Download Ventral division Dorsal division Femoral nerve Lat cut n. of thigh

LOWER LIMB ANATOMY FOR FRCA
LUMBAR PLEXUS: FORMATION
Dorsal division
Upper and
lower
divisions
Lat cut n. of
thigh
Ventral division
L1
Iliohypogastric
nerve
L2
Genitofemoral
nerve Ilioinguinal
nerve
L3
L4
Femoral nerve
Obturator
nerve
Branch to
lumbosacral trunk
LUMBAR PLEXUS: BRANCHES
Quadratus
Lumborum
Ilio-hypogastric N.
Ilio-inguinal N.
Psoas
minor lying
on psoas
major
Lat. Cut.
N. of
thigh
Genitofemoral N.
Femoral N.
Inguinal Ligament
4th lumbar
sympathetic
ganglion
Obturator N.
1
CUTANEOUS NERVES OF THE LOWER LIMB
2
LUMBAR PLEXUS ANATOMY SUMMARY
NERVE
SPINAL
SEGMENT
ILIOHYPOGASTRIC
T 12-L1
ILIOINGUINAL
L1
GENITOFEMORAL
L1-L2
LAT FEMORAL
CUTANEOUS (LAT
CUT N OF THE
THIGH)
L2-L3
FEMORAL
L2 – L4
MOTOR
INNERVATION
MOTION
OBSERVED*
SENSORY
INNERVATION
ARTICULAR
BRANCHES
Int/Ext Oblique
Ant abdominal
wall
None
Int Oblique
Ant abdominal
wall
Cremaster
Testicular
None
Sensory Nerve
Inferior abd wall
Upper lat
quadrant of
buttock
Inferior to medial
aspect of
inguinal
ligament
Portion of
genitalia
Inferior to mid
portion of
inguinal
ligament
Spermatic cord
Anterior lateral
and posterior
aspects of thigh
terminating in
prepatellar
plexus
Sartorius
Medial aspect
of the lower
Thigh
Adductors of
thigh
Knee
extension,
patellar
Ascension
Sensory
Ant medial skin
of the thigh
None
Thigh
adduction
ANT DIVISION
Pectineus
Quadriceps
POST DIVISION
Saphenous
OBTURATOR
None
None
None
None
Ant Thigh
Knee and Hip
Medial leg from
the tibia to
the medial
aspect of the
foot
None
Variable,
posterior medial
thigh, medial
knee
Hip
L2 – L4
ANT DIVISION
POST DIVISION
Gracilus,
adductor brevis
&
longus
pectineus
Obturator
externus,
adductor
magnus
Thigh
adduction with
lateral hip
rotation
Knee
LUMBAR PLEXUS BLOCK
CLINICAL APPLICATIONS: Analogous to the brachial plexus block near the
clavicle, the three nerves of the lumbar plexus that are important for neural
supply to the lower extremity (femoral nerve, lateral femoral cutaneous nerve,
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obturator nerve) are located very closely together. This means that a single
injection at this site is sufficient to anaesthetise all three nerves completely.
POSITION: Lateral, similar to that used in spinal anaesthesia, with the legs
bent and the leg to be blocked uppermost.
LANDMARKS: Spinous process of the 4th lumbar vertebra (L4), the posterior
superior iliac spine (PSIS) and the highest point on the iliac crest.
APPROACH 1
The puncture site is on the line joining the L4 spine and the posterior superior
iliac spine (PSIS), at the junction of the medial 2/3rd and lateral 1/3rd. The
stimulating needle is advanced perpendicular to the skin. In case of bony
contact with the transverse process of the 5th lumbar vertebra (L5), the needle
should be directed cranially to walk over the transverse process. The femoral
nerve is normally contacted at the depth of 1.8 - 2 cm beyond the transverse
process. Contractions of the femoral quadriceps muscle show that the needle
is in the direct vicinity of the nerve. Once a threshold current of 0.2 -0.3 mA is
reached, 20-30mls local anaesthetic is injected.
