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Rectus Abdominis: Origin, Insertion, Action

Rectus Abdominis Origin, Insertion, Action

Rectus Abdominis Muscle

O, I, A of the Rectus Abdominis

  • Origin: Pubic crest and the pubic symphysis
    Insertion: From the fifth to seventh costal cartilages, and the inferomedial costal margin and posterior aspect of the xiphoid process of the sternum
    Actions: Flexion of the vertebral column, posteriorly tilts the pelvis, compresses abdominal contents, assists with forces expiration
    Innervation: Ventral Primary rami of (T7 to T12)
    Blood Supply: Muscular branches from the superior and inferior epigastric arteries

Primary Actions of the Rectus Abdominis:

1. Flexion of the thoracic spine when acting bilaterally

  Agonists: None

  Antagonists: 

  • Iliocostalis cervicis
  • Iliocostalis thoracics
  • Iliocostalis lumborum
  • Longissimus cervicis
  • Longissimus thoracics
  • Spinalis thoracics
  • Semispinalis cervicis

Note:  The internal oblique, external oblique, and psoas major assist with flexion of the thoracic spine. 

2. Flexion of the lumber spine when acting bilaterally

  Agonists: None

  Antagonists: 

  • Iliocostalis lumborum
  • Longissimus thoracics
  • Spinalis thoracics

Note:  The internal oblique, external oblique, and psoas major assist with flexion of the lumbar spine. 

Secondary Actions of the Rectus Abdominis:

1. Assists with forced expiration

  Agonists:

  • Serratus posterior inferior
  • Transversus Abdominis

  Antagonists: 

  • Serratus posterior superior
  • Levatores costarum breve
  • Levatores costarum longi
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Information about cause and effect of rectus abdominis pain:
Rectus Abdominis Muscle: Mid and Low Back, Abdominal, Heartburn, Testicular Pain