Part 1 - Thorax & Lungs

• Thoracic Cage


  Skeleton of the thoracic wall

  
• Thoracic Wall


  • Components: Thoracic cage, Muscles, Fascia and skin

  
• Compartments of thorax


  Mediastinum, Right pleural cavity, Left pleural cavity

  
• Types of ribs


  • True (vertebrosternal) ribs
  • False (vertebrochondral) ribs
  • Floating (free vertebral) ribs

  
• Typical ribs (3rd to 9th)


  • Head: Wedge shaped with 2 facets
  • Neck: Connects head with body at level of tubercle
  • Tubercle: At junction of neck and body, 2 parts - Smooth articular part, Rough non-articular part
  • Body: Thin, flat and curved especially at costal angle

  
• Atypical ribs


  • First rib: Broadest, shortest and most sharply curved true rib
  • Second rib: Thinner, longer and less curved than 1st rib
  • Tenth to twelfth ribs: Only one facet on head and articulates with only one vertebra, 11th and 12th ribs are short with no neck or tubercle

  
• Costal cartilages


  Provide attachment for anterior tips of ribs, Increase in length through first 7 and then gradually decrease, First 7 attach directly to the sternum, 8th to 10th articulate with the costal cartilage superior to them, 11th and 12th form caps but don't attach anywhere

  
• Intercostal spaces


  Separate ribs and costal cartilages, Named according to the rib forming the superior border, Occupied by intercostal muscles, membranes, main intercostal vessels and nerves, collateral intercostal vessels and nerves

  
• Thoracic vertebrae


  • Typical components: Body, Vertebral arch, 7 processes for muscular and articular connections
  • Characteristic features: Bilateral costal facets (demifacets) on vertebral bodies, Costal facets on transverse processes, Long, inferiorly slanting spinous processes

  
• Sternum


  Flat elongated bone, Protects mediastinal viscera, 3 parts: Manubrium, Body of sternum, Xiphoid process

  
• Superior thoracic aperture


  Bounded by T1 posteriorly, 1st pair of ribs and their costal cartilages, Superior border of manubrium anteriorly

  
• Inferior thoracic aperture


  Bounded by T12 posteriorly, 11th and 12th ribs posterolaterally, Costal margins anterolaterally, Xiphisternal joint anteriorly, Oblique due to posterior wall being much longer than anterior wall

  
• Joints of the thoracic wall


  • Intervertebral Symphysis
  • Costovertebral: Joints of head of rib
  • Costovertebral: Costotransverse
  • Costochondral
  • Interchondral
  • Sternocostal
  • Manubriosternal
  • Xiphisternal

  
• Muscles of the thoracic wall


  • Serratus posterior superior
  • Serratus posterior inferior
  • Levator costarum
  • External intercostal
  • Internal intercostal
  • Innermost intercostal subcostal
  • Transversus thoracis

  
• Intercostal nerves


  Primary anterior rami of spinal thoracic nerves T1-T11, Typical intercostal nerves have: Rami communicantes, Collateral branches, Lateral cutaneous branches, Anterior cutaneous branches, Muscular branches

  
• Subcostal nerve


  Primary anterior ramus of T12 spinal nerve
• Dermatomes


  T2-T12 spinal nerves provide cutaneous innervation to thorax and back

  
• Arteries of thoracic wall


  • Posterior intercostals
  • Anterior intercostals
  • Internal thoracic
  • Subcostal

  
• Veins of thoracic wall


  • Anterior intercostal veins
  • Posterior intercostal veins
• Aorta


  Passes between internal and innermost intercostal muscles
• Structures aorta passes through


  • Intercostal muscles
  • Skin
  • Parietal pleura
• Arteries supplying anterior intercostal spaces 1-6

  • Internal thoracic artery
• Arteries supplying anterior intercostal spaces 7-9

  • Musculophrenic artery
• Intercostal arteries


  Occur in ipsilateral pairs
• Structures intercostal arteries pass through


  • Intercostal muscles
  • Skin
  • Parietal pleura
• Internal thoracic artery


  Passes inferiorly and laterally to sternum between costal cartilages and transversus thoracis to divide into superior epigastric and musculophrenic arteries

  
• Thoracic aorta


  Courses along inferior border of 12th rib

  
• Muscles supplied by thoracic aorta

  • Muscles of anterolateral abdominal wall
• Anterior intercostal veins


  2 in each space
• 7th-9th anterior intercostal veins


  Join the vein accompanying musculophrenic artery
• 4th-6th anterior intercostal veins


  Join the vein accompanying internal thoracic artery
• 1st to 3rd anterior intercostal veins

  Join internal thoracic vein
• Internal thoracic vein


  Drains into brachiocephalic vein
• Drainage of right posterior intercostal veins


  • 1st drains into brachiocephalic vein
  • 2nd and 3rd unite to form right superior intercostal vein draining into azygous vein
  • 4th to 11th and subcostal veins drain into azygous vein
• Drainage of left posterior intercostal veins


  • 1st drains into left brachiocephalic vein
  • 2nd and 3rd unite to form left superior intercostal vein draining into left brachiocephalic vein
  • 4th to 8th form superior hemiazygos vein to azygous vein
  • 9th to 11th and subcostal form inferior hemiazygos vein to azygous vein
• Pleural cavity


  Potential space between the layers of pleura containing serous pleural fluid

  
• Visceral pleura


  • Closely covers the lungs and adheres to all its surfaces, including surfaces within fissures
  • Provides lung with smooth and slippery surface, allowing it to move freely on parietal pleura
  • Continuous with the parietal pleura at the hilum of the lung
• Parietal pleura


  • Lines pulmonary cavities
  • Adheres to thoracic wall, mediastinum and diaphragm
  • Thicker than visceral pleura

  
• Parts of parietal pleura

  • Costal part
  • Mediastinal part
  • Diaphragmatic part

  
• Cervical pleura


  Covers the apex of the lung and projects above the 1st rib and clavicle