PSIS
3
1/
3
2/
Spine
L3
L4
L5
APPROACH 2
In this approach 3 lines are drawn, first line is line connecting the spinous
processes. The second line passes cranially from the PSIS and lies parallel to
the 1st line. The 3rd line cuts these two lines and passes from the highest point
on the iliac crest (Tuffier’s line). The part which lies between the 1st and the
second line is then divided into medial 2/3rd and lateral 1/3rd. The puncture site
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lies 1-2 cm cranial to this point. Using a 100mm insulated needle, puncture is
made keeping the needle perpendicular to the skin. Aim is to hit the
transverse process of L4 and walk off it by 1.8-2.0 cm to seek the femoral (L 24)
stimulation.
PSIS
1/3
Spine
L3
L4
2/3
L5
FEMORAL TRIANGLE
BOUNDARIES:
Superior: Inguinal Ligament
Lateral: Medial border of Sartorius muscle
Medial: Medial border of adductor longus
Roof: fascia lata
Floor: Iliacus, Psoas (Iliopsoas), Pectineus, and adductor Brevis & longus
muscles. It also has the anterior division of the Obturator nerve on its surface
Femoral
Nerve
Femoral Sheath
Lat Cut Nerve of
the Thigh
Ilio-psoas
Adductor
Brevis and
Longus
Pectineus
Sartotius
Ant Branch of
Obturator Nerve
5
CONTENTS:
•
Femoral Nerve
•
Femoral artery
•
Femoral Vein
•
Deep Inguinal Nodes
FEMORAL SHEATH AND CANAL
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FEMORAL NERVE AND BRANCHES
FEMORAL
NERVE
L2
PELVIS
L3
ILIACUS
POST DIVISION
L4
ANT DIVISION
LAT CIRCUMFLEX
FEMORAL ARTERY
HIP JOINT
RECTUS
FEMORIS
PECTINEUS
SARTORIUS
MED FEMORAL CUT NERVE
LATERALIS
VASTUS
INTERMEDIATE FEMORAL CUT NERVE
INTERMEDIUS
MEDIALIS
FEMORAL
ARTERY
KNEE
JOINT
DEEP FASCIA BELOW KNEE
INFRAPATELLAR BRANCH
SAPHENOUS NERVE
The femoral nerve is the largest branch of the lumbar plexus. It arises from
the second, third, and fourth lumbar nerves. The nerve descends through the
fibers of the psoas muscle, emerging from the psoas at the lower part of its
border, and passes down between the psoas and the iliacus. (see fig: Lumbar
Plexus branches) Eventually, the femoral nerve passes underneath the
inguinal ligament into the thigh, where it assumes a more flattened shape. As
the femoral nerve passes underneath the inguinal ligament, it is positioned
immediately lateral and slightly deeper than the femoral artery.
Fascia
Iliacus
Fascia Latae
Ilio-psoas
Femoral sheath
Femoral
Nerve
Femoral Artery and vein
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At the femoral crease, the nerve is covered by the fascia iliaca and separated
from the femoral artery and vein by a portion of the psoas muscle and the
ligamentum ileopectineum. This physical separation of the femoral nerve from
the vascular fascia explains the lack of the spread of a "blind paravascular"
injection of local anesthetics toward the femoral nerve
FEMORAL NERVE BLOCK
CLINICAL APPLICATIONS:
Anaesthesia for knee arthroscopy in combination with intra-articular local
anaesthesia
•
Analgesia
for
femoral
shaft
fractures,
anterior
cruciate
ligament
reconstruction (ACL), and total knee arthroplasty (TKA) as a part of
multimodal regimens.
Use of nerve blocks for complex knee operations is associated with lower pain
scores and fewer hospital admissions after same-day surgery.
ANATOMY RELATED TO NERVE STIMULATION:
As the nerve emerges under the inguinal ligament it soon divides into the
posterior and anterior divisions and undergoes extensive arborisation. While
performing femoral nerve block, it is the anterior branch that is most
commonly identified (97% of the time), stimulation of this branch causes the
contraction of the sartorius muscle on the medial aspect of the thigh and
should not be accepted. It is the posterior branch that provides the articular
and muscular branches.
