Pelvis anatomy

Question 1

Obturator internus

Answer 1

Supplied by L5 and S1, attaches to GT of femur

Lateral rotation of femur and abduction of flexed hip

Question 2

Piriformis

Answer 2

Supplied by S1 and S2, attaches to GT of femur above obturator internus
Lateral rotation of femur and abduction of flexed hip
Separates greater sciatic foramen into two regions (one above and one below)

Question 3

Obturator canal

Answer 3

Bordered by obturator membrane, associated obturator muscles and superior pubic ramus. Obturator nerve and vessels pass from pelvic cavity to the thigh through this canal.

Question 4

Greater sciatic foramen

Answer 4

Formed by greater sciatic notch, sacrotuberous and sacrospinous ligaments and spine of ischium.
Superior gluteal nerves and vessels passes through foramen above piriformis
Inferior gluteal nerves and vessels, sciatic nerve, pudendal nerve, internal pudendal vessels, posterior femoral cutaneous nerves and nerves to obturator internus and quadratus femoris muscle passes below piriformis

Question 5

Lesser sciatic foramen

Answer 5

Formed by lesser sciatic notch, ischial spine, sacrospinous ligament, sacrotuberous ligament.
Tendon of obturator internus passes through this foramen to enter gluteal region.
Below attachment of pelvic floor, act as route of communication between perineum and gluteal region.
Pudendal nerve and internal pudendal vessels pass through here as well + greater sciatic foramen

Question 6

Pelvic floor

Answer 6

Formed by pelvic diaphragm, perineal membrane and muscles in deep perineal pouch
Greater sciatic foramen above pelvic floor
Lesser sciatic foramen below pelvic floor

Question 7

Pelvic diaphragm

Answer 7

Levator ani (iliococcygeus, pubococcygeus and puborectalis) and coccygeus muscles from both sides
Innervated by branches of anterior ramus of S4 and branches of pudendal nerve S2-S4

Question 8

External urethral sphincter

All muscles in deep perineal pouch

Answer 8

Innervated by perineal branches of pudendal nerve

Question 9

Ureters

Answer 9

Enters pelvic cavity anterior to bifurcation of common iliac artery and joins base of bladder.
Crossed by
uterine artery in women
ductus deferens in men

Question 10

Bladder

Answer 10

Retroperitoneal structure
apex, two inferolateral surfaces, base and superior surface
Neck is most fixed part of the bladder. Anchored onto posteroinferior aspect of pubic bone by pubovesical ligaments (women) or puboprostatic ligaments (men)

Question 11

Deep perineal pouch

Answer 11

Space between pelvic diaphragm (superior) and perineal membrane at the bottom

Question 12

Bladder cancer spreads via

Answer 12

internal iliac lymph nodes

Question 13

Urethra in women

Answer 13

Short, about 4cm.

Question 14

Urethra in men

Answer 14

Long, about 20cm, bends twice along its course.

Preprostatic, prostatic, membranous and spongy.

Question 15

Preprostatic part of urethra

Answer 15

1cm long, associated with internal urethral sphincter

Question 16

Prostatic part

Answer 16

3-4cm long, site of connection between reproductive and urinary part of men

Question 17

membranous part

Answer 17

passes through deep perineal pouch.

Surrounded by external urethral sphincter

Question 18

Spongy part

Answer 18

longest part of urethra

Question 19

Sacral plexus

Answer 19

formed by anterior rami of S1-S4 and lumbosacral trunk (L4 and L5).
Plexus formed in relation to anterior surface of piriformis muscle.

Question 20

Lumbosacral trunk

Answer 20

part of L4 and all of L5.

Passes into pelvic cavity anterior to sacroiliac joint

Question 21

Sacral splanchnic nerves

Answer 21

Contribute to inferior hypogastric plexus

Question 22

Branches of sacral

Answer 22

Sciatic nerve - tibial part, common fibular part
Pudendal S2-S4
Superior gluteal L4-S1
Inferior gluteal L5-S2
Nerve to obturator internus and superior gemelli L5-S2
Nerve to quadriceps femoris and inferior gemelli L4-S1
Posterior femoral cutaneous nerve S1, S3
Perforating cutaneous nerve
Nerve to piriformis S1-S2
Nerves to levator ani, coccygeus and external anal sphincter S4
Pelvic splanchnic nerves S2-S4

Question 23

Branch of coccygeal plexus

Answer 23

Anococcygeal nerves

Question 24

Sciatic nerve - tibial part

Answer 24

L4 to S3
Forms on anterior surface of piriformis and leaves through greater sciatic foramen inferior to piriformis
Motor:
posterior compartment of thigh (including hamstring of adductor magnus) except for short head of biceps
All muscles of posterior compartment of leg
All muscles in sole of foot
Sensory:
Skin on posterolateral and lateral surface of foot and sole of foot

