Quick Facts
Origin: Internal surfaces of seventh to tenth ribs.
Insertion: Internal surfaces of ninth to twelfth ribs.
Action: Depress ribs at their costovertebral joints.
Innervation: Adjacent intercostal nerves (anterior rami of thoracic nerves).
Arterial Supply: Adjacent posterior intercostal arteries.
Origin
The subcostal muscles originate from the internal surfaces of the seventh to tenth ribs, in the areas that are located adjacent to the angles of these ribs. There can be variations between individuals regarding the origin sites for the subcostal muscles.
Insertion
The fibers of the subcostal muscles travel inferomedially and insert onto the second rib that is inferior to their origin sites (i.e., the ninth to twelfth ribs). They insert onto the areas that are located adjacent to the angles of these ribs.
Key Features & Anatomical Relations
The subcostal muscles are a group of muscles of the thorax. They consist of short, individual, skeletal muscles that are found in the lower half of the posterior thoracic wall.
They are located:
- superficial to the endothoracic fascia and parietal pleura;
- deep to the lower ribs, the internal intercostal muscles and membrane, the anterior rami of lower thoracic nerves (intercostal nerves), and the lower posterior intercostal vessels.
Actions
The subcostal muscles depress the ribs at their costovertebral joints (Standring, 2016).
References
Standring, S. (2016) Gray's Anatomy: The Anatomical Basis of Clinical Practice. Gray's Anatomy Series 41st edn.: Elsevier Limited.
Actions
The subcostal muscles depress the ribs at their costovertebral joints (Standring, 2016).