LANDMARK AND TECHNIQUE:
The puncture site is located approximately in the region of the inguinal fold,
1.5 cm lateral of the femoral artery, approx. 2-3 cm below the inguinal
ligament (IVAN = Inner Vein Artery Nerve). The stimulation needle (40 - 50
mm) is inserted at an angle of approx. 30º to the skin and advanced in a
cranial direction. After reaching a depth of around 2-4 cm, the femoral nerve is
encountered. Contractions of the quadriceps femoris muscle (post division)
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signal the direct proximity to the nerve. Stimulation of the rectus muscle of the
thigh is crucial for the block to be effective.
Femoral
sheath
Fascia lata
Femoral Nerve
Pectineus
Iliopsoas
Femoral Artery and Nerve
Iliacus Fascia
Contractions of the sartorius muscle (ant division) are usually not sufficient. In
case of anterior division stimulation, the needle should be reinserted slightly
laterally and with a deeper direction to encounter the posterior branch of the
femoral nerve. Stimulation of this branch is identified by patellar ascension as
the quadriceps contract (dancing of the patella). While performing femoral
nerve block it is utmost important to continually aspirate before injecting the
local anaesthetic. Keeping distal pressure ensures cranial spread allowing for
blocking branches arising above the inguinal ligament. This can also be
accomplished by lifting up the leg.
DEFINING THE 3-IN-1 BLOCK:
During femoral nerve block, it is commonly believed that using a higher
volume of local anaesthetic and applying distal pressure during and a few
minutes after injection blocks the femoral, lateral femoral cutaneous, and
obturator nerves, the so-named “3-in-1 block”. However, despite many efforts
to consistently produce a 3-in-1 block, the effectiveness of these manoeuvres
has not been shown. In most reports, the femoral nerve is the only nerve
consistently blocked with this approach. Blockade of the lateral femoral
cutaneous nerve occurs through lateral diffusion of local anaesthetic and not
9
through proximal spread to the lumbar plexus. The obturator nerve is less
frequently anesthetised during 3-in-1 block than the lateral femoral cutaneous
(LFC), which is not surprising given the number of fascial barriers between
these structures at the level of the inguinal ligament. Despite the lack of
scientific support for the term 3-in-1, many authors still continue to refer to the
anterior femoral nerve block as a 3-in-1 block.
FASCIA ILIACA BLOCK:
Femoral nerve can also be blindly blocked using this technique. The landmark for this is the inguinal ligament. The ligament is divided into thirds. The
point of needle insertion is 1-2cm below the junction of the medial 1/3 and the
lateral 2/3. A short bevelled needle is used for this technique. After piercing
the skin two distinct ‘pops’ are felt as the needle passes through the fascia
lata and then the ant iliacus fascia.
Fascia lata
Pectineus
Iliacus Fascia
Iliopsoas
Muscle
LATERAL FEMORAL CUTANEOUS ( LFC) NERVE BLOCK:
CLINICAL APPLICATIONS:
This block is useful for skin graft harvesting and can be used in concert with
other peripheral nerve blocks for complete anaesthesia of the lower extremity
ANATOMY RELATED TO THE BLOCK:
The lateral femoral cutaneous nerve or the lateral cutaneous nerve of the
thigh (L2 and L3) emerges at the lateral border of the psoas muscle
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immediately caudad to the ilioinguinal nerve. It descends under the iliac fascia
to enter the thigh deep to the inguinal ligament 1 to 2 cm medial to the
anterior superior iliac spine (ASIS). The nerve emerges from the fascia lata 7
to 10 cm below the ASIS and divides into anterior and posterior branches.
The skin of the lateral portion of the thigh from the hip to midthigh is supplied
by the posterior branch; the anterior branch supplies the anterolateral thigh to
the knee.
Internal oblique muscle
Iliacus Fascia
External oblique Aponeurosis
ASIS
Iliacus Muscle
Lat Cutaneous Nerve of
Thigh
Inguinal ligament
Fascia Lata
POSITION:
Supine
LANDMARK AND TECHNIQUE:
A point is marked 2 cm medial and 2 cm caudad to the anterior superior iliac
spine. A short-bevel 22-gauge, 4-cm needle is advanced perpendicular to the
skin entry site until a sudden release (pop) indicates passage through the
fascia lata. As the needle is moved fanwise laterally and medially, 10 to 15 mL
of solution is injected, depositing local anaesthetic above and below the
fascia.
