Overview
A broad, flat muscle caudal to the scapula. Its fibres converge cranioventrally, pass medial to the long head of the triceps and end in a tendon shared with the teres major.
In the cat, the epitrochlearis (m. tensor fasciae antebrachii) leaves its deep surface and ventral border and accompanies the triceps to the olecranon.
Origin
Thoracolumbar fascia, which attaches it to the spinous processes of the caudal thoracic and lumbar vertebrae.
Insertion
Teres major tuberosity (tuberositas teres major) on the medial surface of the humerus.
Action
Flexes the shoulder and draws the limb caudally. With the limb planted, it pulls the trunk cranially, as when climbing.
Innervation
Thoracodorsal nerve (n. thoracodorsalis).
Clinical relevance
- Feline injection-site sarcoma on the lateral thoracic wall or in the interscapular region can infiltrate this muscle, which then has to be partly removed.
- Its size and constant vascular pedicle make it a useful muscle flap for reconstructing defects of the thoracic wall, including those left by resection of these sarcomas.