The sacral plexus is a network of nerves formed by the lumbosacral trunk (L4, L5) and sacral spinal nerves (S1 - S4). The sacral plexus is located on the posterior pelvic wall, posterior to the internal iliac vessels and ureter, and anterior to the piriformis muscle.

1. Lumbosacral plexus
Sciatic and Femoral nerves
Dr. NDAYISABA CORNEILLE
CEO of CHG
MBChB,DCM,BCSIT,CCNA

2. OBJECTIVES
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.
DR NDAYISABA CORNEILLE

3. 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.
DR NDAYISABA CORNEILLE

4. 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
DR NDAYISABA CORNEILLE

5. 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 & Pectineus
Extensors of knee joint:
Quadriceps femoris.
S
A
R
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DR NDAYISABA CORNEILLE

6. CUTANEOUS
BRANCHES OF
FEMORAL NERVE
• To antero-medial aspect
of the thigh.
• To medial side of:
• Knee,
• Leg and
• Foot (saphenous nerve).
DR NDAYISABA CORNEILLE

7. 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
DR NDAYISABA CORNEILLE

8. FEMORAL NERVE
INJURY
 MOTOR
MANIFESTATION:
 Wasting of quadriceps
femoris.
 Loss of extension of
knee.
 Weak flexion of hip
(psoas major is intact).
 SENSORY EFFECT:
 loss of sensation over
areas supplied (antero-
medial) aspect of thigh
& medial side of knee,
leg & foot.
DR NDAYISABA CORNEILLE

9. 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.
DR NDAYISABA CORNEILLE

10. SACRAL PLEXUS
Main branches:
• Pelvic splanchnic
nerve:
preganglionic
parasympathetic
to pelvic viscera
& hindgut.
• Pudendal nerve:
to perineum.
• Sciatic nerve: to
lower limb.
DR NDAYISABA CORNEILLE

11. 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.
DR NDAYISABA CORNEILLE

12. 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. DR NDAYISABA CORNEILLE

13. 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).
DR NDAYISABA CORNEILLE

14. BRANCHES OF SCIATIC NERVE
CUTANEOUS:
 To all leg & foot
EXCEPT:
 areas supplied
by the
Saphenous
nerve (branch
of Femoral
nerve).
DR NDAYISABA CORNEILLE

15. 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).
DR NDAYISABA CORNEILLE

16. COMMON PERONEAL (FIBULAR) NERVE
Course:
 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.
DR NDAYISABA CORNEILLE

17. • The sciatic nerve is most
frequently injured by…?
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
quadrant of the buttock.
• Most nerve lesions are
incomplete, and in 90% of
injuries, the common
peroneal (part of the nerve)
is the most affected. Why?
- The common peroneal
nerve fibers lie superficial
within he sciatic nerve.
CAUSES OF SCIATIC
NERVE INJURY
II-Posterior
dislocation of
the hip joint
DR NDAYISABA CORNEILLE

18. SCIATIC NERVE INJURY
MOTOR 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-
flexed position, or Foot
Drop.
• (Stamping gait).
DR NDAYISABA CORNEILLE

19. SCIATIC NERVE
INJURY
• Sensory Lesion
• Sensation is lost below the
knee, Except for a narrow
area down the medial side
of 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).
DR NDAYISABA CORNEILLE

20. 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.
DR NDAYISABA CORNEILLE

21. 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. DR NDAYISABA CORNEILLE

22. Common Peroneal
Nerve Injury
The common
peroneal nerve is
in an exposed
position 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 injured
In Fractures of the neck of the fibula and
By pressure from casts or splints.
DR NDAYISABA CORNEILLE

23. • The following clinical features are
present:
Motor:
• The muscles of the anterior and
lateral compartments of the leg are
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 Plantar
Flexed (Foot Drop) and Inverted, an
attitude referred to as Talipes
Equinovarus.
Common Peroneal Nerve
Injury
DR NDAYISABA CORNEILLE

24. 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
DR NDAYISABA CORNEILLE

25. Tibial Nerve Injury
• The tibial 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
the back of the leg
and the sole of the
foot are paralyzed.
The opposing
muscles Dorsiflex
the foot at the ankle
joint and Evert the
foot at the subtalar
joint, an attitude
referred to as
Talipes
Calcaneovalgus.
DR NDAYISABA CORNEILLE

26. Tibial Nerve
Injury
Sensory:
Sensory Loss over:
Lateral side of the leg
and foot (sural nerve).
Trophic ulcers in the
sole.
DR NDAYISABA CORNEILLE

27. Congenital Talipes Equinovarus.
DR NDAYISABA CORNEILLE

28. END
DR NDAYISABA CORNEILLE
THANKS FOR LISTENING
By
DR NDAYISABA CORNEILLE
MBChB,DCM,BCSIT,CCNA
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