Lecture 11: Lumbosacral Plexus Flashcards
What are enlargements of spinal cord
Cervical and lumbar
Correspond with plexus involved in providing innervation to limbs
Enlargements reflect increased numbers of neurons (motor and sensory) coming from/going to limbs
Describe cervical enlargemnt
Brachial plexus
C5-t1
Describe lumbar enlargemnt
Lumbosacral plexus = l1-s4
Swelling higher than nerve levels here, bc have to travel far
Describe what lumbar plexus means
After emerging from spinal cord =nerves cross over, join, plait/braid and travel together for a time and may divide again further in the limb
Usually nerves = combos of diff spinal levels
What is lumbosacral plexus composed of
Anterior rami of spinal nerves l1-s4 - divided into 2 parts = lumbar plexus and sacral plexus
name spinal levels of lumbar plexus
L1-l4
And t12 contributes a bit
Describe cutaneous innervation = lumbar plexus
Innervates anterior, medial and lateral thigh, anterior knee and medial leg and foot (ankle)
Describe motor innervation = lumbar plexus
Innervation to anterior and medial compartments of thigh
Nothing below knee tho
Name levels of sacral plexus
L4-s4
What is special about l4
Split between 2 divisions
Some to lumbar anf some to sacral plexus
Describe cutaneous innervation = sacral plexus
Innervation to lower buttocks, posterior thigh (post cutaneous) and leg, lateral leg and majority of the foot - except small part of ankle
Describe motor innervation = sacral plexus
To gluteal region, posterior thigh compartments of leg and the foot
Everything below knee
Describe iliohypogastric nerve of lumbar plexus = spinal levels
T12-l1
Describe ilioinguinal nerve of lumbar plexus = spinal levels
L1
What is special about iliohypogastric and ilioinguinal nerves of lumbar plexus
Pierce abdominal walll = no passage through pelvis, stay near iliac crest
Describe genitofemoral nerve of lumbar plexus = spinal levels
L1-l2
Describe obturator nerve of lumbar plexus = spinal levels
L2-l4
Exits pelvis via obturator foramen
Describe lateral femoral cutaneous nerve of lumbar plexus = spinal levels
L2-3
Under inguinal ligament to thigh
In iliac fossa
Describe femoral nerve of lumbar plexus = spinal levels
L2-l4
Anterior thigh
Where AND WHICH NERVES = how do lumbar plexus nerves exit generally
Genitofemoral
Lateral femoral cutaneous
Femoral
= all exit pelvis anteriorly through spaces in inguinal region
Where do sacral plexus nerves exit/enter pelvis
Collectively = exit/enter pelvis posteriorly via greater sciatic foramen
Describe superior and inferior gluteal nerves of sacral plexus = spinal levels
Superior = l4-s1
Inferior gluteal = l5-s2
Describe pudendal nerve of sacral plexus = spinal levels
S2-4
Somatic nerve
Describe posterior femoral cutaneous nerve of sacral plexus = spinal levels
S1-3