The Hip Bone

Question 1

What is the pelvic girdle?

Answer 1

The two symmetrical hip bones (pelvic bones), are part of the pelvic girdle, the bony structure that attaches the axial skeleton to the lower limbs.

Question 2

What are the three articulations of the hip bones?

Answer 2

Sacroiliac joint - articulation with the sacrum
Pubic symphysis - articulation with the corresponding hip bone
Hip joint - articulation with the head of femur

Question 3

Name the 3 components of the hip bone

Answer 3

Ilium
Pubis
Ischium

Question 4

What separates the 3 components of the hip bone prior to puberty?

Answer 4

The triradiate cartilage

At the age of 15-17, the three parts begin to fuse

Question 5

What does the fusion of the three parts of the hip bone form?

Answer 5

Their fusion forms a cup-shaped socket known as the acetabulum, which becomes complete at 20-25 years.
The head of femur articulates with the acetabulum to form the hip joint.

Question 6

Describe the Ilium

Answer 6

Forms the superior part of the hip bone
It is the largest and widest of the three parts
The body of the ilium forms the superior part of the acetabulum, immediately above the acetabulum the ilium expands to form the wing.

Question 7

Describe the wing of the ilium

Answer 7

The wing of the ilium has two surfaces. The inner surface is concave and known as the iliac fossa, providing origin to the iliacus muscle. The external surface is convex, providing attachment to the gluteal muscles, hence it’s known as the gluteal surface. The superior margin of the wing is thickened, forming the iliac crest. It extends from the anterior superior iliac spine to the posterior superior iliac spine

Question 8

Name the muscles attaching to the ilium

Answer 8

The gluteal muscles attach to the external surface of the ilium at the anterior, posterior and inferior gluteal lines
The iliacus muscle attaches medially to the iliac fossa

Question 9

What is the anterior superior iliac spine (ASIS) and why is it important?

Answer 9

ASIS is an important landmark, serving as the attachment site of the inguinal ligament, which runs from the ASIS to the pubic tubercle. Midway along the inguinal ligament, the femoral artery can be palpated, with the femoral vein lying medially.

Question 10

Describe the pubis

Answer 10

The pubis is the most anterior portion of the hip bone. It consists of a body and super and inferior rami (branches). The body is located medially, articulating with its opposite pubic body, at the pubic symphysis.
The superior ramus extends laterally from the body, forming part of the acetabulum. The inferior ramus projects towards, and joins the ischium. Together, the two rami enclose part of the obturator foramen, through which the obturator nerve, artery and vein pass through to reach the lower limb.

Question 11

Describe the Ischium

Answer 11

The posterioinferior part of the hip bone is formed by the ischium. It’s composed of a body, an inferior and a superior ramus.
The inferior ischial ramus combines with the inferior pubic ramus forming the ischiopubic ramus which encloses part of the obturator foramen. The posteroinferior aspect of the ischium forms the ischial tuberosities and when sitting, it is these tuberosities on which our body weight falls.
On the posterior aspect of the ischium there is an indentation known as the greater sciatic notch, with the ischial spine at its most inferior edge.

Question 12

Name the two ligaments which attach to the ischium

Answer 12

The sacrospinous ligament - runs from the ischial spine to the sacrum, thus creating the greater sciatic foramen through which lower limb neurovasculature (including the sciatic nerve) transcends
The Sacrotuberous ligament - runs from the sacrum to the ischial tuberosity, forming the lesser sciatic foramen