Respiratory

• Thorax


  The chest cavity
• Mediastinum


  The central compartment of the thoracic cavity, containing the heart and associated structures
• Chest Wall

  The structures that enclose and protect the thoracic cavity
• Breast


  The mammary gland located on the anterior chest wall
• Thoracic Cage

  • Ventilation - Allows muscles to change the thoracic volume and bring about respiration
  • Protection - Strong cage to give protection to some vital organs
• Components of the Thoracic Cage

  • 12 thoracic vertebrae
  • 12 pairs of ribs (i.e. 24 ribs)
  • Cartilage structures
  • Sternum - 3 parts
• Sternum


  A fused bone made of 3 parts: Manubrium, Body, Xiphoid process
• The sternum serves as the anterior attachment point for the clavicles and ribs (specifically their costal cartilages)
• Manubriosternal joint

  The joint between the manubrium and body of the sternum, which can be palpated and is known as the sternal angle
• Many structures lie in the region of the sternal angle
• Xiphoid process


  The most inferior part of the sternum, which can be easily palpated as a good landmark for the anterior-superior attachment of the diaphragm
• Types of Ribs

  • True - Ribs 1-7
  • False - Ribs 8-10
  • Floating - Ribs 11 & 12
• True Ribs


  Ribs that attach directly to the sternum via their own costal cartilage
• False Ribs


  Ribs that attach to the sternum via rib 7's costal cartilage
• Floating Ribs


  Ribs that do not attach to the sternum and have no costal cartilages - pointed ends
• Costal cartilages allow easier expansion and movement of the ribs
• Ribs can ossify in later life, which is important to note when dealing with elderly patients who may be osteoporotic already
• Some medications can weaken ribs, causing them to appear osteopenic on an x-ray, often seen with COPD patients due to steroid use
• Typical vs Atypical Ribs

  • Typical - Ribs 3-9
  • Atypical - Ribs 1, 2, 10, 11, & 12
• Typical Rib

  Head articulates with both same level and above vertebra
• Atypical Rib


  Head articulates with vertebra of same level only, except rib 2 which has no tubercle for attachment to transverse processes
• The most common place for a rib to fracture is ribs 4-10
• Rib Fractures


  Can be a result of trauma, most commonly occurring in RTAs, falls, or assaults
• Ribs 1-3 fracture indicates a high energy trauma, usually sufficient to cause other internal injuries
• How ribs are fractured and where can tell you a lot about the patient (e.g. child abuse, domestic violence)
• Vertebral Column Regions

  • 7 Cervical vertebrae (C1-C7)
  • 12 Thoracic vertebrae (T1-T12)
  • 5 Lumbar vertebrae (L1-L5)
  • 5 (usually all fused) Sacral vertebrae (S1-S5)
  • 4 (some fused) Coccygeal vertebrae (Co1-Co4)
• Typical Thoracic Vertebra


  • 2 costal demi-facets (superior and inferior) on the vertebral body for articulation with the head of rib
  • A facet on the transverse process for articulation with the tubercle of rib
• Costovertebral Joints


  Joints between the vertebral body and head of rib
• Costotransverse Joints


  Joints between the transverse process of the vertebra and the tubercle of the rib
• The head of the rib can articulate with part of the vertebral body above and below, e.g. Rib 7 to T6 and T7
• The tubercle of the rib will always articulate with the transverse process of the same number, e.g. Rib 7 to T7
• Thoracic Inlet


  The superior thoracic opening, bounded by the manubrium, rib 1, and T1, allowing passage for vital structures of the chest, upper limb, head, and neck
• Damage or inflammation at the thoracic inlet can compress important structures as there is very little space
• Pancoast Tumour


  A cancerous tumour at the apex of the lung that can press on structures in the thoracic inlet, causing damage like Horner syndrome and brachial plexus compression
• Chest Wall Variations


  • Barrel chest
  • Pectus excavatum
  • Pectus carinatum
• Mediastinal Pleura


  The pleura that encapsulates most of the mediastinum, blending with the parietal pleura of the lungs laterally and the pericardium internally
• Mediastinum


  The central compartment of the thoracic cavity, located within the pericardium and bordered anteriorly by the anterior mediastinum, posteriorly by the posterior mediastinum, laterally by the pleura of each lung, superiorly by the sternal angle and superior mediastinum, and inferiorly by the diaphragm
• The pericardium attaches directly to the diaphragm, resulting in the heart moving during respiration
• Divisions of the Mediastinum

  • Superior mediastinum
  • Inferior mediastinum (Anterior, Middle, Posterior)
• Contents of the Mediastinum

  • Superior: Thymus, trachea, oesophagus, thoracic duct, aortic arch and branches, superior vena cava and convergent veins, vagus nerve, phrenic nerve, recurrent laryngeal nerve, sympathetic trunk, lymphatics, muscles
  • Anterior: Thymus (in children), adipose tissue, internal thoracic vessels, lymph nodes
  • Middle: Heart in pericardium, ascending aorta, superior vena cava, pulmonary trunk, main/primary bronchi, phrenic nerve, cardiac plexus, vagus nerve
  • Posterior: Descending aorta and branches, azygos venous network, thoracic duct, oesophagus, sympathetic trunk, oesophageal plexus, vagus nerve branches