QS Study

An intercostal membrane is any of the membranous layers between the ribs. They are muscle groups that are situated in between the ribs that create and move the chest wall.

External (anterior) intercostal membrane

Eleven pairs of intercostales extemi muscles extend forward from the rib tubercle behind to the costochondral junction in front, where the muscles are replaced by an aponeurotic layer called the external (anterior) intercostal membrane. It is the sternal continuation of the external intercostal muscles in the intercostal space. It ends on the sternum. The number eleven on each side and are located in the intercostal space, expanding the transverse dimension of the thoracic cavity during inspiration.

Blood supply

  • arterial supply: anterior and posterior intercostal arteries
  • venous drainage: internal thoracic vein and intercostal veins.

Fig: Intercostal Membrane

Internal (posterior) intercostal membrane

Eleven pairs of intercostales intemi muscles extend backward from the sternum in front of the posterior costal angles behind, where each is replaced by an aponeurotic layer called the internal (posterior) intercostal membrane. It is the continuation of the internal intercostal muscles at the vertebral end of the intercostal spaces. The number eleven on each side and are located in the intercostal spaces, reducing the transverse dimension of the thoracic cavity during expiration.

Blood supply

  • arterial supply: anterior and posterior intercostal arteries
  • venous drainage: internal thoracic vein and intercostal veins.
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