Myology
Myology of the
Pelvis
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Pelvic Girdle
• Pelvic girdle: consists of the two hipbones (coxal bones)
– Function of the pelvic girdle is to attach the lower extremity to
the trunk
– Hipbones are united anteriorly at the pubic symphysis (an
amphiarthrosis)
• Hipbones:
– Consist of three separate bones:
• Ilium
• Ischium
• Pubis
– All three bones unite in a depression known as the acetabulum
which is the socket for the femoral head.
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Ilium
• Superior part of the pelvic bone
• Anatomy:
– Iliac crest: superior border of the ilium
– Spines: serve as points of muscle attachment
• Anterior superior iliac spine (ASIS): anterior endpoint of
the iliac crest
• Anterior inferior iliac spine (AIIS): spine below the ASIS
• Posterior superior iliac spine (PSIS): posterior endpoint of
the iliac crest
• Posterior inferior iliac spine (PIIS): spine inferior to PSIS
– Greater sciatic notch: Indentation below the PIIS, allows
passage of the sciatic nerve
– Iliac fossa: concavity on medial surface for the iliacus muscle.
– Auricular surface: on medial side for articulation with the
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sacrum, forming the sacroiliac joint
Ischium
• Inferior and posterior portion of hipbone
• Anatomy:
– Ischial spine: pointed projection above the ischial tuberosity,
serves as a point of muscle attachment
– Lesser sciatic notch: small indentation below the ischial spine
– Ischial tuberosity: large rough quadrilateral process forming
the inferior part of the ischium.
• In the erect sitting position body rest on these tuberosities
– Ramus: branch of bone extending toward the pubic ramus
– Obturator foramen: largest foramen in the skeleton which is
closed up by fibrous membrane
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Pubic bone
• Located on the anterior inferior portion of hipbone
• Anatomy:
– Superior ramus: part of pubis lying between the symphysis
and acetabulum; forming the upper part of obturator foramen
– Inferior ramus: part extending down from symphysis; unites
with ischium
– Pubic crest: upper margin of superior ramus
– Pubic tubercle: rounded process at the end of the crest
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Anatomical Review: Os Coxa
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Pelvis
• Together with sacrum and coccyx, the two hipbones form the
pelvis.
• Anatomy:
– Pelvic brim (inlet): boundary of aperture leading into the true
pelvis.
• Formed by pubic crests, iliopectinial lines, and sacral
promontory
• Size and shape of the inlet have obstetrical importance
– If diameter is to small, infant skull cannot enter the true
pelvis for birth
– False pelvis: broad, shallow space above the pelvic brim,
considered part of the abdominal cavity
– True pelvis: area below pelvic brim, contains pelvic organs
– Pelvic outlet: irregular circumference marking the lower limits
of the true pelvis, bounded by the coccyx and the two ischial
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tuberosities.
Anatomical Review: Pelvic Girdle
Def: Pelvic Girdle: Consists of the two
hipbones. These are also known as innominate or
coxal bones. Pelvic girdle functions to attach the
lower limb to the trunk
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Proximal Femur
• Femur is the longest, heaviest, and strongest bone in the body
• Anatomy:
– Shaft: main portion of the femur
• Angles medially, bringing the knees closer to the midline
• The angle of convergence is greater in females because the
female pelvis is broader
– Head: rounded end on the proximal end of femur
• Articulates with the acetabulum forming the
acetabulofemoral joint.
– Fovea capitis: small depression in the center of the head
• Contains the ligament of the head of the femur to the
acetabulum
– Neck: constricted portion distal to the head
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• Common site of femoral fracture in the elderly
Proximal Femur (cont)
• Anatomy (continued)
– Greater trochanter: large protuberance inferior and lateral to the
head. Point of attachment for many pelvic muscles.
– Lesser trochanter: smaller protuberance located inferiorly and
medial to the greater trochanter
– Intertrochanteric line: line between the trochanters on the
anterior surface; point of muscle attachment
– Intertrochanteric crest: thicker line between the trochanters on
the posterior surface; point of muscle attachment
– Gluteal tuberosity: vertical ridge on the shaft inferior to the
intertrochanteric crest
– Linea aspera: ridge of bone on the posterior shaft of the femur
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Anatomical Review: Proximal
Femur
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Articular Anatomy: Pelvis
Made of four joints:
Pubic symphysis: Articulation between the two pubic bones. A
semi-movable joint containing a fibrocartilage disc.
Sacroiliac joints: (2) joints between the medial hip bones and the
lateral aspect of the sacrum.
