Major Muscles that Act on the Trunk

Question 1

Muscle: Rectus abdominus

Answer 1

Primary Function(s):
Flexes the spine and posteriorly tilts the pelvis

Resistance Exercise(s):
Bent-knee crunches, posterior pelvic tilts

Question 2

Muscle: External oblique

Answer 2

Primary Function(s):
Rotates and laterally flexes the trunk

Resistance Exercise(s):
Twisting crunches, cable rotations, sideways crunches

Question 3

Muscle: Internal oblique

Answer 3

Primary Function(s):
Rotates and laterally flexes the trunk

Resistance Exercise(s):
Twisting crunches, cable rotations, sideways crunches

Question 4

Muscle: Transverse abdominus

Answer 4

Primary Function(s):
Compresses the abdomen and braces the lumbar spine

Resistance Exercise(s):
Sucking in your stomach while exhaling

Question 5

Muscle: Erector spinae

Answer 5

Primary Function(s):
Extends and laterally flexes the spine

Resistance Exercise(s):
Deadlifts, prone back extensions, 4-point kneeling pointing dog (bird dog)

Question 6

Muscle: Multifidi

Answer 6

Primary Function(s):
Contributes to spinal stability during trunk extension, rotation and lateral flexion

Resistance Exercise(s):
4-point kneeling pointing dog (bird dog)