Anatomy
Summary
The visceral pleura covers the external surface of the lungs, while the parietal pleura lines the surfaces against which the lungs come in contact, such as the costal, mediastinal, and diaphragmatic areas. Innervation of these pleural layers is distinct: intercostal nerves provide sensation to the costal parietal pleura with well-localized pain, whereas the phrenic nerve (C3,4,5) innervates the mediastinal and diaphragmatic parietal pleura, leading to poorly localized pain that can be referred to the neck.
The pleural space is usually devoid of content, holding only a small amount of fluid and maintaining a net negative pressure. Pathologies include pneumothorax, which is the presence of air in the pleural space, and pleural effusion, indicating fluid accumulation. These can be differentiated via X-ray, which is the easiest way to diagnose a pneumothorax. Thoracentesis is a procedure for aspirating fluid from the pleural space and is both diagnostic and therapeutic. The optimal location for thoracentesis is 2 rib spaces below the edge of the lungs. Procedures below the 9th rib risk injuring abdominal organs.
Lesson Outline
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FAQs
The visceral pleura is the inner layer that covers the lung and is contiguous with the lung tissue, making it insensitive to pain. The parietal pleura is the outer layer that lines the inside of the chest wall, diaphragm, and mediastinum. It is sensitive to pain and is innervated by the phrenic and the lower six intercostal nerves. The space between the visceral and parietal pleura them is known as pleural space.
An intercostal nerve block is a targeted intervention that utilizes local anesthetic to numb the intercostal nerves, which convey sensation from the costal (rib) parietal pleura. By doing so, it can effectively manage pain associated with conditions like pleural tumors or after surgical procedures. The technique involves the careful injection of anesthetic into the relevant intercostal space, often guided by imaging. While effective for costal pleural pain, this procedure won't alleviate pain in areas innervated by the phrenic nerve.
Pleural effusion refers to the excess accumulation of fluid in the pleural space, the space between the visceral and parietal pleura. This can disturb the delicate balance of pressures needed for normal lung function, leading to reduced lung expansion and difficulty in breathing.
A pneumothorax is a condition characterized by the presence of air or gas in the pleural space. This can cause the lung to collapse as it disrupts the negative pressure maintained in the pleural space, hindering lung expansion during respiration.
Thoracentesis is a procedure performed to remove fluid or air from the pleural space. It often involves the insertion of a needle or tube through the intercostal space into the pleural space, generally under local anesthesia. It's performed to treat conditions like pleural effusion and pneumothorax that upset the balance of fluid or air in the pleural space, thereby affecting lung function.
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