Lumbosacral joints: articulation between the L5 and the sacrum.
Allows for flexion/extension and some lateral rotation.
Sacrococcygeal joints: articulation between sacrum and coccyx.
Generally moveable in children and fixed in adults.
Acetabulofemoral joint: ball and socket joint between the
acetabulum and the head of the femur. Commonly known as the
“hip joint”
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Soft Tissue of the hip joint
Articular Capsule: very dense/strong
tissue extending from rim of the
acetabulum to the neck of the femur
(considered one of the strongest
ligaments in the body)
Iliofemoral Ligament: (A.K.A. “Y
ligament”) thickened portion of the
articular capsule, extending from the
AIIS to the intertrochanteric line of the
femur. Functions to limits extension of
the hip joint.
Pubofemoral Ligament: Thickened
portion of the articular capsule
extending from the pubic ramus to the
neck of the femur. Functions to limit
abduction of the hip joint.
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Soft Tissue of the Hip
Ischiofemoral Ligament: thickened
portion of the articular capsule
extending from the ischium to the
neck of the femur. Functions to limit
abduction of the hip joint
Ligament of the head of the femur:
flat, triangular band extending from
the acetabulum to the head of the
femur. (See slide 15)
Acetabular Labrum: Fibrocartilage
rim attached to the margin of the
acetabulum that enhances the depth
of the acetabulum. (See slide 15)
Trochanteric Bursa: overlies the
greater trochanter. Reduces friction
between greater trochanter and
gluteal muscles.
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Hip Ranges of Motion
Each student should be able to describe and demonstrate the
following movements:
1.
2.
3.
4.
5.
6.
7.
8.
9.
Hip flexion
Hip extension
Medial rotation
Lateral rotation
Hip abduction
Hip adduction
Circumduction
Horizontal abduction
Horizontal adduction
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Palpation of the Pelvis and
Hip
ASIS: Supine: place your hands on the sides of the abdomen, below the level of the umbilicus.
Gently compress inferiorly until you feel the superficial tip of the ASIS.
AIIS: Supine: flex your partner’s knee and again locate the ASIS. Slide inferiorly and medially about
one inch and palpate for a small prominence deep to the overlying tendons.
Iliac Crest: Supine: flex your partner’s knees and place your fingers on the ASIS. Slide your fingers
posteriorly along the iliac crest. Curl your fingers medially and palpate the iliac fossa.
PSIS: Prone: find the iliac crests again and follow them posteriorly to the sacrum. The PSIS will feel
like a small prominence in the shallow depression.
Sacrum: Prone: find both PSIS’s again, move fingers medially and palpate the posterior sacrum.
Along the midline of the sacrum you will feel the sacral spinous processes.
Sacroiliac Joint: Prone: Return to the PSIS’s again and then move inferior and medial. Have your
partner bend the knee and then externally rotate the thigh. Feel for the sacroiliac joint space
becoming wider with the external rotation.
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Palpation of the Pelvis and
Hip (cont.)
Coccyx: Prone: continuing from the posterior sacrum move your fingers inferiorly
toward the gluteal cleft feeling for the bumpy surface of the coccyx. Only the base
of the coccyx can be felt from this position. The apex is usually dipped to far anterior.
Greater Trochanter: Prone: from the iliac crest palpate down the sides to the
wide point of the femurs. This is the greater trochanter.
Ischial Tuberosity: Prone: locate the gluteal fold. At the mid-point of the fold
push up superiorly and medially until you feel the large tuberosity.
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Muscles that move the femur
Gluteus Maximus
Gluteus Medius
Gluteus Minimus
Posterior Group
Piriformis
Gemellus Superior
Obturator Internus
Gemellus Inferior
Obturator externus
Quadratus femoris
Six Deep Lateral Rotators
Psoas Major
Psoas Minor
Iliacus
Tensor Fascia Latae
“GOGO Muscles”
Anterior Group
Pectineus
Adductor Longus
Adductor Brevis
Adductor Magnus
Gracilis
Medial Group
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Gluteus Maximus
O: Posterior aspect of the iliac crest, sacrum,
and coccyx
I: Gluteal tuberosity and iliotibial band
A: Extension and lateral rotation of the
femur. Upper fibers abduct while the
lower fibers adduct the femur.
** Reversed muscles action: When the
lower extremities are stabilized the gluteus
maximus posteriorly tilts the pelvis.
