Neurovasculature of Pelvis and Abdomen

Question 1

What are the 4 somatic nerves of the abdomen and pelvis and their levels?

Answer 1

1. intercostal nerves (T7 - T11)
2. Lumbar plexus (L1 - L4)
3. Subcostal (T12)
4. Sacral plexus (L4 - S4)

Question 2

What landmarks do the following dermatomes signify?

T4, T10, L1

Answer 2

T4: nipples
T10: umbilicus
L1: inguinal ligament

Question 3

The lumbar plexus provides motor and sensory innervation to what areas?

Answer 3

abdominal wall 
scrotum/labia majus 
lower limb (anterior and medial thigh)

Question 4

What is the cremaster reflex and why is it important?

Answer 4

Stroking of inner thigh causes contraction of cremaster muscle = brings testes closer to body
- important for temperature regulation in testes for spermatogenesis

Question 5

What is the innervation to the sensory and motor limb of the cremaster muscle?

Answer 5

sensory limb: ilioinguinal nerve

motor limb: genital branch of the genitofemoral nerve

Question 6

The sacral nerve plexus provides sensory and motor innervation to what areas?

Answer 6

perineum
lower limbs
pelvic floor and wall

Question 7

Most of the branches of the sacral plexus exit what foramen? What’s the exception?

Answer 7

• exit the greater sciatic foramen

- exception is the lumbosacral trunk (which travels over the pelvic brim)

Question 8

Pudendal nerve is the major somatic nerve of what region?

Answer 8

PERINEUM!

Provides both sensory and motor innervation

Question 9

What are the 2 branches of the pudendal nerve?

Answer 9

Inferior rectal nerve 
Perineal nerve (which has further branches)

Question 10

Sympathetic nerves arise from what region?

Answer 10

Thoracolumbar (T1 - L2/3)

Question 11

Pain from foregut structures will be felt in what region?

Answer 11

epigastric region

Question 12

Pain from midgut structures will be felt in what region?

Answer 12

periumbilical

Question 13

Pain from the hindgut structures will be felt in what region?

Answer 13

hypogastric

Question 14

Innervation of parietal peritoneum

- type of pain?

Answer 14

somatic nerve supply from overlying body wall

- sharp, well-localized pain

Question 15

Innervation of visceral peritoneum

- type of pain?

Answer 15

autonomic (visceral) nerve supply as as the organ it covers

- dull, poorly localized pain

Question 16

Somatic motor innervation of diaphragm

Answer 16

Phrenic nn.

Question 17

Somatic sensory innervation of diaphragm

Answer 17

Phrenic nn (central portion) 
T5 - T11 intercostal nn. and subcostal nn. (periphery)

Question 18

Innervation of abdominal vs. pelvic ureter:

Answer 18

Abdominal: renal, aortic, superior hypogastric plexuses

Pelvic: inferior hypogastric plexus

Question 19

What plexus innervates the kidney? What are the 2 sympathetic nerves?

Answer 19

Renal plexus

Thoracic splanchnic nn.
Lumbar splanchnic nn.

Question 20

What do the vagal trunks (anterior and posterior) supply?

Answer 20

Abdominal foregut and midgut (to proximal 2/3 of the transverse colon)

Question 21

What do the pelvic splanchnic nerves supply?

Answer 21

Supply hindgut (distal 1/3 transverse colon to superior part of the rectum) and all of pelvic viscera