
Union of the anterior primary divisions of
C5-8 and the T1 nerve.
› C4 and T2 may contribute as well.
Roots  Trunks  Divisions  Cords 
Terminal nerves (branches). “Robert
Taylor Drinks Cold Beer”.
 Terminal Branches: Axillary, Radial,
Median, Musculocutaneous, and Ulnar.
“ARM MU”.


Performed at the C6 level (cricoid cartilage
level).
› Ask patient to turn head to side.
› Locate groove.

Between the anterior and middle scalene
muscles.
› The anterior scalene is an important landmark
that should be identified.
 Posterior to the posterior aspect of the SCM at the
level of the cricoid.
 Enter behind the External Jugular at 45 degrees
caudad and posterior.
Needle enters 1.2cm above the middle
of the clavicle.
 Administer anesthetic while advancing
needle towards the first rib.

› Anterior-posterior direction until parasthesias
are elicited.

L4-5 and S1-3
› Runs between the ischial spine and greater trochanter of
the femur.
› Becomes superficial at the base of the gluteus maximus.




Cutaneous innervation to posterior thigh and all of
the leg below the knee minus a small medial strip.
Two approaches: Posterior and Anterior.
Usually block is combined with femoral, obturator, or
lateral fem cutaneous nerve blocks.
Disadvantages: technically difficult, painful, possible
hematoma, nerve damage, slight drop in BP due to
blood pooling.
Lateral decub position with leg to be
blocked flexed at the knee with the heel
resting on the opposite knee.
 Connect the posterior superior iliac spine
with the greater trochanter with a
drawing pen. Bisect this line
perpendicularly, extending caudal.
 Needle entry point: 3cm downward from
the perpendicular line.

Supine position.
 Line from ASIS to pubic tubercle. Mark
point 2/3 of the way.
 Draw parallel line from greater
trochanter.
 From point of first line, continue down to
second line. Inject at this site until bone is
hit, then direct medially.
