Lecture Notes: Pleural Membranes

Overview

• Pleural membranes line the lungs.
• Situated internally to the ribs and intercostal muscles.
• Serous membranes to allow lungs to move without friction.
• Lungs connected to the bronchial tree, bifurcation at the carina.

Structure and Function

• Parietal Pleura: lines the internal surface of the ribs and intercostal muscles.
  • Acts like two plates of glass with water, creating a vacuum seal.
  • Allows movement without separating.
• Visceral Pleura: lines the external surface of the lungs.
  • The pleural space is between the parietal and visceral pleura.

Types of Parietal Pleura

• Costal Parietal Pleura: lines the internal surface of the ribs.
• Diaphragmatic Parietal Pleura: lines the diaphragm.
• Mediastinal Parietal Pleura: adjacent to the heart.
• Cervical Parietal Pleura: extends into the neck.

Anatomy of the Pleural Membranes

• Visceral Pleura: intimately associated with lung parenchyma.
• Root of the Lung: where visceral and parietal pleura converge, entry and exit of bronchial tree and pulmonary vessels.
• Costodiaphragmatic Recess:
  • Double membrane of parietal pleura.
  • Space fills when inhaling, empties when exhaling.

Innervation of Pleural Membranes

Parietal Pleura

• Intercostal Nerves: provide somatic innervation (pain, temperature, touch).
• Phrenic Nerve: innervates mediastinal and diaphragmatic parietal pleura, arising from C3, C4, C5.

Visceral Pleura

• Sensory Autonomic Innervation:
  • Travels along sympathetic pathways to the dorsal root.
  • Includes visceral afferent neurons traveling with parasympathetic neurons to the medulla.
  • Senses stretching, airway changes, tissue damage.

Key Points

• Pleural membranes are crucial for lung movement and functionality.
• Different parts of pleura have distinct innervations and sensory roles.
• Understanding the structure and innervation is essential for insights into respiratory mechanics and pathologies.