Anatomy exam 3 muscles

external oblique

origin: 5-12 ribs

insertion: linea alba, iliac crest, & pubic tubercle

innervation: T7-T-11

action: compres/support abdominal viscera

flex and rotate trunk

Internal Oblique

origin: thoracolumbar fascia, iliac crest, and connective tissue deep to inguinal ligament

insertion: ribs 10-12, linea alba

innervation: T6-T12, L1

action: compress/support abdominal viscera

flex and rotate trunk

Rectus abdominis

origin: pubic symphysis and pubic crest

insertion: xiphoid process and 5-7 costal cartilages

innervation: T6-T12

action: -flexes trunk

-compress abdominal visceral

-controls tilt of pelvis

Transversus Abdominis

origin: 7-12 costal cartilage, iliac crest, and connective tissue deep to inguinal ligament

insertion: linea alba and pubic crest

innervation: T6-T12, L1

action: compresses and support abdominal viscera

(strongest and deepest)

Psoas Major

origin: T12-L5

insertion: lesser trochanter of femur

innervation: L1-L3

actions: -flex thigh/hip

-lateral flexion of vertebrae column

-when sitting- flexes trunk

iliacus

origin: iliac fossa and sacrum

insertion: lesser trochanter of femur

innervation: femoral n. (L2-L4)

action: flexes thigh and stabilizes hip joint

quadratus lumborum

origin: rib 12, lumbar transverse process L1-L4

insertion: iliolumbar ligament and iliac crest

innervation: T12, L1-L4

action: - extend vertebral column

-laterally flex vertebral column

diaphragm- anterior muscle fibers

insert into xiphoid process and costal margin

diaphragm- lateral muscle fibers

insert into ribs 6-12

diaphragm- posterior muscle fibers

insert into T12-L3

diaphragm innervation

phrenic nerve (C3-C5)

proximal esophagus muscle

upper 1/3

striated skeletal muscle

voluntary

intermediate esophagus muscle

middle 1/3

striated skeletal muscle

smooth muscle

distal esophagus muscle

lower 1/3

smooth muscle

involuntary

muscles of pelvic floor

levator ani group (most important)

coccygeus

piriformis

muscles in levator ani muscle group

puborectalis

pubococcygeus

iliococcygeus

What is the most important of the pelvic floor muscles?

levator ani group

puborectalis

part of levator ani muscle group

maintain fecal continence

pubococcygeus

part of levator ani muscle group

usually torn during childbirth, can cause stress incontinence

iliococcygeus

posterolateral part of levator ani muscle group

superficial gluteal muscles

large muscles

-gluteus maximus: extension, lateral rotation of thigh

-gluteus medius: abduct, medially rotate thigh

-gluteus minimus: abduct, medially rotate thigh

-tensor fasciae latae: flexor of thigh, not independent

deep gluteal muscles

small muscles; lateral rotators of thigh and stabilizers of hip joints

-piriformis

-obturator internus

-superior gemelli

-inferior gemelli

-quadratus femoris

gluteus maximus

origin: ilium posterior to gluteal line; dorsal surface of sacrum and coccyx; sacrotuberous ligament

insertion: most fibers end in iliotibial tract which inserts into lateral condyle of tibia, some fibers insert on gluteal tuberosity of femur

innervation: inferior gluteal nerve (L5-S2)

action:- major extensor of thigh

- lateral (external) rotator

- steadies thigh and assists in rising from sitting position

gluteus medius

origin: external surface of ilium between anterior and posterior gluteal lines

insertion: lateral surface of greater trochanter of femur

innervation: superior gluteal nerve (L4-S1)

action: -abducts thigh

-medial rotator

-prevents pelvic tilt when walking

gluteus minimus

origin: external surface of ilium between anterior and inferior gluteal lines

insertion: anterior surface of greater trochanter of femur

innervation: superior gluteal nerve (L4-S1)

action: -abduction of hip

-medial rotation of thigh

-assists gluteus medius in it’s actions

Perineal Muscles

external anal sphincter

bulbospongious

ischiocavernosus

external anal sphincter

constrict anal canal during peristalsis resisting defecation

support and fixes perineal body/pelvic floor

bulbospongiosus (M & F)

support and fixes perineal body/pelvic floor

bulbospongiosus- male

compress bulb of penis to expel last drop of urine/semen

assist erection

bulbospongiosus- female

sphincter of vagina

assists in erection of clitoris

ischiocavernosus

maintain erection of penis or clitoris by compressing outflow veins

piriformis

deep small muscle; lateral rotator of the thigh and
stabilizer of the hip joints

psoas minor

posterior abdominal wall