lumbosacral plexus. lumbosacral plexus components: components: lumbar plexus: l1--l4. lumbosacral...

LUMBOSACRAL PLEXUSLUMBOSACRAL PLEXUS

Lumbosacral PlexusLumbosacral Plexus

Components:Components:Lumbar plexus:Lumbar plexus:

L1--L4.L1--L4.

Lumbosacral trunk:Lumbosacral trunk:

L4—L5.L4—L5.

Sacral plexus:Sacral plexus:

S1—S4.S1—S4.

Lumbar PlexusLumbar Plexus

Formed in psoas major:Formed in psoas major:From ventral rami of L1..L4.From ventral rami of L1..L4.

Branches emerge from both lateral and Branches emerge from both lateral and medial sides of psoas major:medial sides of psoas major:

Connect to sympathetic trunk.Connect to sympathetic trunk.


L1:L1:Variably connected to T12 (subcostal) and Variably connected to T12 (subcostal) and L2.L2.Two branches emerge from lateral side of Two branches emerge from lateral side of psoas major:psoas major:

Iliohypogastric (GSA):Iliohypogastric (GSA):to side of buttock and pubis.to side of buttock and pubis.

Ilioinguinal (GSA):Ilioinguinal (GSA):to anterior thigh, scrotum, to anterior thigh, scrotum,

labia majora.labia majora.


Genitofemoral nerve:Genitofemoral nerve:Emerges on anterior surface of psoas Emerges on anterior surface of psoas

major.major.Genital branch:Genital branch:

Enters inguinal canal.Enters inguinal canal.Supplies scrotum and labia majora Supplies scrotum and labia majora (GSA).(GSA).Supplies cremaster muscle (GSE).Supplies cremaster muscle (GSE).

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


Femoral nerve:Femoral nerve:L2—L4.L2—L4.

Largest branch of lumbar plexus.Largest branch of lumbar plexus.

Emerges from lateral side of psoas major.Emerges from lateral side of psoas major.


Femoral nerve:Femoral nerve:Enters thigh behind inguinal ligament.Enters thigh behind inguinal ligament.

Supplies:Supplies:In iliac fossa:In iliac fossa:

Iliacus (GSE); pectineus (GSE); Iliacus (GSE); pectineus (GSE); femoral artery (GVE).femoral artery (GVE).


Femoral nerve:Femoral nerve:Supplies:Supplies:

Distally:Distally:

Sartorius; quadriceps femoris; Sartorius; quadriceps femoris; anterior thigh (GSA).anterior thigh (GSA).

Terminates as:Terminates as:Saphenous nerve (GSA) to medial thigh Saphenous nerve (GSA) to medial thigh and foot.and foot.


Obturator nerve:Obturator nerve:L2..L4.L2..L4.

Emerges from medial side of psoas major.Emerges from medial side of psoas major.

Descends along lateral wall of pelvis.Descends along lateral wall of pelvis.


Obturator nerve:Obturator nerve:Enters thigh through obturator foramen:Enters thigh through obturator foramen:

In obturator groove it divides into:In obturator groove it divides into:

Anterior branch (anterior to Anterior branch (anterior to adductor brevis).adductor brevis).

Posterior branch (posterior to Posterior branch (posterior to adductor brevis).adductor brevis).


Obturator nerve:Obturator nerve:Supplies:Supplies:

Medial thigh muscles (GSE).Medial thigh muscles (GSE).

Skin on medial thigh (GSA).Skin on medial thigh (GSA).

Sacral PlexusSacral Plexus

Superior gluteal nerve:Superior gluteal nerve:

L4..S1.L4..S1.

Passes through greater sciatic notch Passes through greater sciatic notch above above piriformis.piriformis.

Supplies lateral gluteal compartment.Supplies lateral gluteal compartment.


Inferior gluteal nerve:Inferior gluteal nerve:

L5..S2.L5..S2.

Passes through greater sciatic notch Passes through greater sciatic notch below below piriformis.piriformis.

Supplies posterior gluteal compartment.Supplies posterior gluteal compartment.


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

artery.artery.


Posterior femoral cutaneous:Posterior femoral cutaneous:Supplies:Supplies:Skin on buttock (GSA) via inferior cluneal Skin on buttock (GSA) via inferior cluneal nerve.nerve.Skin of external genitalia (GSA) via Skin of external genitalia (GSA) via

perineal perineal branches.branches.Skin on back of thigh.Skin on back of thigh.


Nerves to lateral thigh compartment:Nerves to lateral thigh compartment:

To inferior gemellus (GSE):To inferior gemellus (GSE):

L4..S1.L4..S1.

To quadratus femoris (GSE):To quadratus femoris (GSE):

L4..S1.L4..S1.

To piriformis (GSE):To piriformis (GSE):

S1..S2.S1..S2.


Sciatic nerve:Sciatic nerve:

Fusion of:Fusion of:

Common peroneal (fibular).Common peroneal (fibular).

Tibial.Tibial.

Largest physical nerve in the body.Largest physical nerve in the body.


Sciatic nerve:Sciatic nerve:Exits pelvis through greater sciatic Exits pelvis through greater sciatic

foramen:foramen:Inferior to piriformis (usually).Inferior to piriformis (usually).

Descends between gluteus maximus.Descends between gluteus maximus.Between greater trochanter and ischial Between greater trochanter and ischial

tuberosity.tuberosity.Lies on:Lies on:

Ischium, gemelli, obturator internus, Ischium, gemelli, obturator internus, quadratus femoris.quadratus femoris.

Nerve InjuriesNerve Injuries

Peripheral:Peripheral:

All motor function and sensation supplied All motor function and sensation supplied by by nerve distal to injury is lost.nerve distal to injury is lost.

Total muscle function is lost.Total muscle function is lost.

Sensation over more than one dermatome Sensation over more than one dermatome is is lost.lost.

Nerve InjuriesNerve Injuries

Nerve root:Nerve root:

Usually affected by disc herniation Usually affected by disc herniation immediately cranial (superior) to it.immediately cranial (superior) to it.

Sensory impairment over one dermatome.Sensory impairment over one dermatome.

Muscle weakening.Muscle weakening.

May only affect one root or the other.May only affect one root or the other.