lower extremity neuroanatomy
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LOWER EXTREMITY NEUROANATOMY
Wyndam M. Strodtbeck, MDSection Head, Acute PainDept of Anesthesiology and Pain MedicineVirginia Mason Medical Centerwyndam.strodtbeck@vmmc.org
Disclosures
No financial disclosures No off-label use of medications or
devices will be discussed Patient permission was explicitly
granted for any pictures used
Objectives for our talk
Describe the clinical anatomy of the innervation of the lower extremity
Identify surrounding structures and their implications for sonoanatomy and potential variation
Lumbosacral plexus
L1-L4 form the lumbar plexus
Branches from L4 –S2 from the lateral trunk
Other branches from L3-S3 make up the medial trunk
S1-S5 make up the sacral plexus
Early branching of the lumbar plexus and thick musculature makes identifying a single compartment for lumbosacral blockade difficult
Early Branches of the Lumbar Plexus Ilioinguinal and iliohypogastric nerves
From L1 Iliohypogastric supplies anterior and lateral
cutaneous innervation in hypogastric and gluteal region
Ilioinguinal supplies cutaneous innervation of genital region
Genitofemoral nerve From L1 and L2 Genital division supplies cremasteric muscle
and sensory over genital region Femoral branch supplies cutaneous
innervation over femoral triangle
Early Branches of the Lumbar Plexus
Gray, H. Anatomy of the human body, 1918.
Femoral NerveOrigin is dorsal divisions of L2-L4
Divides into anterior and posterior division typically at level of profunda femoris artery
Nader, Relationship Between Ultrasound Imaging and Eliciting Motor Response, J Ultrasound Med, 28(3):345-350, 2009
Femoral NerveOrigin L2-L4
Anterior division-Medial and intermediate cutaneous nerves-Muscular branches to sartorious-Articular branch to hip joint
Posterior Division-Muscular branches to quads-Articular branches to knee joint-Saphenous nerve is terminal cutaneous branch and provides lower leg anteromedial sensation
Nader, Relationship Between Ultrasound Imaging and Eliciting Motor Response, J Ultrasound Med, 28(3):345-350, 2009
Femoral Nerve
Nader, Relationship Between Ultrasound Imaging and Eliciting Motor Response, J Ultrasound Med, 28(3):345-350, 2009
Femoral NerveUltrasound image shows anterior and posterior divisions
Keep in mind the variations in location and appearance of the nerve
Groups of authors have reported variable splits in the femoral nerve in 2.2-35% of subjects.
Nader, Relationship Between Ultrasound Imaging and Eliciting Motor Response, J Ultrasound Med, 28(3):345-350, 2009
Lateral femoral cutaneous nerveOriginates from dorsal divisions of L2 and L3
May have a variable course as it emerges from psoas
Passes under inguinal ligament and superficial to the sartorious muscle
Located between fascia lata and fascia iliaca
Responsible for pain transmission in meralgia paresthetica
Hurdle, MF et al. Ultrasound-guided blockade of the lateral femoral cutaneous nerve. Arch Phys Med Rehab 88:1362-1364, 2007.
Saphenous Nerve Terminal branch of posterior division of femoral nerve
Provides cutaneous sensation around patella, anteromedial lower leg, and medial ankle
Travels in adductor canal with femoral artery and vein
In distal thigh, the saphenous nerve can be identified deep to the sartorious and between the vastus medialis and the adductor magnus
Saphenous Nerve
Image courtesy of FV Salinas, MD
Saphenous Nerve
Obturator nerveOriginates from ventral branches of L2-L4
Supplies articular branches to hip and knee
Adductors are supplied
Similar to femoral nerve in having anterior and posterior divisions
Obturator nerveAnterior division
Motor innervation to pectineus (may be an accessory obturator nerve) , adductor longus and brevis, gracilis
Articular branch of the hip
Posterior divisionMotor inneravtion to adductor magnus and
brevis as well as obturator externusArticular branches to hip and knee
Nerves of theSacral Plexus
Gray, H. Anatomy of the human body, 1918.
Posterior femoralcutaneous nerveProvides sensation for posterior thigh and leg, gluteal region, and perineum
Originates from S1-S3
Posterior femoralcutaneous nerve
Gray, H. Anatomy of the human body, 1918.
Sciatic NerveLargest nerve in the body
Joining of L4-S3
Two parts: -Tibial (medial)
(L4-S2)- Common Peroneal
(L4-S3)
Provides sensation for posterior leg and foot (except for saphenous distribution) as well as motor for posterior thigh, and all of leg and foot, and articular branches for hip and knee
Wikipedia, Feb 10, 2012
Sciatic NerveAt gluteal level, Sciatic is deep to gluteus maximus and passes out below piriformis muscle, located lateral to ischial spine
This level is useful due to the close proximity of the posterior femoral cutaneous nerve to the sciatic nerve
Sciatic NerveAt subgluteal level, the sciatic nerve is positioned between the gluteus maximus and the quadratus femoris
Sciatic NerveSubgluteal ultrasound
Image courtesy of FV Salinas, MD
Sciatic Nerve
-Shared epineural sheath for tibial and common peroneal nerves separates above popliteal crease-Schwemmer et al (2005) demonstrated high variability for division of sciatic nerve above popliteal crease (1-15 cm with mean of 8 cm) Wikipedia, Feb 10, 2012
Schwemmer et al. Sonographic imaging of the sciatic nerve division in the popliteal fossa. Ultraschall in Der
Medizin, 2005.
Nerves of the ankle and footPrimarily consists of terminal branches from the sciatic
Exception is the saphenous branch of the femoral nerve
Gray, H. Anatomy of the human body, 1918.NYSORA.com, accessed 2-10-2012
Special Thanks
Francis V. Salinas, MD
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