Learning objectives
With improvements in ultrasound (US) imaging equipment and refinements in scanning technique,
an increasing number of peripheral nerves and related pathologic conditions can be identified.
The purpose of our educational exhibit is to:
1.
Illustrate the normal anatomy and normal US appearance of the femoral nerve.
2.
Describe a systematic technique for US evaluation of such structure.
3.
Produce anatomical schemes with didactic purpose and show correlations with sonographic imaging.
Background
The femoral nerve,
created by the dorsal divisions of the anterior rami of L2,
L3,
and L4,
is the largest branch of the lumbar plexus.
It emerges at the inferolateral border of the psoas muscle to run caudally and laterally in the groove formed by the psoas and iliacus muscles.
Then the nerve enters the thigh passing under the inguinal ligament,
and,
within a short distance,
it divides into anterior and posterior branches.
At this level the femoral nerve is lateral and posterior to the...
Imaging findings OR Procedure Details
Place the patient supine,
with the leg extended and slightly externally rotated.
Identify the anterior superior iliac spine (ASIS) and the pubic symphysis,
and draw an imaginary line between these two landmarks that represents the inguinal ligament.
Place the probe in the inguinal crease in a transverse plane,
across the femoral region of the upper thigh,
parallel to the inguinal ligament,
to identify the femoral vein and artery (Fig.
2 a,
Fig.
3 b).
At this level the iliopsoas and pectineus muscles can be clearly...
Conclusion
Ultrasound is a low-cost,
quick and noninvasive imaging method,
providing an excellent view of peripheral nerve anatomy as well as of surrounding structures.
US provides high spatial resolution and the ability to explore long segments of nerve trunks in a single study,
also allowing nerves examination in both static and dynamic conditions,
during passive or active movements of the extremities.To perform US of femoral nerve,
it is important to know its course paying attention to anatomic landmarks and common sites of injury.
References
Bianchi S,
Martinoli C,
editors.
Ultrasound of the musculoskeletalsystem.
Milan,
Italy: Springer Verlag; 2009.
Kele H.
Ultrasonography of the peripheral nervous system.Pers Med.
2012;1:417–21.
Peer S,
Kovacs P,
Harpf C,
Bodner G.
High-resolutionsonography of lower extremity peripheral nerves: anatomiccorrelation and spectrum of disease.
J Ultrasound Med 2002;21:315-22.