Question

What are the surface landmarks of the thorax (reference lines) and related functions?

What are the structures of the thoracic wall (pleura space, sternum, ribs)and related functions?

Answer 1

The chest, properly called the thorax, is the superior part of the trunk located between the neck and abdomen. ... It consists of several components: Thoracic wall.

Bony Landmarks

• Clavicles. Course transversely along the superior portion of the chest wall from the manubrium to the acromion of the scapula and, therefore, are easily palpable. ...
• Jugular notch of the sternum. Located between the medial ends of the clavicles.
• Sternal angle (of Louis). ...
• Xiphoid process. ...
• Costal margins.

◾️The importance of surface anatomy is Understanding and using surface anatomy is key to interpreting normal anatomy on medical images and being able to describe the location, appearance and relationships of palpable anatomical structures. It is the definition of usable anatomy.

Function :

It provides a base for the muscle attachment of the upper extremities, the head and neck, the vertebral column, and the pelvis. The thorax also provides protection for the heart, lungs, and viscera.

Anatomical Parts

◾️The thoracic cavity (or chest cavity) is the chamber of the human body that is protected by the thoracic wall (rib cage and associated skin, muscle, and fascia), limited by the costa and the diaphragm.

◾️the second largest hollow space of the body. It is enclosed by the ribs, the vertebral column, and the sternum, or breastbone, and is separated from the abdominal cavity (the body's largest hollow space) by a muscular and membranous partition, the diaphragm.

Structure.

The bony skeletal part of the thoracic wall is the rib cage, and the rest is made up of muscle, skin, and fasciae. The chest wall has 10 layers, namely skin, superficial fascia, deep fascia, serratus anterior, layer for ribs (containing intercostal muscles), and endothoracic fascia from superficial to deep.

The thoracic cavity has three compartments:

◾️ the mediastinum and two pleural cavities. The mediastinum is home to the heart, trachea, great vessels, and some other structures. The pleural cavities are on either side of the mediastinum and contain the lungs and the pleural linings.

Pleural space

Pleural space: The tiny area between the two layers of the pleura (the thin covering that protects and cushions the lungs) between the lungs and chest cavity. The pleural space is normally filled with a small amount of fluid.

The pleural cavity is a fluid filled space that surrounds the lungs. It is found in the thorax, separating the lungs from its surrounding structures such as the thoracic cage and intercostal spaces, the mediastinum and the diaphragm. The pleural cavity is bounded by a double layered serous membrane called pleura.

The boundaries of the pleural cavity are:

• Superior: root of the neck, 2-3 cm above the level of rib one
• Inferior: The thoracic surface of the diaphragm inferiorly
• Medial: The mediastinum medially
• Anterior, posterior and lateral: The internal surface of the ribs, costal cartilage and intercostal muscles

The lung almost entirely fills the space in the thorax. Therefore, the pleural cavity is described as a potential space, meaning that under normal circumstances, there is no actual space present, and the visceral and parietal pleura are in contact with each other. This potential space is also important as the unfilled spaces of the pleural cavity form recesses, which allow extra space for expansion of the lung. These will be discussed later in this article.

Pleura

The pleurae are two layers of serous membrane that form the boundaries of the pleural cavity. There are two types of pleura;

parietal and visceral.

The parietal pleura is the thicker and more durable outer layer that lines the inner aspect of the thoracic cavity and the mediastinum.

The visceral pleura is the more delicate inner layer of pleura that lines the outer surface of the lung itself. The parietal and visceral layers are not entirely separate, rather they are continuous with each other at the hilum of the lung. Each layer consists of a single layer of mesothelial cells and supporting connective tissue including collagen, elastin, blood vessels and lymphatics. The pleural cavity containing a small amount of pleural fluid is contained between the parietal and visceral layers of pleura.

Sternum

The sternum, or breastbone, is a long, flat, bony plate that forms the most anterior section of the rib cage.

The primary function of the sternum is the protection of the heart, lungs, and blood vessels from physical damage. The sternum is made of the manubrium, the gladiolus, and the xiphoid process.

Ribs

The ribs are a set of twelve paired bones which form the protective 'cage' of the thorax. They articulate with the vertebral column posteriorly, and terminate anteriorly as cartilage (known as costal cartilage). As part of the bony thorax, the ribs protect the internal thoracic organs.

Their main function is to aid respiration. ... Each rib articulates posteriorly with two thoracic vertebrae by the costovertebral joint.