Erector Spinae
Short definition
The muscle groups that extend and rotate the spine and hold posture.
Full definition
The erector spinae is a long group running alongside the spine: longissimus (from iliac crest, lower ribs and spinous processes of the lumbar/thoracic vertebrae to the skull), iliocostalis, multifidus (deep). Functions: extension and lateral flexion of the trunk, segmental stabilization of the spine; the main antagonist of the abdominal musculature. Mass ≈ 2.5–3 % of body mass (at 20–25 % body fat). A prime mover for rows, good-morning and isometric back holds.
Examples
Bent-over row — the erectors hold the torso.