Symptoms of the femoral nerve damage

The femoral nerve (n. Femoralis) is formed from fibers of the dorsal branches of the anterior primary division of LII-LIV spinal nerves, sometimes LI. Starting at level LI, it is first located behind the large lumbar muscle, then comes out from under its outer edge. Next, the nerve is in the groove (trench) between the iliac and the large lumbar muscles. Here it is covered from above by the iliac fascia. The fascia leaflets located above the femoral nerve are divided into four plates: the iliac, pre-umbilical, transverse, and peritoneal. Between these plates can exist up to three bags containing a small amount of connective and adipose tissue. Since the femoral nerve is located in a close and fixed gap between the pelvic bones and the iliac fascia, in this place it can easily be compressed by a hemorrhage with the formation of a hematoma. The pelvic cavity leaves the nerve passing through the bone-fibrous tunnel, formed by the inguinal ligament (front), the branches of the pubic bone and the ilium. Under the ligament, the nerve passes through the muscle lacuna. Upon reaching the thigh, the nerve is located under the sheets of the broad fascia of the thigh, covering the iliac and crest muscles. Here it is in the femoral triangle bounded above by the inguinal ligament, outside - by the tailor and internally - by the long adductor muscle. From the lateral side of the femoral triangle, the deep leaf of the broad fascia of the femur passes into the iliac fascia covering m. Iliopsoas. The femoral artery is medial to the nerve. At this level, the femoral nerve can also be compressed by a hematoma.

Above the inguinal ligament from the femoral nerve branches branch to the iliac, large and small lumbar muscles. These muscles flex the hip in the hip joint, rotating it outward; with a fixed thigh flex the lumbar part of the spinal column, tilting the trunk forward.

Tests to determine the strength of these muscles:

1. in the supine position on the back, the subject raises the straightened lower limb upward; the examiner is resisting this movement, resting his palm on the middle of the thigh area;
2. in the sitting position on the stupa, the subject flexes the lower limb in the hip joint; The examiner impedes this movement by providing resistance at the level of the lower third of the thigh;
3. from the position, lying on the back (on a rigid surface), the subject is offered to sit down without the help of the upper limbs with the lower extremities fixed to the bed.

Under the inguinal ligament or distal the femoral nerve is divided into motor and sensitive branches. Of these, the first are supplied with comb, tail and quadriceps muscles, the second - the skin, subcutaneous tissue and fascia in the region of the lower two-thirds of the anterior and anterior-femoral surface of the thigh, the anterior surface of the shin, sometimes the inner edge of the foot at the medial malleolus.

The comb muscle (m. Pectineus) flexes, leads and rotates the hip outward.

The sartorius muscle (m. Sartorius) flexes the lower limb in the hip and knee joints, rotating the hip outward.

The test for determining the strength of the sartorius muscle: the subject is given a moderate flexion of the lower limb in the knee and hip joints in the supine position and rotate the hip outward; The researcher is resisting this movement and palpating the contracted muscle. A similar test can be examined in the position of the subject sitting on a chair.

The quadriceps femoris flexes the thigh in the hip joint and unbends the shin in the knee joint.

Test to determine the strength of the quadriceps muscle:

1. in the supine position on the tire the lower limb is bent in the hip and knee joints, the subject is offered to undo the lower limb; the examiner is resisting this movement and examines the contracted muscle;
2. sitting on a chair, the subject unbends his lower limb in the rut; The examiner is resisting this movement and palpating the contracted muscle.

The presence of hypotrophy of this muscle can be determined by measuring the circumference of the thigh at strictly symmetrical levels (usually 20 cm above the upper edge of the patella.

The femoral nerve is affected by trauma (including traumatic and spontaneous hematomas along its course, for example, with hemophilia, treatment with anticoagulants, etc.), inguinal lymphadenitis, appendicular abscess, and others.

The clinical picture of lesion of the femoral nerve in the furrow between the iliac and lumbar muscles or in the femoral triangle is almost identical. First, there is pain in the groin. This pain irradiates into the lumbar region and the thigh. Rather rapidly the intensity of pain increases to a strong and constant.

The hip joint is usually held in a position of flexion and external rotation. Patients take a characteristic position in bed. They often lie on the affected side, with the spine bended in the lumbar spine, the hip and knee joints - the flexion contracture in the hip joint. Extension in the hip joint increases pain, but other movements are possible if the lower limb remains in a bent position.

With a hemorrhage at the level of the iliac muscle, there is a paralysis of the muscles supplied with the femoral nerve, but this does not always happen. When forming a hematoma usually affects only the femoral nerve. In very rare cases, the lateral cutaneous nerve of the thigh may be additionally involved. The defeat of the femoral nerve, as a rule, is manifested by pronounced paresis of the flexor of the femur and extensor of the tibia, the prolapse of the knee reflex. Difficulty standing, walking, running and especially climbing the stairs. Compensate for the loss of the function of the quadriceps muscle patients are trying by reducing the muscle, which strains the wide fascia of the thigh. Walking on an even surface is possible, but the gait becomes peculiar; the lower limb is excessively unbent at the knee joint, as a result of which the leg is excessively thrown forward and the foot becomes on the floor with the whole sole. Patients avoid bending the lower limb in the knee joint, since they can not unbend it. The patella is not fixed, it can be shifted passively in different directions.

For the neuralgic variant of femoral nerve defeat, Wasserman's symptom is characteristic: the patient lies on the stomach; the examiner raises the straightened limb up, with pain on the front surface of the thigh and in the groin area. The same will happen when flexing in the knee joint (symptom Matskevich). The pain also increases in a standing position when the torso is tilted back. Disturbances of sensitivity are localized in the lower two-thirds of the anterior and anteroposterior surface of the thigh, the anterior surface of the shin, the inner edge of the foot. Vasomotor and trophic disorders can be attached.

[1], [2], [3], [4]