2. Femoral Triangle + Nerve Flashcards
Borders
bounded superiorly by the inguinal ligament (which curves from the
anterior superior iliac spine to the pubic tubercle).
lateral border is formed by the sartorius
medial border is formed by the adductor longus muscle
roof is formed by areolar tissue, fascia lata, subcutaneous tissue and skin.
floor is a trough composed of the iliacus, psoas and pectineus muscles
Contents
lie the femoral canal, containing lymphatics, and immediately
lateral to it, the femoral sheath, containing the femoral vein (medial) and femoral
artery (lateral).
Outside the femoral sheath and lying lateral to it is the femoral nerve.
The nerve is invested in the fascia of the iliacus muscle (fascia iliaca),
which separates it from the femoral sheath.
Above this is the fascia of the tensor fascia lata muscle.
The distance by which it is separated is variable.
It may bear a close relation to the pulsation of the
femoral artery or may be 1–2 cm or more lateral to it.
It can also be separated from the femoral sheath by a small part of the psoas muscle.
Femoral vein
Femoral vein: this is useful for central venous access
(if other sites are unsuitable)
and for siting large-bore cannulae for haemodiafiltration.
It is the central vein of choice in infants and young children.
It is also the site of access for insertion of vena caval filters.
Access to the femoral vein is not always easy;
it is commonly overlaid by the superficial femoral artery and its anatomy can be variable.
The route is used commonly in children but is more of a last resort in adults in whom the subclavian veins are usually a better alternative
Femoral artery:
this is used for arterial sampling and monitoring
(again if other sites are unsuitable).
The artery also provides access for angiography and for the insertion
of intra-aortic balloon pump catheters
femoral nerve originates
femoral nerve originates from the anterior primary rami of L2, L3 and L4
and enters the anterior thigh beneath the inguinal ligament
(which runs from the anterior superior iliac spine to the pubic tubercle).
femoral sheath is formed from an extension of the extraperitoneal fascia and
contains the femoral vein (medially) and artery (laterally).
It does not contain the femoral nerve.
Sheath?
nerve is invested in the fascia of the iliacus muscle (fascia iliaca),
which separates it from the femoral sheath.
The distance by which it is separated from the vessel is variable.
It may bear a close relation to the pulsation of the femoral artery
or may be 1–2 cm or even more lateral to it
Divisions
divides into a leash of nerves which supply the muscles of the thigh.
One of the main divisions continues as the saphenous nerve,
which passes medially across the knee to provide sensory innervation as far as the medial aspect of the ankle and rear foot
Femoral Nerve, 3-in-1 and Fascia Iliaca blocks
Supply
Indications
the nerve supplies the shaft of the femur, the muscles and skin of the anterior
thigh as far as the knee, and via the saphenous nerve, the medial side of the lower leg
as far as an area surrounding the medial malleolus.
these include the provision of analgesia for fractured shaft of femur
(which is usually very effective, particularly if an indwelling catheter technique is
used), perioperative analgesia for knee surgery, and perioperative analgesia for hip
surgery (usually as part of a 3-in-1 block).
3-in-1 block:
3-in-1 block: this describes a single injection, which aims to block the femoral nerve,
the obturator nerve and the lateral cutaneous nerve of the thigh. A larger volume of
local anaesthetic is used, and during injection firm distal pressure is applied. In theory,
this spreads the local anaesthetic rostrally back up into the psoas compartment so that
all three nerves are blocked
obturator nerve supplies the adductor muscles of the
hip, part of the hip joint, skin on the medial side of the thigh and part of the knee joint.
The lateral cutaneous nerve supplies skin over the anterolateral thigh as far as the knee,
and the over the lateral thigh from the greater trochanter down to the level of the midthigh.
These nerves can also be blocked within the psoas compartment itself.
Fascia iliaca block
the femoral, lateral cutaneous and obturator nerves. Local anaesthetic is
injected behind the fascia iliaca at the junction of the lateral with the two medial
thirds of the inguinal ligament,
producing ‘clicks’ as it passes through tensor fascia lata and fascia iliaca
the iliacus muscle form a potential space in which are found the three nerves
Adductor canal block
The adductor canal block can provide analgesia comparable to that of a
formal femoral nerve block but is relatively motor sparing and so does not delay
immediate post-operative rehabilitation.
saphenous nerve is the terminal sensory
branch of the femoral nerve and can be blocked in the adductor canal which is
the space formed by the sartorius (superiorly), vastus medialis (laterally) and
adductor longus and magnus (medially)
The space contains the neurovascular
bundle, and it is the femoral artery that provides the key anatomical landmark, as
the nerve itself is not always clearly seen on ultrasound. Lower volume and lower
concentration local anaesthetic is sufficient to provide analgesia without the risk of
motor block to vastus medialis; a typical dose would be 10–20 ml of levobupivacaine
0.25%.
iPack
There is a variation in the form of the iPACK block (injection into the
interspace between the Popliteal Artery and the posterior Capsule of the Knee). This
is a modified superior genicular nerve block with the same point of injection as for
the SPANK block. The needle is advanced until it is lateral to the popliteal artery and
then solution is injected continuously during gradual withdrawal.
