intercostal

Examples of intercostal in the following topics:

• Intercostal Nerves

  • The anterior divisions of the thoracic spinal nerves (T1-T11) are called the intercostal nerves.
  • The intercostal nerves are part of the somatic nervous system and arise from anterior divisions (rami anteriores, ventral divisions) of the thoracic spinal nerves from T1 to T11.
  • 2) The other smaller branch, the first intercostal nerve, runs along the first intercostal space and ends on the front of the chest as the first anterior cutaneous branch of the thorax.
  • The seventh intercostal nerve terminates at the xyphoid process, at the lower end of the sternum.
  • The anterior divisions of the seventh, eighth, ninth, tenth, and eleventh thoracic intercostal nerves are continued anteriorly from the intercostal spaces into the abdominal wall; hence they are named thoraco-abdominal nerves (or thoracicoabdominal intercostal nerves).

• Anterior Muscles

  • All intercostal muscles originate on the lower border of a rib and attach to the upper border of the rib below.
  • External Intercostals – The external intercostals are the most superficial of the intercostal muscles.
  • Internal Intercostals- Lying below the external intercostals, the internal intercostals are continuous with the internal oblique muscle of the abdomen.
  • Innermost Intercostals – The deepest lying of the intercostals, these muscles are similar in structure to the internal intercostals.
  • The intercostals are muscles between the ribs that form the chest cavity wall.

• Veins of the Thorax

  • The supreme intercostal vein is a paired vein that drains the first intercostal space on its corresponding side.

• Types of Breathing

  • During eupnea, also referred to as quiet breathing, the diaphragm and external intercostals must contract.
  • 3) Costal breathing: a mode of breathing that requires contraction of the intercostal muscles.
  • As the intercostal muscles relax, air passively leaves the lungs.
  • In addition to the contraction of the diaphragm and intercostal muscles, other accessory muscles must also contract.
  • In addition, accessory muscles (primarily the internal intercostals) help to compress the rib cage, which also reduces the volume of the thoracic cavity.

• Neural Mechanisms (Cortex)

  • Initiation of the voluntary contraction and relaxation of the internal and external intercostal muscles takes place in the superior portion of the primary motor cortex.
  • The posterior thoracic nerves: These nerves stimulate the intercostal muscles located around the pleura.
  • They are considered to be part of a larger group of intercostal nerves that stimulate regions across the thorax and abdomen.

• The Mechanics of Human Breathing

  • During the process of inhalation, the lung volume expands as a result of the contraction of the diaphragm and intercostal muscles (the muscles that are connected to the rib cage), thus expanding the thoracic cavity.
  • The intercostal muscles relax, returning the chest wall to its original position .

• Expiration

  • Internal Intercostal Muscles: Muscles of the ribcage that help lower the ribcage, which pushes down on the thoracic cavity, causing forced exhalation.
  • Note that these are not the same as the external intercostal muscles involved in inspiration.
  • This happens due to elastic properties of the lungs, as well as the internal intercostal muscles that lower the rib cage and decrease thoracic volume.

• Functional Anatomy of the Respiratory System

  • Inhalation is initiated by the activity of the diaphragm and supported by the external intercostal muscles.
  • Active or forced exhalation is achieved by the abdominal and the internal intercostal muscles.
  • During forced exhalation, as when blowing out a candle, the expiratory muscles, including the abdominal muscles and internal intercostal muscles, generate abdominal and thoracic pressure that force air out of the lungs.

• Thoracic Aorta

  • The posterior intercostal arteries are branches that originate throughout the length of the posterior aspect of the thoracic aorta.

• Sympathetic Nervous System

  • This intercostal nerve shows the sympathetic ganglion at the top left.