What are the parts of the birth canal?

The birth canal is the passage for the fetus to leave the mother and come into this world. If the birth canal is deformed, narrow or impassable, it will affect normal delivery. The birth canal is divided into soft birth canal and bone birth canal.

Soft birth canal

The soft birth canal is mainly composed of the lower uterus, cervix, pelvic floor soft tissue, vagina and perineum.

Bone birth canal

The bone birth canal is a real pelvis, which consists of cuboid bone (5 joints), coccyx bone (3 joints) and left and right bones. Every bone and muscle is made up of 1 bone, pubic bone and ischium, which are connected by ligaments and joints. The pelvis is divided into three planes: entrance, middle cavity and exit, which have different shapes. The entrance is transverse oval, the middle cavity and the exit are oblong, and the pelvic axis extends forward and downward. Therefore, the fetus can only pass through the bone birth canal through different movements during childbirth. If any plane of the bone birth canal is narrow or deformed, it may cause dystocia.