A typical intercostal space

An intercostal space refers to the space between adjacent ribs in the thoracic cage. Each intercostal space contains several important structures, including muscles, blood vessels, and nerves. Here is a description of a typical intercostal space:

1. Muscles:
   • External Intercostal Muscles: These muscles are located on the external aspect of the rib cage. They run obliquely downward and forward, and their fibers are oriented in the direction of the hands in pockets. External intercostal muscles play a role in elevating the ribs during inspiration.
   • Internal Intercostal Muscles: Situated deeper than the external intercostals, these muscles have fibers that run perpendicular to those of the external intercostals. Internal intercostal muscles are involved in depressing the ribs during expiration.
2. Intercostal Nerves:
   • Intercostal nerves run in the costal groove on the inferior side of each rib and are located in the costal space. These nerves are branches of the thoracic spinal nerves and provide sensory innervation to the skin and motor innervation to the intercostal muscles.
3. Intercostal Veins, Arteries, and Lymphatics:
   • Intercostal veins and arteries, along with associated lymphatic vessels, travel within the costal grooves of the ribs. These vessels play a crucial role in the circulatory and lymphatic systems of the thoracic region.
4. Costal Cartilages:
   • The superior and inferior borders of each rib are covered by costal cartilages. The cartilages contribute to the flexibility of the thoracic cage and aid in the movements associated with breathing.
5. Pleura:
   • The pleura is a serous membrane that lines the thoracic cavity and covers the lungs. In the intercostal spaces, the parietal pleura lines the inner surface of the rib cage.
6. Adipose Tissue:
   • Adipose tissue, or fat, may be present in the intercostal spaces. The amount can vary among individuals and contributes to insulation and protection of underlying structures.
7. Blood Supply:
   • Branches of the intercostal arteries run along the inferior border of each rib, providing blood supply to the intercostal muscles and other structures in the space.
8. Thoracic Wall Ligaments:
   • Ligaments such as the costotransverse ligaments and radiate ligaments contribute to the stability of the thoracic cage.
9. Thoracic Wall Skin:
   • The skin on the anterior and lateral aspects of the thoracic wall covers the intercostal spaces. The intercostal spaces are easily palpable, especially along the costal margin.

It’s important to note that there are 11 intercostal spaces in the typical human thoracic cage, as there are 12 pairs of ribs. The first intercostal space is located between the first and second ribs, and the spaces are numbered down to the 11th intercostal space, which is between the 11th and 12th ribs. The terms “superior” and “inferior” refer to the position of the space relative to the ribs enclosing it.

Video Lecture of above mentioned subject