Lower back pain is commonly associated with irritation of the L5 and S1 nerve roots bilaterally. Depending on whether the L5 or the S1 nerve root is more irritated, there can be pain and spasm that causes tightening of the muscles that perform external rotation or muscles that perform internal rotation.
Our topic today will be on muscles that perform internal rotation of the hip. These muscles are:- gluteus medius- gluteus minimus- tensor fascia latae muscles.
All these muscles are supplied by the superior gluteal nerve (L4, L5 with the L5 nerve root being more dominant). These muscles also receive contribution from the S1 nerve root. We can test the strength of these muscles by having the patient lie on his stomach with his knee bent up. The patient can attempt to do turn the lower leg outward with the toes pointing inward toward the body. This will produce internal rotation of the hip. The examiner can then attempt to force the lower leg inward toward the body to assess the strength of the hip internal rotators.
