Abdominal Muscles

Question 1

External Oblique

Answer 1

Origin: lower eight ribs
Insertion: xiphoid process, linea alba, pubic crest, pubic tubercle, anterior half of iliac crest
Nerve: anterior rami of lower 6 thoracic nerve and iliohypogastric and ilioinguinal nerve
Action: flexing and rotating trunk; supports abdominal content; assist in forced expiration, micturition (urination), defecation, parturition (giving birth), vomiting

Question 2

Internal Oblique

Answer 2

Origin: lumbar fascia, iliac crest, lateral two thirds of inguinal ligament
Insertion: lower three ribs and costal cartilages, xiphoid process, linea alba, symphysis pubis
Nerve: lower 6 thoracic nerve and iliohypogastric and ilioinguinal nerves
Action: assists in flexing and rotating trunk, supports abdominal content, assist in forced expiration, micturition, defecation, parturition, and vomiting

Question 3

Transversus Abdominis

Answer 3

Origin: lower 6 costal cartilages, lumbar fascia, iliac crest, lateral third of inguinal ligament
Insertion: xiphoid process, linea alba, symphysis pubis
Nerve: lower 6 thoracic nerves and iliohypogastric and ilioinguinal nerve
Action: increases intraabdominal pressure; compresses abdominal content

Question 4

Rectus Abdominis Muscle

Answer 4

Origin: symphysis pubis and pubic crest
Insertion: 5th, 6th, and 7th costal cartilages and xiphoid process
Nerve: Lower 6 thoracic nerves
Action: compresses abdominal contents, flexes vertebral column; accessory muscle of expiration

Question 5

Pyramidalis

Answer 5

Origin: anterior surface of pubis
Insertion: linea alba
Nerve: 12th thoracic nerve
Action: tenses the linea alba

Question 6

Psoas Major

Answer 6

Origin: transverse processes, bodies, and intervertebral discs of 12th thoracic and 5 lumbar vertebrae
Insertion: with iliacus into the lesser trochanter of femur
Nerve: lumbar plexus
Action: flexes thigh on trunk if thigh is fixed, it flexes trunk on thigh as in sitting up from lying down

Question 7

Quadratus Lumborum

Answer 7

Origin: iliolumbar ligament, iliac crest, tps of transverse processes of lower lumbar vertebrae
Insertion: 12th rib
Nerve: lumbar plexus
Action: fixes 12th rib during inspiration; depresses 12th rib during forced expiration; laterally flexes vertebral column on the same side