Lumbosacral Plexus Flashcards
lower limbs
function
support body weight
locomotion
maintain balance
extend from the trunk
gluteal region
transition b/t trunk and free lower limb
buttocks + hip region
leg region
aka crus
b/t knee and ankle
‘leg’ NOT THE SAME as lower limb
hip major movements
ball and socket joint
-flex/extend
-adduct/abduct
-medial/lateral rotate
-circumduct (just a combo of other moves)
knee movements
hinge joint
flex/extend
ankle movements
hinge joint
-plantarflex (point foot)
-dorsiflex (flex foot)
if muscle crosses joint
then what
it will move that joint BC
by definition crossing means it will have an origin proximal and insertion distal
werning rule
fascile direction
Werning rule
muscle will shorten/contract in direction of long axis fascicles
insertion is pulled TOWARD origin = move joint so action
if fascicles go 1+ direction then more than 1 action
origin/insertion in limb muscles
Werning rule
origin will be more medial than the insertion
except it limb-trunk muscle and spine/neck muscles then origin inferior to insertion
naming
Werning rule
if named for origin and insertion then origin is ALWAYS first
otherwise named for shape or action
how to injure a joint
- move in wrong direction
- move too far in right direction
- disconnect the bones via torn ligaments or break bones
how to injure muscle that moves joint
- trauma so injure muscle tissue directly
- disconnect muscle from bones via torn ligaments or break bones
- cut off blood supply
- paralyze via injure nerve supply
parts of lumbosacral plexus
- lumbar (T12-S4) deep to psoas
- sacral (L4-S4) superficial to piriformis
- coccygeal (S4-Co1)
overlap at L4 of lumbosacral trunk
LSP function
- provide motor and cutaneous innervatino to lower limb
- carry postganglionic symp fibers that regulate vasoactivity of lower limb vessels
blood supply of LSP
from internal iliac and it’s branches
-lateral sacral, iliolumbar, superior gluteal
makes lumbar plexus resistant to ischemia bc roots run through psoas major so very well vascularized
anterior divisons actions
flexion and abduction
posterior division actions
extension and adduction
roots of LSP
ventral primary rami of T12-S4
ignoring coccygeal
divisions of LSP
T12-L1 no divisions
L2-S4 each have anterior and posterior
pre-torsion embryology
dorsal mass inn by posterior divisions > extensor and abductor muscles
ventral mass inn by anterior divisions > flexor and adduction muscles
post-torsion divisions
posterior divisions + extensor muscles are ANTERIOR
anterior divisions + flexor muscles on POSTERIOR side of adult free lower limb
big 4 motor nerves
1.femoral (post divs of L24)
2.obturator (ant divs of L2-4)
————–
3.common fibular/peroneal (post divs L4-S2)
4.tibial (ant divs L4-S3)
*will run together in gluteal and posterior thigh regions as sciatic N
superficial thigh inn
superior to F/O N
lateral femoral cutaneous N
(post divs L2-L3)
up one from F/O
inguinal region inn
superior to F/O N
- iliolinguinal L1
- genitofemoral (L1-L2)
up two from F/O
no divisions
body wall inn
superior to F/O N
- subcostal T12
- iliohypogastric L1
up 3 from F/O
between F/O and T/CF
gluteal nerves
1. superior gluteal (post divs L4-S1)
2. inferior gluteal (post divs L5-S2)
superficial thigh inn
inferior to T/CF
- posterior femoral cutaneous (ant and post divs of S1-3)
perineum inn
inferior to T/CF
pudendal (ant divs of S2-4)
pelvis inn
inferior to T/CF
nerves of coccygeal plexus
LSP symmetry pattern
- nerve to perineum
- a femoral cutaneous N
- 2 big motor nerves (both sides post + ant)
- a gluteal N (both sides post)
repeat 4-1 inferiorly
smaller branches of LSP
- direct to psoas major (L1-3 ventral rami)
- N to quadratus femoris (ant div L4-S1)
- N to obturator internus (ant div L5-S2)
- N to piriformis (post div S1-2)
pelvic outlet route
for digestive, urinary, most reprod organs
over pelvic rim/inguinal lig route
for few LSP nerves and spermatic cord
spaces route
for arteries, veins, lymphatics, most LSP nerves
aka obturator foramen/canal, sciatic foramina, and retroinguinal spaces
paired sacral foramina route
for dorsal rami of sacral spinal nerves and branches of lateral sacral A
superior to pelvic rim/inguinal ligament
nerves
- subcostal T12
- iliohypogastric L1
lateral and anterior body wall
inguinal canal
nerves
- ilioinguinal L1
- genital branch genitofemoral L1-2
anterior body wall and perineum
retroinguinal space
nerves
superior space:lateral and anterior thigh
1. lateral femoral cut. L2-3
2. femoral N L2-4
inferior space: anterior thigh
1. femoral of genitofemoral L1-2
obturator canal
nerves
- obturator N L2-4
medial thigh
greater sciatic foramen- above piriformis
nerves
- superior gluteal L4-S1
gluteal region
greater sciatic foramen below piriformis
nerves
- inferior gluteal L5-S2
gluteal region - sciatic N with common fibular (L4-S2) + tibial (L4-S3)
posterior thigh + leg + foot - posterior femoral cut. S1-S3
posterior thigh - pudendal S2-4
as exits pelvis
lesser sciatic foramen
nerves
- pudendal S2-4
as enter the perineum
obturator N
ANT DIV-exits pelvis anteromedially
hip adductors
-og on pubis
medial compartment thigh
femoral N
POST DIV-exit pelvis anterolateral
hip flexors and knee extensors
-og from ant surfaces of ilium or femur
anterior compartment thigh
tibial N
ANT DIV-exit pelvis posteromedial
knee flexors and lateral hip rotators
-og from ischium
-posterior thigh compartment or deep gluteal
OR
knee flexor, ankle plantarflexor, foot everters, toe flexor
-posterior and lateral leg and plantar foot compartments
common fibular and gluteal N
POST DIV- exit posterolateral
hip extensors, hip abductors, hip medial rotators
-og from posterior and lateral surfaces of ilium
-superficial gluteal region and lateral hip
OR
ankle dorsiflexors, foot inverters, toe extensors
-anterior leg and dorsal foot regions
upper root plexopathies
reflect femoral and obturator N symptoms
lower root plexopathies
reflect common fibular/gluteal and tibial/lateral rotator symptoms
