What is the bone located at the top of the os coxae?

Answer 1

The pelvis is the bony structure located at the base of the spine (properly known as the caudal end). The pelvis incorporates the socket portion of the hip joint for each leg (in bipeds) or hind leg (in quadrupeds). It forms the lower limb (or hind-limb) girdle of the skeleton
The pelvis is symmetrical and each side is actually made up of three separate bones:

***The upper half (the broad "wings") is the ilium.
The middle (the top half of the lower "loops") is the pubis.
The bottom (the lower half of the "loops") is the ischium
These three bones fuse together with age and are collectively known as the hip bone, OS COXAE, or the innominate bone. The pelvis is joined to the sacrum bone by ligaments (the sacroiliac joint), and the hip bones nest in specially shaped sockets (the acetabulum) on each side. The upper edge of the ilium is known as the iliac crest. The place at the front of the pelvis where both pubis bones join together is called the symphisis pubica. This is normally a very inflexible joint, but it softens and becomes more flexible during late pregnancy, allowing it to expand during labour for the baby's head to pass through