Anatomy of the Pelvis
LO1: Describe the bones of the Pelvis
• The pelvis lies between the abdomen and the lower limb; forming the lower the portion of the
trunk
• In anatomical position, the pelvis is oriented so that the front edge of the top of
the pubic symphysis and the ASIS lie in the same vertical plane
• Functions of the Pelvis
o Strong stable connection between trunk and lower extremities
o Bears and transmits the weight from the upper body to femora
o Contains, supports and protects pelvic viscera
o Attachment for trunk and lower limb muscles
• The body’s centre of gravity is in the pelvis – curvature in the vertebral column centre the weight
in the upper body and transmit it through the pelvis to the femora
• Bones of the pelvis
o Innominate bone – fusion of the following bones:
§ Ilium
§ Ischium
§ Pubis
o At birth, these bones are connected by a triradiate
cartilage at a cup-shaped socket forming the acetabulum
o The acetabulum is the socket of the hip bone where the
head of the femur fits
o Fusion into a single bone begins at puberty
• Joints of the Pelvis
o Weight is transferred from the vertebral column to the sacrum, it
tilts the sacrum anteriorly
o The ligaments prevent the lower portion of the sacrum from being
rotated upwards at the sacroiliac joint
o Articulating bones – right innominate, left innominate, sacrum,
coccyx
o Five joints – lumbrosacral, right sacroiliac, left sacroiliac, pubic symphysis,
sacrococcygeal symphysis
o Lumbrosacral joint – symphysis (anterior intervertebral joint), synovial plane joints
(zygapophyseal joints)
§ Articulation between L5 and S1 vertebrae
§ Formed by two separate articulations – anterior intervertebral joint and
zygopophyseal joints
§ Anterior intervertebral joint – between vertebral bodies of L5 and S1
§ Zygopophyseal joint – between inferior articular processes of L5 and superior
articular process of S1
o Sacroiliac joints – synovial on anterior side, syndesmosis on posterior side
§ Between the sacrum and the coccyx
§ Syndesmosis – fibrous joint which two adjacent bones are linked by a strong
membrane or ligament
o Pubic symphysis – secondary cartilaginous (fibrocartilage)
§ Between the pubis bodies of the two hip bones
o Sacrococcygeal symphysis – secondary cartilaginous (fibrocartilage)
§ Between the sacrum and the coccyx
o Sacrospinous ligament
§ Triangular in shape and extends from the lateral sacrum and coccyx to the ischial
spine
§ Transforms the lesser sciatic notch into a foramen
§ Links pelvic bone to the sacrum and coccyx
o Sacrotuberous ligament
§ Triangular ligament with a broad attachment that extends from the posterior
ilium and lateral sacrum and coccyx to the ischial tuberosity
§ Transforms the greater sciatic notch into a foramen
§ Links pelvic bone to the sacrum and coccyx
• Iliac crest – superior margin of the wing of the ilium, extends from the ASIS (anterior superior
iliac spine) to the PSIS (posterior superior iliac spine)
• Inferior pubic ramus – projects towards the ischium and enclose part of the obturator foramen
• Superior pubic ramus – extends laterally from the body of the pubis bone, joins with the ilium
and ischium at its base to form part of the acetabulum
• Ischial tuberosity – the most prominent feature of the ischium on the posteroinferior aspect of
the bone
• Ischial spine – prominent posterior margin of the bone separating the lesser sciatic notch from
the greater sciatic notch
LO2: Describe the main foramina of the pelvis
• Greater sciatic foramen
o Gluteal arteries and veins
o Gluteal nerve
o Sciatic nerve
§ Lies deep to the piriformis muscle
o Pudendal nerve
o Internal pudendal artery & vein
• Lesser sciatic foramen
o Pudendal nerve
o Internal pudendal artery and vein
• Obturator foramen
o Obturator artery
o Obturator nerve
o Obturator vein
LO3: Describe the boundaries of the lesser & greater pelvis, pelvic inlet and pelvic outlet
The junction between the greater and lesser pelvis is known as the pelvic inlet. The outer bony edges
of the pelvic inlet are called the pelvic brim.
• Boundaries of the pelvic inlet (superior pubic aperture)
o Anterior – pubic symphysis
o Posterior – sacral promontory, sacral alae
o Lateral – arcuate line, pecten pubic, pubic crest
• Boundaries of the pelvic outlet (inferior pubic aperture)
o Anterior – pubic symphysis, pubic arch (right and left
ischiopubic rami), ischial tuberosities, sacrotuberous ligament
o Posterior – coccyx
• Boundaries of the greater/false pelvis
o Superior to the pelvic inlet
o Contains peritoneal content
o Limited inferiorly by parietal peritoneal reflections
• Boundaries of the lesser/true pelvis
o Inferior to pelvic inlet and superior to pelvic outlet
o Contains the true pelvic cavity and content
o Limited inferiorly by pelvic diaphragm
LO4: Di@erentiate between male and female pelvis
LO5: Briefly describe the contents of the lesser and greater pelvic spaces
• Greater/false pelvis
o Peritoneal content e.g. ileum and sigmoid colon
• Lesser/true pelvis
o Reproductive viscera
§ Male – seminal vesicles, prostate, ductus deferens
§ Female – uterus, vagina, ovaries, uterine tubes
o Urinary viscera – bladder
o GI viscera – rectum
o Neurovasculature