The nerve can also be blocked just medial and posterior to the anterior
superior iliac crest with 10 mL of solution. Combining the two techniques (beltand-suspenders method) increases the success rate, but the total volume of
solution used may be limiting. Because this is a pure sensory nerve, electrical
stimulation is not helpful in performing this block.
11
SAPHENOUS NERVE BLOCK:
CLINICAL APPLICATIONS:
Saphenous is a purely sensory nerve supplying the skin on the medial side of
the leg below the knee. It is commonly blocked along with the sciatic nerve to
complete the anaesthesia of the leg for procedures on the tibia & fibula and
the ankle.
FEMORAL VEIN AND ARTERY
SARTORIUS
SAPHENOUS NERVE
GENICULAR
BRANCHES
POSITION:
Supine
LANDMARK AND TECHNIQUE:
There are multiple approaches at different levels to the saphenous nerve
block.
SEEKING PARESTHESIA (TRANS SARTORIAL APPROACH)
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In an awake and cooperative patient, electrical nerve stimulation can be used
to seek paresthesia. The compartment between the vastus medialis and
sartorius muscles is identified at about 2 - 4 cm above and medial to the
patella. Here, the stimulation needle is inserted perpendicular to the table until
it reaches the subsartorial fatty tissue. At a pulse duration of 1.0 ms and an
amplitude of 0.3 - 0.5 mA, electrical paresthesia can be elicited and 10 to 15
ml of local anaesthetic injected.
[In many cases, the saphenous nerve is still accompanied by a muscular
branch of the femoral nerve which innervates the vastus medialis muscle. In
such cases, a motor stimulatory response from the vastus medialis muscle
can be judged as successful. A catheter can be placed without any trouble.]
INFILTERTION TECHNIQUES:
The saphenous nerve can be blocked just below the knee joint or at the level
of the ankle by subcutaneous infiltration. At the level of the knee,
subcutaneous infiltration is carried out from the medial head of the
gastrocnemius up to the tibial tuberosity.
OBTURATOR NERVE BLOCK:
ANATOMY RELATED TO THE BLOCK:
The obturator nerve is derived primarily from the third and fourth lumbar
nerves (L3,4)with an occasional minor contribution from L2. The nerve lies
deep in the obturator canal, having descended from the medial border of the
psoas muscle. As the nerve leaves the obturator canal, it divides into anterior
and posterior branches. The anterior branch supplies an articular branch to
the hip and the anterior adductor muscles and a variable cutaneous branch to
the lower medial thigh. The posterior branch innervates the deep adductor
muscles and may send an articular branch to the knee.
CLINICAL APPLICATIONS:
Blocked as part of regional anaesthesia for knee surgery.
Primarily a motor nerve, it is rarely blocked on its own; however, obturator
nerve block can be useful in treating or diagnosing the extent of adductor
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spasm in patients with cerebral palsy and other muscle or neurological
diseases affecting the lower extremities prior to surgical intervention (adductor
tenotomy).
FEMORAL VESSELS
OBTURATOR NERVE
FEMORAL NERVE
2Cms
2Cms
POSITION:
Supine
LANDMARK AND TECHNIQUE:
Mark is made 1 to 2 cm lateral and 1 to 2 cm caudad to the pubic tubercle. A
skin wheal is raised, and a short-bevel 22-gauge, 8-10 cm needle is advanced
perpendicular to the skin entry site with a slight medial direction.
