Pelvic walls Flashcards
describe the boundaries of the pelvis
anterior, posterior and lateral walls are bony and muscular
inferior boundary (floor) is muscular at the pelvic outlet
superior boundary at the pelvic inlet is open to the abdominal cavity
what makes up the anterior wall of the pelvis
pubic bodies
pubic rami
pubic symphysis
what makes up the posterior wall of the pelvis
sacrum
coccyx
piriformis
what bones form the pelvis
2 innominate bones that articulate with eachother and with the sacrum
why is the anterior part of the pelvis lighter
obturator foramen - less bone
why is the obturator foramen almost completely closed
by obturator internus, obturator externus and obturator membrane
what is the bony landmark between the greater and lesser sciatic notch
ischial spine
the ischial spine is an important landmark for what
pudendal nerve
what do the greater and lesser sciatic notches allow
passage of nerves, arteries, veins and muscles from the internal surface of the pelvis to the perineum and gluteal region
how do the greater and lesser sciatic notches become foramina
presence of ligaments
what kind of joint is the lumbosacral joint
secondary cartilaginous
what kind of joint is the pubic symphysis
secondary cartilaginous
the iliac blades provide attachment sites for what
iliacus anteriorly
gluteal muscles posteriorly
the iliac crest allows attachment for what
muscles of the abdominal wall
the ASIS is an attachment site for what
sartorius
the AIIS is an attachment site for what
rectus femoris
the ASIS and pubic tubercle are attachment sites for what
inguinal ligament
the secondary cartilaginous joints at the lumbosacral joint and pubic symphysis allow what
cushioning of the stresses passing into the pelvis from the trunk and passing around the pelvic bowl
the sacrum is formed from _ fused vertebrae
5
the sacrum articulates with
L5 vertebrae, coccyx and ilia
what is the purpose of the sacral foramina
sacral nerves pass through the sacral foramina to exit the vertebral column and supply structures within the pelvis and lower limb
what are the two large ligaments that attach to the sacrum
sacrotuberous and sacrospinous ligaments
where does the sacrotuberous ligament pass between
sacrum and ischial tuberosity
where does the sacrospinous ligament pass between
sacrum and ischial spine
the sacrotuberous and sacrospinous ligaments form the posterior boundaries of the
greater and lesser sciatic foramina
how is the inguinal ligament formed
formed by the aponeurosis of the external oblique as it rolls over itself to create the anterior wall and floor of inguinal canal
as well as forming the posterior boundaries of the greater and lesser sciatic foramina, what else do the sacrotuberous and sacrospinous ligaments do
support the posterior wall and floor of the pelvic cavity
describe the sacroiliac joints
combination of plane synovial joint anteriorly and fibrous joint posteriorly
how is the sacroiliac joint supported anteriorly
anterior sacroiliac ligament
how is the sacroiliac joint supported posteriorly
posterior sacroiliac ligament
describe the features of the female pelvis that increase the internal diameter compared to the male
- pubic angle at the pubic symphysis is wider
- ischial spines do not protrude into the pelvic cavity as markedly
- sacrum is flatter
what is the term for the classic female shape at the pelvic inlet
gynaecoid
what is the term for the classic male shape at the pelvic inlet
android
what is the term for a more flattened pelvic inlet in the anterior-posterior direction
platypelloid shape
what is the term for a wider inlet in the anterior-posterior direction
anthropoid (similar to the shape seen in apes)
what are the attachments of iliacus
iliac fossa
joints psoas to form iliopsoas
inserts onto lesser trochanter of femur
what is the function of iliacus
hip flexion
what is the innervation of iliacus
femoral nerve
what are the attachments of psoas
superficial: T12-L4 vertebral bodies and IVDs
deep: L1-5
join iliacus to form iliopsoas and inserts onto lesser trochanter of femur
what is the function of psoas
hip flexion
bend trunk laterally (one)
raise trunk from supine (both)
what is the innervation of psoas
lumbar plexus direct branches L2-4 anterior rami
what are the gluteal muscles
gluteus maximus, medius and minimus
what are the attachments of the gluteus muscles
attach to pelvic bones but not within pelvic cavity - posterior surface of iliac blades
the gluteal muscles act on
hip joint
what muscle covers the external surface of the obturator foramen
obturator externus
what are the attachments of obturator externus
outer surface of the obturator membrane to the trochanteric fossa of the femur
what are the attachments of obturator internus
inner surface of the obturator membrane to the medial surface of the greater trochanter of the femur
what is the function of the obturator internus
lateral rotation of the hip
what is the innervation of the obturator internus
nerve to the obturator internus direct from sacral plexus (L5, S1)
what muscle covers the inner surface of the obturator membrane
obturator internus
describe how obturator internus attaches
attaches to the obturator membrane then sends its tendon through the lesser sciatic notch to reach the greater trochanter of the femur
when seen in the gluteal region, obturator internus is a
tendon
in the gluteal region, obturator internus is closely associated with
the superior and inferior gemelli muscles that lie either side of the tendon of obturator internus
the thickened fascia above obturator internus provides an attachment site for the
iliococcygeus part of levator ani muscles that form the pelvic floor
the obturator internus also acts to support
the lateral pelvic wall covering the opening of the obturator foramen
what are the attachments of piriformis
pelvic surface of the sacrum then passes through greater sciatic foramen to the greater trochanter of the femur
what is the function of piriformis
lateral rotation of the hip joint
what is the innervation of piriformis
nerve to piriformis direct branch of sacral plexus (S1, S2)
piriformis is a useful landmark inside the pelvis for what
useful landmark inside the pelvis as the sciatic nerve and pudendal nerve form on its superior surface
piriformis is a useful landmark in the gluteal region for what
superior and inferior gluteal nerves and vessels lie either side of piriformis and the sciatic nerve descends from the greater sciatic notch beneath it
piriformis also acts to support
the pelvic wall by partially covering the opening of the greater sciatic foramen