Lumbosacral plexusSciatic and Femoral

nerves

By Prof. Saeed Abuel Makarem

OBJECTIVESOBJECTIVESBy 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.

LUMBAR PLEXUS

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

FEMORAL NERVE

Origin: From lumbar plexus

( L2,3,4). 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

MOTOR EFFECT:Iliacus

Pectinus

sartorius

Quadriceps

FEMORAL NERVE INJURY

MOTOR MANIFESTATION::

Wasting of quadriceps femoris.

Loss of extension of knee.

Weak flexion of hip (psoas major is intact).

SENSORY EFFECT:SENSORY EFFECT: loss of sensation over

areas supplied (antero-medial) aspect of thigh & medial side of knee, leg & foot.

SACRAL PLEXUS

Formation: by ventral (anterior) rami of a part of L4 & whole L5 (lumbosacral trunk) + S1,2,3 and most of S4.

Site: in front of piriformis muscle.

SACRAL PLEXUSSACRAL PLEXUS

Main branches:• Pelvic splanchnic

nerve: preganglionic parasympathetic to pelvic viscera & hindgut.

• Pudendal nerve: to perineum.

• Sciatic nerve: to lower limb.

Sciatic nerve

Origin:From Sacral Plexus, (L4,5, S1, 2,3).It is the largest branch of the plexus.It is the largest nerve of the body.

SCIATIC NERVE

Course: 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.

Termination: Divides into tibial &

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

BRANCHES OF THE SCIATIC NERVE

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).

BRANCHES OF SCIATIC NERVEBRANCHES OF SCIATIC NERVE

CUTANEOUS:To all leg & foot

EXCEPT: areas supplied

by the Saphenous nerve (branch of Femoral nerve).

TIBIAL NERVE 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).

COMMON PERONEAL (FIBULAR) NERVECOMMON PERONEAL (FIBULAR) NERVECourse:Leaves popliteal fossa &

turns around the lateral aspect of neck of fibula, (dangerous position).

Then divides into:Superficial peroneal or (musculocutaneous) to

supply the Lateral compartment of the leg.

Deep peroneal or (anterior tibial) : to supply the Anterior

compartment of the leg.

• The sciatic nerve is most most frequently injuredfrequently injured by…?

I- I- Badly placed intramuscular injections in the gluteal region.

• To avoid this, injections into the gluteus maximus or medius should be made… into the upper outer upper outer quadrant of the buttock. quadrant of the buttock.

• Most nerve lesions are Most nerve lesions are incomplete,incomplete, and and in 90% of in 90% of injuries, injuries, the common peroneal (part of the nerve) is the most affected. Why? - The common peroneal nerve fibers lie superficialsuperficial within he sciatic nerve.

CAUSES OF SCIATIC NERVE INJURY

II-Posterior dislocation of the hip joint

SCIATIC NERVE INJURYSCIATIC NERVE INJURYMOTOR EFFECT:• Marked wasting of the

muscles below the knee.• Weak flexion of the knee

(sartorius & gracilis are intact).

• Weak extension of hip (gluteus maximus is intact).

• All the muscles below the knee are paralyzed, and the weight of the foot causes it to assume the plantar-plantar-flexed position,flexed position, or Foot Foot Drop.Drop.

• ((Stamping gaitStamping gait).).

SCIATIC NERVE SCIATIC NERVE INJURYINJURY

• Sensory Lesion• Sensation is lost below the the

knee,knee, ExceptExcept for a narrow for a narrow area down the medial side area down the medial side of the lower part of the legof the lower part of the leg and along the medial border of the foot as far as the ball of the big toe, which is supplied by the saphenous nerve (femoral nerve).

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: Prolapse of an intervertebral disc, with pressure on

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

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

Inflammation of the sciatic nerve or its terminal branches.

Common Peroneal Nerve Injury

The common common peroneal nerveperoneal nerve is in an exposed exposed positionposition as it leaves the popliteal fossa it winds around neck of the fibula to enter peroneus longus muscle, (Dangerous Position).

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

• The following clinical features are present:Motor: Motor:

• The muscles of the anterior and The muscles of the anterior and lateral compartments of the leg are lateral compartments of the leg are paralyzed,paralyzed,

• As a result, the opposing muscles, the plantar flexors of the ankle joint and the invertors of the subtalar joints, cause the foot to be cause the foot to be Plantar Plantar Flexed (Foot Drop) and Inverted,Flexed (Foot Drop) and Inverted, an attitude referred to as Talipes EquinovarusEquinovarus..

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

• The tibial nervetibial nerve leaves the popliteal fossa by passing deep to the gastrocnemius & soleus.

• Because of its deep and protected position, it is rarely injured.

Complete division results in the following clinical features:Motor: All the muscles in All the muscles in the back of the leg the back of the leg and the sole of the and the sole of the foot are paralyzed. foot are paralyzed. The opposing muscles DorsiflexDorsiflex the foot at the ankle joint and Evert the and Evert the footfoot at the subtalar joint, an attitude referred to as Talipes Calcaneovalgus.Calcaneovalgus.

Tibial Nerve Injury

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

Congenital Talipes Equinovarus.Equinovarus.