The anatomical insertions on 3 different structures give rise to 3 groups of fibers of different orientation:
- The fibers, which start at the top of the twelfth side and attach, at the bottom, to the iliac crest and the iliolumbar ligament (shaded from the transverse process of L5 towards the iliac crest) are almost vertical.
- The fibers that start from the iliac crest and will attach to the transverse processes of the first 4 lumbar vertebrae are oblique.
- The fibers that start from the transverse processes of the 2nd to the 4th or 5th lumbar vertebrae are also oblique but in the opposite direction to the fibers described above.
The group of vertical fibers have a role in controlling the curvature of the lumbar spine.
The oblique fibers play one in the lateroflexion of the lumbar spine.
- Major role in stabilizing the lumbar spine when walking
- Stabilization role of the last rib in forced inspiration and expiration
- In unilateral contraction, the square of the loins leads to lateroflexion of the spine, elevation of the homolateral hip and lumbar scoliosis.
- In bilateral contraction it causes an extension of the spine
Myofascial syndrome of the square muscle of the loins
The pain referred from the trigger points of the square muscle of the loins is located for its deep part at the level of the sacroiliac joint and the lower part of the buttock. The more superficial part of the muscle causes pain in the upper lateral part of the iliac crest with irradiation towards the inguinal fold, the lower part of the iliac fossa and especially next to the greater trochanter:
Referred pain can be intense and increases when standing or sitting, lateral rotation of the trunk. The subject sometimes cannot get out of bed without help from the upper limbs. Coughing or sneezing can be very painful. This pain can be so intense that during the first morning movements, the patient can only move by crawling.
Sometimes the pain can radiate into the inguinal fold, the scrotum, see the territory of the sciatic nerve.
Triggers and maintenance factors
- The most common factor triggering the myofascial syndrome of the square of the loins and the collection of a more or less heavy load the trunk in anterior lateroflexion. Likewise rising from a low, deep seat, getting out of a car, putting on pants while standing leaning forward and to the side can trigger it.
- Car accidents can also be responsible
- Certain trades with repeated positions such as gardening, cleaning floors, carrying heavy loads…
- A unilateral rise in height of the acute hip can also cause it (walking on a side slope, elevation of a plastered limb, etc.)
- Small hemi-basin
- Lower limb length discrepancy
- Arms too short
- Leaning forward position when working
- Mattress too soft
- The patient standing from behind: we find a pelvis inclined downwards on the unaffected side with a scoliotic convexity attitude on the healthy side.
- Palpation of the muscle is difficult due to its depth
- Pinching the skin over the trigger points relieves the pain momentarily
- We will systematically look for a postural asymmetry which maintains the myofascial syndrome.
- Massage and stretching are required
- The correction of a posture disorder is essential.
- Infiltrations of local anesthesia followed by stretching are sometimes effective.
- The dry needling, finds there, an indication of treatment which seems effective.