Question 25

Sciatic nerve - common fibular part

Answer 25

L4 to S2 Motor: Short head of biceps All muscles in anterior and lateral compartment of leg Extensor digitorum brevis in foot Sensory: Skin on anterolateral surface of leg and dorsal surface of foot

Question 26

Pudendal nerve

Answer 26

S2-S4 Motor: Skeletal muscles in perineum including urethral and anal sphincters and levator ani Sensory: Most skin of perineum, penis and clitoris

Question 27

Superior gluteal

Answer 27

L4 to S1 | Motor: gluteus medius, gluteus minimus and tensor fasciae latae

Question 28

Inferior gluteal

Answer 28

L5 to S2 | Motor: gluteus maximus

Question 29

Pelvic splanchnic nerves

Answer 29

Motor visceral: erection, mobility in GI system distal to left colic flexure, inhibitory to internal urethral sphincter Sensory visceral: Pelvic viscera and distal parts of colon.

Question 30

Obturator nerve

Answer 30

L2 to L4 - branch of lumbar plexus. Passes posterior to common iliac artery and medially to the internal iliac artery at the pelvic inlet and along lateral pelvic wall. Travel through obturator canal and supplies adductor region of thigh

Question 31

Pelvic prevertebral plexus hypogastric nerves

Answer 31

Enters pelvis as two hypogastric nerves, cross the pelvic inlet medial to internal iliac vessels. Formed by splitting of superior hypogastric plexus into right and left bundles.

Question 32

Inferior hypogastric plexus

Answer 32

Formed when hypogastric nerves joined by pelvic splanchnic nerves S2 to S4. Course medially to major vessels and somatic nerves Gives rise to: rectal, uterovaginal, prostatic and vesical plexus Innervate erectile tissue of penis and clitoris in perineum.

Question 33

Sympathetic fibers of inferior hypogastric plexus

Answer 33

``` Mainly T10 to L2 Innervate blood vessels Contraction of internal anal/urethral sphincters Contraction of reproductive tract Ejaculation ```

Question 34

Parasympathetic fibers of pelvic plexus

Answer 34

``` From pelvic splanchnic nerves S2-S4 Generally vasodilatory Stimulate bladder contraction Stimlate erection Modulate activity of enteric nervous system of colon distal to left colic flexure ```

Question 35

Major artery supply to pelvis and perineum

Answer 35

Internal iliac artery

Question 36

Site of origin of internal iliac artery

Answer 36

Level of L5-S1, anteromedial to sacro-iliac joint | Divides into anterior and posterior trunk at superior border of greater sciatic foramen

Question 37

Branches of posterior trunk of internal iliac artery

Answer 37

Supply lower posterior abdominal wall, posterior pelvic wall and gluteal region Iliolumbar artery, lateral sacral artery and superior gluteal artery

Question 38

Branches of anterior trunk of internal iliac artery

Answer 38

Pelvic viscera, perineum, gluteal, adductor of thigh, placenta Superior vesical artery, umbilical artery, inferior vesical artery/vaginal, middle rectal artery, uterine artery, obturator artery, internal pudendal and inferior gluteal

Question 39

Obturator artery

Answer 39

In between obturator nerve (above) and obturator vein (below) enters and supplies adductor region of thigh

Question 40

internal pudendal artery

Answer 40

Leaves pelvic cavity through greater sciatic foramen inferior to piriformis muscle With pudendal nerve on its medial side, passes laterally to ischial spine and through lesser sciatic foramen to enter perineum. Main artery of the perineum.

Question 41

Inferior gluteal artery

Answer 41

Passes through greater sciatic foramen beneath piriformis to enter gluteal region

Question 42

Pelvic veins

Answer 42

Follow course of arteries except for umbilical and iliolumbar artery Drain into internal iliac veins which leave the pelvic cavity to join common iliac veins just superior and lateral to the pelvic inlet

Question 43

Deep dorsal vein

Answer 43

Drains erectile tissues of clitoris and penis, joins prostatic plexus in men and vesical plexus in women. Superficial veins that drain skin of penis and corresponding regions of clitoris drain into external pudendal veins (tributaries of saphenous vein in thigh)

Question 44

Lymphatics in pelvis

Answer 44

Lymphatics from most pelvic viscera drain mainly into lymph nodes distributed along internal iliac and external iliac arteries and their associated branches

Question 45

Internal iliac nodes

Answer 45

Also receive drainage from gluteal region and deep areas of perineum