Rib Cage - Structure, Thoracic Organ Protector, Conditions, Prevention

The Bony Cage : Protects the Thoracic Organs

Dr.Surya Rao Poodipeddi profile Authored by Dr.Surya Rao Poodipeddi on 11 Mar 2014 - 15:32.

As the name implies the human bony cage is a shield formed with the help of several bones to protect important organs in the thorax like heart, lungs, esophagus, bronchial tree and the great vessels emerging from and entering the heart. Similar to an iron chest which can withstand attempts by a robber to rob its contents, the bony cage, also called the rib cage, bears the brunt of external blows and injuries to protect the main organs in the thoracic region like the heart and the lungs.

Rib cage structure: The bony cage is slightly less broad at the top than at the bottom end. It is formed by a combination of several bones. 12 pairs of circular bones called ribs form the cage. In front is the bone cum cartilaginous structure called the breast bone or the sternum with a broad piece above called the manibruim sterni and a hollowed piece at the bottom called the xiphisternum which forms an inverted V-shaped parting. The 12 thoracic vertebrae or dorsal vertebrae receive the back end of each rib to which it is attached.

The 12 pairs of ribs are of three types namely true ribs, false ribs and floating ribs. There are seven pairs of true ribs, which are attached direct to the sternum in front and the corresponding thoracic vertebrae behind. The three pairs of false ribs get attached in front to the sternum indirectly with the help of a cartilage and the three corresponding thoracic vertebrae behind. The two pairs of the floating ribs are only attached behind to the corresponding thoracic vertebra but remain floating in front and one cam feel these two rubs at the lowest part of the bony cage in front.

At the top of the breastbone are two hollows where the inner ends of the clavicles fit forming the sternoclavicular joints. The outer ends of the clavicles help in the formation of the shoulder joint in combination with the scapula behind and the arm bone called the humerus. There is a notch at the top of the breastbone called the suprasternal notch with whose help doctors count the ribs from above downwards.

A big structure with two domes, one on the right and one on the left called the diaphragm separates the thorax from the abdominal cavity with openings for the esophagus to join the stomach and the big vessels from and to the heart. Blunt injuries on the bony cage with the fists or any blunt object results in fractures of the ribs, which if displaced may pierce the soft lung tissue. Just behind the sternum is the heart which lies more towards the left side than the right.

Rib Facts at a Glance:

  • The ribs are flattish, thin bones which curve around your chest. All the ribs together make up the rib cage.
  • The rib cage is made in such a way that the backbone and breastbone, as well as your vital organs – heart, lungs, liver, kidneys, stomach, spleen are well protected.
  • Each rib is attached to the breastbone in front and vertebrae that make up the backbone. Each rib curves around to join the vertebra  via a strip of costal cartilage
  • There are a total 12 pairs of ribs of which seven pairs are called true ribs.
  • Three pairs form the false ribs. These are attached to vertebrae but are not linked to the breastbone. Instead, the cartilage connects each of these ribs to the rib above it.
  • There are two pairs of floating ribs. These are attached only to the vertebrae of the backbone.
  • The gaps between the ribs are called intercostal spaces, and they contain thin sheets of muscle which expand and relax the chest during breathing.
  • When many ribs are broken (often in a car accident) it is called a flail chest, when the lungs heave the chest in and out. 

The two lungs with lobes lie adjacent to the heart. Behind the heart are the food pipe or esophagus and the main bronchus that divides to enter each lung. The important vessels in the chest area are, the inferior and superior vena cava that bring impure blood from the lower and upper parts of the body respectively.

The great arteries that supply blood to the neck and head above and the thorax and lower part of the body pass through the thorax. Also situated in the thorax within the bony cage are several lymphatics, the thoracic duct and several nerves meant for their allotted duties. Though rare, some persons have accessory rib over and above the 12 pairs of ribs, which are also called the cervical ribs because of their origin in the cervical region of the neck. The cervical ribs if present, cause severe brachialgia (Pain in the arms) due to compression of the brachial nerves by the additional rib at the root of the neck from where the brachial plexus emerges.

The space between the ribs is called intercostal space which has muscles attached to the margins of each. The intercostal muscles are the main muscles of respiration with help from the diaphragm. When there is respiratory distress the abdominal muscles take over to aid respiration when you encounter predominantly abdominal respiration, which is a sure sign of some serious problem either in the lungs or the heart.

Conditions: There are myriads of conditions, which can affect any part stationed with in the bony cage. To describe these would mean writing a book, and hence is beyond the scope of this article. The main conditions which affect the organs with in the bony cage and the cage itself are fractures due to fall or blows, piercing injuries either due to fall on a sharp object or a sharp object piercing the chest wall, gunshot injuries and some rare congenital malformations.

Prevention: Breathing exercises help to maintain smooth respiration. Avoiding smoking and any obnoxious materials dangerous for the lungs like narcotics and stimulants can do good to the body and lungs. Depending upon the nature of injury or disease one should take immediate steps to seek emergency measures because respiratory or circulatory failure can be very dangerous if not attended to, immediately.

*Disclaimer: This is not medical advice. The content is for educational purposes only. Please contact your doctor for any health care issues.