The inferior pubic ramus is encountered at a depth of 2 to 4 cm, and the
needle is walked in a lateral and caudad direction, until it passes into the
obturator canal. The obturator nerve is located 2 to 3 cm past the initial point
of contact with the pubic ramus. After negative aspiration, 10 to 15 mL of local
anaesthetic is injected. A nerve stimulator can be successfully used for
locating the obturator nerve; correct needle position produces contractions of
the adductor muscles of the medial thigh
14
SACRAL PLEXUS
L4
L5
S1
S2
S3
SUP
GLUTEAL
NERVE
S4
S5
ANOCOCCYGEAL
NERVE
PERFORATING
CUT NERVE
INF
GLUTEAL
NERVE
POST
FEMORAL
CUT
NERVE
C1
PUDENDAL
NERVE
SCIATIC NERVE
SCIATIC NERVE AND BRANCHES
L4
L5
S1
Pelvis
S2
S3
piriformis
Hip Joint
Inf Gemellus
Quad. femoris
Semi-tendinosus
Sup Gemellus
Obt Internus
Short Head of Biceps femoris
Semi-membranosus
Long Head of
Biceps femoris
Thigh
Tibial L4,5, S1,2,3
Common Peroneal
(fibular) L4,5 ,S1,2
15
SACRAL PLEXUS ANATOMY: SUMMARY
NERVE
SPINAL
SEGMENT
GLUTEAL
NERVES
L4 – S2
SCIATIC,
TIBIAL
L4 – S3
MOTOR
INNERVATION
MOTION
OBSERVED
SENSORY
INNERVATION
ARTICULAR
BARNCHES
Piriformis, sup/inf
gemellus
obturator
internus,
quadratus
femoris
Buttocks with lat
hip rotation
Upper medial
aspect of
buttock
Hip
Hip
Biceps femoris,
semitendinosus,
adductor magnus
Hamstrings with
knee
extension
Medial and lat
heel
Sole of foot
Hip Knee and
Ankle
Popliteus
Knee flexion
Plantar flexion
Gastrocnemius,
soleus,
flexors of foot
Toe flexion
Knee and Ankle
SCIATIC,
PERONEAL
L4 – S3
SUPERFICIAL
DEEP
SURAL
COMPONENTS
FROM
PERONEAL &
TIBIAL
POST CUT
NERVE OF
THIGH
None
S1 – S3
Short head of
biceps
femoris peroneus
longus, brevis
Knee flexion
Foot inversion
Distal anterior
leg,
dorsum of foot
Extensors of
foot, toes
Dorsiflexion of
foot,
ankle
Web space of 1st
toe
None
None
Post calf, lat
border of foot
and 5th toe
None
None
None
Distal medial
quadrant
of buttock
perineum,
post thigh
including
popliteal fossa
None
16
SACRAL PLEXUS: BRANCHES (GLUTEAL REGION)
SCIATIC NERVE BLOCK: PARASACRAL APPROACH
CLINICAL APPLICATIONS:
The parasacral block targets the sciatic nerve at its most proximal point where
it induces fast and full anaesthesia.
POSITION:
Seated or in the lateral recumbent position. The lateral recumbent position is
preferred , given that, in combination with the psoas compartment block, the
technique is especially suited for complex surgical interventions on the leg,
and avoids the inconvenience of repositioning and re-draping of the patient
between the two procedures. The side to be blocked is uppermost; the lumbar
spine shows a kyphosis and the hip flexed to facilitate orientation.
LANDMARKS AND TECHNIQUE:
17
The posterior superior iliac spine (PSIS) and the ischial tuberosity (IT) are
marked. From the posterior superior iliac spine, the palpating finger follows
the tuberosity until no more bony structures are encountered. Here,
approximately 5 - 7 cm caudad to the posterior superior iliac spine, the
puncture site is marked. The stimulation needle (80 -120 mm) is advanced
perpendicular to the skin in the direction of the tuberosity until a stimulatory
response is elicited from the peroneal or tibial part of the sciatic nerve.
GT
IT
5 – 7 Cms
PSIS
Sacral Hiatus
TIP OF
COCCYX
Once the desired amplitude is reached (0.3 – 0.4 mA) 20 to 40 ml of local
anaesthetic is injected.
If no primary stimulatory response is achieved or bony resistance
encountered, the needle is directed in a caudal and slightly lateral direction
(pointing towards the mid point between greater trochanter and ischial
tuberosity). Do not consider the contractions of the gluteal muscles as a sign
of success. Always look for signs of stimulation of the tibial or peroneal
components.
SCIATIC NERVE BLOCK: LATERAL/ CLASSIC APPROACH ( LABAT’S)
POSITION:
Lateral recumbent position, with the leg to be blocked uppermost. The other
leg is extended. The upper leg is bent approx. 30-40º at the hip joint and
approx. 90º at the knee joint. The heel of the leg to be blocked should be
touching the knee of the other leg.
