Levator ani muscles

The levator ani is the largest component of the pelvic floor. It forms a dome-shaped muscular sheet and is composed of three muscles:

The levator ani muscles attach to the internal surfaces of the pubic bodies and rami anteriorly, ischial spines laterally, and coccyx and sacrum posteriorly. 

These muscles also attach to the obturator fascia. The iliococcygeus attaches more specifically to the arcus tendineus, which is a condensation of the mentioned fascia. The arcus tendineus lies on the lateral and anterior aspect of this area and goes from the inner anterior aspect of the inferior pubic ramus to the ischial spine along the inferior border of the obturator internus muscle

Note: The puborectalis sometimes is regarded as a component of the external anal sphincter distinct from the levator ani muscles because of its developmental and histological differences.