Thorax and lung

• Thorax


  Portion of the body extending from the base of the neck superiorly to the level of the diaphragm inferiorly

  
• Thoracic cage


  Outer structure of the thorax
• Thoracic cavity


  Contains the respiratory components

  
• Structures of the thoracic cage

  • Sternum
  • 12 pairs of ribs
  • 12 thoracic vertebrae
  • Muscles
  • Cartilage

  
• Function of the thoracic cage


  • Provides support and protection for many important organs including those of the lower respiratory system
• Sternum


  Breastbone that lies in the center of the chest anteriorly
• Parts of the sternum

  • Manubrium
  • Body
  • Xiphoid process
• Manubrium


  Connects laterally with the clavicles and the first two pairs of ribs

  
• Ribs


  12 pairs that constitute the main structure of the thoracic cage

  
• First 7 pairs of ribs


  • Articulate with the sternum by way of costal cartilages

  
• First pair of ribs


  • Curve up immediately under the clavicles so that only a small portion is palpable

  
• Second ribs and intercostal spaces


  • Easily located adjacent to the sternal angle

  
• Ribs 3-6


  • Easy to count anteriorly because of their articulation with the sternal body

  
• Ribs 7-10


  • Connect to the cartilages of the pair lying superior to them rather than to the sternum

  
• Ribs 11-12


  • Called "floating" ribs because they do not connect to either the sternum or another pair of ribs anteriorly

  
• Thoracic cavity


  Consists of the mediastinum and the lungs and lined by pleural membranes
• Contents of the mediastinum

  • Trachea
  • Bronchi
  • Esophagus
  • Heart
  • Great vessels

  
• Trachea


  Flexible structure that lies anterior to the esophagus, begins at the level of the cricoid cartilage in the neck and is approximately 10 to 12 cm long in an adult

  
• Hyaline cartilage


  1. shaped rings which compose the trachea and help to maintain its shape and prevent its collapse during respiration
• Functions of trachea and bronchi


  • Passageway for both inspired and expired air
  • Help sweep dust, foreign bodies and bacteria that have been trapped by the mucous toward the mouth for removal
• Lungs


  Two cone-shaped, elastic structures suspended within the thoracic cavity
• Lungs


  • Apex extends slightly above the clavicle
  • Base is at the level of the diaphragm
  • Not completely symmetric
  • Divided into lobes by fissures
  • Right lung has 3 lobes, left lung has 2 lobes
• Pleural membranes


  Thin, double layered serous membrane that lines the thoracic cavity and covers the external surfaces of the lungs
• Pleural space


  Lies between the two pleural layers
• Purpose of respiration


  • Maintain adequate oxygen level in the blood to support cellular life
  • Provide oxygen and eliminate carbon dioxide to assist in rapid compensation for metabolic acid-base defects
• Chest physical assessment


  • Identifying physical landmarks correctly
  • Describing physical examination techniques adequately
  • Documenting findings correctly
• Midclavicular line


  Important landmark of the bony thoracic anatomy

  
• Intercostal spaces


  Identified by palpating and sliding fingers slowly along the border of the sternum anteriorly
• Respiratory findings


  Various reference lines and angles are commonly used to identify them

  
• Chest physical assessment (lung)


  1. Inspect: Symmetry of respiratory movement, Approximation of antero-posterior (A-P) diameter

  2. Palpate: Tenderness of costo-vertebral angle spinous process, Muscular development, swelling, tumors, Breast for symmetry, nipples for dimpling/inversion/discharge, Chest for point of maximal impulse (PMI) and other precordial pulsation or heaves, Breathing pattern, Chest for thrills, lifts, tenderness over precordium

  
• Chest physical assessment (lung)

  1. Confirm bilaterally equal chest movements by palpation, testing from the apex to the base of the lungs

  2. Assess respiratory excursion (anterior): Place thumbs along each costal margin, ask patient to inhale deeply, watch for thumbs to separate as thorax expands, feel for range and symmetry of respiratory movement

  3. Assess respiratory excursion (posterior): Place thumbs about the level of and parallel to the 10th rib, slide hands medially to raise loose skin folds, feel for range and symmetry of respiratory movement

  
• Chest physical assessment (lung)

  1. Palpate tactile fremitus: Evaluate by palpating the same areas of the chest with the palms of the hands while asking the patient to say the same words ("ninety-nine")

  2. Percuss the patient's anterior chest: In a healthy patient, the entire upper chest is resonant except for the area of cardiac dullness, percuss across the top of the body and work downward, symmetrically

  3. Percuss the patient's posterior chest: Compare percussion notes on both lung fields at same intercostal levels, normal percussion note is resonant, dullness indicates consolidation or fluid, hyperresonance indicates pneumothorax

  
• Chest physical assessment (lung)

  1. Auscultate the anterior chest wall (both right and left), especially the apex of both lungs

  2. Auscultate the posterior chest in right and left lung fields, especially at the base of the lungs, for breath sounds and adventitious sounds

  
• Dullness on percussion


  Caused by consolidation (as in pneumonia), fluid (as in pleural effusion)
• Hyperresonance


  Heard in case of a pneumothorax
• Percussion technique


  1. The percussing finger (plexor) should be sharply struck against the distal interphalangeal joint of the middle finger of the opposite hand (pleximeter)

  2. Motion should be generated at the wrist
• Auscultate the anterior chest wall (both right and left), especially the apex of both lungs

  
• Auscultation of the right and left lung must be done at the same intercostal level for comparison of auscultatory findings
• Auscultate the posterior chest in right and left lung fields, especially at the base of the lungs, for breath sounds and adventitious sounds

  
• Auscultation for breath sounds

  Tested by listening with the diaphragm of the stethoscope over the projections of each lobe while asking the patient to repeatedly say "ninety-nine"