Lumbosacral plexusSciatic and Femoral

nerves

Dr. Mohammed ElfaTihMBBS,MSc

By the end of the lecture, students should be able to:

§ Describe the formation of lumbosacral plexus (site & root value).

§ List the main branches of lumbosacral plexus.§ Describe the course of femoral & sciatic nerves.§ List the motor and sensory distribution of femoral

& sciatic nerves.§ Describe the main motor & sensory effects in

cases of lesion of femoral & sciatic nerves.

Ø Formation: Ø Ventral (anterior) rami of the upper 4 lumbar spinal nerves (L1,2,3 and L4).Ø Site: Within the substance of the psoas major muscle.Ø Main branches:Ø Iliohypogastric & ilioinguinal: to skin of the anterior abdominal wall.Ø Genitofemoral: to skin of the thigh & cremaster muscle.Ø Obturator: to medial (adductor) group of the thigh.Ø Femoral: to anterior group of the thigh.

Ø Origin:Ø From lumbar plexus

( L2,3,4).Ø Course:• Descends lateral to

psoas major & enters the thigh behind the midpoint of the inguinal ligament.

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

Femoral N

MUSCULAR BRANCHES OF

FEMORAL NERVE

• In abdomen: To iliacus (flexor of hip

joint).• In lower limb: • To the muscles of the

anterior compartment of the thigh:

Flexors of hip joint: Sartorius & PectineusExtensors of knee joint: Quadriceps femoris.

S A R T

P

CUTANEOUS BRANCHES OF

FEMORAL NERVE

• To antero-medial aspect of the thigh.

• To medial side of:• Knee,• Leg and • Foot (saphenous nerve).

INJURY OF THE FEMORAL NERVE

Paralysis of

Movement affected

Iliacus Flexion of the hip

Sartorius Flexion and abduction of the hip

Pectineus Flexion and adduction of the hip

Quadriceps femoris

Extension of the knee

Ø MOTOR EFFECT:Iliacus

Pectinus

sartorius

Quadriceps

FEMORAL NERVE INJURY

SACRAL PLEXUS

Main branches:• Pelvic splanchnic

nerve: preganglionic parasympathetic to pelvic viscera & hindgut.

• Pudendal nerve: to perineum.

• Sciatic nerve: to lower limb.

Sciatic nerve

SCIATIC NERVE

Ø Course:Ø Leaves the pelvis through

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

Ø Termination:Ø Divides into tibial &

common peroneal (fibular) nerves in the middle of the back of the thigh.

BRANCHES OF THE SCIATIC NERVE

q MUSCULAR:• To Hamstrings (flexors of knee &

extensors of hip).• To all muscles below the knee (in

leg & foot).1. Common peroneal: Muscles of anterior & lateral

compartments of leg (Dorsi flexors of ankle, Extensors of toes, Evertors of foot).

1. Tibial: Muscles of posterior compartment

of leg & intrinsic muscles of sole (Planter flexors of ankle, Flexors of toes, Invertors of foot except tibialis anterior).

qCUTANEOUS: To all leg & foot

EXCEPT: areas supplied

by the Saphenous nerve (branch of Femoral nerve).

TIBIAL NERVEØ Course:• Descends through popliteal

fossa to the posterior compartment of leg.

• Accompanied with posterior tibial vessels.

• Passes behind the medial malleolus (deep to flexor retinaculum) to reach the sole of foot where it divides into 2 terminal branches, (Medial & Lateral planter nerves).

CAUSES OF SCIATIC NERVE INJURY

II-Posterior dislocation of the hip joint

SCIATICA • Sciatica describes the condition in which patients have pain along the sensory distribution of the sciatic nerve.

• Thus the pain is experienced in the posterior aspect of the thigh, the posterior and lateral sides of the leg, and the lateral part of the foot.

Sciatica can be caused by: Ø Prolapse of an intervertebral disc, with pressure on

one or more roots of the lower lumbar and sacral spinal nerves.

Ø Pressure on the sacral plexus or sciatic nerve by an intrapelvic tumor.

Ø Inflammation of the sciatic nerve or its terminal branches.

Common Peroneal Nerve Injury

The common peroneal nerve is commonly injuredIn Fractures of the neck of the fibula and By pressure from casts or splints.

Common Peroneal Nerve Injury

Common Peroneal Nerve Injury

Sensory :Sensation is lost between the first and second toes.Dorsum of the foot and toes.Medial side of the big toe. Lateral side of the leg.

Superficial peroneal

Tibial Nerve Injury

Tibial Nerve Injury

Sensory: Sensory Loss over: Lateral side of the leg and foot (sural nerve).Trophic ulcers in the sole.