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A cutout of the thoracic wall showing the three layers of intercostal muscle - from the left wall. The muscles extend from the tubercles of the ribs behind, to the cartilages of the ribs in front, where they end in thin membranes, the external intercostal membranes, which are continued forward to the sternum.
External intercostal muscles also known as intercostalis externus aid in quiet and forced inhalation. They originate on ribs 1–11 and have their insertion on ribs 2–12. The external intercostals are responsible for the elevation of the ribs and bending them more open, thus expanding the transverse dimensions of the thoracic cavity. The ...
Unlike the other two intercostal muscles, the external intercostal muscle does not retain its muscular character all the way to the sternum, and so the tissue in this location is called the external intercostal membrane. The fibers of the external intercostal muscles run downward and forward between adjacent ribs.
The intercostal space (ICS) is the anatomic space between two ribs (Lat. costa). Since there are 12 ribs on each side, there are 11 intercostal spaces, each numbered for the rib superior to it. Since there are 12 ribs on each side, there are 11 intercostal spaces, each numbered for the rib superior to it.
external surfaces of ribs 5-12 linea alba, pubic tubercle, anterior half of iliac crest: lower posterior intercostal arteries, subcostal artery, deep circumflex iliac artery: motor: intercostal nerves (T7-T11), subcostal nerve sensory: iliohypogastric nerve: flexes trunk to same side, rotates trunk to opposite side, expiration, compresses ...
The intercostal nerves are part of the somatic nervous system, and arise from the anterior rami of the thoracic spinal nerves from T1 to T11. [1] [2] The intercostal nerves are distributed chiefly to the thoracic pleura and abdominal peritoneum, and differ from the anterior rami of the other spinal nerves in that each pursues an independent course without plexus formation.
The external intercostal muscles are most important in respiration. These have fibres that are angled obliquely downward and forward from rib to rib. [ 2 ] The contraction of these fibres raises each rib toward the rib above, with the overall effect of raising the rib cage , assisting in inhalation.
The spaces between the ribs are known as intercostal spaces; they contain the instrinsic intercostal muscles and the neurovascular bundles containing intercostal nerves, arteries and veins. [4] The superficial surface of the rib cage is covered by the thoracolumbar fascia , which provides external attachments for the neck , back , pectoral and ...