Muscles
Rotatores
Muscle that originates on the transverse process of one vertebral segment, inserts on the spinous process of the first or second vertebral segment above, and the actions are rotates the vertebral column (unilateral contraction) and extends the vertebral column (bilateral contraction).
Iliocostalis
Muscles that hug the costals (ribs).
Spinalis
Originates on spinous processes of C4-T12 and the nuchal ligament. Inserts on the spinous processes of C2-T8 and the occipital bone (between the superior and linferior nuchal line). The actions are; laterally flexes the vertebral column (unilateral contraction), extends the vertebral column (bilateral contraction), and extends the head (bilateral contraction).
Iliocostalis
Origins; posterior iliac crest, posterior sacrum, ribs 1-12 (posterior surface). Insertions; ribs 1-12 (posterior surface), transverse processes of C4-C7. Actions; laterally flexes the vertebral column (unilateral contraction), extends the vertebral column (bilateral contraction).
Semispinalis
The origin of this muscle is the transverse process of one vertebral segment (cervical and thoracic regions), the insertion is the spinous process of the fifth, sixth, and seventh vertebral segments above (cervical and thoracic regions except C1), and the actions are; rotates the vertebral column (unilateral contraction) and extends the vertebral column (bilateral contraction).
Erector Spinae
This muscle group refers to the action--erection of the spine.
Spinalis
This muscle hugs the spine spine and lies in the lamina groove (or between the tranverse and spinous processes)
Quadratus Lumborum
This muscle is known as the "hip hiker" muscle, since it hikes up the leg.
Rotatores
This muscle is the deepest of the transversospinalis group and spans one to two vertebrae.
Longissimus
This muscle is the intermediate track of the erector spinae and covers a long territory stretching from sacrum to skull.
Semispinalis
This muscle is the most superficial of the transversospinalis and is one of the strongest muscles of the neck.
Quadratus Lumborum
This muscle originates in the posterior iliac crest, inserts on rib 12 (inferior surface) and the transverse processes of L1-L4, and it's actions are; laterally flexes the vertebral column (unilateral contraction), elevates the hip (unilateral contraction), extends the lumbar spine (bilateral contraction) and anteriorly tilts the pelvis (bilateral contraction).
Longissimus
This muscle originates on the posterior sacrum, spinous processes of T1-L5, and the transverse processes of C4-T12. The insertions are the mastoid process, transverse processes of C2-T12. Insertions are; mastoid process, the transverse processes of C2-T12, and ribs 4-12 (posterior surface). Actions are; laterally flexes the vertebral column (unilateral contraction), rotates the vertebral column (unilateral contraction), extends the vertebral column (bilateral contraction), and extends the head (bilateral contraction).
Multifidus
This muscle originates on the transverse process of one vertebrae segement, inserts on the spinous processes of the 2nd, 3rd and 4th vertebral segments above, and the actions are; rotates the vertebral column (unilateral contraction), laterally flexes the vertebral column (unilateral contraction), and extends the vertebral column (bilateral contraction).
Multifidus
This muscle spans 2-4 vertebrae and lies over the rotatores.
