This document provides an overview of the muscles of the spine and thorax, including bony landmarks and three groups of deep back muscles - the spinalis, longissimus, and iliocostalis muscles. It describes the actions, origins, insertions, and innervations of muscles within each group, including the spinalis cervicis, spinalis thoracis, longissimus thoracis, longissimus cervicis, and iliocostalis lumborum. The document also outlines tests to locate the erector spinae group and assess back extensor strength.

1. Spine and Thorax

2. Topographical views

4. Bony landmark trail Trail 3. Cervical vertebrae Trail 4. Thoracic and Lumbar vertebrae

6. Muscles of the spine and thorax Superficial muscles of the back

7. Muscles of the spine and thorax Intermediate muscles of the back Deep muscles of the back

8. Muscles of the spine and thorax Schematic cross section view of the muscles of the spine

9. Muscle layers of the post. neck

22. Test for back extensors