| Muscle | Origin | Insertion | Action | Innervation | Artery | Notes |
|---|---|---|---|---|---|---|
| cremaster | inguinal ligament | forms thin network of muscle fascicles around the spermatic cord and testis or around the distal portion of the round ligament of the uterus | elevates testis (not well developed in females) | genital branch of the genitofemoral nerve | cremasteric a., a branch of the inferior epigastric a. | the cremaster m. is internal abdominal oblique muscle's contribution to the coverings of the spermatic cord and testis; the cremasteric reflex may be elicited by stroking the medial thigh (where the femoral branch of the genitofemoral n. distributes cutaneously) |
| dartos | subcutaneous connective tissue of the scrotum and the penis or labium majus and clitoris | skin of the scrotum and penis (or labium majus and clitoris) | elevates testis (tenses the skin of the pudendal region in the female) | postganglionic sympathetic nerve fibers arriving via the ilioinguinal nerve and the posterior scrotal nerve | cremasteric a., posterior scrotal (labial) a. | the dartos elevates the testis in response to cold (it is modified arrector pili fibers, or the goose-bump muscles) |
| diaphragm | xiphoid process, costal margin, fascia over the quadratus lumborum and psoas major mm.(lateral & medial arcuate ligaments), vertebral bodies L1-L3 | central tendon of the diaphragm | pushes the abdominal viscera inferiorly, increasing the volume of the thoracic cavity (inspiration) | phrenic nerve (C3-C5) | musculophrenic a., superior phrenic a., inferior phrenic a. | left crus attaches to the L1-L2 vertebral bodies, the right crus attaches to the L1-L3 vertebral bodies |
| external abdominal oblique | lower 8 ribs | linea alba, pubic crest & tubercle, anterior superior iliac spine & anterior half of iliac crest | flexes and laterally bends the trunk | intercostal nerves 7-11, subcostal, iliohypogastric and ilioinguinal nerves | musculophrenic a., superior epigastric a., intercostal aa. 7-11, subcostal a., lumbar aa., superficial circumflex iliac a., deep circumflex iliac a., superficial epigastric a., inferior epigastric a., superficial external pudendal a. | the inguinal ligament is a specialization of the external abdominal oblique aponeurosis; the external spermatic fascia is the external abdominal oblique muscle's contribution to the coverings of the testis and spermatic cord |
| iliacus | iliac fossa and iliac crest; ala of sacrum | lesser trochanter of the femur | flexes the thigh; if the thigh is fixed it flexes the pelvis on the thigh | femoral nerve | iliolumbar a. | inserts in company with the psoas major m. via the iliopsoas tendon |
| iliopsoas | iliac fossa; bodies and transverse processes of lumbar vertebrae | lesser trochanter of the femur | flexes the thigh; flexes and laterally bends the lumbar vertebral column | branches of the ventral primary rami of spinal nerves L2-L4; branches of the femoral nerve | iliolumbar a. | a combination of the iliacus and psoas major mm. |
| interfoveolar | transversus abdominis fibers that lie superficial to the inferior epigastric vessels | anterior lamina of femoral sheath, immediately distal to origin of inferior epigastric vessels | compresses abdominal contents | iliohypogastric and ilioinguinal nerves | inferior epigastric a. | an inconstant part of the transversus abdominis m. which may be replaced by a ligament (interfoveolar ligament) |
| internal abdominal oblique | thoracolumbar fascia, anterior 2/3 of the iliac crest, lateral 2/3 of the inguinal ligament | lower 3 or 4 ribs, linea alba, pubic crest | flexes and laterally bends the trunk | intercostal nerves 7-11, subcostal, iliohypogastric and ilioinguinal nerves | musculophrenic a., superior epigastric a., intercostal aa. 7-11, subcostal a., lumbar aa., superficial circumflex iliac a., deep circumflex iliac a., superficial epigastric a., inferior epigastric a., superficial external pudendal a. | anterior fibers of internal abdominal oblique course up and medially, perpendicular to the fibers of external abdominal oblique; the cremaster muscle and fascia is the internal abdominal oblique muscle's contribution to the coverings of the testis and spermatic cord |
