Bones of the lower limb

The foot bone’s connected to the...leg bone. And the leg bone’s connected to the... thigh bone! Alright, as a quick recap… just kidding. The lower limbs actually have an incredibly detail-rich skeleton that can be divided into two functional components: the pelvic girdle, which connects the lower limb to the axial skeleton, and the bones of the free lower limb. 

The pelvic girdle is a bony ring, known as the pelvic ring, consisting of the right and left hip bones, and the sacrum which is common to both the pelvic girdle and axial skeleton. Each hip bone consists of the ilium, ischium, and pubic bone and has three articulations. Posteromedially, it articulates with the sacrum at the sacroiliac joint, anteromedially  it articulates with the other hip bone at the pubic symphysis. And finally, it articulates with the head of the femur to form the hip joint. 

Ok so, the ilium is the largest and most superior part of the hip bone and it can be divided into a body and a wing. The wing, or ala of the ilium,has a lateral and a medial surface, a crest, and two borders: anterior and posterior. Superiorly, there's the iliac crest, which begins at the anterior superior iliac spine and it extends posteriorly to the posterior superior iliac spine. The crest has an internal and external lip, and serves as an important attachment site for muscles and deep fascia. Next, the lateral surface of the ala has three rough arched lines called the posterior, anterior, and inferior gluteal lines, where the gluteal muscles attach, which are the muscles of your bottom. Next, the medial surface can be divided into two by the internal lip of the iliac crest. The anterior portion is concave, and it forms the iliac fossa - which is where the iliacus muscle attaches. 
The posteromedial portion is rough and it presents the auricular surface - which is shaped like an ear and articulates with an identical surface on the sacrum to form the sacroiliac joint.. Next, the anterior border presents the anterior superior iliac spine superiorly, where the inguinal ligament and the sartorius muscle attach; and underneath it there’s the anterior inferior iliac spine, where the straight head of the rectus femoris muscle and the iliofemoral ligament of the hip joint attach. Finally, the posterior border has a posterior superior iliac spine, which is where the oblique portion of the posterior sacroiliac ligaments and the multifidus muscle attach. Underneath it, there’s the posterior inferior iliac spine, below which is a deep notch, the greater sciatic notch. Ok, so the ala continues inferiorly with the body of the ilium, which joins the pubis and ischium to form the acetabulum.