trunk muscles

erector spinae

Extension, lateral flexion, & ipsilateral rotation of spine & head, Anterior pelvic rotation, Lateral pelvic rotation to contralateral side

quadratus lumborum

Lateral flexion to ipsilateral side, Stabilizes pelvis & lumbar spine, Extension of lumbar spine, Anterior pelvic rotation, Lateral pelvic rotation to contralateral side

rectus abdomnis

Both sides: lumbar flexion, Posterior pelvic rotation,

Right side: weak lateral flexion to right,

Left side: weak lateral flexion to left

sternocleidomastoid  

Both sides: extension of head at atlantooccipital joint & flexion of neck

Right side: rotation to left & lateral flexion to right of head & neck

Left side: rotation to right & lateral flexion to left of head & neck

splenius muscles

Both sides: extension of head (splenius capitis) & neck (splenius capitis & cervicis)
Right side: rotation & lateral flexion to right of head (capitis) & neck
Left side: rotation & lateral flexion to left head (capitis) & neck

external oblique 

Both sides: lumbar flexion Posterior pelvic rotation
Right side: lumbar lateral flexion to right, rotation to left & lateral pelvic rotation to left
Left side: lumbar lateral flexion to left, rotation to right & lateral pelvic rotation to
right

Internal Oblique Abdominal Muscle

Both sides: lumbar flexion Posterior pelvic rotation
Right side: lumbar lateral flexion to right, rotation to right, & lateral pelvic rotation to left
Left side: lumbar lateral flexion to left, rotation to left, & lateral pelvic rotation to
right

Transversus Abdominis Muscle

Forced expiration
by pulling the
abdominal wall
inward