Lumbosacral Plexus Flashcards
How is the lumbar plexus formed ?
- Within the psoas major muscle
- Formed by the ventral rami of L1-3 & the sup part of L4 spinal nerves
- %50 of cases show a contribution from T12 (subcostal nerve)
What are the major branches of the lumbar plexus ?
- Iliohypogastric nervous .
- Ilioinguinal nervous .
- Genitofemoral nervous.
- Lateral cutaneous nerve of the thigh
- Femoral nerve .
- Obturator nerve .
What is the largest branch of the lumbar plexus ?
(L2-4):
- obturator nerve
- femoral nerve
Where dose the obturator nerve (L2,L3,L4) pass from ?
• descends through the psoas major muscle
• pierces the psoas fascia
• crosses the sacroiliac joint
• emerges from the obturator canal
• takes cutaneous innervation of medial part of thigh
• motor innervation to the adductor muscles of thig
Where dose the femoral nerve (L2,L3,L4) ?
• emerges between the psoas major and iliacus m
• thickest branch Cutaneous branches:
• Medial cutaneous n of thigh
• Intermediate cutaneous n of thigh
• Saphenous n
Motor branches:
• Muscles located at the anterior part of thigh
• Pectineus muscle
Where are the Iliohypogastric nerve & Ilioinguinal nerve derived from ?
areboth derived from T12-L1-often by a common stem
What is the function of the Iliohypogastric nerve (T12, L1) ?
• it sends a “lateral branch” to supply the skin of the gluteal region
• acts as the “ant. branch” to the skin of the hypogastric region
Where is the gentifemoral nerve (L1,L2) ?
-runs along the anterior surface of the psoas major muscle
-Feeding into the femoral branch, genital branch
Where dose the femoral cutaneous nerve (L2,L3) pass through ?
It passes through the psoas major muscle, iliac crest
What is the function of the lateral femoral cutaneous nerve ?
It supplies skin over the anterior and lateral thigh
What is the lumbosacral plexus formed from ?
- nerve plexus in the lumbar and sacral region. - the ventral rami L1-L3 nerves and the superior branch of L4 form the LUMBAR PLEXUS
- inferior branch of L4 and all L5 form the LUMBOSACRAL TRUNK and it descends to the SACRAL PLEXUS
Where is the sacral plexus located ?
It is located in the lesser pelvis ( true pelvis )
What is the sacral plexus related to ?
It is closely related to the piriformis muscle
What is the sacral plexus formed by ?
It is formed by :
- lumbosacral trunk
– ventral rami of the S1-3
– part of S4
How do the branches of the sacral plexus leave the pelvis ?
Through the greater sciatic foramen- except for the nerve of the piriformis muscle
What is the sciatic nerve ( L4,L5,S1,S2,S3) ?
It is the main branch of the sacral plexus, it is the largest nerve and it converts on the interior surface of the pirifomis muscle
What is the projection of the sciatic nerve ?
It enters the glory region and passes through the greater sciatic foremen
What does the sciatic nerve supply?
It usually supplies no structures in the gluteal region
What are the two terminal branches of the sciatic nerve?
-Tibial
- Common fibular (peroneal):
• Superficial peroneal
• Deep peroneal
How are the tibial nerve and the common fibular nerve (sciatic nerves) bound?
They are bound together in the same epineurium they usually separate from each other halfway of the thigh.
Where is there pudendal nerve located at?
It is most immediately located at the inferior edge of the piriformus muscle . As it intervenes the structures in the perineum.
What is the function of the posterior femoral cutaneous nerve (S2,S3)?
It’s supplies, the cutaneous intervention of the inferior part of the glutes region and the posterior side of the thigh and proximal part of the leg
Where does the posterior femoral cutaneous nerve pass-through?
The infrapiriform foramen.
Where does the superior gluten nerve (L4, L5, S1) pass through?
It versus through the greater sciatic foremen ( suprapiriform foramen ) along the superior gluteal vessels ?
What does the superior gluten nerve intervate ?
It intervenes the gluteus medias, minimus and tenor facia lateral muscle.
How dose the inferior gluteal nerve ( L5, S1, S2 ) leave the pelvis ?
It Leaves the pelvis at the inferior part of the greater sciatic foramen (infrapiriform foramen) alongside the inferior gluteal vessels.
What dose the inferior gluteal nerve innervate ?
innervates the gluteus maximus muscle
Where dose the nerve to quadratus femoris muscle (L4, L5, S1) innervate ?
Innervation of the quadrates femoris muscle .
What dose the nerve to obtuctor internus muscle ( L5, S1, S2 ) innervate ?
innervation ofobturator internus muscle
What is the Coccygeal plexus made from ?
Ventral rami of the :
• S4,S5, and coccygeal spinal nerves
• cutaneous innervation of coccygeal region
