This information has been displayed with the kind permission of SportsInjuryClinic and Get Body Smart who can be found at the links below:
Origin: Lateral and medial sacral crest and medial iliac crests.
Insertion: Angles of ribs 7-12, medial to insertions of iliocostalis lumborum.
Actions: Bilateral action extends the spine. Unilateral contraction laterally flexes the vertebral column.
Innervation: Dorsal rami of thoracic spinal nerves .
Daily uses: Maintaining straight spine in standing.
Other muscles of the Rotator Cuff
Origin: Supraspinous fossa
Insertion: Greater tuberosity of the humerus
Actions: Abduction Stabilisation of the humerus
Innervation: Suprascapular nerve
Daily uses: Holding shopping bags away from the body
Origin: Mid section of the lateral border of the scapula
Insertion: Greater tuberosity on the humerus
Actions:External rotation, Shoulder adduction
Innervation: Axillary nerve
Daily uses: Brushing hair
Origin: Anterior (costal) surface of the scapula
Insertion: Lesser tuberosity of the humerus
Actions: Internal rotation , Adduction
Innervation: Upper and lower subscapular nerves
Daily uses: Tucking the back of your shirt into your trousers