2. Definition
The anterior rami of the L1-S3 roots come
together to form the lumbosacral plexus,
from which all major lower extremity
nerves are derived.
4. Lumbar plexus
• Formed in Posterior part of psoas major
muscle-
From ventral rami of L1-L4.
Branches emerge from both lateral and
medial sides of psoas major muscle.
10. Lumbar plexus
Femoral nerve :
Supplies:
Distally-
Sartorius
quadriceps femoris
Terminates as:
Saphenous nerve to medial
thigh and foot.
11. Lumbar plexus
Femoral nerve :
Function:
Motor:
Flexor of the hip & extensor
of the knee
Sensory:
Anterior thigh & medial
surface of leg
12.
13.
14. Lumbar plexus
• Obturator Nerve:
L2-L4.
Emerges from medial side
of psoas major.
Descends through the
lateral wall of pelvis to exit
through the obturator
foramen
15. Lumbar plexus
• Obturator Nerve:
Supplies to the thigh adductors
(adductor longus, adducto
magnus, adductor brevis and
gracilis)
Sensory to a small area of skin on
the medial thigh
16.
17. Lumbar plexus
Lateral cutaneous nerve of thigh
L2-L3
Enter thigh behind
lateral end of inguinal
ligament near superior
iliac spine
19. Lumbar plexus
Iliohypogastric nerve (L1)
Sensory innervation:
Skin of anterior
abdominal wall
Motor innervation:
Internal and external
obliques
Transversus
abdominis
20. Lumbar plexus
Ilioinguinal nerve (L1):
Sensory:
skin of upper medial thigh;
male scrotum and root of penis;
female labia majora
Motor :
Internal and external
obliques
Transversus
abdominis
25. Sacral plexus
Branches:
1. Sciatic nerve(L4-S3)
a) Common fibular/ peroneal
nerve(Dorsal division of L4-S2),
b) Tibial nerve(ventral division of L4-
S3)
2. Superior gluteal nerve(Dorsal L4-S1)
27. Sacral plexus
• Sciatic nerve
• Derived from the L4-S3 roots.
• Leaves the pelvis through the sciatic notch
under the piriformis muscle accompanied
by other branches.
28. Sacral plexus
Sciatic nerve:
Runs between the ischial tuberosity and
greater trochanter of femur covered by
the gluteus maximus.
•Two branches:
-Tibial
-common peroneal nerves.
42. Common causes of Upper
Plexus lesions:
• Diabetic amyotrophy;
• Abdominal surgery- either directly or
retraction, or due to positioning;
• Lumbosacral plexitis.
45. Common causes of lower plexus
lesions:
• Lumbosacral plexitis
• Perioperative
• Cancer infiltration
• Radiation
46. Haemorrhagic plexopathy
as a complication of
– anticoagulation,
– hemophilia,
– aortic aneurysm rupture.
•significant pain & often hold the hip flexed &
slightly externally rotated.
47. Tumor & other mass lesions
local invasion of tumors from
bladder,cervix,uterus,ovary,prostate,
colon or rectum
Lymphomas & leukemia can directly
infiltrate nerves
Also with endometriosis, implantation of
abnormal tissue on plexus
48. Inflammatory plexitis
• Underlying pathology is not known
• Often occurring within a few weeks of a
possible inciting immunologic event such
as a cold, flu or immunization
49. Contd.
• Patients initially develop severe deep pain
either proximal in the pelvis or in the upper
leg, persists for 1-2 weeks
• Weakness & sensory loss may develop
52. Factors
first pregnancy, a large fetal head with
a small maternal pelvis, a small
mother,
prolonged or difficult labor
53. Clinical presentation:
• Peroneal weakness
• Mild weakness of knee flexion (hamstring), &
hip abduction, extension & internal rotation
• Sensory loss over the dorsum of the foot &
lateral calf but may involve the sole of the
foot, posterior calf & thigh
54. Diabetic plexopathy
• Painful lumbosacral plexopathy affects the
upper lumbar plexus & nerve roots
• Present with severe deep pain in the pelvis
or thigh, may last week
• Movement is often difficult
56. Radiation plexopathy
• Occurs from radiation damage; from radiation
administered years previously for the Rx of a
tumor
• Slowly progressive with little pain
57. Lateral femoral cutaneous
neuropathy
• Entrapment of lateral cuteneous nerve of
thigh may occur as it passes under the
inguinal ligament
• Painful, burning, numb patch of skin over
the anterior and lateral thigh
59. Femoral nerve injury
Causes of injury:
• Gunshot wound
• by pressure or traction during an operation
or
• by bleeding into the thigh.
60. Clinical features
• Quadriceps action is lacking
• unable to extend the knee actively.
• numbness of the anterior thigh & medial
aspect of the leg.
• knee reflex is depressed.
• Severe neurogenic pain is common.
61. Sciatic nerve
Causes of injury:
• Intervertebral disc prolapse
• Dislocation of hip joint
• Piriformis syndrome
• Intramuscular injection
• Penetrating wound and fracture of pelvis
63. Contd.
Sciatic nerve injury in
misplaced intra gluteal
injection:
• Sciatic nerve passes
midway between greater
trochanter and ischial
tuberosity
64. Contd.
Sciatic nerve and
piriformis syndrome:
Certain leg positions pull
the piriformis up against
the sciatic nerve causing
buttock pain & radiating
leg pain
65. Contd.
Sciatic nerve injury in
dislocation of hip joint:
• Sciatic nerve travels in
gluteal region on the
posterior surface of hip
joint
• Prone to injury in posterior
dislocation of hip joint
66. Contd.
In sciatic nerve injury
• Hamstring muscles and all the muscles
below knee;
• Severe impairment in knee flexion
• Loss of all movements at foot
• Foot drop due to weight of foot.
67. Contd.
• All sensation below knee except the
medial aspect of leg and foot up to
ball of big toe.
• Loss of sensation of sole makes the
patient vulnerable to trophic ulcers
69. Contd.
Sciatica
• Pain along the sensory
distribution of sciatic nerve
• Posterior aspect of thigh
• Posterior and lateral sides of
leg
• Lateral part of foot
71. Injury to common peroneal nerve
Cause
• Fracture of fibular neck, entrapment by leg
casts or splints
Muscles paralyzed
• Anterior and lateral muscles of leg
Deformity
• Equinovarus-- foot is plantar flexed and
inverted due to actions of unopposed
plantar flexors and invertors.
72. Contd.
Sensory loss
• Anterior and lateral side of leg
• Dorsum of foot and digits
• Medial side of big toe
• Lateral border of foot and lateral side of
little toe along with medial border upto the
ball of great toe is unaffected
74. Injury to tibial nerve
Cause
• Rarely injured in fractures of upper end of
tibia or penetrating wound
Muscle paralyzed
• All muscles of back of leg and sole
78. Contd.
Features of cauda equina syndrome:
-Difficulty in micturation
-Loss of anal sphincter tone or fecal
incontinence
-Saddle anesthesia
-Gait disturbance
-Pain, numbness or weakness affecting one
or both legs
