Bones Of Pelvis

Question 1

What is the hip bone?

Answer 1

Large flat bone part of pelvic girdle

2 symmetrical hip bones aka innominate bones, pelvic bones

Question 2

What is the hip bone composed of?

Answer 2

Ilium, ischium, pubis
The triradiate cartilage separates these constituents pre-puberty, at age of 15-17 they fuse

Fusion forms a socket known as the acetabulum - fusion completed at 20-25 yrs

Question 3

Bony landmarks of ilium

Answer 3

Body forms the superior part of acetabulum
Immediately above, ilium expands to form the wing
Wing has 2 surfaces - inner = iliac fossa (provides origin to iliacus muscles), external = provides attachment to gluteal muscles hence it is known as the gluteal surface
Superior margin is thickened forming the iliac crest - extends from ASIS to PSIS

Question 4

What muscles attach to ilium?

Answer 4

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

Question 5

Why is the ASIS an important anatomical landmark?

Answer 5

Halfway between ASIS and pubic symphysis is the mid inguinal point - the femoral artery can be palpated here

Halfway between ASIS and pubic tubercle is the mid point of the inguinal ligament

Question 6

What is the pubis? Bony landmarks

Answer 6

Most anterior portion of hip bone

Body - medial, articulates with opposite pubic body at the pubic symphysis
Superior ramus - extends laterally forming part of acetabulum
Inferior ramus - joins the ischium

The two rami enclose part of the obturator foramen - where obturator nerve artery and vein pass

Question 7

What is the ischium?

Answer 7

The posterior & inferior portion of the pelvis.

Question 8

What ligaments attach to ischium?

Answer 8

Sacrospinous - ischial spine to sacrum, creates greater sciatic foramen through which lower limb vasculatur incl. sciatic nerve run

Sacrotuberous - sacrum to ischial tuberosity forming lesser sciatic notch

Question 9

Fractures of pelvic girdle

Answer 9

2 common ways:
Direct trauma eg vehicular accident
Forces transmitted from the lower limb eg heavy fall on feet

Often occur at weaker points of bones - pubic rami, acetabulum, region of sacroiliac joint

Common implication = soft tissue injury. Bladder and urethra are at high risk of damage

Question 10

What is pelvic girdle?

Answer 10

the basin-shaped structure that attaches the lower limbs to the axial skeleton

Question 11

Structure of pelvic girdle

Answer 11

2 hip bones, sacrum and coccyx

Question 12

Articulations within pelvis

Answer 12

Sacroiliac x2 - between ilium of hip bones and sacrum
Sacrococcygeal symphysis - sacrum and the coccyx
Pubic symphysis - between pubic bodies of the two hip bones

Question 13

Functions of pelvis

Answer 13

Transfer weight from upper axial skeleton to lower appendicular components of the skeleton esp during movement
Provides attachment for a number of muscles and ligaments used in locomotion
Contains and protects the abdominopelvic and pelvic viscera

Question 14

Bony landmarks of ischium

Answer 14

Inferior ischial ramus + inferior pubic ramus = is hip pubic ramus which enclosed part of obturator foramen

Posteroinferior aspect forms ischial tuberosities - when sitting, it is these tuberosities on which body weight falls

Posterior aspect = indentation known as greater sciatic notch with the ischial spine at its most inferior edge