Innermost Intercostals - Podcast Version 0:00 / 0:00 1x 0.25x 0.5x 0.75x 1x 1.25x 1.5x 1.75x 2x The innermost intercostals are a muscle of the thoracic wall. They are the deepest of the intercostal muscles. Their fibres are orientated in an inferior and posterior direction. Attachments: Originates from the medial edge of the costal groove and inserts onto the superior surface of the rib below. Actions: Stablises the position of the ribs during normal respiration. Depresses the ribs and decreases the thoracic volume during forced expiration. Innervation: Intercostal nerves (T1-T11) Blood supply: Anterior and posterior intercostal arteries By TeachMeSeries Ltd (2026) Fig 2View of the internal aspect of the thoracic wall. The internal intercostal and transverse thoracis muscles are visible. Pro Feature - 3D Model You've Discovered a Pro Feature Access our 3D Model Library Explore, cut, dissect, annotate and manipulate our 3D models to visualise anatomy in a dynamic, interactive way. Learn More Frequent questions What are the innermost intercostals? The innermost intercostals are a group of muscles located in the deepest layer of the thoracic wall. They play a crucial role in stabilising the ribs during breathing. What is the function of the innermost intercostal muscles? These muscles stabilise the ribs during normal respiration and assist in depressing the ribs, which reduces thoracic volume during forced expiration. Where do the innermost intercostals attach? The innermost intercostals originate from the medial edge of the costal groove and insert onto the superior surface of the rib directly below. How are the innermost intercostals innervated? The innermost intercostal muscles are innervated by the intercostal nerves, specifically those from T1 to T11. What is the blood supply to the innermost intercostals? The blood supply to the innermost intercostal muscles comes from both the anterior and posterior intercostal arteries, ensuring they receive adequate oxygen and nutrients. Rate This Article