Lower limb
Psoas Major
Musculus psoas major
- Origin
- Transverse processes and bodies of T12-L5, including the intervertebral discs
- Insertion
- Lesser trochanter of the femur
- Function
- Primary hip flexor, together with iliacus (iliopsoas); causes unilateral lateral flexion of the lumbar spine
- Innervation
- Direct ventral rami of L1-L3 (lumbar plexus)
- Movement & chain
- Works together with iliacus as a functional unit (iliopsoas) when lifting the leg, for example when climbing stairs or running.
- Palpation
- Palpable deeply through the relaxed abdominal wall, lateral to the rectus abdominis, at the level of the umbilicus.
- Clinical
- Prolonged sitting can lead to shortening and a hip flexor contracture; overuse causes iliopsoas tendinopathy with groin pain, especially during active hip flexion.
- Segmental innervation
- L1-L3.
- In clinical practice
- Basis of the psoas sign in physical examination for appendicitis, and a point of attention in postural advice due to its relation to low back complaints.
- Region in the model
- Lower limb