Levatores costarum muscles

The levator muscles of the ribs (Musculi levatores costarum) are a series of small muscles, hardly distinguishable form the external intercostal muscles, that originate from the transverse and mammillary processes of all but the last thoracic vertebrae and pass caudoventrally to  the angle of the adjacent ribs to insert on the cranial border of the second to last rib.

In dogs:

Origin: Transverse processes of the first through twelfth thoracic vertebrae.

Insertion: Cranial borders of the second through twelfth ribs.

Action: Inspiration.

Nerve: Intercostal nerves one to twelve.