Final answer:
The levator ani muscles, consisting of the pubococcygeus and iliococcygeus, meet on the anococcygeal ligament and play a key role in pelvic floor support and functions like defecation and childbirth.
Step-by-step explanation:
The muscles that have left and right portions that meet on the anococcygeal ligament are the levator ani muscles. These muscles include the pubococcygeus and the iliococcygeus, which form a part of the pelvic diaphragm. The levator ani is crucial for supporting the pelvic viscera and plays a vital role in functions such as defecation and childbirth. It also creates skeletal muscle sphincters at the urethra and anus.