Download LUMBO SACRAL PLEXUS, CUTANEUS NERVES, DERMATOME

LUMBO SACRAL PLEXUS, CUTANEUS NERVES,
DERMATOME, MAPPING
LEARNING OBJECTIVES
 At the end of the lecture, the student should be able to:
 Discuss the formation of lumbar plexus.
 List the branches of lumber plexus with their root
values.
 Discuss relation of the nerves with psoas major muscle.
 Structures supplied by lumbar plexus.
 Know the formation of sacral plexus.
 Describe the composition and relations of sacral plexus.
 Enumerate branches of this plexus.
 Discuss the cutaneous supply of lower limb.
 Discuss few applied points about these plexuses.
INTRODUCTION
 Somatic motor
and general
sensory
innervation of
the lower limb is
by peripheral
nerves
emanating from
the lumbar and
sacral plexuses
on the posterior
abdominal and
pelvic walls
 These plexuses
are formed by
the anterior rami of L1 to L3 and most of L4 (lumbar
plexus) and L4 to S5 (sacral plexus).
 Nerves originating
from the lumbar
and sacral
plexuses and
entering the lower
limb carry fibers
from spinal cord
levels L1 to S3
 Nerves from lower
sacral segments
innervate the
perineum.
 Terminal nerves
exit the abdomen
and pelvis through
a number of apertures and foramina and enter the limb.
 Lumbar and upper sacral
nerves are tested
clinically by examining
the lower limb.
 As a consequence of
this innervation, lumbar
and upper sacral nerves
are tested clinically by
examining the lower limb
 In addition, clinical signs (such as pain, 'pins and
needles', paresthesia, and fascicular muscle twitching)
resulting from any disorder affecting these spinal
nerves (e.g. herniated intervertebral disc in the lumbar
region) appear in the lower limb.
LUMBAR PLEXUS:
 The lumbar plexus is formed by the anterior rami of
nerves L1 to L3, and most of the anterior ramus of L4
and
 It also receives a contribution from the T12 (subcostal)
nerve
BRANCHES OF THE LUMBAR PLEXUS INCLUDE
 The Iliohypogastric
 Ilio-Inguinal
 Genitofemoral
 Lateral Cutaneous Nerve Of
Thigh (Lateral Femoral
Cutaneous)
 Femoral, And
 Obturator Nerves
 Division
 Name
 Roots
 Target
 Main
 Iliohypogastric
nerve
 1L
 Skin over
the lateral
gluteal
region and
above the
pubis
 Main
 Ilioinguinal nerve
 1L
 Skin over
the root of
the penis
and upper
part of the
scrotum
(male), skin
covering the
mons pubis
and labium
majus
(female)
 Main
 Genitofemoral
nerve
 1, 2 L
 Cremaster
muscle
 Dorsal
 Lateral femoral
 2, 3 L.
 Skin on the
cutaneous
lateral part
 Venttral
 Obturator nerve
(and Accessory
obturator nerve,
when present
 2, 3, 4 L
 Medial
compartmen
t of
 Dorsal
 Femoral nerve
 2, 3, 4 L
 Anterior
compartmen
t of thigh
 The lumbar plexus forms in the substance of the psoas
major muscle anterior to its attachment to the
transverse processes of the lumbar vertebrae.
 Relative to the psoas major muscle the various
branches emerge either:
 Anterior Genitofemoral
Nerve;
 Medial
Obturator Nerve;
 Lateral Iliohypogastric,IlioInguinal, And

Femoral Nerves, And
 The Lateral Cutaneous
Nerve Of The Thigh.
ILIOHYPOGASTRIC AND ILIO-INGUINAL NERVES
(L1)
 The iliohypogastric and ilioinguinal nerves arise as a
single trunk from the
anterior ramus of nerve L1
 Either before or soon after
emerging from the lateral
border of the psoas major
muscle, this single trunk
divides into the
iliohypogastric and the ilioinguinal nerves.
THE ILIOHYPOGASTRIC NERVE
 It passes across the anterior surface of the quadratus
lumborum muscle, posterior to the kidney
 It pierces the
transversus abdominis
muscle and continues
anteriorly around the
body between the
transversus abdominis
and internal oblique
muscles
 Above the iliac crest, a
lateral cutaneous
branch pierces the
internal and external
oblique muscles to
supply the
posterolateral gluteal
skin
 The remaining part of the iliohypogastric nerve (the
anterior cutaneous branch) continues in an anterior
direction, piercing the internal oblique just medial to the
anterior superior
iliac spine.
 Becoming
cutaneous, just
above the
superficial inguinal
ring, after piercing
the aponeurosis of the external oblique, it distributes to
the skin in the pubic region
 Throughout its course, it also supplies branches to the
abdominal musculature.
THE ILIO-INGUINAL NERVE
 It is smaller than, and inferior to, the iliohypogastric
nerve as it crosses the quadratus lumborum muscle
 Near the anterior end of the iliac crest, it pierces the
transversus abdominis muscle, and then pierces the
internal oblique muscle and enters the inguinal canal.
