Anal Triangle Muscles

Question 1

Coccygeus Origin

Answer 1

ischial spine

Question 2

Coccygeus Insertion

Answer 2

inferior end of sacrum and
coccyx

Question 3

Coccygeus Innervation

Answer 3

branches of S4 and S5

Question 4

Coccygeus Action

Answer 4

forms part of pelvic diaphragm to
support pelvic viscera, flexes coccyx

Question 5

Coccygeus Arterial Supply

Answer 5

inferior vesical, inferior
gluteal and internal pudendal arteries
(branches of the internal iliac artery)

Question 6

Levator Ani Origin

Answer 6

body of pubis, tendinous arch of levator ani, ischial spine

Question 7

Levator Ani Insertion

Answer 7

perineal body, coccyx, anococcygeal ligament, walls
of prostate or vagina, anal canal

Question 8

Levator Ani Innervation

Answer 8

nerve to the levator ani (S4), inferior anal nerve
(S2-S4) , coccygeal plexus

Question 9

Levator Ani Action

Answer 9

helps support pelvic viscera, resists increase in intra-
abdominal pressure

Question 10

Levator Ani Arterial Supply

Answer 10

inferior vesical, inferior gluteal and internal
pudendal arteries (branches of the internal iliac artery)

Question 11

Obturator Internus Origin

Answer 11

Pelvic surface of ilium and ischium; obturator membrane

Question 12

Obturator Internus Insertion

Answer 12

medial surface of greater
trochanter (trochanteric fossa) of
femur

Question 13

Obturator Internus Innervation

Answer 13

Nerve to the obturator
internus (L5, S1)

Question 14

Obturator Internus Action

Answer 14

laterally rotate extended hip
joint; abduct flexed hip joint; steady
femoral head in acetabulum
(stabilizes hip joint)

Question 15

Obturator Internus Arterial Supply

Answer 15

obturator artery

Question 16

Piriformis Origin

Answer 16

anterior surface of 2nd -4th sacral
segments; superior margin of greater
sciatic notch and sacrotuberous ligament

Question 17

Piriformis Insertion

Answer 17

superior border of greater
trochanter of femur

Question 18

Piriformis Innervation

Answer 18

anterior rami of S1 and S2

Question 19

Piriformis Action

Answer 19

laterally rotate extended hip
joint; abduct flexed hip joint; steady
femoral head in acetabulum (stabilizes
hip joint)

Question 20

Piriformis Arterial Supply

Answer 20

superior and inferior
gluteal arteries

Question 21

Psoas Major Action

Answer 21

acting inferiorly with the
iliacus, flexes the thigh; acting
superiorly, flexes the vertebral column
laterally to help with posture and
balance

Question 22

Psoas Major Insertion

Answer 22

Lesser trochanter of femur

Question 23

Quadratus Lumborum Course

Answer 23

-12th rib, lumbar vertebrae to iliac crest
- Passes under lateral arcuate ligament

Question 24

Quadratus Lumborum Action

Answer 24

Assists in lateral flexion of the
vertebral column