NeuroTeach 42 - Lumbosacral plexus

Lumbosacral Plexus!!!

2) Formation “ventral rami of L1-S4” 2 components: a. lumbar plexus (L1-L4) – forms within psoas major anterior to lumbar transverse process - 6 branches b. sacral plexus (L4-S4) – forms anterior to piriformis muscle - 12 main branches

3) Lumbar plexus (L1-L4)

Simple “I (twice) Got Lunch On Friday” 2 nerves w/ single root 2 nerves w/ double root 2 nerves w/ triple root

4) Progression of the lumbar root values

1 – Ilioinguinal & Iliohypogastric nerves 1,2 – Genitofemoral nerve 2,3 – Lateral femoral cutaneous nerve 2,3,4 – Obturator & Femoral nerves

5) Lumbar plexus drawing

1st roots T12 to L4 2nd ⧓ and FEE 3rd there is something ⬆️and⬇️ the bowtie

6) Lumbar plexus additional

4th Simple “I (twice) Got Lunch On Friday”

5th 2 nerves x 1 root, 2 nerves x 2 roots, 2 nerves x 3 roots

7) Summary – mnemonic

8) Summary – table

9) Sacral plexus

“formed from ventral rami of L4-S4” Six P’s and five major branches (SIPPS)

10) Six P’s

all of the nerves of the anterior rami (prior to division) start w/ P PArasympathetic pelvic splanchnic nerves(S2-S4) PErforating cutaneous nerve(S2-S3); PErineal branch of S4 (S4) PIriformis (S1-S2) POsterior femoral cutaneous nerve (S1-S3) PUdendal nerve (S2-S4)

11) Five major branches

SIPPS Sup gluteal; quadratus; inf gem Inf gluteal; obturator; sup gem Post cut femoral Pudendal Sciatic

12) Sacral plexus drawing

1st roots L4 to S4 2nd SIPPS rule 3rd Below sciatic, the six P’s

13) Sacral plexus – summary

14) How to remember the 12 sacral branches?

1st SIPSS and extras (quadratus&obturator) 2nd Six P’s; remove the PArasympathetic & PErineal branch 3rd Remember that sciatic is formed by common fibular & tibial 4th add the coccygeal

15) Lumbosacral plexopathy

Lumbar plexus - weakness of hip flexion and adduction and/or knee extension vs Lumbosacral trunk and upper sacral plexus - foot drop or flail foot