Lung Anatomy and Thoracic Cavity

Lungs in the Thorax

• Lungs are situated within the thoracic cavity
• The lungs are surrounded by the pleura, a two-layered membrane
  • Visceral pleura directly adheres to organ surface
  • Parietal pleura lines the thoracic cavity walls
• Pleural space is the potential space between these layers, containing a small amount of lubricating fluid

Lung Anatomy

• Apex is the uppermost part of the lung, extending slightly above the clavicle
• Base rests on the diaphragm, the muscle that separates the chest cavity from the abdomen.
• Lungs have fissures, deep grooves that divide them into lobes:
  • Right lung: Oblique and horizontal fissures, resulting in three lobes (superior, middle, and inferior)
  • Left lung: Singular oblique fissure, resulting in two lobes (superior and inferior)
• Hilum is the area on the medial (inner) surface of each lung
  • Where bronchi, blood vessels, nerves, and lymphatic vessels enter and leave the lung

Bronchial Tree

• Trachea branches into the right and left main bronchi, which enter the lungs at the hilum.
• Bronchi divide into smaller and smaller branches, eventually forming bronchioles.
  • Each bronchiole leads to alveoli, tiny air sacs where gas exchange occurs.

Pleura

• Pleura surrounds the lungs, creating a closed space.
• Pleural fluid lubricates and reduces friction between the pleura layers during breathing.
• This allows for smooth lung expansion and contraction.

Lymphatic System in the Thorax

• Plays a crucial role in fluid balance and immune function
• Lymphatic vessels collect excess fluid from tissues and return it to the bloodstream.
• Lymph nodes: small, bean-shaped organs found along lymphatic vessels.
  • Filter lymph fluid and contain lymphocytes, cells involved in the immune response
  • Lymph node enlargement can indicate infection or disease.
• Lymphatic ducts: drain lymphatic fluid into the venous system, returning it to circulation.
  • Right lymphatic duct drains lymph from the right upper quadrant of the body.
  • Thoracic duct drains lymph from the rest of the body.

Clinical Scenario

• A 2 ½-year-old presents to the A&E with sore throat, refusal to eat, and vomiting
• History suggests possible pharyngitis (inflammation of the throat)
• Concern for the child's well-being and potential complications, given the symptom severity and lack of improvement despite previous antibiotic treatment.
• The clinician should assess the child's condition thoroughly and consider further investigations and interventions.

Chest X-Ray

• A radiographic image of the chest, used to visualize the lungs, heart, and bony structures.
• PA view:
  • Posterior-anterior view, with the X-ray beam passing from the back to the front of the chest.
• AP view:
  • Anterior-posterior view, with the X-ray beam passing from the front to the back of the chest.
  • Often used for patients who cannot stand, like those in bed.
• Can help identify various conditions, including:
  • Pneumonia (infection of the lungs)
  • Pneumothorax (collapsed lung)
  • Pleural effusion (fluid buildup in the pleural space)
  • Cardiomegaly (enlarged heart)
  • Pulmonary edema (fluid in the lungs)

Lymphatic System

• Palpable axillary lymph nodes in a patient with a breast lump are suggestive of potential cancer spread.
• The lymphatic system is a crucial aspect of immune function, transporting lymph (fluid containing lymphocytes) and filtering it through lymph nodes.
• Lymph node enlargement can indicate lymphoma, infection, or other conditions.

Spot the Difference

• This section highlights the differences in the location and features of the right and left principal bronchi.
• The right principal bronchus is wider and more vertical, making it more susceptible to aspiration (foreign bodies entering the airway).
• The left principal bronchus is narrower and more angular, with a more horizontal orientation.

This quiz explores the anatomy of the lungs and their position within the thoracic cavity. Topics include the structures surrounding the lungs, the organization of lung lobes, and the components of the bronchial tree. Test your knowledge on the essential functions and anatomy of the respiratory system.