Projections of heart, lungs and pleura onto thoracic wall, puncture of thorax

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Physical examination of the thorax includes inspection, palpation, percussion and auscultation. It requires a deep understanding of the position of thoracic organs and their projection onto the thoracic wall.  

Projection of lungs and pleura:  

• Midsternal line- vertical line down the middle of sternum
• Mid-clavicular line- vertical line from middle of clavicle  
• Axillary line- include the anterior, midaxillary, and posterior  
• Scapular line- vertical line passing through the inferior angle of scapula  
• Paravertebral line- vertical line passing through the transverse processes of the spine

Pleural cavity has a defined borders:  

Anteriorly:  

• Travel from pleural cupula- toward the 2nd sternocostal joint. Running toward midline and creating the superior interpleural area  
• From the 2nd rib- toward the 4th rib, following parasternal lines  
• Beneath the 4th rib pleural anterior margins turn in lateral caudal direction, forming the inferior interpleural area  
• Pleural borders intersect with cartilage of the 7th rib at midclavicular line, with the 9th in at midaxillary line, with the 11th rib at scapular line, and with the 12th rib at the paravertebral line  
• Costodiaphragmatic recess- due to the difference between lung height at inferior aspect in comparison to pleural height, a recess is created, filled with pleural fluid

Superiorly:

Lesser supraclavicular fossa. Here lies the top of pleural cupula.  

• Apex of lungs- fills pleural cupula
• Anterior margin of lungs- follows anterior boundaries of pleural cavities
• Inferior borders- as seen in the following table:  

Line	Sternal	Mid-clavicular	Axillary	Scapular	Paravertebral
Lung border	6th rib	6th rib	8th rib	10th rib	Spinous process of T10
Pleural border	6th rib	7th rib	9th rib	11th rib	Spinous process of T11

*Posterior border of lungs are the same as the borders of pleura  

Projection of heart:  

• Projected on anterior chest surface from 2nd to 5th intercostal spaces  
• 1/3 of the heart is located on right side from the midline  
• 2/3 of the heart is located on left side from the midline

4 points exist in heart and corresponding to points of auscultation, reaching all 4 points gives an approximate shape of the  heart:

• A point- 2nd intercostal space, 1cm left from sternum. Aortic valve point  
• T point- 5th intercostal space, next to the right sternal margin. Tricuspid valve point
• M point- 5th intercostal space, left side, medial to midclavicular line, about 8-9 cm from midline. Mitral valve point
• P point- 2nd intercostal space, 2cm from sternal margin on left side. Pulmonary valve point.  

Puncture of thorax:  

• Thoracentesis- procedure of puncture of the pleural cavity using a hollow needle or cannula in order to remove fluid or air from pleural cavity for diagnostic or therapeutic way. In contrast to chest drain, the cannula here is not flexible
• VATS- Video-Assisted Thoracic Surgery. Involving making a small incision (about 1 cm), in the intercostal space, placing there a small camera on a telescope and manipulating other instruments though additional small incisions. Can be used in order to obtain lung biopsy, thoracotomy
• Chest drain (tube) insertion- commonly performed procedure. Indicates the presence of pneumothorax (abnormal collection of air in the pleural cavity, between lungs and chest wall. May caused due to a chest injury), malignant pleural effusion. Position determined by a “safe triangle”- apex below axilla, lateral border of pectoral is mitral valve point, anterior border by latissimus dorsi muscle. Anesthesia supplied to the superior border of the rib and inferior aspect of intercostal space  
• 
  Thoracotomy- creation of an opening through the thoracic wall to enter a pleural cavity. Anterior thoracotomy for  example, may involve making H-shaped cuts through the perichondrium of one or more costal cartilages and then shelling out  segments of costal cartilage to gain entrance to the thoracic cavity. The posterolateral aspects of 5th–7th intercostal  spaces are important sites for posterior thoracotomy incisions. In general, a lateral approach is most satisfactory for entry  through the thoracic cage, with the patient lying on the contralateral side, the upper limb is fully abducted, placing the forearm beside the patient’s head. This elevates and laterally rotates the inferior angle of the scapula, allowing access as high as the 4th intercostal space
• Median sternotomy- to gain access to the thoracic cavity for surgical procedure, for example on heart and great vessels, the sternum is divided in the median plane and spread apart. After surgery, the halves of the sternum are reunited and held together with wire sutures

Sources

Stingl, J., Grim, M., & Druga, R. (2012). ''Regional anatomy''. Galen.

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