Original Author(s): Sophie Fidoe Show
Original Author(s): Sophie Fidoe The hip bone is comprised of the three parts; the ilium, pubis and ischium. Prior to puberty, the triradiate cartilage separates these parts – and fusion only begins at the age of 15-17. Together, the ilium, pubis and ischium form a cup-shaped socket known as the acetabulum (literal meaning in Latin is ‘vinegar cup‘). The head of the femur articulates with the acetabulum to form the hip joint. We shall now look at the individual parts of the hip bone, and their respective bony landmarks. Fig 2 – The hip bone of a 5 year old, with triradiate cartilage still present. The IliumThe ilium is the widest and largest of the three parts of the hip bone, and is located superiorly. The body of the ilium forms the superior part 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:
The superior margin of the wing is thickened, forming the iliac crest. It extends from the anterior superior iliac spine (ASIS) to the posterior superior iliac spine (PSIS). On the posterior aspect of the ilium there is an indentation known as the greater sciatic notch. Fig 3 – The bony landmarks of the ilium. Clinical Relevance: Anterior Superior Iliac SpineThe anterior superior iliac spine (ASIS) is an important anatomical landmark:
In clinical practice, a patient’s “true” leg length is measured from the ASIS to the medial malleolus at the ankle joint. This is distinct from “apparent” leg length, which is measured from the umbilicus to the medial malleolus. True leg length discrepancy is a feature of various hip disorders, as well as being a potential complication of hip joint replacement (arthroplasty). The PubisThe pubis is the most anterior portion of the hip bone. It consists of a body, superior ramus and inferior ramus (ramus = branch).
Together, the superior and inferior rami enclose part of the obturator foramen – through which the obturator nerve, artery and vein pass through to reach the lower limb. Fig 4 – Bony landmarks of the pubis. Fig 5 – The orientation of the hip bones within the pelvis. Clinical Relevance – Pubic Rami FracturesPubic rami fractures can sometimes be observed on x-rays in elderly patients who are investigated after simple low energy falls from standing height. In this context and provided they are the only injury a patient has sustained, these fractures are usually treated without surgery. Healing can be expected within 6-8 weeks and patients are encouraged to fully weight bear straightaway. The IschiumThe ischium forms the posteroinferior part of the hip bone. Much like the pubis, it is composed of a body, an inferior ramus and superior ramus. The inferior ischial ramus combines with the inferior pubic ramus forming the ischiopubic ramus, which encloses part of the obturator foramen. The posterorinferior aspect of the ischium forms the ischial tuberosities and when sitting, it is these tuberosities on which our body weight falls. Near the junction of the superior ramus and body is a posteromedial projection of bone; the ischial spine. Two important ligaments attach to the ischium:
Read more about the greater and lesser sciatic foramen here. Fig 6 – Bony landmarks of the ischium. Clinical Relevance: Pelvic FracturesThere are two broad groups of pelvic fractures:
In the context of a high energy major trauma patient, the pelvis can be a major source of bleeding due to fracture. As a result, major trauma patients are assumed to have a pelvic fracture until proven otherwise and a ‘pelvic binder’ is used to stabilise the pelvis and minimise further bleeding. Circumferential pressure is applied by the binder at the level of the greater trochanters – an important anatomical landmark. By James Heilman, MD [CC-BY-SA-3.0], via Wikimedia Commons Fig 7 – X-Ray demonstrating an acetabular fracture (arrow). This website uses cookies. We use cookies to improve your experience on our site and to show you relevant advertising. To find out more, read our privacy policy. What 3 bones make up the acetabulum?Bones and Joints
The ball of the hip joint is made by the femoral head while the socket is formed by the acetabulum. The Acetabulum is a deep, circular socket formed on the outer edge of the pelvis by the union of three bones: ilium, ischium and pubis.
Which of the following is involved in the formation of acetabulum?So, the correct option is 'Ilium, Ischium, Pubis'.
Which bones form the acetabulum 1 ilium ischium pubis?Acetabulum- It is a cavity formed by the fusion of ilium, ischium and pubis. The femur or thigh bone articulates with the acetabulum. The coccyx is attached to the lower part of the sacrum by sacrococcygeal symphysis. Obturator foramen- It is the large opening between the ischium and the pubis bone.
Which of the following bones participate in the formation of the acetabulum 1 ilium 2 ischium 3 pubis quizlet?The three bones; ilium, ischium, and pubis, join together to form the acetabulum.
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