Figure 1

Illustrations of muscles sampled. A) A schematic figure presenting mm. iliocostalis, longissimus dorsi, diaphragm, gluteus medius, biceps femoris, sacrocaudalis dorsalis lateralis (SCDL) and sacrocaudalis dorsalis medialis (SDCM). B) A schematic diagram depicting; mm. multifidi fascicles emanating from the 18th thoracic vertebra crossing between 1–4 vertebral segments attaching caudally onto the mammillary process of the proceeding vertebrae; m. sacrocaudalis dorsal lateralis (SCDL) with tendinous attachments in the lumbar spine extending onto the sacrum and caudal vertebrae and m. sacrocaudalis dorsalis medialis (SCDM) emanating from the sacrum and extending to the caudal vertebrae. C) Magnetic resonance image (MRI) showing the relationship between epaxial and hypaxial musculature in cross section at the level of L3. Presented are mm. multifidi (M), longissimus (L), iliocostalis (IC), psoas major (PM), psoas minor (P), and gluteus medius (G).