18
LANDMARK AND TECHNIQUE:
The greater trochanter (GT) and the posterior superior iliac spine (PSIS) at
the dorsal end of the iliac crest should be identified and marked. A second line
is drawn passing from the sacral hiatus to the greater trochanter. A line is then
perpendicularly dropped from the midpoint of the first on to the second. The
puncture site is marked at a point this line touches the second line (~4-5 cm).
GT
IT
PSIS
Sacral Hiatus
The stimulating needle is inserted perpendicular to the skin surface (80 mm
long). Sciatic nerve is usually contacted at a depth of 5 to 8 cm. Contractions
of the calf musculature with plantar or dorsal flexion of the foot are considered
as sign of successful localisation and after appropriate reduction in stimulation
current is reached (0.3-0.4 mA) 20-30mL of local anaesthetic is injected.
SCIATIC NERVE BLOCK: ANTERIOR APPROACH
POSITION:
Supine, with the leg in a neutral position, not rotated outwardly like in the
femoral nerve block.
LANDMARK AND TECHNIQUE:
A line connecting the anterior superior iliac spine (ASIS) and the pubic
tubercle is marked. A line passing through the greater trochanter (GT) lying
parallel to the first is drawn. The length of the first line is divided into thirds. A
19
perpendicular line is dropped inferiorly from the medial third point to the
second line. The puncture is made at the point of this intersection.
ASIS
GT
SCIATIC
NERVE
Feel along the muscle compartment between the rectus femoris muscle and
the vastus medialis and/or the sartorius muscle. The puncture is made lateral
to this, thereby minimising the risk of hitting a vessel. Insert the stimulating
needle (120 mm) at a 75-85° angle, guiding it in a dorsal and cranial direction.
Stimulation of parts of the femoral nerve is sometime observed. At a depth of
6-10 cm, the post thigh compartment is reached. The sciatic nerve is sought
by advancing the needle a bit further. The nerve is successfully located when
plantar flexion (tibial part) or dorsal flexion (peroneal part) are elicited.
SCIATIC NERVE BLOCK: HIGH LATERAL APPROACH
POSITION:
The patient is supine, with the leg in a neutral position or rotated slightly
inwards. Padding placed under the lower leg and pelvis helps facilitate
puncture, but is not imperative.
LANDMARK AND TECHNIQUE:
By passive rotation of the hip joint, it is possible to palpate and mark the
greater trochanter, even in obese patients. The puncture site is located
approx. 2 cm inferior and 4 cm distal to the greater trochanter. The direction of
20
insertion is horizontal and slightly cranial towards the ischial tuberosity. This
approach requires needles of between 80 and 120 mm in length.
GT
X
2 Cms
4 Cms
If the femur is encountered during puncture, the insertion point must be
changed slightly dorsal. Should stimulation at a reasonable depth fail to
achieve the desired response, a redirection in a slightly ventral direction and
inward rotation of the hip sometimes helps. Stimulating catheters can also be
placed using this approach.
SCIATIC NERVE: LITHOTOMY APPROACH
This is probably the commonest approach used by trainees in the UK.
POSITION:
Supine with the hip hyperflexed and the knee partially extended
LANDMARKS AND TECHNIQUE:
Ischial tuberosity and greater trochanter are the main landmarks. A line is
drawn connecting this two landmarks and the midpoint on this line marked.
The insertion point lies 2-3 cms distal to this point. A 50 - 80mm needle is
sufficient to perform this block.
