Thorax and Lungs

• Thorax


  Identifies the portion of the body extending from the base of the neck superiorly to the level of the diaphragm inferiorly.
• Thoracic cavity


  Consists of the mediastinum and the lungs and is lined by the pleural membranes.
• Parts of the Thorax

  o Thoracic Cage

  o The sternum, or breastbone

  o Clavicles extend from the manubrium to the acromion of the scapula.
• Parts of the Thoracic Cavity

  o Mediastinum.

  o Trachea

  o Bronchi

  o Lungs
• Thoracic cage


  It is constructed of the sternum, 12 pairs of ribs, 12 thoracic vertebrae, muscles, and cartilage. It provides support and protection.
• Sternum 


  It is also known as the breastbone. It lies in the center of the chest anteriorly and is divided in three parts: manubrium, the body and xiphoid process.
• Manubrium


  Connects laterally with the clavicles (collar bones) and the first two pair of ribs.
• Suprasternal notch


  A U-shaped indentation located on the superior border of the manubrium is an important landmark known as?
• Sternal angle 


  It is also known as the angle of Louis. It is a reference point for counting ribs and intercostal spaces. A bony ridge that can be palpated at the point where the manubrium articulates with the body sternum.
• 12 pairs of ribs


  What constitute the main structure of the thoracic cage?
• Costal angle 


  An angle between the left and right costal margins meeting at the level of the xiphoid process.
• Floating ribs


  The 11th and 12th pairs of ribs are referred to as this because they do not connect to either the sternum or another pair of ribs anteriorly.
• Vertebra prominens


  The spinous process of the seventh cervical vertebra (C7) can be easily felt when the neck is flexed.
• Midsternal line and Right and Left Midclavicular lines


  The lines in the anterior chest
• Vertebral (or spinal) line and Right and Left Scapular lines

  Extend through the inferior angle of the scapulae when the arms are at the client's side.
• Midaxillary line


  It runs from the apex of the axillae to the level of the 12th rib.
• Anterior axillary line


  Extends from the anterior axillary fold along the anterolateral aspect of the thorax.
• Posterior axillary line


  Runs from the posterior axillary fold down the posterolateral aspect of the chest wall.
• Thoracic Cavity


  It consists of mediastinum and lungs.
• Mediastinum 


  It refers to the central area in the thoracic cavity that contains the trachea, esophagus, heart, and great vessels.
• Lungs


  Are two cone-shaped, elastic structures suspended within the thoracic cavity.
• Apex


  Extends slightly above the clavicle
• Base


  It is at the level of diaphragm.
• Pleura


  The thin, double-layered serous membrane in the thoracic cavity.
• Parietal pleura


  It lines the chest cavity
• Visceral pleura 


  It covers the external surfaces of the lungs
• Pleural space


  It lies between the two pleural layers.
• Trachea


  It is a 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 adult.
• Hyaline cartilage 


  C-shaped rings that compose the trachea.
• Right main bronchus 


  It is shorter and more vertical than the left main bronchus.
• Dead space


  The bronchi and trachea represent this space in the respiratory system, where air is transported but no gas exchange takes place.
• Cilia 


  These hair-like projections help sweep dust, foreign bodies, and bacteria that have been trapped by the mucus toward the mouth for removal.
• Bronchioles


  The bronchi repeatedly bifurcate into smaller passageways known as?
• Alveolar sacs


  Eventually the bronchioles terminate at the alveolar ducts, and air is channeled here. This contain a number of alveoli in a cluster formation (resembling grapes), creating millions of interalveolar walls that increase the surface area available for gas exchange.
• Purpose of respiration

  Maintain an adequate oxygen level in the blood to support cellular life.
• External Respiration (Ventilation)


  The mechanical act of breathing and is accomplished by expansion of the chest, both vertically and horizontally.
• Vertical expansion


  It is accomplished through contraction of the diaphragm.
• Horizontal expansion


  It occurs as intercostal muscles lift the sternum and elevate the ribs, resulting in an increase in anteroposterior diameter.
• Inspiration 


  A slight negative pressure is created in the lungs in relation to the atmospheric pressure, resulting in an inflow of air into the lungs.
• Expiration 


  • Mostly passive in nature

  • Occurs with relaxation of the intercostal muscles and the diaphragm

  • As the diaphragm relaxes, it assumes a domed shape

  • The resultant decrease in the size of the chest cavity

  creates a positive pressure, forcing air out of the lungs.