Fig. 9.

Schematic drawing illustrating the structural features of muscles that originate on the ribs and insert on the vertebral column. (a) Three distinct divisions of the scalenus supracostalis (SS) insert on the caudal aspect of the transverse processes of C₄ and C₅ by means of two tendons. (b) The insertion site of the intermediate division of the scalenus primae costae (SPI) was found to be C₆ in some dogs, whereas in other dogs it was C₇ (c).