Lumbosacral Plexus Flashcards
Spinal nerves that from lumbosacral plexus
L1-L4
S1-S5
L4 ramus + L5 ramus =
Lumbosacral trunk
Posterior divisions of lumbar plexus nerves supply
Anterior thigh (embryo rotation)
Ilioinguinal nerve
L1 root
Innervates skin of genitalia and upper medial thigh
Genitofemoral nerve
L1 and L2 roots
Genital and femoral branches
Femoral - innervates skin on upper anterior thigh
Lateral cutaneous nerve (lateral femoral cutaneous)
Posterior divisions of L2 and L3 roots
Purely sensory function
Innervates anterolateral thigh as far inferiorly as the knee.
Obturator nerve
Anterior divisions of the L2, L3 and L4 roots.
Innervates skin over medial thigh
and the muscles of the medial compartment of the thigh
(Obturator externus, pectineus, adductor longus, adductor brevis, adductor magnus, gracilis muscle)
Femoral nerve
Posterior divisions of the L2, L3 and L4 roots.
Femoral cutaneous branch = Skin of anterior thigh
Saphenous branch = skin of medial leg
Anterior compartment thigh
(Iliacus, pectineus, sartorius, rectus femoris, vastus latoralis, vastus medialis, vastus intermedius)
Lumbar plexus branches and root
I get left overs on Fridays
Iiliogiunal (L1) Genitofemoral (L1, L2) Lateral femoral cutaneous (L2, L3) Obturator (L2, L3, L4) Femoral (L2, L3, L4)
Which spinal nerve roots form the sacral plexus?
S1 - S4 (L4 and 5 via lumbosacral trunk)
Superior gluteal nerve:
What are the roots?
Where does it enter and leave the pelvis?
Which structures does it innervate?
What doesn’t it have?
What is it accompanied by?
- L4, L5, S1 roots
- Leaves the pelvis via the greater sciatic foramen (described here) and enters the gluteal region above the piriformis muscle
- Innervates gluteus medius, gluteus minimus, tensor fascia lata
- NO SENSORY INNERVATION
(Accompanied by superior gluteal artery and vein)
Inferior gluteal nerve
L5, S1, S2
Leaves the pelvis via the greater sciatic foramen but enters the gluteal region below the piriformis muscle
Innervates gluteus maximus
NO SENSORY BRANCHES
(Accompanied by inferior gluteal artery and vein)
sciatic nerve
- L4, L5, S1, S2, S3
- 2 - Divides into tibial and common peroneal nerve (fibial)
- Tibial - hamstring
EXCEPT short head bicep femoris - common peroneal - No branches in the gluteal region
Posterior cutaneous nerve
S1 - S3
It leaves the pelvis via the greater sciatic foramen below the piriformis muscle
Innervates skin of posterior thigh and leg
No motor function
Sacral plexus and roots
Salmon is so perfectly pink
Superior gluteal (L4, L5, S1) Inferior gluteal (L5, S1, S2) Sciatic (L4,L5,S1,S2, S3) Posterior femoral (S1, S2, S3) Pudendal ( S2, S3, S4)
How are the greater and lesser sciatic foramina formed?
Sacrospinous and sacrotuberous ligaments
Greater and lesser sciatic notch
Where do the superior gluteal nerve and vessels exit the pelvis?
Greater sciatic foramen superior to piriformis muscle
Which structures exit pelvis via greater sciatic foramen inferior to the piriformis muslce?
Sciatic nerve Inferior gluteal nerve, artery and vein Nerve to quadratus femoris Nerve to obturator internus Pudendal nerve
Which structures pass through the lesser sciatic foramen?
Tendon of obturator internus
Nerve to obturator internu
Pudendal nerve
Internal pudendal vessels
Safe areas to inject gluteal intramuscular injection on child (3-7 years)
Dorsogluteal site
Upper outer quadrant
(Outer top Corners of top quadrants)
Safe intramuscular injection adults (7+)
- Ventrogluteal (you form a v with your hand)
- Palm of hand over greater trochanter of femur
Thumb towards inguinal region (top of thigh)
Spread index and middle finger to make a V
Carefully inject between the proximal interphalangeal joints of your fingers into the patient’s gluteus medius muscle.
