10.2 - Nerves of LL

Question 1

Dorsal or ventral rami from lateral wall? From which nerve roots?

Answer 1

Ventral L1 - 4 (sometimes T12 or L5 contributes)

Question 2

Where does the Lumbar Plexus occur?

Answer 2

Within Psoas Major

Question 3

What nerves emerge from:

1) Lateral border
2) Onto anterior surface
3) Medial border

Answer 3

1) From lateral border
- Ilioinguinal and iliohypogastric nerves (L1)
- Lateral cutaneous nerve of thigh (L2,3)
- Femoral nerve (L2,3,4)

2) Onto anterior surface
Genitofemoral nerve (L1,2)

3) From medial border
Obturator nerve (L2,3,4)

Question 4

Where (which muscle) does the sacral plexus join the lumbar plexus?

Answer 4

Lumbosacral trunk joins S1-4 on piriformis

Question 5

Femoral Nerve

1) Nerve roots
2) Which border of the Psoas?
3) Motor innervation
4) Sensory innervation
5) Articular branches to

Answer 5

Femoral Nerve

1) L2, 3, 4 posterior divisions
2) Lateral border of Psoas -> beneath inguinal lig. -> divides into terminal branches just distal to lig.
3) Motor to quads, Sartorius, Pectineus
4) Anteromedial thigh and medial side of knee, leg and ankle
- Anterior cutaneous branches
- Saphenous nerve
5) Articular branches to hip and knee

Question 6

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Answer 6

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Question 7

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Answer 7

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Question 8

Obturator nerve

1) Nerve roots
2) Which border of the Psoas?
3) Motor innervation
4) Sensory innervation
5) Articular branches to

Answer 8

Obturator nerve

1) L2, 3, 4 anterior divisions
2) Medial border of Psoas -> lateral wall of pelvis -> obturator canal -> medial compartment of thigh
3) Motor to adductor muscles (+Pectineus and hamstring part of Adductor Magnus)
4) Sensory to inferomedial thig
5) Articular branches to hip

Question 9

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Answer 9

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Question 10

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Answer 10

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Question 11

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Answer 11

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Question 12

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Answer 12

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Question 13

Sciatic nerve

1) Nerve roots
2) Where does it exit?
3) Motor innervation
4) Sensory innervation
5) Articular branches to

Answer 13

Sciatic nerve
1) L4,5,S1-3 anterior and posterior divisions
•Tibial and Common Fibular components
2) Exits pelvis via GSF → emerges beneath Piriformis in gluteal region → posterior to hip → descends posterior thigh → divides at apex of popliteal fossa (variations)
3) Motor to hamstrings (all tibial except SHOB)
4) Sensory is via terminal branches only
5) Articular branches to hip

Question 14

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Answer 14

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Question 15

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Answer 15

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Question 16

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Answer 16

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Question 17

Tibial nerve

1) Nerve roots
2) Where does it exit?
3) Motor innervation
4) Sensory innervation

Answer 17

Tibial nerve

1) L4 - S3
2) Vertical descent through popliteal fossa → beneath fibrous arch of Soleus → descends on Tibialis Posterior in calf → posterior to medial malleolus → sole of foot → medial and lateral plantar nerves
3) Motor to muscles of posterior leg and sole of foot
4) Sensory to posterolateral leg and lateral side of foot (sural nerve) and sole of foot (medial calcaneal, medial and lateral plantar nerves)

Question 18

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Answer 18

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Question 19

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Answer 19

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Question 20

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Answer 20

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Question 21

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Answer 21

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Question 22

Common Fibular nerve

1) Nerve roots
2) Where does it exit?
3) Sensory innervation
4) Motor innervation

Answer 22

Common Fibular nerve
1) L4,5,S1-2 posterior divisions
2) Medial to Biceps → superficial to lateral head of Gastrocnemius → winds round neck of fibula → Fibularis Longus → terminal branches
3) Sensory to upper lateral leg via lateral sural nerve and gives communicating branch to sural nerve
4) Deep Fibular Nerve is motor to anterior compartment of leg and sensory to 1st toe cleft
Superficial fibular nerve is motor to lateral compartment of leg and sensory to lateral leg and dorsum of foot

Question 23

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Answer 23

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Question 24

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Answer 24

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Question 25

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Answer 25

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Question 26

MOTOR INNERVATION

1) Large muscles in the gluteal region are supplied by the _ and _
2) Anterior compartment of thigh is supplied by the _
3) Medial compartment of thigh is supplied by the _
4) Posterior compartment of thigh and leg, and sole of foot are supplied by the _ except _
5) Anterior and lateral compartments of leg, and dorsum of foot are supplied by the _

Answer 26

MOTOR INNERVATION

1) Superior and inferior gluteal nerves
2) Femoral
3) Obturator
4) Tibial part of the Sciatic - except the short head of biceps
5) Common peroneal part of the sciatic nerve

Question 27

SENSORY INNERVATION
The femoral nerve innervates skin on the anterior and medial thigh and medial side of leg and foot
The obturator nerve innervates the medial side of the thigh just above the knee
The tibial part of the sciatic nerve innervates the posterior leg, lateral side of the ankle and foot via the sural branch and the sole
of the foot
The common peroneal part of the sciatic nerve innervates the lateral side of leg and dorsum of foot
The lateral cutaneous nerve of thigh and posterior cutaneous nerve of thigh branch directly from the plexus

Answer 27

SENSORY INNERVATION