Dermatomes & myotomes of LL

Question 1

How do you check for a lesion in the femoral nerve?

Answer 1

• innervates anterior compartment of thigh
• check knee extension (can use patellar reflex)

Question 2

How do you check for a lesion in the sciatic nerve?

Answer 2

• innervates posterior compartment of thigh
• check knee flexion & ankle movements

** mainly tibial nerve

Question 3

How do you check for a lesion in the obturator nerve?

Answer 3

• innervates medial compartment of thigh
• check hip adduction

Question 4

How do you check for a lesion in the deep fibular nerve?

Answer 4

• innervates anterior compartment of leg
• check ankle dorsiflexion

Question 5

How do you check for a lesion in the tibial nerve?

Answer 5

• innervates posterior compartment of leg
• check ankle plantarflexion (can use Achilles tendon reflex)

Question 6

How do you check for a lesion in the superficial fibular nerve?

Answer 6

• innervates lateral compartment of leg
• check foot eversion

Question 7

How do you check for a lesion in the superior gluteal nerve?

Answer 7

• innervates glute medius/minimus & TFL
• check hip abduction (can use Trendelenburg test)

Question 8

How do you check for a lesion in the inferior gluteal nerve?

Answer 8

• innervates gluteus maximus
• check hip extension w/ knee flexed (leaves out hammies)

Question 9

The upper limb dermatomes are supplied by _______ nerves.

Answer 9

C5-T1

Question 10

The lower limb dermatomes are supplied by _______ nerves.

Answer 10

L2-S2

Question 11

Since dermatomes overlap, how to we test individual dermatomes in the limbs?

Answer 11

• along the upper limb, the axial lines have no overlap of dermatomes
• best to perform sensory test around the limb (around axis) rather than along the limb

Question 12

Draw the pattern of the lower limb dermatomes (anterior & posterior).

Answer 12

Question 13

Compare dermatomes to myotomes.

Answer 13

Dermatome: area of skin supplied by a single spinal nerve

Myotome: area of muscle supplied by a single spinal nerve

** actions require cooperation of more than 1 myotome

Question 14

Myotomes: hip extension

Answer 14

L5-S1 (90˚ lunge)

Question 15

Myotomes: knee flexion

Answer 15

L5-S1 (90˚ lunge)

Question 16

Myotomes: toe extension

Answer 16

L5-S1 (90˚ lunge)

Question 17

Myotomes: ankle eversion

Answer 17

L5-S1 (weird 90˚ lunge)

Question 18

Myotomes: hip flexion

Answer 18

L2-3 (staff pose)

Question 19

Myotomes: knee extension

Answer 19

L3-4 (staff pose)

Question 20

Myotomes: ankle dorsiflexion

Answer 20

L4-5 (staff pose)

Question 21

Myotomes: ankle inversion

Answer 21

L4-5 (weird staff pose)

Question 22

Myotomes: ankle plantarflexion

Answer 22

S1-2 (ballet)

Question 23

Myotomes: toe flexion

Answer 23

S1-2 (ballet)

Question 24

You suspect an L2 lesion. How would you test this myotome?

Answer 24

hip flexion (L2-3; staff pose)

Question 25

You suspect an L3 lesion. How would you test this myotome?

Answer 25

knee extension (L3-4; staff pose) - can use knee jerk reflex

Question 26

You suspect an L4 lesion. How would you test this myotome?

Answer 26

foot inversion (L4-5; weird staff pose) - can use knee jerk reflex

Question 27

The knee jerk tells you about ____ myotomes.

Answer 27

L3-4 (knee extension)

Question 28

You suspect an L5 lesion. How would you test this myotome?

Answer 28

great toe extension (L5-S1; 90˚ lunge)

Question 29

You suspect an S1 lesion. How would you test this myotome?

Answer 29

ankle plantarflexion (L5-S1; ballet) - can use ankle jerk reflex