Overview
It has a cervical and a thoracic part. It is the main component of the thoracic limb synsarcosis: since the dog has no functional clavicle, the trunk hangs between the two scapulae, held by these muscles.
Origin
- Cervical part: transverse processes of the last five cervical vertebrae.
- Thoracic part: first seven or eight ribs, by digitations.
Insertion
Serrated face (facies serrata), on the dorsal part of the medial surface of the scapula.
Action
Supports the trunk and moves the scapula. The cervical part draws the dorsal angle of the scapula cranially and the thoracic part caudally. With the limb fixed, the thoracic part assists inspiration.
Innervation
Ventral branches of the cervical nerves (cervical part) and long thoracic nerve (n. thoracicus longus) for the thoracic part.