In this anatomy lesson, ns going come cover the pelvic girdle, which is composed of the 2 hip bones. The hip skeleton are described by various names, such together os coxae or coxal bones, innominate bones, or the pelvic bones.

You are watching: Identify the region of the coxal bone that articulates with the sacrum.

The pelvic girdle is part of the appendicular skeleton, and it not just protects the organs in your pelvic region, but it also attaches the lower limbs that the appendicular skeleton come the sacrum that the axial skeleton.

Are the Hipbones Classified as Irregular or level Bones?

Most anatomists this particular day classify the i know good bones as irregular bones, though part sources have actually classified lock as flat bones in the past, therefore be conscious of that.

Hip Bone Anatomy (Pelvic Girdle)

Each i know well bone is split into three key regions: The ilium, ischium, and also pubis. These 3 regions start as different bones in youth, however they later on fuse with each other to kind one heavy hip bone. The image below is fancy to aid you visualize the various areas, which help in identify landmarks.


These 3 hip regions satisfy in and around the acetabulum, i beg your pardon is the deep socket the the hip bone. The acetabulum is conveniently recognized in a rap exam, and also it receive the head that the femur to kind the acetabulofemoral joint, a ball-and-socket synovial joint.

The indigenous acetabulum sounds a lot like “acid tablets,” and also the indigenous literally means vinegar cup. So ns remember the this is the tiny cup that vinegar the I should swallow my mountain tablets.

Now let’s talk about each major region of the i know good bone, starting with the ilium.

Ilium Anatomy Landmarks and Features

The ilium renders up the remarkable (or upper) an ar of the i know well bone, and also it is called after a Latin word that method “flank” or “entrails,” because that’s what the supports.

The ilium deserve to be subdivided into two portions:

an inferior an ar (near the acetabulum) called the “body”a superior, fanned out part called the “wing,” or alaAnterior exceptional iliac spine – ~ above the anterior (or front) next of the ilium, the ilium has two points (spines). The superior (or top) spine is referred to as the anterior superior iliac spine, and also it permits for the attachment of the inguinal ligament, and also the sartorius muscle.Anterior worse iliac spine – The anterior worse iliac spine allows for the attachment of the the rectus femoris muscle, as well as the iliofemoral ligament that the i know good joint.Posterior premium iliac spine – ~ above the posterior (or back) side of the ilium, we also have two spines. The posterior premium (top) iliac spine permits for the attachments of component of the posterior sacroiliac ligaments, and the multifidus.Posterior worse iliac spine – The posterior worse (lower) iliac spine is just below the exceptional iliac spine.Greater sciatic notch – just under the posterior worse iliac spine, you’ll notice a large notched area, i m sorry is called the better sciatic notch. This notch allows for the i of the sciatic nerve, and also it will help you identify the posterior region of the hip bone.Gluteal surface – indigenous the lateral (side) see of the ilium, you have the right to see three distinctive lines top top the ala (wing) the are named after their loved one directional terms (posterior, anterior, and also inferior gluteal lines). These lines provide attachment for gluteal muscles.Iliac fossa – once you flip the hip bone around and look at the medial (inner) view, you’ll notice the big depression in ~ the anterior region, called the iliac fossa. This is wherein the iliacus muscle attaches.Auricular surface – The auricular surface is ~ above the posterior an ar of the ilium, and also this articulates v the sacrum that the vertebral tower to kind the sacroiliac joint.Arcuate line – Finally, we have actually a significant line top top the medial side the extends native the auricular surface ar down to the pubis, referred to as the arcuate line. This heat serves as a landmark the separates the human body of the ilium from the ala (wing).

Ischium Anatomy Landmarks and Features

Now let’s talk about the ischium the the hip bone (coxal bone), i beg your pardon is the lower rear portion (or posterior inferior region) the the hip bone.

Like the ilium, the ischium deserve to be divided into two key regions:

The ischial body, which renders up the superior an ar of the ischium and forms about two-fifths that the acetabulumThe ischial ramus, i m sorry is a branch-like framework that makes up the inferior section of the ischium and also connects to the worse ramus of the pubisIschial spine – ~ above the posterior region, you’ll notice a projection called the ischial spine. This enables for the attachment of various muscles and also ligaments: gemellus superior, coccygeus, levator ani, pelvic fascia, and also sacrospinous ligament.Lesser sciatic notch – below the ischial spine is the lesser sciatic notch, which allows the i of nerves and vessels.Ischial tuberosity – ~ above the lateral next of the ischium is the ischial tuberosity, a roughened bang that permits for the attachments of the sacrotuberous ligament, and several muscles: adductor magnus, the biceps femoris, and also the semitendinosus.

Pubis Anatomy Landmarks and Features

Finally, we have actually the last major section of the i know good bone, the pubis. Words pubis method “sexually mature,” and also by thinking of your pubic region and private parts, you can remember that this is the area of the i know well bone that is the anterior (front) portion. You can usually feel her pubic bone if you palpate in the region.


Like the ischium and also ilium, the pubis additionally has a body, however it has actually two rami coming off the body, which permit for the attachment of miscellaneous muscles and also ligaments.

Superior ramus – The exceptional ramus is the upper part of the pubis the branches out. There is a ridge on superior border of this ramus dubbed the pectineal line, which permits for the attachment of miscellaneous ligaments and muscles, and also it forms part of the pelvic brim. Some of the frameworks that attach to this encompass the lacunar ligament, conjoint tendon, pectineal ligament, pectineus muscle, and also psoas young muscle.Inferior ramus – The inferior ramus is the lower part of the pubis that branches out.Obturator foramen – These two rami that the pubis join the ischium, forming a large hole in the hip bone dubbed the obturator foramen. The word foramen refers to a feet in a bone, and this is the largest “bone hole” in the human body. This huge hole permits for the passage of the obturator artery, vein, and also nerve. The obturator muscles likewise attach close to this region. I had actually an anatomy professor in college who told us that come remember the obturator muscle, we have the right to imagine a man running his hand up a girl’s leg, reasoning that he’s some type of smooth obturator (like the song).Pubic crest – top top the anterior (front) next of the pubis body, you’ll find a rim of bone dubbed the pubic crest, which permits for the attachments of the inguinal falx, and the abdominal external oblique and pyramidalis muscles.Pubic tubercle – over there is a little bump whereby the pubic stakes (laterally) joins with the remarkable pubic ramus (medially), dubbed the pubic tubercle, to which the inguinal ligament attaches.Pubic symphysis (or symphysis pubis) – The 2 pubic bones space joined with each other by a cartilaginous joint called the pubic symphysis, which is a nonsynovial amphiarthrodial joint.

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Free Quiz and an ext Anatomy Videos

Take a free hip skeleton anatomy quiz come test your knowledge. In addition, you could want to watch our anatomy and also physiology lectures top top YouTube, or check our anatomy and also physiology notes.