Clinical Anatomy of the Thoracic Wall

@elity-sitio here again. Welcome to another post today, and in today's post I will be sharing on pulmonology which is the branch of medicine that deals with the clinical anatomy, diagnosis, and treatment of diseases and conditions affecting the lungs and the respiratory system. In this post, I will be discussing the anatomy of the thorax. In layman's terms, I will be discussing the anatomy of the chest, which is the upper part of the trunk between the neck and the abdomen. Since we are dealing with pulmonology, I will be doing the Anatomy, Histology, Pharmacology, pathology, and the Physiology of the thorax.

In the anatomy of the thorax, I will be taking in two categories which will be the Thoracic wall, made up of bones and muscles, and the soft tissues of the thorax.

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The Thoracic Wall
The thoracic wall is made up of bones and muscles. The Bones in the thoracic wall include the thoracic vertebrae, the Ribs, and the Sternum.

The thoracic vertebrae are a group of 12 bones between the cervical vertebrae of the neck and the lumbar vertebrae of the lower region. These bones are larger than the cervical vertebrae, and they also have a pair of articulating facets (zygapophysial joints) on the back of the body, which allow for movement of the rib cage while protecting the lungs and the heart. Importantly, there are 7 cervical vertebrae and 12 thoracic vertebrae. From the 5th to the 8th thoracic vertebrae are vertebrae in contact with the descending thoracic aorta.

The Rib is the second part of the thoracic wall, which is made up of 12 pairs, with the first 7 pairs being called "true ribs" because they are directly attached to the sternum via cartilages, the next 3 pairs of ribs are referred to as "false ribs" because they are attached to the sternum indirectly, while the last 2 pairs of ribs are known as "floating ribs" since they are not attached to the sternum. Ribs are weak at their coastal angle, which could cause them to fracture (it is very surprising how things like sneezing, and strong hugging can cause rib fractures). It is very important to visit the hospital when a rib fracture can cause lung injury or injury to the spleen. When the rib is fractured, it can lead to pleuretic chest pain during breathing which can lead to decreased air as a result of pain and cause the lungs not to receive adequate air, causing restrictive lung disease. It is important to know that children's and infants' ribs are elastic and will be less likely to fracture, while in adults, it can be very deadly, as it can cause hypoventilation, atelectasis, and atelectatic pneumonia.

While most thoracic issues are associated with chest pain, it is good to differentiate chest pain from one condition to others. Heart attack and Rib fracture. In the case of rib fracture, the chest pain is usually sharp and pointed while in a heart attack, the pain is dull, squeezing, and pressure-like. The pain is usually positioned, and increased during inhalation for rib fracture, while in heart attacks, the pain is not pleuritic, and positional. People can also experience a flail chest which occurs when a segment of the rib cage is separated from the rest of the chest wall as a result of multiple rib fractures in more than two places, causing the segment to move independently of the rest of the chest with each breath. This can lead to the paradoxical movement of the chest where there will be inward movement of the chest in inhalation and outward movement in exhalation. This can be fixed through Thoracotomy where the chest wall is cut, and in this case, removing the rib, autologous bone grafting, and short rib excision which will regenerate from the remaining periosteum. Some people have an accessory rib which can be found either at the cervical rib or at the lumbar rib. It can be attached to C7 which could lead to thoracic outlet syndrome which causes the compression of the lower trunk of the brachial plexus, and the compression of the subclavian artery. It can also cause lymphosarcoma.

The Sternum which we commonly refer to as the breastbone is a long, flat bone located at the center of the thorax, running down the middle of the chest. It serves as a point of attachment for several muscles and bones such as the rib cage and the clavicles (collarbones). The Sternum is divided into the manubrium (the uppermost part of the sternum where the attachment for the clavicles and the first rib is possible), the body, and the xiphoid process (the lowermost part of the sternum which serves as an attachment region for certain muscles and ligaments). The sternum is very strong and difficult to break, so a fractured sternum would possibly be a result of a hidden disaster which could be a result of a traumatic rupture of the aorta, cardiac contusion, or pulmonary contusion, it could occur as a result of previous thoracic surgery, and pectus excavatum.

Let me quickly touch the diaphragm. Remember I said that the thoracic wall is made up of bones and muscles, so we have discussed the bones, now we are about to discuss the muscles and I will be starting with the Diaphragm. The diaphragm is an important respiratory muscle but it is not essential. A person without a diaphragm will not be able to perform stressful activities that would cause lead to heavy breathing, but normal breathing can be done since the intercostal muscles are still available.

The Intercostal Muscles are muscles located between the ribs, responsible for the movement of the rib cage when breathing. It is divided into two layers which are the external intercostals, and the internal intercostals muscle. The External intercostal muscle lifts the chest upwards and outwards increasing the transverse diameter of the chest, while the internal intercostal muscle depresses the chest inwards basically in expiration decreasing the transverse diameter of the chest.

Conclusion

I just explained the clinical anatomy of the Thoracic Wall, where I explained the thoracic vertebrae, the rib, the sternum, the diaphragm, and the intercostal muscles. In my next post, I will be discussing the soft tissues of the Thorax.