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 (2025)
Fig 2
View of the internal aspect of the thoracic wall. The internal intercostal and transverse thoracis muscles are visible.