3.7 Femoral Nerve

Question 1

Outline Motor and sensory distribution Nerve along course

Answer 1

Femoral N largest branch LP

Anterior rami L2-4 divide into anterior and posterior

Posterior division
unite within sub of psoas major
form fem n

Fem n leaves lat border of psoas major
Runs down
Cross inguinal ligament
lateral to femoral vessels 
enter femoral triangle

Lies lateral to femoral canal and sheath
seperated from them by fascia iliaca

Question 2

Anatomy fem N cont

Answer 2

Branching:
Anterior and posterior branch

further subdivide
below ligament usually

variation
(occass anterior branch from LP)

Anterior branch
Skin over front and medial thigh
medial and intermediate cutaneous N of thigh

Posterior branch

Question 3

Posterior branch

Answer 3

Posterior branch
Divides 3 further branch
1. Articular branch - innervation to hip and knee

2. Muscular branch - quadriceps

3. Largest terminal division
saphenous
- runs through adductor canal
becomes superficial
continues below knee
skin medial aspect calf
great toe

Question 4

Technique in Femoral Nerve block

Answer 4

SLIMRAG

Lie
Leg marked
Hip and knee joint neutral

LA to skin if awake

Puncture site:

1cm Lat -> Femoral pulse

1cm Inf -> Inguinal Lig

Question 5

Technique Femoral N Block

Answer 5

Short peripheral N stimulator
attached to PNS
advanced 45 degree angle
to 1-3 cm
Occasionally >4 cm
2 clicks may be felt as pass lata + iliaca

Negative aspiration:
15-20ml LA
injected
Continuous aspiration - check IV

Can be single shot
or catheter

Question 6

Nerve stimulation response Femoral N block

Answer 6

Correct:
Visible + palpable contraction quad
Movement patella

Incorrect
Sartorius - repositioned more laterally

US technique
Accurate ID nerve
Visualization LA within Iliaca plane

Question 7

Complications

Answer 7

Immediate

Early

Late

Question 8

Immediate complications

Answer 8

IV injection
Subsequent LAST

Intraneural injection

Failure

Question 9

Early complications

Answer 9

Haematoma formation

Motor - weak hip flexion

Prox migration of LA
block more prox LP branches

Superficial infection
indwelling catheter >48h

Question 10

Late complications

Answer 10

Compression Neuropathy

Sensory loss

Pain

Quad weakness