The left and right hip bones (innominate bones, pelvic bones) room two irregularly shame bones that kind part that the pelvic girdle – the bony framework that attaches the axial skeleton to the reduced limbs.

You are watching: The projection at the inferior end of the greater sciatic notch is the ischial spine.

The i know good bones have actually three key articulations:

Sacroiliac joint – articulation v the sacrum.Pubic symphysis – articulation between the left and also right hip bones.Hip joint – articulation through the head the femur.

In this article, us shall look in ~ the anatomy that the hip bones – your composition, bony landmarks, and clinical relevance.


Fig 1 – synopsis of the anatomical position of the i know good bones.

Composition the the i know well Bone

The i know good bone is comprised of the 3 parts; the ilium, pubis and also ischium. Prior come puberty, the triradiate cartilage the end these components – and fusion only begins at the age of 15-17.

Together, the ilium, pubis and also ischium kind a cup-shaped socket well-known as the acetabulum (literal meaning in Latin is ‘vinegar cup‘). The head that the femur articulates through the acetabulum to kind the i know well joint.

We shall currently look at the individual components of the hip bone, and also their corresponding bony landmarks.


Fig 2 – The i know good bone that a 5 year old, through triradiate cartilage quiet present.

The Ilium

The ilium is the widest and largest of the three components of the i know good bone, and is situated superiorly. The body of the ilium forms the superior component of the acetabulum (acetabular roof). Immediately above the acetabulum, the ilium expands to form the wing (or ala).

The wing of the ilium has two surfaces:

Inner surface – has a concave shape, i m sorry produces the iliac fossa (site of origin of the iliacus muscle).External surface (gluteal surface) – has a convex shape and provides attachments to the gluteal muscles.

The exceptional margin that the soup is thickened, creating the iliac crest. It extends from the anterior superior iliac spine (ASIS) come the posterior exceptional iliac spine (PSIS).

On the posterior facet of the ilium there is an indentation well-known as the greater sciatic notch.


Fig 3 – The bony landmarks that the ilium.

Clinical Relevance: Anterior remarkable Iliac Spine

The anterior superior iliac spine (ASIS) is an essential anatomical landmark:

Mid-inguinal point – halfway in between the ASIS and the centre of the pubic symphysis. The femoral artery can be palpated here.Mid-point of the inguinal ligament – halfway between the ASIS and the pubic tubercle.

In clinical practice, a patient’s “true” leg length is measured from the ASIS come the medial malleolus at the fishing eye joint. This is distinctive from “apparent” leg length, which is measured indigenous the umbilicus to the medial malleolus.

True leg length discrepancy is a function of assorted hip disorders, and being a potential complication of hip share replacement (arthroplasty).

The Pubis

The pubis is the many anterior section of the hip bone. It consists of a body, premium ramus and inferior ramus (ramus = branch).

Pubic body – situated medially, the articulates with the the opposite pubic body at the pubic symphysis. That is superior facet is marked by a rounded thickening (the pubic crest), which extends laterally as the pubic tubercle.Superior pubic ramus – extends laterally native the human body to type part of the acetabulum.Inferior pubic ramus – jobs towards the ischium.

Together, the superior and inferior rami enclose component of the obturator foramen – through i beg your pardon the obturator nerve, artery and also vein pass with to with the reduced limb.


Fig 4 – Bony landmarks the the pubis.


Fig 5 – The orientation of the i know good bones in ~ the pelvis.

Clinical relationship – Pubic Rami Fractures

Pubic rami fractures can sometimes be observed on x-rays in elderly patients who room investigated after simple low energy falls indigenous standing height. In this paper definition and listed they are the only injury a patient has sustained, this fractures space usually treated without surgery.

Healing deserve to be expected within 6-8 weeks and also patients are motivated to fully weight be afflicted with straightaway.

The Ischium

The ischium forms the posteroinferior component of the i know well bone. Much like the pubis, the is created of a body, an worse ramus and also superior ramus.

The inferior ischial ramus combines with the inferior pubic ramus developing the ischiopubic ramus, i m sorry encloses part of the obturator foramen. The posterorinferior facet of the ischium creates the ischial tuberosities and also when sitting, that is these tuberosities on which our body load falls.

Near the junction of the exceptional ramus and also body is a posteromedial estimate of bone; the ischial spine.

Two crucial ligaments attach to the ischium:

Sacrospinous ligament – operation from the ischial spine to the sacrum, thus creating the better sciatic foramen through which reduced limb neurovasculature (including the sciatic nerve) transcends.Sacrotuberous ligament – runs from the sacrum come the ischial tuberosity, forming the lesser sciatic foramen.

Clinical Relevance: Pelvic Fractures

There space two wide groups of pelvic fractures:

Low power injuries:For example, a simple fall native standing height in one osteoporotic patient resulting in pubic rami fracture.These room usually ‘stable’ injuries, no requiring surgery.High energy injuries with direct ortransfer trauma:For example, after a high speed roadway traffic accident. These result in an ext extensive fractures i m sorry may incorporate the acetabulum and also sacroiliac joint.These deserve to be ‘unstable’ injuries and may need urgent surgery.Higher power injuries can be associated with soft tissue and also vascular injury. In particular, the bladder and urethra are at high hazard of damage. Vascular injury can an outcome in life threatening haemorrhage.

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In the context of a high energy major trauma patient, the pelvis deserve to be a significant source of bleeding because of fracture. As a result, significant trauma patients space assumed to have a pelvic fracture until proven otherwise and a ‘pelvic binder’ is provided to stabilise the pelvis and minimise additional bleeding. Circumferential press is applied by the binder in ~ the level that the greater trochanters – crucial anatomical landmark.