Principle muscle of trunk

Sacrospinalis

Diaphragm

External abdominal oblique

Internal and External Intercostals

Perineum

Levator ani

dome forms the partition between the thoracic cavity and abdominal cavity below (moves down with inhalation)

Compresses abdominal cavity, expel substances from body, and flex spinal column.

elevate ribs and enlarge thoracic cavity attached to a fill the spaces between the ribs (lie at angles in opposite directions to each other)

aids defecation, support the pelvic viscera (posterior from tip of the coccyx to the anal canal)

extends vertebral column to produce erect posture (long and thick below the trapezium and latissimus)

floor of pelvis, provides support (horizontal lie near genitalia)