Unilateral contraction causes contralateral
rotation of the trunk
N: Inferior Gluteal nerve
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Gluteus Medius
O: External aspect of the ilium and iliac
crest
I: Greater trochanter
A: Abduction and medial rotation of the
femur. Anterior fibers flex the femur
while the posterior fibers can extend
the femur.
** Reversed muscle action: stabilizes
the pelvis when standing on one leg.
N: Superior gluteal nerve
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Gluteus Minimus
O: Deep to the gluteus medius. External
aspect of the ilium and iliac crest
I: Greater trochanter
A: Abduction and medial rotation of the
femur. Anterior fibers flex the femur while
the posterior fibers can extend the femur.
** Reversed muscle action: stabilizes the
pelvis when standing on one leg.
N: Superior gluteal nerve
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Piriformis
O: Anterior aspect of the sacrum. Exits
the pelvis through the greater sciatic
foramen (usually above the sciatic
nerve)
I: Greater trochanter of the femur
A: Lateral rotation of the femur.
Piriformis can also abduct and
medially rotate the femur when the
femur is flexed
**Reversed muscle action:
contralateral rotation of the pelvis
N: Nerves to the deep lateral rotators
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Gemellus Superior
O: Ischial spine
I: Greater trochanter of
the femur
A: Lateral rotation of the
femur
N: Nerves to the deep lateral
rotators
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Obturator Internus
O: Internal surface of the
pelvic bone
I: Greater trochanter of
the femur
A: Lateral rotation of the
femur
N: Nerves to the deep lateral
rotators
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Gemellus Inferior
O: Ischial tuberosity
I: Greater trochanter of
the femur
A: Lateral rotation of the
femur
N: Nerves to the deep
lateral rotators
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Obturator Externus
O: External surface of the
pelvic bone
I: Medial aspect of the femur
A: Lateral rotation of the
femur
N: Obturator nerve
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Quadratus Femoris
O: Ischial tuberosity
I: Intertrochanteric
crest
A: Lateral rotation of the
femur. QF can also
cause adduction of the
femur
N: Nerves to the deep
lateral rotators
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Psoas Major
O: Tp’s and bodies of lumbar vertebrae
I: passes deep to inguinal ligament into the lesser
trochanter.
A: Flexion and lateral rotation of the femur.
When the lower extremities are stabilized,
bilateral contraction of the psoas major will
cause flexion of the trunk, while unilateral
contraction will cause lateral flexion
**Reversed muscle action: unilateral
contraction will cause contralateral rotation of
the trunk
N: Femoral nerve and muscular branches of
lumbar nerves
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Psoas Minor
O: Bodies of T12 and L1
I: Pelvic brim
A: Bilaterally flexes the trunk at
the lumbosacral joint and causes
a posterior tilt of the pelvis.
N: Femoral nerve and muscular
branches of lumbar nerves
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Iliacus
O: Iliac Fossa
I: Lesser trochanter of the
femur
A: Flexion and lateral rotation
of the femur. When the lower
extremities are stabilized the
bilateral contraction of the iliacus
will cause anterior pelvic tilting.
N: Femoral nerve
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Tensor Fascia Latae
O: ASIS
I: Iliotibial band
A: Flexion, abduction, and medial
rotation of the femur. Also tenses
the iliotibial band.
**Reversed muscle action causes
anterior tilting of the pelvis and
ipsilateral rotation of the pelvis.
N: Superior gluteal nerve
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Pectineus
O: Pubic bone
I: Posterior aspect of the
proximal shaft of the femur
A: Flexion and adduction of the
thigh.
N: Femoral nerve
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Adductor Longus
O: Pubic bone
I: Linea aspera of the femur
A: Flexion and adduction of the
thigh
N: Obturator nerve
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Adductor Brevis
O: Pubic bone
I: Linea aspera of the femur
A: Flexion and adduction of the
thigh
N: Obturator nerve
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Adductor Magnus
O: Pubic bone and ischial tuberosity
I: Linea aspera and adductor tubercle
of the femur
A: Adduction of the thigh.
Anterior fibers assist in
flexion of the hip.
Posterior fibers assist
in extension of the hip
N: Obturator nerve (anterior fibers).
Sciatic nerve (posterior fibers)
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Gracilis
O: Pubic bone
I: Proximal anteromedial tibia (via the
pes anserine)
A: Hip: adduction and flexion of the
thigh
Knee: flexion of the leg and medial
rotation of the leg when the knee is
bent
** Reversed muscle action causes
anterior tilting of the pelvis.
N: Obturator nerve
Pes Anserine: common insertion of
the Sartorius, Semitendinosus, and
Gracilis
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