Rectus Abdominis Anatomy

Rectus Abdominis Muscle

Origin: The fifth to seventh costal cartilages, and the inferomedial costal margin and posterior aspect of the xiphoid process of the sternum
Insertion: Pubic crest and the pubic symphysis
Actions: Flexion of the vertebral column
Innervation: Ventral Primary rami of (T7 to T12)
Blood Supply: Branches from the musculophrenic artery, the lower two or three posterior intercostal arteries, the subcostal artery and branches from the superficial epigastric artery.

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: 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: Internal oblique, external oblique, and psoas major assist with flexion of the thoracic spine.

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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

Note: The internal and external obliques also assist with forced expiration.