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Rectus abdominis

Contents

Anatomy

Rectus abdominis - anterior
Rectus abdominis - anterior unilateral
Rectus abdominis - anterolateral

Position

  • Superficial

Origin

  • Symphysis pubis
  • Crista pubis

Insertion

  • Costal cartilage of 5.-7. ribs
  • Processus xiphoideus

Main function

  • Trunk
    • Flexion
  • Pelvis
    • Posterior tilt

Secondary function

  • Trunk
    • Lateral flexion
    • Compresses abdominal content

Nerve innervation

  • Segmental
    • Th5-12

Arterial supply

  • Superior epigastriac artery
  • Inferior epigastriac artery

Referred pain pattern

Rectus abdominis - pain pattern

Muscle type

  • Phasic
    • Tendency to weaken when overactivated

Symptoms

  • Pain when lifting from a forwarded bent position
  • Problems with forceful abdominal breathing
  • Excessive flatus
  • Lax and distended abdomen
  • Loss of abdominal tone
  • Painful menses
  • Infant collic

OBSERVATION

Thoracic Kyphosis

  • The Rectus Abdominis is often involved in thoracic kyphosis since it is an antagonist to the thoracic back extensor muscles. When the Rectus Abdominis is shortened it pulls the thoracic back extensor muscles into an elongated position where it has to work against the tension of the abdominals
  • Please note that very skinny individuals might have more protrusion of the upper thoracic spinosus processi, giving a false impression of degree of thoracic kyphosis

Posterior Tilt And Flat Lumbar Spine

  • Notice any posterior tilt as the Rectus Abdominis has a direct influence on this position

Possible causes for tension

  • Postural faults
  • Breathing dysfunction
  • Overuse and strain
  • Trauma
  • Environmental stressors such as cold and damp
  • Nutritional deficiencies
  • Surgery and resulting scars
  • Viscerosomatic influences as a result of visceral disease
  • Viscerosomatic influences resulting from digestive disturbance
  • Emotional stress

Muscular attachments

Origin of rectus abdominis

Insertion of rectus abdominis

Videos

Short version

Detailed version

Important functions

  • The abdominal muscles play a significant role in positioning the thorax and in rotating the entire upper body
  • They are also known to play a key part in spinal stabilization and intersegmental stability, particularly the transversus abdominis
  • Rectus abdominis, external and internal obliquues and transversus abdominis are inolved in respiration due to their role in positioning the abdominal viscera as well as depression of the lower ribs, assisting in forced expiration and coughing
  • The upper fibers of rectus abdominis can pull the upper body anterior to the coronal line and help sustain a forward head position
  • The abdominals have a important function in maintaining postural equilibrium during unexpected movements
  • During tests it has been shown that when a subject stand on a narrow beam that is abruptly moved backward, the anterior muscles - Abdominals and Quadriceps are recruited to flex the trunk and extend the ankles, moving the hips backward
    • This demonstrates the body's coping mechanism with correcting imbalance by using synergistic muscles

Compensation

Muscles which compensates when this muscle is dysfunctional

Scaleni

  • When the abdominals locks the rib cage into depression, this causes problems for the Scaleni which is supposed to elevate the rib cage. This forces the Scaleni to increase it's force in order to prevent further depression

Increased tension in the muscle may cause problems with

  • Breathing
    • The abdominals depresses the rib cage, which causes a restriction to elevation of the rib cage, which again can cause problems with deep breathing
  • Back pain
  • Neck pain
  • Decreased neck rotation
  • Headaches

Too low tone in the muscle may case problems with

  • Anterior tilt of the pelvis causing increased lumbar lordosis
  • Lower back pain

Myofascial lines

Superficial ventral line

Supportive ventral line

Synergists

Flexion

  • External obliquue
  • Internal obliquue
  • Iliopsoas

Compression of abdominal viscera

  • External obliquue
  • Internal obliquue
  • Transversus abdominis
  • Pyramidalis
  • Quadratus lumborum
  • Diaphragma

Forced expiration

  • External obliquue
  • Internal obliquue
  • Transversus abdominis
  • Internal intercostals
  • Latissimus dorsi
  • Serratus posterior inferior
  • Quadratus lumborum
  • Iliocostalis lumborum

Antagonists

To flexion

  • Paraspinal muscles

To forced expiration

  • Diaphragma
  • Scalene
  • Parasternal internal intercostals
  • Levator costorum
  • Upper and lateral external intercostals
  • Sternocleidomastoideus
  • Upper trapezius
  • Serratus anterior
  • Serratus posterior inferior
  • Pectoralis major
  • Pectoralis minor
  • Latissimus dorsi
  • Erector spinae
  • Subclavius
  • Omohyoid