6. Abdominal Wall Muscles Flashcards
External oblique
Origin
Insertion
Action
Largest and most superficial of the three lateral muscles; fibers run downward and medially - (same direction outstretched fingers take when hands put into pockets); apaneurosis turns under inferiorly, forming in GUI all ligament
O- by fleshy strips from outer surfaces of lower eight ribs
I- most fibers insert into linea alba vis a broad aponeurosis; some insert into public crest and tubercle and iliac crest
A- flex vertebral column and compress abdominal wall when pair contacts simultaneously; acting individually, aid muscles of back in trunk rotation and lateral flexion, used in oblique curls
Internal oblique
Origin
Insertion
Action
Most fibers run superiorly and medially,the muscle fans such that it’s inferior fibers run inferiorly and medially
O- lumbar fascia, iliac crest and inguinal ligament
I- linear alba, pubic crest, last three or four ribs and costal margin
A- flex vertebral column and compress abdominal wall when pair contacts simultaneously; acting individually
, aid muscles of back in trunk rotation and lateral flexion,used in oblique curls
Transversus abdominis
Origin
Insertion
Action
O- inguinal ligament, lumbar fascia, cartilages of last six ribs, iliac crest
I- aponeurosis of post and anterior rectus sheath and conjoint tendon to pubic crest and pectineal line
A- supports abdominal wall, aids forced expiration and raising intraabdominal pressure. conjoint tendon supports post wall of inguinal canal
Rectus abdominis
Origin
Insertion
Action
O-pubic crest and symphysis
I- xiphoid process and costal cartilages of ribs 5-7
A- flex and rotate lumbar region of vertebral column, fix and depress ribs, stabilize pelvis during walking, increase intra -abdominal pressure: used in sit ups and curls
Quadratics lumborum
Origin
Insertion
Action
O- Inferior border of 12th rib
I- Apices of transverse processes of L1-4, iliolumbar lig and post third of iliac crest
A-Fixes 12th rib during respiration and lateral flexes trunk
Pelvic diaphragm
Location
Action
Composed of levator ani and coccygenus
Urogential diaphragm
Location
Action
L- triangular ligament, which was described as a layer of the pelvis that separates the deep perineal sac from the upper pelvis, lying between the inferior fascia of the urogenital diaphragm (perineal membrane) and superior fascia of the urogenital diaphragm
A- supports the prostate in the male, is traversed by the vagina in the female, gives passage to the membranous part of the urethra, and encloses the sphincter urethrae
Ishiocavernosus
Location
Action
L- runs from pelvis to base of penis or clitoris
A- retards venous drainage and maintains erection of penis or clitoris
Bulbospongiosus
Location
Action
L- encloses base of penis (bulb) in males and lies deep to labia in females
A- empties male urethra; assists in erection of penis and clitoris
Levator ani
Location
Action
L- Broad, thin, tripartite muscle (pubococcygeus, puborectalis, iliococcygeus parts); its fibers extend inferomedially, forming a muscular “sling” around the prostate (or vagina), urethra, and anorectal junction before meeting in the median plane
A- supports and maintains position of pelvic organs; resists downward thrusts that accompany rises in intrapelvic pressure during coughing, vomiting, and expulsive efforts of abdominal muscles; forms sphincters at anorectal junction and vagina; lifts anal canal during defecation
Coccygeus
Location
Action
L-small triangular muscle lying posterior to levator ani; forms posterior part of pelvic diaphragm
A- supports pelvic organs; supports coccyx and pulls it forward after it has been reflected posteriorly by defecation and childbirth
