LUMBAR HYPAXIAL MUSCLES
The psoas minor muscle can be found between the iliac fascia and peritoneum ventrally and the iliopsoas and quadratus lumborum muscles dorsally. It originates from the bodies of the last thoracic and the first four to five lumbar vertebrae.
The strong flat tendon has a shiny appearance and inserts on the iliopubic eminence at the pelvic inlet. It stabilizes and flexes the lumbar part of the vertebral column.The iliopsoas muscle consists of the psoas major and the iliacus. It lies ventral to the quadratus lumborum and dorsal to the psoas minor. The psoas major arises from the bodies of the lumbar vertebrae and passes caudally, medial to the wings of the ilium, where it fuses with the iliacus to form the iliopsoas (see Figure 2-24, B∕77). The iliacus arises from the wing and shaft of the ilium. Both muscles have a common insertion on the lesser trochanter of the femur. The combined muscle flexes the lumbar vertebral column and plays a role in protraction of the hindlimb.
The quadratus lumborum lies directly ventral to the bodies of the last three thoracic vertebrae and the bodies and transverse processes of all the lumbar vertebrae and ends on the medial surface of the wing of the ilium (see Figure 2-24, B∕5).