1 Myology Myology of the Pelvis. 2 Pelvic Girdle Pelvic girdle: consists of the two hipbones (coxal...

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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

sacrum, forming the sacroiliac joint

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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 tuberosities.

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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

• Common site of femoral fracture in the elderly

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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 MotionEach student should be able to describe and demonstrate the

following movements:

1. Hip flexion2. Hip extension3. Medial rotation4. Lateral rotation5. Hip abduction6. Hip adduction7. Circumduction8. Horizontal abduction9. 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 femurGluteus MaximusGluteus Medius Posterior GroupGluteus Minimus

PiriformisGemellus SuperiorObturator InternusGemellus Inferior Six Deep Lateral Rotators “GOGO Muscles” Obturator externusQuadratus femoris

Psoas MajorPsoas Minor Anterior GroupIliacusTensor Fascia Latae

PectineusAdductor LongusAdductor Brevis Medial

GroupAdductor MagnusGracilis

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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 MediusO: 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.


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PiriformisO: 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


A: Lateral rotation of the femur


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Obturator Internus

O: Internal surface of the pelvic bone




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Gemellus Inferior

O: Ischial tuberosity




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Obturator Externus

O: External surface of the pelvic bone

I: Medial aspect 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


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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.


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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

1 Myology Myology of the Pelvis. 2 Pelvic Girdle Pelvic girdle: consists of the two hipbones (coxal...

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Transcript of 1 Myology Myology of the Pelvis. 2 Pelvic Girdle Pelvic girdle: consists of the two hipbones (coxal...