Lumbosacral Plexus Flashcards
Which roots form the lumbar plexus?
L1 to L4 spinal roots (with some T12 and L5) form the lumbar plexus.
Where does the plexus emerge anatomically?
Originates behind the psoas muscles and emerges laterally and medially to psoas major.
What are the main branches of the lumbar plexus and which roots do they come from?
The main branches are: iliohypograstic and ilioinguinal from L1, lateral femoral cutaneous from L2 and L3, femoral and obturator nerves from L2, L3 and L4 and the lumbosacral trunk from L4 and L5.
What is the lumbosacral trunk
The lumbosacral trunk is formed from the L4 and L5 and connects the lumbar and sacral plexi.
What roots form the sacral plexus
Lumbosacral trunk and S1 – S4 forms the sacral plexus.
Where does the sacral plexus emerge anatomically?
It forms anterior to the piriformis muscle.
What are the main branches of the sacral plexus
The main branches are: superior (L4, L5 andS1) and inferior (L5, S1 and S2) gluteal nerves, common peroneal nerve (L4, L5, S1 and S2) and tibial nerve (L4, L5, S1, S2 and S3) joint into the sciatic nerve, posterior cutaneous nerve of thigh (S1, S2 and S3) and the pudental nerve (S2, S3 and S4).
What do the superior and inferior gluteal nerves supply?
Superior and inferior gluteal nerves supply the gluteal muscles
What does the femoral nerve supply
The anterior thigh muscles. Cutaneously it supplies the anterior thigh and the medial leg as the saphenous nerve.
What does the obturator nerve supply
Medial thigh muscles and cutaneously the medial thigh
What does the Tibial nerve supply
Posterior compartment of all the leg and foot and cutaneously the bottom of the food, the postero-lateral aspect of the foot (as the sural nerve) and the posterior aspect of the foot (as the calcaneal nerve).
What does the Superficial peroneal/fibular nerve supply
Lateral leg muscles and cutaneously the lateral aspect of the leg and the dorsum of the foot.
What does the deep peroneal/fibular nerve supply
anterior leg muscles and the bit of skin in between the 1st and 2nd toes.
What are the Myotomes of the lumbosacral plexus.
L2 - Hip felxion
L3 - knee extension and adduction
L4 - dorsiflexion
L5 great toe extension, inversion and hip abduction
S1 - plantar flexion, eversion and hip extension
S2 - knee flexion and great tow flexion
S3 and S4 - anal wink
What are the common causes of damage to the femoral nerve and what are the consequences?
Femoral nerve can be injured in hip fractured/dislocations/femoral stab. This will result in loss of flexion of hip and extension of knee and sensation over the lower leg.
