Transcript Muscles of the Pelvic Floor (Pelvic Diaphragm)

Pelvis
Bony pelvis
• Composition: formed by paired
hip bones, sacrum, coccyx, and
their articulations
• Two portions
– Greater pelvis
– Lesser pelvis
• Terminal line ( pelvic inlet):
formed by promontory of sacrum,
arcuate line, pectin of pubis,
pubic tubercle, upper border of
pubic symphysis
• Pelvic outlet: formed by tip of
coccyx, sacrotuberous ligament,
ischial tuberosity, ramus of
ischium, inferior ramus of pubic
symphysis
Identify the bony walls and ligamentous landmarks of the pelvis.
Iliopectineal Line
Sacrotuberous Ligament
Greater
Sciatic
Foramen
Sacrospinous Ligament
Lesser
Sciatic
Foramen
Sacrospinous
Ligament
Sacrotuberous Ligament
Pubic Arch
Pubic Symphysis
Ischial Tuberosity
Ant. Sup. Iliac Spine
Pubic symphysis
Pelvic
Outlet
Tip of Coccyx
Sacrotuberous
Ligament
Coccyx
Muscular Walls
Greater
Sciatic
Foramen
Piriformis
Muscle
Sacrotuberous
Ligament
Piriformis
Muscle
Sacrospinous
Ligament
Sacrotuberous
Ligament
Gemellus
Superior &
Inferior
Greater Trochanter
Obturator Internus
Ischial Tuberosity
Lesser Trochanter
Muscles of pelvic wall
• Piriform
• Obturator internus
• Iliacus
Piriform muscle
• Arise from the ant surface of the lateral
mass of the sacrum and enter the gluteal
region by passing through the greater sciatic
notch to be inserted on to the upper border
of the greater trochanter of the femur.
• It’s a lateral rotator of the hip
• Receives nerve supply from
sacal plexus.
Obturator internus
• Arises from the pelvic
surface of the obturator
membrane and the
adjoining part of the hip
bone.
• Muscle fibres from a
tendon which exit the
pelvis through lesser
sciatic foramen and gets
inserted on to the greater
trochanter.
Iliacus
• The iliacus arises from the iliac fossa on the
interior side of the hip bone, and also from
the region of the anterior inferior iliac
spine (AIIS). It joins the psoas major to
form the Iliopsoas and gets inserted on to
the lesser trochanter of the femur.
• The iliopsoas is innervated by the femoral
nerve and direct branches from the lumbar
plexus.
Muscles of the Pelvic Floor (Pelvic
Diaphragm)
• The pelvic diaphragm is composed of two paired
muscles – levator ani and coccygeus
• These muscles:
–
–
–
–
Close the inferior outlet of the pelvis
Support the pelvic floor
Elevate the pelvic floor to help release feces
Resist increased intra-abdominal pressure
• PD is is pierced by the rectum and urethra and
vagina in females
• Region inferior to the pelvic diaphragm is the
perineum
Muscles of the Pelvic Floor: Pelvic Diaphragm
Figure 10.12a
Levator ani
• The levator ani is a broad, thin muscle, situated on the
side of the pelvis.
• It is attached to the inner surface of the side of the lesser
pelvis, and unites with its fellow of the opposite side to
form the greater part of the floor of the pelvic cavity
• The levator ani is divided into three parts:
1. Iliococcygeus muscle
2. Pubococcygeus muscle
3. Puborectalis muscle
Iliococcygeus
• The Iliococcygeus arises from the inner
side of the ischium and from the posterior
part of the tendinous arch of the obturator
fascia, and is attached to
the coccyx and anococcygeal raphé.
Pubococcygeus
• stretches from the pubic bone to the coccyx.
Puborectalis
• The fibers which form a sling for the rectum are named
the Puborectalis or Sphincter recti.
• They arise from the lower part of the pubic symphysis,
and from the superior fascia of the urogenital
diaphragm.
• They meet with the corresponding fibers of the
opposite side around the lower part of the rectum, and
form for it a strong sling. Relaxation reduces the angle
between rectum and anus, allowing defecation in
conjunction with relaxation of the internal and external
sphincters.
Coccygeus
• The Coccygeus is a muscle of the pelvic wall (i.e.
peripheral to the pelvic floor), located posterior
to levator ani and anterior to thesacrospinous
ligament.
• It is a triangular plane of muscular and tendinous
fibers, arising by its apex from the spine of
the ischium and sacrospinous ligament, and
inserted by its base into the margin of
the coccyx and into the side of the lowest piece of
the sacrum.
Muscles Inferior to the Pelvic Floor:
The Urogenital Diaphragm
• Muscles inferior to the pelvic floor
• Stretches between two sides of the pubic
arch in the anterior half of the perineum
• Contains
– Deep transverse perineal muscle
– Extrnal urethral sphincter muscle
• The ischiocavernosus and bulbospongiosus
assist in erection of the penis and clitoris;
lie superficial to the urogenital diaphragm
Muscles of the Pelvic Floor
Muscles of the Pelvic Floor
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