The thorax, or chest, is a vital part of the human anatomy as it contains the heart, lungs, and other important organs. It is also an area of the body that is easily visible and therefore has various surface markings that can be used for diagnostic and clinical purposes.
One important surface marking of the thorax is the sternal angle, also known as the angle of Louis. This is the junction between the manubrium, or upper part of the sternum, and the body of the sternum. It is located at the level of the second thoracic vertebra and serves as a reference point for determining the location of other structures in the chest.
The xiphoid process is another prominent surface marking of the thorax. It is a small, pointed extension of the lower part of the sternum and is located just below the sternal angle. It is used as a reference point for measuring the depth of respiration and for locating the liver and other abdominal organs.
The nipples are another important surface marking of the thorax. They are located at the level of the fourth intercostal space and are used to locate the underlying mammary glands. In men, the nipples may be less prominent and may not be used as a reference point in the same way as in women.
The intercostal spaces are the spaces between the ribs and are an important surface marking of the thorax. They are used to locate the underlying organs and to measure the depth of respiration. The intercostal spaces are numbered from the top to the bottom, with the first intercostal space located just below the clavicle and the last intercostal space located at the level of the xiphoid process.
The thorax also has various other surface markings, including the trachea, which is a tube-like structure that extends from the larynx to the bronchi and is located in the midline of the neck and upper chest. The trachea is used as a reference point for locating the underlying organs and for diagnostic purposes.
In conclusion, the thorax has a number of important surface markings that are used for diagnostic and clinical purposes. These include the sternal angle, xiphoid process, nipples, intercostal spaces, and trachea. Understanding these surface markings is important for healthcare professionals, as it allows them to accurately locate and examine the underlying organs and tissues of the chest.
Surface Landmarks of the Thoracic wall
On the posterior surface of the thorax the scapular line is drawn vertically through the inferior angle of the scapula. It may, however, extend as high as 4 or 5 cm. On the left side the pleural edge arches laterally at the 4th costal cartilage and descends lateral to the border of the sternum, due, of course, to its lateral displacement by the heart; apart from this, its relationships are those of the right side. By means of these horizontal planes the abdomen is divided into three zones named from above, the subcostal, umbilical, and hypogastric zones. In the position of expiration the lower border of the lung may be marked by a slightly curved line with its convexity downward, from the sixth sternocostal junction to the tenth thoracic spinous process. The spinous processes of all the thoracic vertebrae can be palpated in the midline posteriorly, but it should be remembered that the first spinous process that can be felt is that of C7 the vertebra prominens.
Surface Markings of the Abdomen
According to Birmingham the limits of the normal liver may be marked out on the surface of the body in the following manner. The space is therefore known as the triangle of ausculation. The coils of the ileum lie toward the right in the right lumbar and iliac regions, in the right half of the umbilical region, and in the hypogastric region; a portion of the ileum is within the pelvis. Immediately below this is the infrasternal notch; between the sternal ends of the seventh costal cartilages, and below the notch, is a triangular depression, the epigastric fossa, in which the xiphoid process can be felt. From this point the two lines run downward, practically along the midsternal line, as far as the level of the fourth costal cartilages.  Key facts about the thorax Thoracic wall Openings: superior and inferior thoracic apertures Skeleton: sternum, twelve pairs of ribs, twelve thoracic vertebrae Joints: intervertebral discs, costovertebral, joint of head of rib, sternocostal, sternoclavicular, costochondral, interchondral joints Intercostal spaces: intercostal vein, artery, nerve Muscles: intercostal muscles, external, internal, innermost , transversus thoracis, subcostals, levatores costarum, serratus posterior superior, serratus posterior inferior muscles Thoracic cavity The mediastinum is located centrally and bordered by two pleural cavities laterally. A curved line, convex downward and to the left, joining these points indicates the lesser curvature.