21
KNEE JOINT: NERVE SUPPLY AND MOVEMENTS
Nerve Supply:
Femoral
Obturator via posterior division and
Sciatic via both tibial and common peroneal branches
Movements:
Flexion : Semimembranosus, Semitendinosus, Biceps femoris, Gracilis,
sartorius ( Gastrocnemius, Plantaris, Popliteus)
Extension: Quadriceps femoris, Iliotibial tact ( Gluteus maximus, Tensor
Fasciae latae)
SCIATIC NERVE BELOW THE KNEE AND BRANCHES
SCIATIC NERVE
POPLITEAL FOSSA
COMMON PERONEAL
TIBIAL NERVE
SURAL COMMUNICATING
BRANCH
SUPERFICIAL
PERONEAL
MED & LAT PLANTAR
NERVES
SURAL NERVE
DEEP RERONEAL
22
POPLITEAL FOSSA
Diamond shaped
Borders:
•
Upper medial – Semimembranosus (& Semitendinosus)
•
Upper lateral – Biceps Femoris
•
Lower medial – Gastronemius (Medial head)
•
Lower lateral – Plantaris & Gastronemius (Lateral head)
•
Roof –
Short saphenous & communicating veins
Lateral sural cutaneous nerve
Sural communicating nerve
End of posterior femoral cutaneous nerve
Fascia latae
RIGHT SUPERFICIAL POPLITEAL FOSSA
23
CONTENTS:
Popliteal artery and vein
Tibial nerve
Common Peroneal Nerve
Fat
Lymph Nodes
POLITEAL ARTERY:
8” Long
Starts medial to Tibial Nerve
Ends lateral to Tibila nerve
Vein always between the artery and the Nerve ( unlike other places where
Vein, Artery and Nerve follow the VAN pattern)
DEEP POPLITEAL FOSSA
24
SCIATIC NERVE BLOCK AT THE POPLITEAL FOSSA BLOCK
CLINICAL APPLICATION:
This technique affords a block of the sciatic nerve just superior to its
bifurcation without any complicated positioning.
POPLITEAL FOSSA BLOCK (LATERAL APPROACH)
POSITION:
The patient is supine on his back, with the leg in a neutral position; padding is
placed distally under the lower leg to allow the knee to hang suspended.
LANDMARK AND TECHNIQUE:
The compartment between the vastus lateralis muscle and the biceps femoris
muscle is identified by palpation approx. 11 cm above the patella. This site is
marked.
11 cm
A needle of 100 mm in length is usually sufficient for the puncture. The needle
is inserted initially perpendicular to the skin. The needle in this position should
come in contact with the femur. The needle is then withdrawn and the
insertion direction changed to 30° dorsally and 5 - 10° cranially (towards the
hip joint) looking for the tibial / peroneal response.
25
1
30O
2
Once the threshold electrical current is reached, 30 - 50 ml of local
anaesthetic is injected. Compared to the proximal sciatic nerve blocks, onset
of action is significantly longer, between 20 - 40 min. A catheter for continuous
block can be positioned easily.
One common error that is often made, searching for the nerve too ventrally
and at a depth (The nerve's position is always more superficial and dorsal
than one thinks).
POPLITEAL FOSSA BLOCK ( INTERTENDINOUS APPROACH)
POSITION:
The patient is either in the prone position or lying on the side that is not to be
anaesthetised. The upper leg must then be well extended. The patient may
also lie supine and the assistant can hold the leg with the hip flexed at 90o and
the knee partially extended.
LANDMARK AND TECHNIQUE:
Landmarks for the intertendious approach to popliteal block are easily
recognizable even in obese patients. All three landmarks should be outlined
by a marking pen:
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1. Popliteal fossa crease
2. Tendon of biceps femoris (laterally)
3. Tendons of semitendinosus and semimembranosus (medially)
With the patient in one of these positions, the popliteal fossa is first identified
and then demarcated medial to the semitendinosus muscle and lateral to the
biceps femoris muscle.
Biceps
femoris
ST
7-11
cms
X
In this technique, the needle is introduced at the midpoint between the biceps
femoris and semitendinosus tendons at about 7-11 cms from the popliteal
crease. The nerve stimulator should be initially set to deliver 1.5 mA current (2
Hz, 100µsec) because this higher current allows detection of the inadvertent
needle placement into the hamstrings muscles and stimulation of the sciatic
nerve through the epineural sheath as the needle is approaching its target.
When the needle is inserted in a correct plane, advancement of the needle
should not result in any local muscular twitches; the first response to nerve
stimulation is typically that of the sciatic nerve (foot twitch).
Keeping fingers of the palpating hand on the biceps muscle is important for
early detection of twitches of the biceps or semitendinosus muscles
underneath the fingers.
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These local twitches are the result of direct muscle stimulation when the
needle is placed too laterally or medially, respectively:
When local stimulation of the biceps muscle is felt under the fingers of the
palpating hand, the needle should be redirected medially.
