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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.
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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 roots They give many branches (Motor and Sensory) Branches emerge from both lateral and medialsides of psoas major: Connect to sympathetic trunk.
Branches of the Lumbar Plexus • IliohypogastricL1 • Ilioinguinal L1 • Genitofemoral L1-2 • Lateral femoral cutaneous L2-3 • Femoral L2,3,4 • Obturator L2,3,4
Lumbar Plexus Two branches emerge from lateral side of psoas major: 1- IliohypogastricL1: to side of buttock and pubis. 2- IlioinguinalL1: to anterior thigh, scrotum,labiamajora.
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 & pectineus Extensors of knee joint: quadriceps femoris.
Lumbar plexus • Femoral n. cond. • Cutaneousbrs: • 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 muscles Skin 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: infrontof the piriformis muscle
Branches of the Sacral Plexus • Sciatic nerve L5-S3 • Superior gluteal nerve • Inferior gluteal nerve • Nerve to obturatorinternus • Nerve to quadratusfemoris • 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 belowpiriformis. 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 quadratusfemoris (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 thigh The 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.