lower limb dermatomes and myotomes

Question 1

L1 dermatome

Answer 1

1. Inguinal region
2. Skin over upper anterior aspect of thigh

Question 2

L1 myotome

Answer 2

Hip flexion
* iliopsoas

Question 3

L2 dermatome

Answer 3

Anterolateral aspect of upper thigh

Question 4

L2 myotome

Answer 4

Hip flexion
* iliopsoas

Question 5

L3 dermatome

Answer 5

Anteromedial area of thigh

Question 6

L3 myotome

Answer 6

Hip adduction
* adductor group

Knee extension
* quadriceps femoris

Hip flexion

Question 7

L4 dermatome

Answer 7

Anteromedial aspect of leg and medial malleolus

Question 8

L4 myotome

Answer 8

Knee extension
* quadriceps femoris

Hip adduction
* adductor group

Ankle dorsiflexion

Question 9

L5 dermatome

Answer 9

1. Lateral aspect of the thigh and knee
2. Anterolateral aspect of the leg
3. Dorsum of the foot,
4. The big toe + 1st 4 toes

Question 10

L5 myotome

Answer 10

Ankle dorsiflexion
*Tibialis anteriormuscle: difficulty heel walking (foot drop)

First toe dorsiflexion:
* Extensor hallucis longus muscles

Knee flexion
* hamstring muscles

Hip extension
* hamstring
* gluteus maximus

Question 11

S1 dermatome

Answer 11

1. Dorsolateral aspect of thigh and leg
2. lateralaspect of the foot + heel (posterior)
3. pinky toe

Question 12

S1 myotome

Answer 12

Foot plantarflexion:
* Gastrocnemius muscle

Foot eversion
* Peroneus longus and brevis muscles

Question 13

S2-4 dermatome

Answer 13

Posterioraspect of the thigh and leg (S2),perineum(S3–S4), perianal (S4)

Question 14

S2-4 myotome

Answer 14

Abduction of digits (S2-3)

Question 15

Ilioinguinal nerve roots

Answer 15

L1

Question 16

Ilioinguinal nerve dermatome

Answer 16

1. skin over anteromedial part of upper thigh
2. adjacent skin of perineum

Question 17

Genitofemoral nerve roots

Answer 17

L1-L2

Question 18

Genitofemoral dermatome

Answer 18

(femoral branch)
* skin on anterior central part of upper thigh

(genital branch)
* anterior part of perineum

Question 19

Femoral nerve roots

Answer 19

L2-L4

Question 20

Femoral nerve dermatome

Answer 20

1. skin over anterior thigh,
2. anteromedial knee
3. medial side of leg and foot

Question 21

Femoral nerve myotome

Answer 21

all muscles in anterior compartment of thigh
1. quadriceps femoris
2. sartorius
3. iliacus
4. psoas major
5. pectineus

Question 22

Obturator nerve dermatome

Answer 22

• skin over medial aspect of thigh
• articular branches: hip and knee joint

Question 23

Obturator nerve myotome

Answer 23

all muscles in medial compartment of thigh (except pectineus and part of adductor magnus attached to ischium)
1. adductor longus
2. adductor magnus
3. adductor brevis
4. gracilis
5. external obturator

Question 24

Obturator nerve roots

Answer 24

L2-L4

Question 25

Sciatic nerve roots

Answer 25

S4-L3

Question 26

Sciatic nerve dermatome

Answer 26

1. Skin over lateral side of leg and foot 2. Over the sole 3. dorsal surface of the foot

Question 27

Branches of the sciatic nerve

Answer 27

1. tibial nerve 2. Common fibular nerve (superficial and deep branches)

Question 28

Tibial nerve myotome

Answer 28

muscles in posterior compartment of leg 1. gastrocnemius 2. plantaris 3. soleus 4. popliteus 5. tibialis posterior 6. flexor digitorum longus 7. flexor hallucis longus intrinsic muscles of the foot 1. most plantar muscles

Question 29

3 branches of tibial nerve

Answer 29

1. medial calcaneal nerve 2. medial plantar nerve 3. lateral plantar nerve

Question 30

Dermatome of medial calcaneal nerve (branch of tibial nerve)

Answer 30

skin over heel

Question 31

Dermatome of medial plantar nerve (branch of tibial nerve)

Answer 31

medial half of the sole (excluding the heel) and plantar aspect of medial 3.5 toes

Question 32

Dermatome of lateral plantar nerve (branch of tibial nerve)

Answer 32

lateral half of sole and plantar aspect of lateral 1.5 toes

Question 33

Tibial nerve roots

Answer 33

L4-S3

Question 34

Common fibular nerve roots

Answer 34

L4-S2

Question 35

Common fibular nerve myotome

Answer 35

muscles in the anterior and lateral compartment

Question 36

Superficial fibular nerve roots

Answer 36

L5-S1

Question 37

Superficial fibular nerve myotome

Answer 37

muscles in the lateral compartment 1. fibularis longus 2. fibularis brevis Eversion of subtalar joint and plantarflexion of ankle

Question 38

Deep fibular nerve roots

Answer 38

L4-S1

Question 39

Deep fibular nerve myotome

Answer 39

muscles in the anterior compartment 1. tibialis anterior 2. extensor digitorum longus 3. extensor hallucis longus 4. fibularis tertius intrinsic muscles of foot 1. extensor hallucis brevis 2. extensor digitorum brevis

Question 40

superior gluteal nerve roots

Answer 40

L4-S1

Question 41

superior gluteal nerve myotome

Answer 41

muscles of the gluteal region 1. gluteus medius 2. gluteus minimus 3. tensor fasciae latae

Question 42

inferior gluteal nerve roots

Answer 42

L5-S2

Question 43

inferior gluteal nerve myotome

Answer 43

muscles of the gluteal region 1. gluteus maximus

Question 43

lateral cutaneous nerve of thigh nerve roots

Answer 43

L2-L3

Question 44

lateral cutaneous nerve of thigh dermatome

Answer 44

1. parietal peritoneum in iliac fossa 2. skin over anterolateral thigh

Question 45

posterior cutaneous nerve of thigh nerve roots

Answer 45

S1-S3

Question 46

posterior cutaneous nerve of thigh dermatome

Answer 46

1. skin over gluteal fold 2. upper medial aspect of thigh and adjacent perineum 3. posterior aspect of thigh 4. upper posterior leg