is fixed or to pull the body towards the leg when the leg is fixed. For example, when one performs a sit-up that brings the torso (including the lower back) away from the ground and towards the front of the leg, the hip flexors (including the iliopsoas) will flex the spine upon the pelvis. Owing to the frontal attachment on the vertebrae, rotation of the spine will stretch the psoas. Clinical significance Tightness of the psoas can result in spasms or lower-back pain by compressing the lumbar discs. A hypertonic and inflamed psoas can lead to irritation and entrapment of the ilioinguinal and the iliohypogastric nerves, resulting in a sensation of heat or water running down the front of the thigh. Psoas can be palpated with active flexion of the hip. A positive psoas contracture test and pain with palpation reported by the patient indicate clinical significance. Care should be taken around the abdominal organs, especially the colon when palpating deeply. The appearance of a protruding belly can visually indicate a hypertonic psoas, which pulls the spine forward while pushing the abdominal contents outward. The psoas lies posterolateral to the lumbar sympathetic ganglia, and the needle tip will often pass through the psoas major during a lumbar sympathetic block. The genitofemoral nerve is formed in the midsection of the psoas muscle by the union of branches from the anterior rami of L1 and L2 nerve roots. The nerve then courses inferiorly within the psoas muscle and finally "pierces" the muscle and emerges on the anterior surface of the psoas distally. The nerve then traverses the retroperitoneum, descending over the anterior surface of the psoas. See also Iliopsoas Iliacus Hip flexor Psoas minor muscle Iliopsoas tendinitis Tenderloin Notes References Additional images External links Hip flexors Hip muscles Spine flexors Iliopsoas muscles Muscles of the lower limb