 It emerges through the superficial inguinal ring, along
with the spermatic cord, and provides cutaneous
innervation to the upper medial thigh, the root of the
penis, and the anterior 1/3 rd of the scrotum in men, or
the mons pubis and labium majus in women
 Throughout its course, it also supplies branches to the
abdominal musculature
THE
GENITOFEMORAL
NERVE
 It arises from the
anterior rami of the
nerves L1 and L2
(ventral rami)
 It emerges on the
anterior surface of
psoas major
 Then descends on the surface of the muscle, in a
retroperitoneal position
 Eventually it divides into genital and femoral branches
 The genital branch continues downward and enters
the inguinal canal through the deep inguinal ring
 In men, it innervates the cremasteric muscle and
terminates on the skin in the upper anterior part of the
scrotum
 in women, it accompanies the round ligament of the
uterus and terminates on the skin of the mons pubis
and labium majus
 The femoral branch descends on the lateral side of the
external iliac artery and passes posterior to the inguinal
ligament, entering the femoral sheath lateral to the
femoral artery
 It pierces the anterior layer of the femoral sheath and
the fascia lata to supply the skin of the upper anterior
thigh
LATERAL CUTANEOUS NERVE OF THIGH (L2 AND
L3)
 It arises from the anterior rami of nerves L2 and L3
(dorsal divisions)
 It emerges from the lateral border of the psoas major
muscle, passing obliquely downward across the iliacus
muscle towards the anterior superior iliac spine
 It passes posterior to the inguinal ligament and enters
the thigh
 It supplies the skin on the anterior and lateral thigh to
the level of the knee
LUMBOSACRAL TRUNK
 Formed by the union of the descending branch of nerve
L4 with nerve L5( ventral rami).
 It enters the lesser pelvis by passing over the lateral
part of the ala of the sacrum, posterior to the common
iliac vessels and the medial part of the psoas
 In the pelvis, it takes part in the formation of the sacral
plexus
SACRAL PLEXUS
 In human anatomy, the
sacral plexus is a nerve
plexus emerging from the
sacral vertebrae (S1-S4), and
which provides nerves for the
pelvis and lower limbs.
COMPOSITION OF SACRAL PLEXUS
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The sacral plexus is formed by:
The lumbosacral trunk
The anterior division of the first sacral nerve
Portions of the anterior divisions of the second and third
sacral nerves
Its constituent nerves divide into anterior and posterior
division.
The nerves forming the sacral plexus converge toward
the lower part of the greater sciatic foramen, and unite
to form a flattened band, from the anterior and posterior
surfaces of which
several branches
arise.
The band itself is
continued as the
sciatic nerve,
which splits on
the back of the
thigh into the
tibial nerve and
common fibular
nerve; these two
nerves
sometimes arise
separately from
the plexus,.
Often, the sacral plexus and the lumbar plexus are
considered to be one large nerve plexus, the
lumbosacral plexus. The lumbosacral trunk connects
the two plexuses.
RELATIONS OF THE SACRAL PLEXUS:
 Dissection of side wall of pelvis showing sacral and
pudendal plexuses.
 The sacral plexus lies on the back of the pelvis between
the piriformis
muscle and
the pelvic
fascia.
 In front of it
are the
internal iliac
artery,
internal iliac
vein, the
ureter, and
the sigmoid
colon.
 The superior gluteal artery and vein run between the
lumbosacral trunk and the first sacral nerve, and the
inferior gluteal artery and vein between the second and
third sacral nerves
BRANCHES OF SACRAL PLEXUS
 Its branches total around a dozen, six from the nerves
before they divide, and three each from anterior and
posterior divisions.
 The six branches from the
main nerves all come from
sacral segments and all
have initial ‘P’.
BRANCHES FROM ANTERIOR RAMI:
 S1,2- Nerves to piriformis
 S2,3- Perforating cutaneous
 S2,3- Posterior femoral cutaneous
 S2,3,4- Pelvic splanchnic nerves
 S2,3,4-
Pudendal
 S4- Perineal branch.
BRANCHES FROM ANTERIOR DIVISION OF
ANTERIOR RAMI
 L4,5,S1- Nerves to quadratus femoris
 L5,S1,2- Nerves to obturatuor internus
 L4,5,S1,2,3- Tibial part of the sciatic
BRANCHES FROM POSTERIOR DIVISION OF
ANTERIOR RAMI
 L4,5,S1- Superior gluteal
 L5,S1,2- Inferior gluteal
 L4,5,S1,2- Common
peroneal part of sciatic.
NERVES FORMED
 All the nerves entering the plexus, with the exception of
the third sacral, split into ventral and dorsal divisions,
SCIATICA AND SCIATIC NERVE PAIN
 Sciatica is a layman's term for
a pinched nerve that can cause
pain that runs from the buttocks
down the back of the leg.
 The sciatic nerve is about an
inch or so long in the buttocks
made of multiple spinal nerves.
 When people commonly refer
to sciatica it is not necessarily a
problem of the sciatic nerve, it's
a problem of the nerve when it
is being pinched as it exits from
the spine from a herniated disc
or a bone spur.
CUTANEOUS SUPPLY OF LOWER LIMB:
THANK YOU