LUMBOSACRAL PLEXUS Flashcards
Lumbar plexus is derived of nerves from which spinal levels?
Sacral plexus?
- T12 to L4
- L4 to S4
Patient had abdominal surgery in which a transverse incision was made in hypogastric (suprapubic) region.
Afterwards she complains of burning pain and tingling which radiates from the incision line to the suprapubic area. Which nerve has most likely damaged? Explain why and where this comes off of the lumbar plexus
Iliohypogastric nerve
- originates from lumbar plexus (T12-L1)
- supplies sensation to skin over lateral gluteal and suprapubic regions and motor to internal oblique and transverse abdominal muscles
- can be damaged in transverse incision and sutures may trap nerve
An absent cremasteric reflex, decrease sensation to anterior thigh and scrotum (or labia) indicates damage to which nerve? From where in plexus does it originate? Describe a normal reflex
Genitofemoral nerve (L1 to L2)
cremasteric reflex: stroke inner thigh → scrotum rises on ipsilateral side
This man is complaining of lateral femoral burning pain, paraesthesia and diminished sensation. Which condition does he have? What nerve is implicated (root in plexus)? Give risk factors
Meralgia paraesthetica → compression of lateral femoral cutaneous nerve (L2 to L3) under inguinal ligament
Risk factors: tight clothing, obesity, pregnancy
Which nerve is responsible for adducting the thighs? At what level does it come off the lumbosacral plexus? What is the sensory component of this nerve?
Obturator nerve (L2 to L4)
Medial thigh
Surgery in which part of the body increases risk of obturator nerve damage? What would the symptoms be?
Pelvis: nerve courses through posterior pelvis
Weak adduction of hips and numbness in medial thigh
Which nerve innervates the hip flexors? What is the origin of this nerve?
Femoral nerve (L2 to L4)
Which nerve innervates the quadriceps? What is the function of these muscles?
Femoral nerve
→ knee extension
Why might a patient experience lower leg numbness after CABG?
In this procedure the saphenous vein is often used, this can damage saphenous nerve which supplies lower leg with sensation. Saphenous nerve is a branch of femoral nerve.
To carry out a femoral nerve block for surgical procedures of the leg, how do you find the femoral nerve?
Palpate femoral pulse and inject laterally
NAVL
What nerve is responsible for the patellar reflex?
Femoral nerve
What is the origin of the sciatic nerve? What is the major motor function? What are the two main branches?
- L4 to S3
- Hip extension
- Common peroneal (fibular) and tibial nerve
What is an important motor function of the common peroneal nerve?
Dorsiflexion of the foot and extension of the toes (via deep branch)
What bone does the common peroneal nerve wrap around?
Fibula
Which nerve is responsible for planter flexion of the foot? What is the sensory innervation of this nerve?
Tibial nerve
Sole of the foot
What is the origin of the pudendal nerve? What is the motor and sensory supply?
S2 to S4: Nerve supply to genital area
- Motor: external urethral sphincter, external anal sphincter
- Sensory: penis, clitoris, skin of perineum
Perineal pain worsening with sitting, vulvar/scrotal pain and faecal/urinary incontinence all indicate damage to which nerve?
Pudendal nerve, often injured from stretching in childbirth
