Innervation & Dermatomes

Question 1

Spinal levels to lower limb?
What kind of innervation?

Answer 1

L1-S5
Motor & Sensory

Question 2

Where do bulk of nerves to lower limb come from?
What spinal levels?

Answer 2

Lumbosacral Plexus
L1-S4
(largest & longest nerves of body)

Question 3

What size difference happens to dermatomes closer to anus?

Answer 3

Concentrically smaller

Question 4

What do dermatome bands look like as go down leg?
Why?

Answer 4

Spiral
(L1 = horiz., S5 = circle)
Medial rotation of leg during embryonic development (fetal position)

Question 5

What 2 nerves innervate anus area?

Answer 5

S5 and coccygeal

Question 6

Why do dermatomes have a twisting pattern?

Answer 6

Embryo lower libs rotate in womb = dermatomes twist too

Question 7

What would loss of sensation/numbness in “saddle region” indicate?
Urgent?

Answer 7

Compression of cauda equina
Surgical emergency

Question 8

What spinal levels to lower limb dermatomes span?

Answer 8

T10-S5