Lumbosacral plexus by dr swapan (1)

neuroanatomy

1. Lumbosacral plexus
Dr. SWAPAN KUMAR RAY
RESIDENT (PHASE-A), NEUROLOGY
National Institute of Neurosciences & Hospital

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.

3. Components
The lumbosacral plexus is anatomically
consisting of-
1. Lumbar plexus ( L1-L4 )
2. Lumbosacral trunk (L4-L5)
3. Sacral plexus (S1-S4)

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.

6. Lumbar plexus

7. Lumbar plexus
Branches:
Femoral nerve
Obturator nerve
Lateral femoral cutaneous nerve
Iliohypogastric nerve
Ilioinguinal nerve
Genitofemoral nerve

8. Lumbar plexus
Femoral nerve :
L2—L4.
Largest branch of lumbar plexus.
Emerges from lateral side of
psoas major.

9. Lumbar plexus
Femoral nerve :
Enters thigh behind inguinal
ligament.
Supplies:
In iliac fossa: Iliacus
pectineus

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

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

17. Lumbar plexus
Lateral cutaneous nerve of thigh
L2-L3
Enter thigh behind
lateral end of inguinal
ligament near superior
iliac spine

18. Lumbar plexus
Distribution
A large
oval area
of skin over
the lateral
and anterior
thigh

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

21. Genitofemoral Nerve
Sensory :
skin of middle
anterior thigh
male scrotum
labia majora
Motor :
Cremasteric muscle

22. Cutaneous Innervation

23. Sacral plexus

• Formation
By the lumbosacral trunk (L4-L5)
& ventral rami of S1 S2 S3)

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)

26. Sacral plexus
Branches:
3.Inferior gluteal nerve(Dorsal L5-S2)
4.Posterior cutaneous nerve of thigh (S1-
S3)

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.

31. Sacral plexus
Tibial nerve:
Motor function:
planter flexion and inversion, toe
flexion
Sensory function:

32. Sacral plexus
Common peroneal nerve:
Motor function:
Superficial peroneal nerve:Foot eversion
Deep peroneal nerve :Foot dorsiflexion &
toe extension
Sensory function:

34. Sacral plexus
•Superior gluteal nerve:
Dorsal Division of L4 L5 S1
Muscles innervated
•Gluteus medius
•Gluteus minimus
•Tensor fascia lata

35. •Inferior gluteal nerve
Muscle innervated
•Gluteus maximus

36. Sacral plexus
Pudendal nerve:
Ventral rami of S2, S3, S4.
Motor:
Levator ani, urogenital diaphragm, anal
and striated urtheral sphincter.
Sensory:
Perineum, scrotum, penis.

37. CLINICAL ANATOMY

38. Disorders affecting the plexus
•Trauma
•Intraoperative damage
•Retroperitoneal haemorrhage
•Radiotherapy
•Neoplastic invasion

39. Contd.
•Diabetes mellitus
•Pregnancy & labor
•Retroperitoneal abscess
•Abdominal aortic aneurysm
•Idiopathic lumbosacral plexopathy

40. Upper plexus
•Nerve roots: L2 - L4
•Muscles involved:
-Weakness of thigh flexion (Psoas)
-Thigh adduction and
-Knee extension (Quadriceps)

41. Contd.
Sensory loss:
-Anterior thigh and medial leg
-Absent knee jerk

42. Common causes of Upper
Plexus lesions:
•Diabetic amyotrophy;
•Abdominal surgery- either directly or
retraction, or due to positioning;
•Lumbosacral plexitis.

43. Lower plexus lesions
•Nerve roots: L4 - S2
•Muscles involved:
-Weakness of thigh extension (gluteal)
-Knee flexion (hamstring),
-Foot dorsiflexion & plantar flexion

44. Contd.
Sensory loss:
-Posterior thigh,
-Lateral leg and entire foot,
-Absent ankle jerk

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

50. Post partum plexopathy
•maternal peroneal palsy,
•maternal birth palsy,
•neuritis puerperalis,
•maternal obstetric paralysis

51. Mechanism
•compression of the fetal head against
the underlying pelvis & lumbosacral
plexus

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

55. Contd.
•Significant weakness
•Commonly affects the femoral & obturator
nerve
•Proximal wasting of anterior & medial
thigh musculature

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

58. Contd.
•Predisposing factors:
obese, wear tight under wear or pants or
diabetes mellitus

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

62. Contd.
Sciatic nerve injury in intervertebral
disc prolapse:

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

68. Contd.

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

70. Contd.
Causes
•Prolapse of intervertebral disc
•Intrapelvic tumor
•Inflammation of sciatic nerve

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

73. Contd.

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

75. Contd.
Deformity
•Calcaneovulgus Dorsiflexion and
Eversion of foot
Sensory loss
•Whole of the sole of foot
•May result into trophic ulcers

76. Contd.

77. Cauda equina syndrome

Causes:
Truama
Herniated nucleus pulposus
Degenerative (Lumbar stenosis)
Neoplasm
Infection/ abscess
Idiopathic

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

79. Conus medullaries syndrome
Clinical features:
-Bilateral saddle anesthesia
-Prominent bladder & bowel dysfunction
-Impotence
-Bulbocavernosus & anal reflexes absent
-Muscle strength is largely preserved

83. Investigations
•NCS with EMG
•MRI
•CT scan
•X-ray
•CBC with ESR
•RBS
•Vit B-12 assay
•CSF etc.