Trunk and Pelvic Floor Muscles

  1. 43. Rectus abdominis
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    Origin: pubic crest & symphysis

    Insertion: xyphoid process &  ribs 5-7

    Function: flex and rotate lumbar region of vertebral column, fix & depress ribs, stabilize pelvis during walking, increase inta-abdominal pressure

    Nerve: Intercostals T7-T11, Subcostal T12
  2. 44. External oblique
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    Origin: outer surface of lower 8 ribs

    Insertion: linea alba via aponeurosis, ilac crest (external part)

    Function: when togetherm synergist to rectus abdomis, flex bertebral column & compress abdominal wall, when alone, synergist to muscles of back, rotate & lateral flexion of trunk

    Nerve: Intercostals T7-T11, Subcostals T12
  3. 45. Internal oblique
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    Origin: thoracolumbar fascia, iliac crest & inguinal ligament 

    Insertion: linea alba, last 3 or 4 ribs, lower margin of aponeurosis with tranverse abdominis = falx inguinalis

    Function: when together, synergist to rectus abdominis, flex vertebral column & compress abdominal wall, when alones, synergist to muscles of back, rotate & lateral flexion of trunk

    Nerve: Intercostals T8-T11, Subcostal T12, Iliohypogastric T12, Ilioinguinalis L1
  4. 46. Transverse abdominis
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    Origin: inguinal ligament, lumbar fascia, cartilages of last 6 ribs, iliac crest

    Insertion: linea alba, pubic crest

    Function: compresses abdominal contents

    Nerve: Intercostal T7-T11, Subcostal T12, Iliohypogastric, Ilioinguinal
  5. Serratus posterior superior
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    Origin: ligamentum nuchae, spinous process C6-Th2, supraspinal ligaments

    Insertion: angle of ribs 2 - 5

    Function: raises ribs; accesory respiratory muscle

    Nerve: intercostal (2 - 5)
  6. Serratus posterior inferior
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    Origin: spinous process Th11-L2, supraspinal ligaments

    Insertion: angle of rib 9-12

    Function: antagonist - draws in the lower ribs (helps with exhalation), fixes lower ribs for more action from diaphragm (helps with breathing)

    Nerve: intercostal nerves 9-12
  7. Erector spinae
    38-A Iliocostalis
    38-B Longissimus
    38-C Spinalis
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    Origin: [iliocostalis] iliac crests (lumborum), inferior 6 ribs (thoracic), ribs 3-6 (cervicis), [longissimus] transverse process of lumbar through cervical vertebrae, [spinalis] spines of upper lumbar & lower thoracic vertebrae

    Insertion: [iliocostalis] angle of ribs, cervical vertebrae, [longissimus] transeverse process of thoracic or cervical vertebrae, ribs, mastoid process, [spinalis] spines of upper thoracic & cervical vertebrae

    Function: [iliocostalis] extend vertebral column, bend vertebral column side to side when act on one side [longissimus] extend vertebral column, act on one side (bend it laterally), extends head + turns face toward same side [spinalis] extends vertebral column

    Nerve: Spinal nerves, posterior branch (dorsal rami)
  8. mm. Multifidi
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    Origin: superior articulations of C4 - C7 (cervicis), transverse processes of thoracic vertebrae (thoracis), mamillary process of lumbar vertebrae, sacrum (lumborum)

    Insertion: spinous processes of vertebrae

    Function: Bilateral contraction: Extension of spineUnilateral contraction: Lateral flexion of spine (ipsilateral), rotation of spine (contralateral)

    Nerve: Spinal nerves (dorsal rami)
  9. Diaphragm
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    Origin: (sternal part) inner surface of sternum (xiphoid process) + inner side of rectus abdominis, (costal part) rib cartilages 7 - 12, (lumbal part) Medial and lateral arcuate ligaments (lumbocostal arches), bodies of vertebrae L1-L3 (+intervertebral discs), anterior longitudinal ligamentInsertion: central tendonFunction: Depresses costal cartilages, primary muscle of breathing (inspiration)Nerve: Phrenic nerve (cervical plexus, C3, C4, C5)
  10. 39. Quadratus lumborum
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    Origin: posterior boarder of iliac crest + lumbar fascia

    Insertion: transverse process of L1 - L5 + lower margin of  12th rib

    Function: flexes vertebral column + laterally, extends lumbar spine

    Nerve: T12 + 1st - 4th anterior lumbar spinal nerves, anterior branch (L1-L4)
  11. 47 Levator ani
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    Puborectalis: Posterior surface of bodies of pubic bones

    Pubococcygeus: Posterior surface of bodies of pubic bones (lateral to puborectalis)

    Iliococcygeus: Tendinous arch of interal obturator fascia, Ischial spine


    Puborectalis: None (forms 'puborectal sling' posterior to rectum)

    Pubococcygeus: Anococcygeal ligament, Coccyx, Perineal body and musculature of prostate/ vagina

    Iliococcygeus: Anococcygeal ligament, Coccyx

    Function: Stability and support of the abdominal and pelvic organs, resistance against increased intra-abdominal pressure, opening and closing of the levator hiatus

    Nerve: sacral plexus S3, S4
  12. 48 Coccygeus
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    Origin: Ischial spine

    Insertion: coccyx

    Function: Supports pelvic viscera, part of the diaphragm of pelvis

    Nerve: sacral plexus S3 - S4
Card Set
Trunk and Pelvic Floor Muscles
origin, insertion and innervation