lumbar and sacral plexuses Flashcards
Which spinal nerves form the lumbar plexus?
L1-L4 (sometimes T12)
The lumbar plexus is embedded in which muscle?
Psoas major
What are the nerve fibers that connect the lumbar and sacral plexuses called?
The lumbosacral trunk
The lumbosacral trunk is formed from which spinal nerves?
L4 and L5
Which spinal nerve is common to both the lumbar and sacral plexuses?
L4
What is the segmental innervation of the iliohypogastric nerve?
L1 (sometimes T12)
Is the iliohypogastric nerve formed from the anterior or posterior division?
Anterior
Motor supply of the iliohypogastric nerve?
Internal onlique and transverse abdominis
Cutaneous supply of the iliohypogastric nerve?
Proximal lateral aspect of the buttocks.
Segmental innervation of the ilioinguinal nerve?
L1
Ilioinguinal nerve: anterior or posterior division?
Anterior
What structures are supplied by the ilioinguinal nerve?
Skin of the proximal medial aspect of the thigh.
Segmental innervation of the lateral femoral cutaneous nerve?
L2 and L3
Lateral femoral cutaneous nerve: anterior or posterior division?
Posterior
Structures supplied by the lateral femoral cutaneous nerve?
Lateral aspect of the thigh
What is the term for compression neuropathy of the lateral femoral cutaneous nerve?
Meralgia paresthesia
Causes of meralgia paresthesia?
Obesity, tight pants, and excessive flexion of the hip joint.
Segmental innervation of the genitofemoral nerve?
L1 and L2
Genitofemoral nerve: anterior or posterior division?
Anterior
Structures supplied by the genitofemoral nerve?
Cremaster muscle, skin over genitalia, and a small area inferior to the inguinal ligament
Segmental innervation of the femoral nerve?
L2-4
Femoral nerve: anterior or posterior division?
Posterior
Structures supplied by the femoral nerve?
Motor: iliacus, psoas major, sartorial, quadriceps, pectinius
Cutaneous: medial and intermediate aspect of the anterior thigh and the medial aspect of the leg and foot
Articular: hip and knee
What is the name of the cutaneous branch of the femoral nerve and what areas does it supply?
The saphenous nerve, the medial aspect of the leg and foot.
How should you test for femoral nerve damage?
Test flexion at the hip and extension at the leg
Where might the saphenous nerve be compressed?
Within the adductor canal or as it exits.
What are symptoms of entrapment neuropathy of the saphenous nerve?
Knee pain and paresthesia
Segmental innervation of the obturator nerve?
L2-4
Obturator nerve: anterior or posterior division?
Anterior
Structures supplied by the obturator nerve?
Motor: pectineus, adductor magnus, longus and brevis, gracilis, and obturator exturnus
Cutaneous: med aspect of the thigh
Articular: hip and knee
Segmental innervation of the accessory obturator nerve?
L3-4
Structures supplied by the accessory obturator nerve?
Pectinius and hip joint
What percentage of the population has an accessory obturator nerve?
20%
How might damage to the obturator nerve occur?
Chilbirth or anterior dislocation of the hip joint
How might damage to the obturator nerve be tested?
Adduction of the femur against resistance
Which spinal nerves form the sacral plexus?
L4-S4 (L4 and L5 through the lumbosacral trunk)
Segmental innervation of the posterior femoral cutaneous nerve?
S1-3
Posterior femoral cutaneous nerve: anterior or posterior division?
Both
Structures supplied by the posterior femoral cutaneous nerve?
Distal part of the buttocks, posterior thigh, and popliteal fossa
Segmental innervation of the superior gluteal nerve?
L4-S1
Superior gluteal nerve: anterior or posterior division?
Posterior
Structures supplied by the superior gluteal nerve?
Gluteus medius and minimus, and tensor fascia lata
Segmental innervation of the inferior gluteal nerve?
L5-S2
Inferior gluteal nerve: anterior or posterior division?
Posterior
Structures supplied by the inferior gluteal nerve?
Gluteus maximus
Segmental innervation of the pudendal nerve?
S2-4
Pudendal nerve: anterior or posterior division?
Anterior
Segmental innervation of the sciatic nerve?
L4-S3
Structures supplied by the sciatic nerve?
Adductor magnus, semitendinosus, semimembranosus, biceps femoris
What are the names of the two branches of the sciatic nerve?
The tibial nerve and the common fibular nerve
Tibial nerve: anterior or posterior division?
Anterior
Structures supplied by the tibial nerve?
Muscles and most of the skin of the posterior leg and plantar surface of the foot.
Common fibular nerve: anterior or posterior division?
Posterior
Structures supplied by the common fibular nerve?
Muscles and skin of the anterior leg, lateral leg, and dorsum of the foot
What are the names of the two branches of the common fibular nerve?
Deep fibular nerve, and superficial fibular nerve
What are possible causes of sciatica?
Compression, inflammation, or subluxation of L4-S3, compression in the gluteal area, or intrapelvic tumor.
Dermatome of L1
Proximal anterior thigh
Dermatome of L2
Middle anterior thigh
Dermatome of L3
Distal anterior thigh, posterior medial leg
Dermatome of L4
Distal lateral thigh, medial leg and foot, digit one
Dermatome of L5
Lateral leg; digits two, three, and four
Dermatome of S1
Posterior lateral thigh and leg, lateral foot, digit 5
Dermatome of S2
Medial posterior thigh and leg
Dermatome of S3
Perineum