedius will split into middle lobar bronchus and inferior lobar bronchus

  • Main bronchus → lobar bronchi (supply lobe of a lung)

  • 3 lobes in the right bronchus and 2 lobes in the left (i.e. no middle lobe in the left)

  • Lobar bronchi further divide into segmental bronchi → segmental bronchi that are responsible for forming brochopulmonary segments

Bronchopulmonary Segments





JAS Crash Course Notes

Lungs and Pleura

  • Trachea starts with the cricoid cartilage at the inferior border and ends at the Carina where it bifurcates.

  • Carina is found at the sternal angle

  • Should know how to palpate the sternal angle for this reason

  • Innervation by the recurrent laryngeal nerve

  • Right lung closer to veins and left lungs clower to the arteries

  • Left lung has the cardiac notch for the aorta

  • Left Lung has 2 lobes but right like has 3, left lung has to make space for the heart

  • Horizontal fissure only in the right lung because it has more sections

  • Right primary bronchi is shorter, wider and taller (when someone has inhaled an object it is most likely found in the right bronchus)

    • Innervated by the Vagus nerve

  • Bronchopulmonary Segements - segment supplied by 1 segmental bronchi and 1 pulmonary artery

    • Can be resected without compromising the neighbouring tissue

  • Hilum - destination and origin of all the pulmonary related vasculature

    • Where the trachea bifurcates is known as the hilum

    • Contents are 1 pulmonary artery, 2 pulmonary veins (anterior and inferior), bronchial arteries and veins, lympatics, pulmonary ligament, areolar tissue

  • Phrenic nerve passes anterior to the hilum

  • Vagus nerve passes posterior to the hilum

  • Pleural layers

    • Pleura is thin layer of cells, lining the lungs

    • Parietal pleura - lines the lung in contact

      • Innervated y the diaphgramatic prt (phrenic nerve), costal and cervical parts (intercostal nerves)

    • Visceral pleura - lining other structures

      • Autonomic innvervations

    • Pleural space is between parietal and visceral pleura

  • Trachea is a tube-like structure extending CG-T4/5 spported by cartilage discs

    • C-shaped discs to allow food to pass through smoothly when swallowing

Diaphragm

  • Sheet of muscle that control the thoracic volume and indirectly the intrathoracic pressure

  • Attachments

    • Lumbar verterbrae and arcurate ligaments

    • Xiphoid process

    • Costal cartilages 7-10 and directly to ribs 11 and 12

  • Has 2 crura

    • Right crus L1 - L3

    • Left crus L1 - L2

    • Also has a central

  • Innervation - C3,4,5 keep me alive (phrenic nerve)

  • Inspiration - contracts and flattens

  • Expiration - relaxes and returns (it becomes dome shaped again)

  • Hiatus - hole through which that structure passes through

    • Cava hiatus at T8 - vena cava has 8 letters so T8

    • Oesophageal Hiatus T10 - oesophagus has 10 letters so T10

    • Aortic Hiatus T12


Diagnostic Imaging

  • x-rays: RIPE ABCD is the pneumonic

  • CT Scan

    • Orientation is important → best to orientate yourself around the spine

    • Find spinal cord and then check the heart

    • Check the lung and see if there is the aortic notch, cuz that would be the left

  • MRI

    • If you can identify the arch of the aorta you can determine that is the left lung



SBAs

  • Oblique fissure is present on the T3 level of the spine

  • Inferior vena cava is on the right hand side because the venous return is on the right hand side