Lumbosacral plexus

Objectives

1- Make a list of contributing spinal nerves to the lumbar plexus.2- Discuss the arrangement of the plexus.3- Describe the location of this plexus and its relation to the psoas muscle.4- List the terminal branches and follow up each branch to its final destination.5- Make a list of contributing spinal nerves to the sacral plexus.6- Discuss the arrangement of this plexus.7-Describe the location of this plexus.

Lumbosacral Plexus

• Components:Lumbar plexus:

L1--L4.Lumbosacral trunk:

L4—L5.Sacral plexus:

S1—S4.

Lumbar Plexus

• Formed in psoas major:

From ventral rami of L1-L4.There is a connection between the

different rootsThey give many branches (Motor and Sensory)

Branches emerge from both lateral and medial sides of psoas major:Connect to sympathetic trunk.

Branches of the Lumbar Plexus

• Iliohypogastric L1• Ilioinguinal L1• Genitofemoral L1-2• Lateral femoral

cutaneous L2-3• Femoral L2,3,4• Obturator L2,3,4

Lumbar PlexusTwo branches

emerge from lateral side of psoas major:

1- Iliohypogastric L1:to side of buttock and pubis.

2- Ilioinguinal L1:to anterior thigh,

scrotum,labia majora.

Lumbar Plexus

• 3- Genitofemoral nerve L1 :Emerges on anterior surface of psoas major.Genital branch:

Enters inguinal canal.Supplies1- scrotum

2-labia majora 3-cremaster muscle

Femoral branch:Enters femoral sheath.Supplies skin over the femoral triangle.

Lumbar Plexus• 4- Femoral

nerve:L2—L4.

Largest branch of lumbar plexus.

Emerges from lateral side of psoas major.

Enters thigh behind inguinal ligament.

Passes lateral to femoral artery & divides into anterior & posterior divisions.

BRANCHES OF FEMORAL NERVE

Muscular:• In abdomen: To iliacus (flexor of hip

joint).• In lower limb: To anterior compartment of the thigh:Flexors of hip joint: sartorius & pectineusExtensors of knee joint: quadriceps femoris.

Lumbar plexus

• Femoral n. cond.Cutaneous brs:• To antero-medial aspect of the thigh.• To medial side of knee, leg and foot

(saphenous nerve).

Terminates as:Saphenous nerve to medial thigh and foot.

Lumbar Plexus

• Obturator nerve:L2--L4.Emerges from medial side of psoas major.Descends along lateral wall of pelvis.

Enters thigh through obturator foramen:In obturator groove it divides into:1-Anterior branch (anterior to adductor brevis).2- Posterior branch (posterior to adductor brevis).

Lumbar Plexus

• Obturator nerve:Supplies:

Medial thigh musclesSkin on medial thigh

Sacral Plexus

• Collection of nerves that provide sensory, motor, and autonomic innervation to parts of the lower limb

• It arises from the L5-S4 • There are some connections between different roots• It gives many branches to the lower limb Site of formation: infront of the piriformis muscle

Branches of the Sacral Plexus• Sciatic nerve L5-S3• Superior gluteal

nerve• Inferior gluteal nerve• Nerve to obturator

internus• Nerve to quadratus

femoris• Pudendal nerve S2-4• Posterior cutaneous

nerve of the thigh S1-3

• Perforating nerve of the thigh S2-3

• Pelvic splanchnic nerves are the sacral part of the parasympathetic system and arise from the S2,3,4.

• They are distributed to the pelvic viscera

Sacral Plexus

• Superior gluteal nerve:

L4--S1.Passes through greater

sciatic notch above piriformis.

Supplies lateral gluteal compartment.

Sacral Plexus

• Inferior gluteal nerve:L5--S2.Passes through greater sciatic notch below

piriformis.Supplies posterior gluteal compartment.

Sacral Plexus• Posterior femoral

cutaneous:Runs with gluteal nerves deep to gluteus maximus.Then runs with sciatic nerve and gluteal artery.

Supplies:1-Skin on buttock via

inferior cluneal nerve.

2-Skin of external genitalia via perineal branches.

3-Skin on back of thigh

Sacral Plexus

• Nerves to lateral thigh compartment:To inferior gemellus (GSE):

L4..S1.To quadratus femoris (GSE):

L4..S1.To piriformis (GSE):

S1..S2.

Sacral Plexus• Sciatic nerve: It is the largest nerve of the body. Origin: Sacral plexus (L4,5, S1, 2,3). Course: Leaves the pelvis through greater sciatic foramen, below piriformis

& passes in the gluteal region (between ischial tuberosity & greater trochanter) then to posterior compartment of thigh.

Termination: Divides into tibial & common peroneal (fibular) nerves in the

middle of the back of the thighThe sciatic supplies: nearly the whole of the skin of the leg, the muscles of the back of the thigh, and those of the leg and foot.

Thank u