Muscles Of Thoracic Wall Flashcards
Internal intercostal Origin? Insertion? Innervation? Action?
O: Inferior border of ribs
I: Superior border of ribs below
Inner: Intercostal nerve
Action: During forced inspiration: interosseous part depresses ribs; interchondral part elevates ribs
External intercostal Origin? Insertion? Innervation? Action?
O: Inferior border of ribs
I: Superior border of ribs below
Inner: Intercostal nerve
Action: During forced inspiration elevates ribs
Innermost intercostal Origin? Insertion? Innervation? Action?
O: Inferior border of ribs
I: Superior border of ribs below
Inner: Intercostal nerve
Action: During forced inspiration: interosseous part depresses ribs; interchondral part elevates ribs
Transversus thoracis Origin? Insertion? Innervation? Action?
O: Posterior surface of lower sternum
I: Internal surface of costal cartilages 2-6
Inner: Intercostal nerve
Action: Weakly depresses ribs
External oblique Origin? Insertion? Innervation? Action?
O: External surfaces of 5th-12th ribs
I: Linea alba, pubic tubercle, and anterior half of iliac crest
Innervation: Thoraco-abdominal nerves (anterior rami of T7-T11) and subcostal nerve
Action: Compress and support abdominal viscera; flex and rotate trunk
Internal oblique Origin? Insertion? Innervation? Action?
O: Thoracolumbar fascia, anterior 2/3 of iliac crest, and connective tissue deep to inguinal ligament
I: Inferior border of 10-12th ribs, linea alba, and pubis via conjoint tendon
Inner: Thoraco-abdominal nerves (anterior rami of T7-T11) and first lumbar nerve
Action: Compress and support abdominal viscera; flex and rotate trunk
Transversus abdominis Origin? Insertion? Innervation? Action?
O: Internal surfaces of 7th-12th costal cartilages, thoracolumbar fascia, iliac crest, and connective tissue deep to inguinal ligament
I: Linea alba with aponeurosis of internal oblique, pubic crest, and pectin pubis via conjoint tendon
Inner: Thoraco-abdominal nerves (anterior rami of T7-T11) and first lumbar nerve
Action: Compresses and supports abdominal viscera
Rectus abdominis Origin? Insertion? Innervation? Action?
O: Pubic symphysis and pubic crest
I: Xiphoid process and 5th-7th costal cartilages
Inner: Thoraco-abdominal nerves (anterior rami of inferior 6 thoracic nerves)
Action: Flexes trunk (lumbar vertebrae) and compresses abdominal viscera; stabilizes and controls tilt of pelvis (antilordosis)
Psoas major Origin? Insertion? Innervation? Action?
O: Transverse processes of lumbar vertebrae; sides of bodies of T12-S1 vertebrae and intervening IV discs
I: By a strong tendon to lesser trochanter of femur
Inner: Lumbar plexus via anterior branches of nerves L2-L4
Action: Acting inferiorly with iliacus, flexes thigh. Acting superiorly, flexes vertebral column laterally to balance the trunk. When sitting, acts inferiorly with iliacus to flex trunk.
Iliacus Origin? Insertion? Innervation? Action?
O: Superior 2/3 of iliac fossa, ala of sacrum, and anterior sacro-iliac ligaments
I: Lesser trochanter of femur and shaft inferior to it, and to psoas major tendon
Inner: Femoral nerve (L2-L4)
Action: Flexes thigh and stabilizes hip joint. Acts with psoas major.
Quadratus lumborum Origin? Insertion? Innervation? Action?
O: Medial half of inferior border of 12th rib and tips of lumbar transverse processes
I: Iliolumbar ligament and internal lip of iliac crest
Inner: Anterior branches of T12 and L1-L4 nerves
Action: Extends and laterally flexes vertebral column. Fixes 12th rib during inspiration
Levator ani Origin? Insertion? Innervation? Action?
O: Body of pubis, tendinous arch of levator ani, ischial spine
I: Perineal body, coccyx, anacoccygeal ligament, walls of prostate or vagina, rectum anal canal
Inner: Nerve to levator ani (branches of S4), inferior anal (rectal) nerve, coccygeal plexus
Action: Helps support pelic viscera; resists increases in intra-abdominal pressure
Coccygeus Origin? Insertion? Innervation? Action?
O: Ischial spine
I: Inferior end of sacrum
Inner: Branches of S4 and S5 nerves
Action: Forms small part of pelvic diaphragm that supports pelvic viscera; flexes coccyx
Obturator internus Origin? Insertion? Innervation? Action?
O: Pelvic surface of ilium and ischium; obturator membrane
I: Greater trochanter of femur
Inner: Nerve to obturator internus (L5, S1, and S2)
Action: Rotates thigh laterally; assists in holding head of femur in acetabulum
Piriformis Origin? Insertion? Innervation? Action?
O: Pelvic surface of 2nd-4th sacral segments; superior margin of greater sciatic notch and sacrotuberous ligament
I: Greater trochanter of femur
Inner: Anterior rami of S1 and S2
Action: Rotates thigh laterally; abducts thigh; assists in holding head of femur in acetabulum
