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  1. Muscles of the thorax
    1. Intercostal (external)
      attachments - from rib to rib oriented from superior-lateral to inferior-medial
      actions - elevation of ribs
      innervation - intercostal nerve
    2. Intercostal (internal & innermost)
      attachments - from rib to rib oriented superior-medial to inferior-lateral
      actions - depression of ribs
      innervation - intercostal nerve
    3. Transversus thoracis
      attachments - from posterior sternum to costal cartilages
      actions - depress ribs
      innervation - intercostal nerves
  2. Muscles of the abdomen
    1. Cremaster (G. kremaster, a suspender)
      attachments - from the medial edge of the internal oblique to spermatic cord
      actions - elevation of testis
      innervation - genitofemoral nerve
    2. Diaphragm
      attachments - from xiphoid process, inner surface of the lower ribs & costal cartilages, medial & lateral arcuate ligaments & lumbar vertebrae via the crura to the central tendon
      actions - inspiration (negative thoracic pressure by inferior displacement)
      innervation - phrenic nerve
    3. External oblique
      attachments - from lower 8 ribs to iliac crest & rectus sheath
      actions - flexion & rotation of the trunk, & compression of the abdominal cavity
      innervation - ventral rami T7-12
    4. Internal oblique
      attachments - from thoracolumbar fascia to inguinal ligament, iliac crest & rectus sheath
      actions - flexion & rotation of the trunk, & compression of the abdominal cavity
      innervation - lower thoracic & L1 ventral rami
    5. Quadratus lumborum
      attachments - from 12th rib to iliolumbar ligament & iliac crest
      actions - extension & lateral flexion of the trunk, and fixes 12th rib during respiration
      innervation - ventral rami T12-L3
    6. Rectus abdominis
      attachments - from xiphoid process & adjacent costal cartilages to pubic crest & tubercle
      actions - flexion of trunk & compression of abdominal cavity
      innervation - lower thoracic ventral rami
    7. Transversus abdominis
      attachments - from lower six costal cartilages & thoracolumbar fascia to inguinal ligament, iliac crest & rectus sheath
      actions - compression of the abdominal cavity
      innervation - lower thoracic & L1 ventral rami
  3. Muscles of the pelvis
    1. Iliacus (details under Lower Extremity)
    2. Psoas (details under Lower Extremity)
    3. Piriformis (details under Lower Extremity) (L. pirum, pear)
    4. Obturator internus (details under Lower Extremity)
    5. Pelvic diaphragm
      1. Coccygeus
        attachments - from ischial spine & sacrospinous ligament to coccyx
        actions - supports & compresses posterior pelvic floor
        innervation - ventral rami S4-5
      2. Levator ani
        attachments - from pubic symphysis, obturator fascia & ischial spine to midline raphe & anococcygeal ligament
        actions - supports pelvic viscera, & compresses rectum & vagina
        innervation - pudendal nerve (inferior rectal branches) & S4
  4. Muscles of the perineum
    1. Bulbospongiosus
      attachments - in male from median raphe & perineal body (central tendon) to surround bulb of penis; in female from the perineal body to surround vestibular bulb, vaginal orifice & clitoris
      actions - in male empties urethra, maintains erection & contracts during ejaculation; in female constricts vaginal orifice & contributes to erection of clitoris
      innervation - perineal branch of pudendal nerve
    2. Ischiocavernosus
      attachments - from ischial tuberosity & ramus to aponeurosis surrounding crus of penis or clitoris
      actions - compresses crus during erection
      innervation - perineal branch of pudendal nerve
    3. Sphincter ani externus
      attachments - from perineal body (central tendon) to anococcygeal raphe
      actions - closes anal canal & fixes perineal body
      innervation - inferior rectal branch of pudendal nerve
    4. Sphincter urethrae
      attachments - surrounds urethra
      actions - compresses urethra
      innervation - perineal branch of pudendal nerve
    5. Compressor urethrae
      attachments - in the female from the ischiopubic ramus to midline passing ventral to the urethra and inferior to the sphinchter urethrae with a variable number of fibers fanning out medially to reach the vagina (thus replacing the deep transverse perineus)
      actions - compresses urethra
      innervation - perineal branch of the pudendal nerve
    6. Sphincter urethrovaginalis
      attachments - from perineal body, surrounds vagina & urethra to meet contralateral muscle inferior to compressor urethrea
      actions - compresses urethra & vagina
      innervation - perineal branch of the pudendal nerve
    7. Deep transverse perineus
      attachments - from ischial tuberosity to perineal body (central tendon)
      actions - fixes perineal body
      innervation - perineal branch of pudendal nerve
    8. Superficial transverse perineus
      attachments - from ischial tuberosity to perineal body (central tendon)
      actions - fixes perineal body
      innervation - perineal branch of the pudendal nerve

Overview