It is made up of 3 groups of fibres:
- At the top, muscle fibers insert on the first rib and join behind the scapula.
- Intermediate, groups of fibers are inserted on the 2nd and 3rd rib to join the median part of the scapula
- The third group of fibers inserts on the next 5 or 6 ribs to go on the tip of the scapula. This muscle group is the strongest muscle.
- Participates in flexion and abduction of the arm
- Brings the scapula forward (in protraction)
- Raises the scapula (lower part of the muscle)
- Attachment of the scapula to the thorax (middle part)
- Supports the thorax during efforts of antepulsion of the arm (push-ups)
- The lowest fibers would cause a drop in the scapula (controversial)
Serratus Anterior Myofascial Syndrome
The pain can be permanent in severe cases. Otherwise it can occur during deep breathing. Besides, deep inspiration is limited by pain.
The appearance of this syndrome may be linked to prolonged muscular effort leading to a marked increase in minute ventilation, coughing, traction, lifting a heavy load above the head.
When the serratus anterior is stretched, the scapula pars forward causing the upper edge and spine of the scapula to protrude. The patient describes easy shortness of breath. Palpation finds painful points on the axillary line, generally at the level of the 5th and 6th ribs.
- Stretching, patient in contralateral lateral decubitus, with backward movement of the arm and associated deep inspiration.
- Ischemic compression of painful points on the thorax then stretching as described above
- Infiltration of local anesthetic in the painful points followed by the stretching described above.
- We will avoid the movements that triggered the first decompensation, breathing movements like deep inspiration will be performed.
- At night, in contralateral lateral decubitus, the arm will be wedged with a pillow in order to avoid the shortening of the muscle.