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ANATOMY
Medicine Made Simple
, Hip bone
The innominate or hip bone is formed of three bones, which fuse in a Y-shape, in the
acetabulum.
The anterior two-thirds of the ilium forms the iliac fossa, part of the posterior abdominal
wall.
The posterior one-third carries the auricular surface for the sacrum
The outer surface of the ilium gives attachment to buttock muscles.
In the anatomical position of the bone, the pubic tubercle and anterior superior iliac spine lie
in the same vertical plane, and the upper border of the symphysis pubis and the ischial spine
lie in the same horizontal plane.
Lateral surface of the hip bone
The acetabulum is a concave hemisphere which is directed downwards and slightly
backwards along the axis of the femoral neck.
There is a deficiency at its inferior margin, the acetabular notch.
The hyaline cartilage lining the inside of the acetabulum over the iliac part of the fossa
overlies the weight-bearing area.
Pubis and ilium meet at the iliopubic eminence on the anterior margin of the acetabulum
The convex upper margin of the ilium, the iliac crest, extends from the anterior superior iliac
spine to the posterior superior iliac spine.
The tubercle of the iliac crest lies 5cm behind the anterior superior spine and forms the most
lateral part of the bony pelvis, but not the highest part.
The line between the highest points of the two iliac crests, the supracrestal plane – L4
The tubercle -L5
The posterior superior iliac spine makes a characteristic dimple (Venus dimple) in the skin of
the buttock - S2
The gluteal surface of the ilium shows three curved gluteal lines. (ant., pos., inf.)
The fascia lata is attached along the whole length of the external lip of the iliac crest
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, Pubis
The body of the pubis projects laterally as a superior ramus which joins the ilium and ischium
at the acetabulum
Inferior ramus fuses with the ischial ramus medial to the obturator foramen.
The symphyseal surface of the body forms the secondary cartilaginous joint that constitutes
the pubic symphysis
The upper border of the body is the pubic crest.
It is marked laterally by a prominence – the pubic tubercle.
From the pubic tubercle two ridges diverge laterally onto the superior ramus.
The upper ridge, sharp, is the pectineal line; it forms part of the pelvic brim and joins the
arcuate line of the ilium.
Pectineus arises from the pectineal line and the adjacent surface of the superior ramus.
The lower ridge, more rounded, is the obturator crest.
Below the obturator crest on the pubic ramus is the obturator groove, which lodges the
obturator nerve.
The pubic tubercle receives the attachment of the inguinal ligament,
Ischium
The ischium is an L-shaped bone
The body joins with pubis and ilium at the acetabulum and extends down to the ischial
tuberosity; it supports the sitting weight.
The obturator membrane is attached to the margin of the foramen.
Outer surface - obturator externus inner surface – obturator internus
The spine of the ischium projects medially to divide the greater from the lesser sciatic notch
below it.
The sacrospinous ligament is attached to it, contributing to conversion of the greater sciatic
notch into the greater sciatic foramen
The lesser sciatic notch lies between the spine and the ischial tuberosity.
It is bridged by the sacrotuberous ligament, which with the sacrospinous ligament converts
the notch into the lesser sciatic foramen
Obturator internus emerges through this foramen into the buttock, and the internal
pudendal vessels and nerve pass forward into the perineum.
The ischial tuberosity
Medial surface of hip bone
The auricular area
extends from the pelvic
brim to the posterior
inferior iliac spine
It articulates with the ala of the sacrum.
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ANATOMY
Medicine Made Simple
, Hip bone
The innominate or hip bone is formed of three bones, which fuse in a Y-shape, in the
acetabulum.
The anterior two-thirds of the ilium forms the iliac fossa, part of the posterior abdominal
wall.
The posterior one-third carries the auricular surface for the sacrum
The outer surface of the ilium gives attachment to buttock muscles.
In the anatomical position of the bone, the pubic tubercle and anterior superior iliac spine lie
in the same vertical plane, and the upper border of the symphysis pubis and the ischial spine
lie in the same horizontal plane.
Lateral surface of the hip bone
The acetabulum is a concave hemisphere which is directed downwards and slightly
backwards along the axis of the femoral neck.
There is a deficiency at its inferior margin, the acetabular notch.
The hyaline cartilage lining the inside of the acetabulum over the iliac part of the fossa
overlies the weight-bearing area.
Pubis and ilium meet at the iliopubic eminence on the anterior margin of the acetabulum
The convex upper margin of the ilium, the iliac crest, extends from the anterior superior iliac
spine to the posterior superior iliac spine.
The tubercle of the iliac crest lies 5cm behind the anterior superior spine and forms the most
lateral part of the bony pelvis, but not the highest part.
The line between the highest points of the two iliac crests, the supracrestal plane – L4
The tubercle -L5
The posterior superior iliac spine makes a characteristic dimple (Venus dimple) in the skin of
the buttock - S2
The gluteal surface of the ilium shows three curved gluteal lines. (ant., pos., inf.)
The fascia lata is attached along the whole length of the external lip of the iliac crest
1
, Pubis
The body of the pubis projects laterally as a superior ramus which joins the ilium and ischium
at the acetabulum
Inferior ramus fuses with the ischial ramus medial to the obturator foramen.
The symphyseal surface of the body forms the secondary cartilaginous joint that constitutes
the pubic symphysis
The upper border of the body is the pubic crest.
It is marked laterally by a prominence – the pubic tubercle.
From the pubic tubercle two ridges diverge laterally onto the superior ramus.
The upper ridge, sharp, is the pectineal line; it forms part of the pelvic brim and joins the
arcuate line of the ilium.
Pectineus arises from the pectineal line and the adjacent surface of the superior ramus.
The lower ridge, more rounded, is the obturator crest.
Below the obturator crest on the pubic ramus is the obturator groove, which lodges the
obturator nerve.
The pubic tubercle receives the attachment of the inguinal ligament,
Ischium
The ischium is an L-shaped bone
The body joins with pubis and ilium at the acetabulum and extends down to the ischial
tuberosity; it supports the sitting weight.
The obturator membrane is attached to the margin of the foramen.
Outer surface - obturator externus inner surface – obturator internus
The spine of the ischium projects medially to divide the greater from the lesser sciatic notch
below it.
The sacrospinous ligament is attached to it, contributing to conversion of the greater sciatic
notch into the greater sciatic foramen
The lesser sciatic notch lies between the spine and the ischial tuberosity.
It is bridged by the sacrotuberous ligament, which with the sacrospinous ligament converts
the notch into the lesser sciatic foramen
Obturator internus emerges through this foramen into the buttock, and the internal
pudendal vessels and nerve pass forward into the perineum.
The ischial tuberosity
Medial surface of hip bone
The auricular area
extends from the pelvic
brim to the posterior
inferior iliac spine
It articulates with the ala of the sacrum.
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