Muscles of the Trunk

These muscles stabilise the association between the appendicular and axial skeletons. There are six pairs of large muscles in the back, in addition to those forming the posterior abdominal wall. These six pairs of muscles are arranged the same on either side of the back. These are the shown in the table below:

TrapeziusMedial third of the superior nuchal line
External occipital protuberance
Ligamentum nuchae
Spinous processes of vertebrae C7-T12
Lateral third of the clavicle
Medial side of the acromion and the upper crest of the scapular spine
Tubercle of the scapular spine
Elevates and depresses the scapula (depending on which part of the muscle contracts)
Rotates the scapula superiorly; retracts scapula
Latissimus DorsiVertebral spines from T7 to the sacrum
Posterior third of the iliac crest
Lower 3 or 4 ribs, sometimes from the inferior angle of the scapula
 iliac crest
Lower 3 or 4 ribs, sometimes from the inferior angle of the scapula
Floor of the intertubercular groove
Extends the arm
Rotates the arm medially
Quadratus Lumborum

Posterior part of the iliac crest
Iliolumbar ligament
Transverse processes of lumbar vertebrae 1-4
12th rib
Laterally bends the trunk
Fixes the 12th rib
muscle anatomy – the quadratus lumborum
Psoas MajorBodies and transverse processes of lumbar vertebraeLesser trochanter of femur via iliopsoas tendonFlexes the thigh
Flexes & laterally bends the lumbar vertebral column
muscle anatomy – the psoas major
Erector SpinaeIliac crest
Transverse and spinous processes of vertebrae
Supraspinal ligament
Angles of the ribs
Transverse and spinous processes of vertebrae
Posterior aspect of the skull
Extends and laterally bends the trunk, neck and head