Femoral nerve block | |
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![]() Ultrasound guided femoral nerve block | |
Other names | Femoral block |
A femoral nerve block is a nerve block that uses local anesthetic to achieve analgesia in the leg. The block works by affecting the femoral nerve.
A femoral nerve block (FNB) results in anesthesia of the skin and muscles of the anterior thigh and most of the femur and knee joint, as well as the skin on the medial aspect of the leg below the knee joint. [1]
The block can be performed using anatomical landmarks, ultrasound or a nerve stimulator. [2]
For hip surgery, a femoral nerve block and fascia iliac block (FIB) are alternative methods for providing analgesic relief. A meta-analysis concluded that compared to FIB, the FNB decreased visual analog scale at 24 hrs and the incidence of nausea, vomiting and oversedation. [3]
For knee surgery, a femoral nerve block may lead to delayed postoperative mobilization of the patient and greater risk of falls as it causes motor blockade of the quadriceps muscles. [4] Due to the sparing of the thigh muscles the adductor canal block is becoming a preferred choice for providing post-operative analgesia for knee surgery. [5]
The human leg is the entire lower limb of the human body, including the foot, thigh or sometimes even the hip or buttock region. The major bones of the leg are the femur, tibia, and adjacent fibula. The thigh is between the hip and knee, while the calf (rear) and shin (front) are between the knee and foot.
The sartorius muscle is the longest muscle in the human body. It is a long, thin, superficial muscle that runs down the length of the thigh in the anterior compartment.
The femoral artery is a large artery in the thigh and the main arterial supply to the thigh and leg. The femoral artery gives off the deep femoral artery and descends along the anteromedial part of the thigh in the femoral triangle. It enters and passes through the adductor canal, and becomes the popliteal artery as it passes through the adductor hiatus in the adductor magnus near the junction of the middle and distal thirds of the thigh.
The femoral triangle is an anatomical region of the upper third of the thigh. It is a subfascial space which appears as a triangular depression below the inguinal ligament when the thigh is flexed, abducted and laterally rotated.
The popliteal artery is a deeply placed continuation of the femoral artery opening in the distal portion of the adductor magnus muscle. It courses through the popliteal fossa and ends at the lower border of the popliteus muscle, where it branches into the anterior and posterior tibial arteries.
The inguinal ligament, also known as Poupart's ligament or groin ligament, is a band running from the pubic tubercle to the anterior superior iliac spine. It forms the base of the inguinal canal through which an indirect inguinal hernia may develop.
Nerve block or regional nerve blockade is any deliberate interruption of signals traveling along a nerve, often for the purpose of pain relief. Local anesthetic nerve block is a short-term block, usually lasting hours or days, involving the injection of an anesthetic, a corticosteroid, and other agents onto or near a nerve. Neurolytic block, the deliberate temporary degeneration of nerve fibers through the application of chemicals, heat, or freezing, produces a block that may persist for weeks, months, or indefinitely. Neurectomy, the cutting through or removal of a nerve or a section of a nerve, usually produces a permanent block. Because neurectomy of a sensory nerve is often followed, months later, by the emergence of new, more intense pain, sensory nerve neurectomy is rarely performed.
In the human body, the adductor longus is a skeletal muscle located in the thigh. One of the adductor muscles of the hip, its main function is to adduct the thigh and it is innervated by the obturator nerve. It forms the medial wall of the femoral triangle.
The gracilis muscle is the most superficial muscle on the medial side of the thigh. It is thin and flattened, broad above, narrow and tapering below.
The iliopsoas muscle refers to the joined psoas major and the iliacus muscles. The two muscles are separate in the abdomen, but usually merge in the thigh. They are usually given the common name iliopsoas. The iliopsoas muscle joins to the femur at the lesser trochanter. It acts as the strongest flexor of the hip.
The femoral nerve is a nerve in the thigh that supplies skin on the upper thigh and inner leg, and the muscles that extend the knee. It is the largest branch of the lumbar plexus.
The popliteal fossa is a shallow depression located at the back of the knee joint. The bones of the popliteal fossa are the femur and the tibia. Like other flexion surfaces of large joints, it is an area where blood vessels and nerves pass relatively superficially, and with an increased number of lymph nodes.
The lumbar plexus is a web of nerves in the lumbar region of the body which forms part of the larger lumbosacral plexus. It is formed by the divisions of the first four lumbar nerves (L1-L4) and from contributions of the subcostal nerve (T12), which is the last thoracic nerve. Additionally, the ventral rami of the fourth lumbar nerve pass communicating branches, the lumbosacral trunk, to the sacral plexus. The nerves of the lumbar plexus pass in front of the hip joint and mainly support the anterior part of the thigh.
The lateral cutaneous nerve of the thigh is a cutaneous nerve of the thigh. It originates from the dorsal divisions of the second and third lumbar nerves from of lumbar plexus. It passes under the inguinal ligament to reach the thigh. It supplies sensation to the skin on the lateral part of the thigh by an anterior branch and a posterior branch.
The iliac fascia is the fascia overlying the iliacus muscle.
The femoral sheath is a funnel-shaped downward extension of abdominal fascia within which the femoral artery and femoral vein pass between the abdomen and the thigh. The femoral sheath is subdivided by two vertical partitions to form three compartments ; the medial compartment is known as the femoral canal and contains lymphatic vessels and a lymph node, whereas the intermediate canal and the lateral canal accommodate the femoral vein and the femoral artery (respectively). Some neurovascular structures perforate the femoral sheath. Topographically, the femoral sheath is contained within in the femoral triangle.
The saphenous nerve is the largest cutaneous branch of the femoral nerve. It is derived from the lumbar plexus (L3-L4). It is a strictly sensory nerve, and has no motor function. It commences in the proximal (upper) thigh and travels along the adductor canal. Upon exiting the adductor canal, the saphenous nerve terminates by splitting into two terminal branches: the sartorial nerve, and the infrapatellar nerve. The saphenous nerve is responsible for providing sensory innervation to the skin of the anteromedial leg.
The following outline is provided as an overview of and topical guide to human anatomy:
Medial knee injuries are the most common type of knee injury. The medial ligament complex of the knee consists of:
Fascia iliaca blocks is a local anesthetic nerve block, a type of regional anesthesia technique, used to provide analgesia or anaesthesia to the hip and thigh. FICB can performed by using ultrasound or with a loss of resistance technique, the latter sometimes referred to as the "two-pop-method". FICB works by affecting the femoral, obturator and the lateral cutaneous nerves with a local anesthetic.