Anatomy of Pubis and Ischium

1. LECTURE2: PUBIS, ISCHIUM AND
ACETABULUM
external features and attachments
Dr. EIMAAN SUMAYYAH
DPT (IPMR-KMU) MS NEUROLOGY* (KMU)

2. PUBIS BONE
• Pubis forms anteroinferior part of hip bone,
contributes to anterior one fifth of acetabulum, and
forms anterior boundary of obturator foramen.
• Pubis consists of body, superior ramus
and inferior ramus

3. BODY OF PUBIS
• flattened anteroposteriorly
• has a border superiorly called pubic crest which ends in a
pubic tubercle laterally.
• In males the tubercle is crossed by the spermatic cord.
• It has three surfaces
• Anterior surface:
• Posterior surface or pelvic surface:
• Medial surface or symphyseal surface articulates with
opposite pubic symphysis.
• Superior and inferior rami are extension from body of
pubis

4. SUPERIOR RAMUS
• Three borders
• Superior border [also called pectin pubis or pectineal
line] is sharp and extends from pubic tubercle to
posterior aspect of iliopubic eminence. It forms part
of arcuate line.
• The anterior border is called the obturator crest.
extending form the public tubercle to the acetabular
notch.
• The inferior border is sharp and forms the upper
margin of the obturator foramen.

5. SUPERIOR RAMUS
• Three surfaces
1. The pectineal surface is a triangular area between the
anterior and superior borders, extending from the pubic
tubercle to the iliopubic eminence.
2. The pelvic surface lies between
the superior and inferior borders.
• Pelvic surface is crossed by ductus deferens in males and
round ligament of uterus in females.
3. The obturator surface or inner surface lies between the
anterior and inferior borders.
It present the obturator groove.
Obturator groove transmits obturator vessel and nerves.

6. INFERIOR RAMUS
• Inferior ramus extends from the body of the pubis to
the ramus of the ischium, medial to the obturator
foramen.
• It unites with the ramus of the ischium to form the
conjoined ischiopubic rami.

7. ATTACHMENTS OF PUBIS BONES

8. PUBIC TUBERCLE
• inguinal ligament
• cremaster muscle.

9. PUBIC CREST
• The lateral part of the crest gives origin to
the lateral head of the rectus abdominis , and to the
pyramidalis.
• Medial head of the rectus abdominis which takes
origin from pubic symphysis crosses the medial part
of the pubic crest.

10. BODY OF PUBIS
• Anterior surface
• Anterior pubic ligament medially
• Adductor longus
• Gracilis
• Adductor brevis origniates lateral to the gracilis

11. BODY OF PUBIS
• Posterior surface
• Levator ani from middle part
• Obturator internus laterally

12. SUPERIOR RAMUS
• The pectineal line provides attachment to:
• Medial end of lacunar ligament
• Pectinate ligament
• Pectineus muscle and its covering fascia.
• Psoas minor
• Pectineal surface: in its upper part give rise to
pectineus muscle.

13. ISCHIUM BONE

14. ISCHIUM
• Ischium is posteroinferior part of hip bone and forms
two fifth of acetabulum and posterior body of
obturator foramen.
• Ischium has a body and a ramus.

15. BODY OF THE ISCHIUM
• It is below and behind acetabulum and ends in ischial
tuberosity.
• Its anterior border forms post margin of obturator
foramen.
• Posterior border continues with post border of ilium and
takes part in lower border of greater sciatic notch and
gives out a projection below that called ischial spine.
Below that is lesser sciatic notch.
• The lesser sciatic notch is occupied by the tendon of the
obturator internus and a bursa deep to the tendon.

16. BODY OF THE ISCHIUM
1. Dorsal surface of body of ischium is continuous
with gluteal surface of ilium.
• Piriformis, the sciatic nerve, and the nerve to the
quadratus femoris are closely related to this surface.
The groove transmits the tendon of the obturator
internus .
2. The surface between anterior and lateral borders is
called femoral surface.

17. Ischial tuberosity
• Ischial tuberosity has upper and lower areas
demarcated by transverse ridge. An oblique ridge
further divides upper area into superolateral and
inferomedial area. The inferomedial area is covered
with fibrofatty tissue which supports body weight in
the sitting position.
• Lower area of ischial tuberosity is divided into inner
and outer areas by a longitudinal ridge

18. • Ramus of Ischium
• Ramus of ischium combines with inferior pubic
ramus to form conjoined ischiopubic ram

19. ATTACHMENTS OF ISCHIUM BONE:

20. ISCHIAL SPINE
• Sacrospinous ligament along its margins
• origin for the coccygeus and posterior fibers of
levator ani from its pelvic surface.

21. Lesser Sciatic Notch
• The upper and lower margins of the notch give origin
to the superior and inferior gemelli.

22. FEMORAL SURFACE OF THE
ISCHIUM
• Origin to obturator externus along the margin of the
obturator foramen
• Quadratus femoris along the lateral border of the
upper part of the ischial tuberosity

23. ISCHIAL TUBERSOITY
• Surperolateral part: origin to the semimembranosus
• Inferomedial area: semitendinosus and the long head
of the biceps femoris
• Inferolateral area: adductor magnus. .
• Sacrotuberous ligament on medial margin
• Ischiofemoral ligament on lateral border, just below
the acetabulum.

24. PELVIC SURFACE
• obturator internus.

25. • Acetabulum is a deep cup-shaped hemispherical cavity
on the lateral aspect of the hip bone roughly about its
centre. Acetabulum is directed laterally, downwards and
forwards. Margin of the acetabulum is deficient
inferiorly. This deficiency is called the acetabular notch
and is bridged by the transverse ligament.
• The acetabulum is formed by
• Ilium – Upper 2/5
• Pubis – anterior 1/5
• Ischium the posterior 2/5.

26. • Acetabular fossa is nonarticular roughened floor of the
acetabulum. It contains of fat and is lined by synovial
membrane.
Articular surface is horseshoe shaped articular surface
and is called lunate. It occupies anterior, superior , and
posterior part of the acetabulum. It articulates with the
head of the femur to form the hip joint. Acetbular labrum
is fibrocartilaginous rim on the margins of the
acetabulum which functions to deepen the acetabular
cavity.

27. • Obturator Foramen
• Obturator foramen is a large gap in the hip
bone anteroinferior to acetabulum, between pubis
and ischium. It is large and oval in males; and small
and triangular in females. Obturator membrane is
attached to its margins, except at the obturator
groove, where the obuterior vessels and nerve pass
out of the pelvis.

28. • Clinical Significance
• The anterior superior iliac spine (ASIS) is an important
landmark. Its comparative level with opposite side is
important in spine, pelvis and hip examination. Midway
along the inguinal ligament [midway between ASIS
and pubic tubercle], the femoral artery can be palpated.
• ASIS also serves a s a point for measuring leg lengths.
• Hip bone can be injured and trauma and its its treatment
is dictated by fracture site, pattern and patient age.