lumbo sacral plexus
TRANSCRIPT
LUMBOSACRAL
PLEXUSDr. Khadija Iqbal
Lets revise and then go ahead
Muscles
• Muscles of the thigh are arranged in
three compartments separated by
intermuscular septa
medial compartment of thigh
• six muscles
• Gracilis-obturator nerve
• pectineus- femoral nerve
• adductor longus,
• adductor brevis
• adductor magnus-sciatic nerve
• obturator externus
•
anterior compartment of thigh
• sartorius
• four large quadriceps femoris muscles
(rectus femoris, vastus lateralis, vastus
medialis, and vastus intermedius).
• the terminal ends of the psoas major
• and iliacus muscles pass into the upper
part of the anterior compartment from
sites of origin on the posterior abdominal
wall.
• The posterior compartment of thigh
contains three large muscles termed the
'hamstrings'. All are innervated by the
sciatic nerve.
Adductor canal
• Laterally vastus medialis
• Anteromedially sartorius
• Posteriorly adductor longus
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.
Anterior rami of
upper 4 lumbar
spinal nerves (+L5)
and from the
contribution of
subcostal nerve
(T12)
in the lumbar
region, within
the psoas major
muscle.
Lat
femora
l
obturator
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.
(L2-L4)
largest branch
both motor and sensory.
Emerges from the lateral
border of the psoas major
Flexors of the hip and
extensors of the knee
Skin of the anterior and
lateral thigh, medial leg
and foot
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.
largest cutaneous
branch of the femoral
nerve
continuation of the
femoral nerve
Skin of medial aspects
of leg and foot
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.
Emerges from the medial
border of the psoas
major
Leaves the lesser
pelvis through
the obturator canal
Skin on the superior
medial thigh
Adductor muscles of the
leg
Gluteal region
deep group of small muscles,
• piriformis, obturator internus, gemellus
superior, gemellus inferior, and quadratus
femoris;
superficial group
gluteus minimus, gluteus medius, and
gluteus maximus-
• the tensor fasciae latae,
Second lecture
24.4.13
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Sensory and motor innervation of the whole
lower limb
arises from the spinal roots L1-S4
Lumbal plexus
Sacral plexus
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.
Descending part of
the L4 nerve unites
with the anterior
ramus of the L5
nerve to form the
lumbosacral trunk.
Participates in the
formation of the
sacral plexus with
the anterior rami
of S1-S4 nerves.
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.
o Leaves the
gluteal region by
passing deep to
the long head of
the biceps
femoris,at the
lower margin of
the quadratus
femoris muscle
o Divides into the
common peroneal
and tibial
nerves, at a
variable site
above the
popliteal fossa
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L4
L5
S1
S2
S3
Semitendinosis
Biceps femoris
semimembranosus
Ham
str
ings
Gastrocnemius
and posterior
compartment of
the leg and foot
Tibial
nerve
Common
peroneal
nerve Deep peroneal
nerveAnterior
compartment of
leg
Lateral
compartment of leg
Superficial peroneal
nerve
Motor Branches of the
Sciatic Nerve
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Greater sciatic foramen
• The greater sciatic foramen is formed on the posterolateral pelvic wall and is the major route for structures to pass between the pelvis and the gluteal region of the lower limb . The margins of the foramen are formed by:
• the greater sciatic notch;• parts of the upper borders of the sacrospinous and sacrotuberous ligaments;• the lateral border of the sacrum. •
•
• The piriformis muscle passes out of the pelvis into the gluteal region through the greater sciatic foramen and separates the foramen into two parts, a part above the muscle and a part below:
• the superior gluteal nerve and vessels pass through the greater sciatic foramen above the piriformis;
• the sciatic nerve, inferior gluteal nerves and vessels, pudendal nerve and internal pudendal vessels, posterior cutaneous nerve of thigh, nerve to the obturator internus and gemellus superior and the nerve to the quadratus femoris and gemellus inferior pass through the greater sciatic foramen below the muscle.
•
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Lesser sciatic foramen
• The lesser sciatic foramen is inferior to the greater sciatic foramen on the posterolateral pelvic wall .It is also inferior to the lateral attachment of the pelvic floor to the pelvic wall and therefore connects the gluteal region with the perineum:
• the tendon of obturator internus passes from the lateral pelvic wall through the lesser sciatic foramen into the gluteal region to insert on the femur;
• the pudendal nerve and internal pudendal vessels, which first exit the pelvis by passing through the greater sciatic foramen below the piriformis muscle, enter the perineum below the pelvic floor by passing around the ischial spine and sacrospinous ligament and medially through the lesser sciatic foramen.
•
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Trendelenburg's Test
• – assesses functioning of hip abductors
• Stand behind patient and ask to stand on
one leg for 30 seconds
• Pelvis should tilt up on side of unsupported
leg = Trendelenburg negative (normal)
• If pelvis tilts down towards unsupported leg =
Trendelenburg positive (pathological)
• Repeat for other leg
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A 51-year-old man experiences a loss of
skin sensation along the medial
compartment of the thigh. No other
areas of skin are affected. Which of the
following best describes the area of deficit?
A. L2 dermatome
B. L3dermatome
C. L4 dermatome
D. Cutaneous field of the femoral nerve
E. Cutaneous field of the obturator nerve
F. Cutaneous field of the saphenous nerve
27. A 55-year-old man has difficulty
extending his hip while walking up a flight
of stairs.He experiences no cutaneous
deficits. Which damaged nerve is most
likely responsible
for causing this man’s symptoms?
A. Inferior gluteal nerve
B. S1 nerve root
C. S2 nerve root
D. Superior gluteal nerve
28. A 33-year-old man’s pelvis drops on
the right side when
he steps with his right foot. He has no
cutaneous deficits.
Which nerve lesion is most likely causing
this problem?
A. Femoral nerve
B. Inferior gluteal nerve
C. Obturator nerve
D. Superior gluteal nerve
E. Tibial nerve