| oblique, external abdominal | lower 8 ribs | linea alba, pubic crest & tubercle, anterior superior iliac spine & anterior half of iliac crest | flexes and laterally bends the trunk | intercostal nerves 7-11, subcostal, iliohypogastric and ilioinguinal nerves | musculophrenic a., superior epigastric a., intercostal aa. 7-11, subcostal a., lumbar aa., superficial circumflex iliac a., deep circumflex iliac a., superficial epigastric a., inferior epigastric a., superficial external pudendal a. | the inguinal ligament is a specialization of the external abdominal oblique aponeurosis; the external spermatic fascia is the external abdominal oblique muscle's contribution to the coverings of the testis and spermatic cord |
| oblique, internal abdominal | thoracolumbar fascia, anterior 2/3 of the iliac crest, lateral 2/3 of the inguinal ligament | lower 3 or 4 ribs, linea alba, pubic crest | flexes and laterally bends the trunk | intercostal nerves 7-11, subcostal, iliohypogastric and ilioinguinal nerves | musculophrenic a., superior epigastric a., intercostal aa. 7-11, subcostal a., lumbar aa., superficial circumflex iliac a., deep circumflex iliac a., superficial epigastric a., inferior epigastric a., superficial external pudendal a. | anterior fibers of internal abdominal oblique course up and medially, perpendicular to the fibers of external abdominal oblique; the cremaster muscle and fascia is the internal abdominal oblique muscle's contribution to the coverings of the testis and spermatic cord |
| psoas major | bodies and transverse processes of lumbar vertebrae | lesser trochanter of femur (with iliacus) via iliopsoas tendon | flexes the thigh; flexes & laterally bends the lumbar vertebral column | branches of the ventral primary rami of spinal nerves L2-L4 | subcostal a., lumbar aa. | the genitofemoral nerve pierces the anterior surface of the psoas major m. |
| psoas minor | bodies of the T12 & L1 vertebrae | iliopubic eminence at the line of junction of the ilium and the superior pubic ramus | flexes & laterally bends the lumbar vertebral column | branches of the ventral primary rams of spinal nerves L1-L2 | lumbar aa. | absent in 40% of cases |
| pyramidalis | pubis, anterior to the rectus abdominis | linea alba | draws the linea alba inferiorly | subcostal nerve | subcostal a., inferior epigastric a. | the pyramidalis m. is not always present |
| quadratus lumborum | posterior part of the iliac crest and the iliolumbar ligament | transverse processes of lumbar vertebrae 1-4 and the 12th rib | laterally bends the trunk, fixes the 12th rib | subcostal nerve and ventral primary rami of spinal nerves L1-L4 | subcostal a., lumbar aa. | the lateral arcuate ligament of the diaphragm crosses the anterior surface of the quadratus lumborum m. |
| rectus abdominis | pubis and the pubic symphysis | xiphoid process of the sternum and costal cartilages 5-7 | flexes the trunk | intercostal nerves 7-11 and subcostal nerve | superior epigastric a. intercostal aa., subcostal a., inferior epigastric a. | rectus sheath contains rectus abdominis and is formed by the aponeuroses of external and internal oblique and transversus abdominis mm. |
| transversus abdominis | lower 6 ribs, thoracolumbar fascia, anterior 3/4 of the iliac crest, lateral 1/3 of inguinal ligament | linea alba, pubic crest and pecten of the pubis | compresses the abdomen | intercostal nerves 7-11, subcostal, iliohypogastric and ilioinguinal nerves | musculophrenic a., superior epigastric a., intercostal aa. 7-11, subcostal a., lumbar aa., superficial circumflex iliac a., deep circumflex iliac a., superficial epigastric a., inferior epigastric a., superficial external pudendal a. | transversus abdominis muscle does not contribute to the coverings of the spermatic cord and testis; transversalis fascia, the deep fascia that covers the inner surface of the transversus abdominis, forms the internal spermatic fascia |