Local twitches of the semitendinosus muscle indicates a too medial needle
insertion. The needle should be withdrawn to the skin level and reinserted
laterally.
ANKLE
AXIAL CROSS SECTION RIGHT ANKLE
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CUTANEOUS INNERVATION OF THE FOOT
Saphenous
Sural
Superficial
Peroneal
Deep Peroneal
Medial plantar
Lateral plantar
CLINICAL APPLICATIONS:
Ankle blocks are simple to perform and offer adequate anaesthesia for
surgical procedures of the foot not requiring a tourniquet above the ankle.
ANATOMY OF THE NERVES AROUND THE ANKLE:
Four of the five individual nerves that can be blocked at the ankle to provide
anaesthesia of the foot are terminal branches of the sciatic nerve: the
posterior tibial, sural, superficial peroneal, and deep peroneal branches. The
sciatic nerve divides at or above the apex of the popliteal fossa to form the
common peroneal and tibial nerves. The common peroneal nerve descends
laterally around the head of the fibula, where it divides into the superficial and
deep peroneal nerves.
The tibial nerve divides into the posterior tibial and sural nerves in the
lower leg. The posterior tibial nerve becomes superficial at the medial
border of the Achilles tendon near the artery of the same name, and the
sural nerve emerges lateral to the Achilles tendon.
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POST TIBIAL AND SURAL NERVE BLOCKS:
POST TIBIAL
NERVE
MEDIAL MALLEOLUS
SURAL
NERVE
MEDIAL
MALLEOLUS
POST TIBIAL
ARTERY AND
NERVE
ACHILLES TENDON
The posterior tibial nerve can be blocked with the patient in either the prone or
the supine position. The posterior tibial artery is palpated, and a 22-gauge, 3cm needle is inserted posterolateral to the artery at the level of the medial
malleolus. In an awake patient paresthesia can often be elicited; however, it is
not necessary for a successful block. If a paresthesia is obtained, 3 to 5 mL of
local anaesthetic should be injected. Otherwise, 7 to 10 mL of solution should
be injected as the needle is slowly withdrawn back from the posterior aspect
of the tibia. A nerve stimulator and / ultrasound can also be used for this
block. Blockade of the posterior tibial nerve provides anaesthesia of the heel,
plantar portion of the toes, and the sole of the foot as well as some motor
branches in the same area.
The sural nerve is located superficially between the lateral malleolus and the
Achilles tendon. A 25-gauge, 3-cm needle is inserted lateral to the tendon and
is directed toward the malleolus as 5 to 10 mL of solution is injected
subcutaneously. This block provides anaesthesia of the lateral foot and the
lateral aspects of the proximal sole of the foot.
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DEEP AND SUPER FICIAL PERONEAL & SAPHENOUS NERVE BLOCKS
The deep peroneal, superficial peroneal, and saphenous nerves can be
blocked through a single needle entry site.
A line is drawn across the dorsum of the foot connecting the two malleoli. In
an awake patient the extensor hallucis longus tendon can be identified by
asking the patient to dorsiflex the big toe. The anterior tibial artery lies
between this structure and the tendon of the extensor digitorum longus
muscle and is palpable at this level. A skin wheal is raised just lateral to the
pulsation between the two tendons on the intermalleolar line. A 25-gauge, 3cm needle is advanced perpendicular to skin entry site, and 3 to 5 mL of local
anaesthetic injected deep to the extensor retinaculum to block the deep
peroneal nerve. This technique anaesthetises the skin between the first and
second toes and the short extensors of the toes.
SAPHENOUS
NERVE
SUPERFICIAL
PERONEAL
NERVE
DEEP PERONEAL
NERVE
SUPERFICIAL
PERONEAL
NERVE
The needle can now be directed laterally through the same skin wheal while
injecting 3 to 5 mL of solution subcutaneously, thus blocking the superficial
peroneal nerve and resulting in anaesthesia of the dorsum of the foot,
excluding the first interdigital space. The same manoeuvre can now be
performed in the medial direction, thereby anaesthetising the saphenous
nerve, a terminal branch of the femoral nerve that supplies a strip along the
medial aspect of the foot.
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