Trunk muscles in 3D

Groups of trunk muscles

On the back, the superficial layer (trapezius, rhomboids) connects the spine to the shoulder girdle. The intermediate layer, serratus posterior superior and inferior, attaches to the ribs. The deep intrinsic muscles lie in the groove beside the spinous processes: erector spinae, and below it the semispinalis, rotatores, interspinales and intertransversarii.

On the front, pectoralis major and minor, subclavius and serratus anterior cover the thoracic wall. The intercostal muscles, transversus thoracis and levatores costarum fill and move the rib cage, and the dome-shaped diaphragm separates chest from abdomen. Psoas major runs along the lumbar spine, and the pelvic floor closes the outlet of the pelvis.

What the 3D model shows

The muscles and bones view shows over a hundred muscle parts on the trunk skeleton: pectoralis major in its three parts, pectoralis minor, serratus anterior, the trapezius, rhomboids and erector spinae columns, semispinalis, splenius cervicis, supraspinatus, infraspinatus, teres major and minor, the intercostals, diaphragm, external oblique, psoas major and the levator ani, coccygeus and external anal sphincter. The all-systems view adds the vessels, nerves and organs of the trunk, more than 1,100 parts in total.

How to study the trunk muscles

Start in the posterior view and use the muscle layers control to remove one layer at a time: trapezius and rhomboids first, then the serratus posterior muscles, then the three columns of erector spinae, and finally the short muscles between the vertebrae. Switch to the anterior view, hide pectoralis major to reveal pectoralis minor and serratus anterior, and use the inferior view for the pelvic floor. For each muscle you isolate, say its attachments and main action aloud, then close the model and repeat the list from memory.