Watching this resources will notify you when proposed changes or new versions are created so you can keep track of improvements that have been made.
Favoriting this resource allows you to save it in the “My Resources” tab of your account. There, you can easily access this resource later when you’re ready to customize it or assign it to your students.
The anterior divisions of the thoracic spinal nerves (T1-T11) are called the intercostal nerves.
Describe the function of intercostal nerves
The intercostal nerves arise from the somaticnervous system. This enables them to control the contraction of muscles, as well as provide specific sensory information regarding the skin and parietal pleura.
The thoracic nerves are the spinal nerves emerging from the thoracic vertebrae. Branches also exit the spine and go directly to the sympathetic chain ganglia of the autonomic nervous system where they are involved in the functions of organs and glands in the head, neck, thorax, and abdomen.
The peritoneum is the serous membrane that forms the lining of the abdominal cavity or the coelom—it covers most of the intra-abdominal (or coelomic) organs—in amniotes and some invertebrates (annelids, for instance). It is composed of a layer of mesothelium supported by a thin layer of connective tissue. The peritoneum both supports the abdominal organs and serves as a conduit for their blood and lymph vessels and 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 (shown in ). The intercostal nerves are distributed chiefly to the thoracic pleura and abdominal peritoneum and differ from the anterior divisions of the other spinal nerves in that each pursues an independent course without plexus formation.
The first two nerves supply fibers to the upper limb in addition to their thoracic branches. The anterior division of the first thoracic nerve divides into two branches: one, the larger, leaves the thorax in front of the neck of the first rib, and enters the brachial plexus; 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 next four are limited in their distribution to the parietes of the thorax; the lower five supply the parietes of the thorax and abdomen. The seventh intercostal nerve terminates at the xyphoid process, at the lower end of the sternum. The tenth intercostal nerve terminates at the umbilicus. The twelfth (subcostal) thoracic is distributed to the abdominal wall and groin.
Unlike the nerves from the autonomic nervous system that innervate the visceral pleura of the thoracic cavity, the intercostal nerves arise from the somatic nervous system. This enables them to control the contraction of muscles, as well as provide specific sensory information regarding the skin and parietal pleura. This explains why damage to the internal wall of the thoracic cavity can be felt as a sharp pain localized in the injured region. Damage to the visceral pleura is experienced as an un-localized ache.