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Anatomy Block 4 > Lumbosacral Plexus > Flashcards

Lumbosacral Plexus Flashcards

1
Q

What nerves are formed from the anterior division of the lumbar plexus (4)

A

Iliohypogastric nerve
Ilioinguinal nerve
Genitofemoral nerve
Obturator nerve

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2
Q

The lumbosacral plexus is composed of nerves from where

A

the anterior primary rami of spinal nerves L1 to S4

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3
Q

What happens to the anterior rami of the lumbo sacral plexus and which are the exception

A

anterior rami split into anterior and posterior divisions

the first lumbar and fourth sacral nerves

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4
Q

Which division are the first lumbar and 4th sacral nerves considered part of

A

anterior division

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5
Q

What do the anterior and posterior divisions innervate

A

Embryonic preaxial ((in front of the bone or anterior) musculature

postaxial (behind the bone or posterior) musculature

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6
Q

Do the neural associations of the lumbosacral plexus change with embryonic rotation of the lower limb

A

no

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7
Q

how do postganglionic sympathetic fibers

join the spinal nerves

A

via gray rami communicantes

then distribute with branches of the lumbosacral plexus

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8
Q

Which fibers are not contained in the lumbosacral branches to pelvic or lower limb structures

A

parasympathetic fibers

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9
Q

where are the anterior rami of the first three lumbar nerves and part of the fourth (ie. the lumbar plexus) located

A

within the psoas major muscle

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10
Q

What do branches of the lumbar rami provide before the rami enter the plexus

A 
Quadratus Lumborum (L1-L4)
Psoas Major (L1-L2)
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11
Q

What does quadratus lumborum do

A

extends and laterally flexes the vertebral

column

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12
Q

What does the lumbar plexus supply innervation to

A

the muscles and skin of the anteromedial thigh

the skin of the medial leg and foot

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13
Q

What does the iliohypogastric nerve pass across and then enter

A

passes inferolaterally across the quadratus lumborum muscle

and then pierces the transversus abdominis muscle

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14
Q

What is the nerve source of the iliohypogastric nerve and what does it innervate

A

L1

innervates abdominal musculature

supplies the skin of the suprapubic region and superior gluteal region

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15
Q

What path does the Ilioinguinal nerve follow?

A

same as iliohypogastric but inferior to it, then passes through inguinal canal and out superficial inguinal ring

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16
Q

What is the nerve source of the ilioinguial nerve and what does it innervate

A

L1

Supplies: abdominal musculature

Post superficial inguinal ring:
cutaneous branches supply superomedial thigh
and anterior part of scrotum (labia majus)

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17
Q

What path does the Genitofemoral nerve follow?

A

runs along top of Psoas major and divides into genital and femoral branches

Femoral more lateral

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18
Q

What is the nerve source of the genitofemoral nerve and what does it innervate

A

L1 L2

Genital:
supplies cremaster of spermatic cord and small cutaneus areas of scrotum

Femoral
Supplies skin over femoral triangle

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19
Q

What path does the obturator nerve follow?

A

emerges from medial border of soas major to pass though obturator canal and enter thigh

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20
Q

What happens when the obturator nerve emerges from the canal into the thigh

A

Divides into anterior and posterior branches

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21
Q

what seperates the anterior and posterior branches of the obturator nerve

A

Adductor brevis muscle

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22
Q

What does the anterior branch of Obturator supply (6)

A

Adductor longus
adductor brevis
Gracilis
Sometimes pectineus

sensory to hip joint and skin of medial thigh

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23
Q

What does the posterior branch of obturator supply

A

Obturator externus
adductor (horiz) portion of adductor magnus

provides an articular branch to knee joint

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24
Q

What nerves form the posterior division of the lumbar plexus

A

Lateral femoral cutaneous

Femoral

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25
Q

What is the path of the Lateral femoral cutaneous nerve

A

passes infrolaterally across iliacus
toward ASIS
enters thigh inferior to inguinal ligament

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26
Q

What is the nerve source of the Lateral femoral cutaneous nerve and what does it innervate

A

L2 L3

skin over lateral thigh and buttock

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27
Q

What is the largest nerve branch of the lumbar plexus

A

Femoral

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28
Q

What supplies the iliacus muscle

A

Femoral as it crosses by it

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29
Q

What is the path of the femoral nerve

A
  • emerges from lat border of psoas major

- enters anterior thigh lateral to femoral artery

30
Q

What happens to the femoral nerve in the thigh and where

A

Breaks up into a number of muscular articular and cutaneous branches in the femoral triangle

31
Q

What is the nerve source of the Femoral nerve and what does it innervate

A

L2 - L4

sartorious
quadriceps femoris
Pectineus

articular branches to hip and knee joints

32
Q

What major cutaneous branches does the femoral give off and what do they innervate

A

Medial and intermediate femoral cutaneous nerves:
-Skin of anteromedial thigh

Saphenous nerve:

  • Anteromedial knee and leg
  • Medial side of foot
33
Q

What is the path of the saphenous nerve

A

Accompanies femoral vessels in the adductor canal

34
Q

What do the remaining fibers of L4 not used in lumbar plexus do?

A

Join L5 to form Lumbosacral trunk

NOT A PART OF THE LUMBAR PLEXUS

35
Q

What is the path of the lumbosacral trunk

A
  • emerges from the medial border of psoas major

- Passes over sacral ala into pelvis

36
Q

What does the lumbosacral trunk contribute to the formation of

A

sacral plexus

37
Q

What forms the sacral plexus

A

Lumbosacral trunk

First 4 sacral nerves

38
Q

Where does the Sacral plexus lie

A

Posterior pelvic wall anterior to piriformis muscle

39
Q

Where do the pelvic splanchnic nerves exit and what are they composed of

A

leave from spinal nerves
S2 S3 S4

Preganglionic parasympathetics

40
Q

Do pelvic splanchnic nerves distribute with the somatic branches of the sacral plexus

A

no

-Join inferior hypogastric plexus to distrubite to viscera via pelvic arterioal branches

41
Q

What does sacral plexus supply (in general)

A

muscles and skin of gluteal region, posterior thigh, leg, and foot

42
Q

What is the major nerve of the sacral plexus and what forms it

A

Sciatic nerve

L4 L5 S1-S3

43
Q

Which division of the sacral plexus forms the sciatic nerve

A

BOTH
Anterior and posterior

Sciatic is two nerves

44
Q

What encloses the sciatic nerve components

A

Connective tissue sheath

45
Q

What is the largest nerve in the body

A

Sciatic nerve

46
Q

What are the two components of the sciatic nerve

A 
Tibial (anterior division)
Common fibular (posterior division)
47
Q

When do the components of the sciatic nerve seperate

A

popliteal fossa

48
Q

From what nerve makes up the anterior division contribution to the sciatic?

49
Q

From what nerve makes up the posterior division contribution to the sciatic?

A

Common fibular

50
Q

What nerves are formed by the anterior division of the sacral plexus? (6)

A

-Tibial
-Nerve to quadratus femoris and inferior gemellus
-Nerve to obturator internus and superior gemellus
-Posterior femoral cutaneous
-Pudendal
-Nerve to levator ani and coccygeus
TPPNNN

51
Q

What is the path of the Tibial nerve

A
  • passes through greater sciatic foramen as part of sciatic w/ com fib
  • Supplies articular branch to hip and descends the posterior thigh
  • supplies articular branches to knee and continues into posterior leg toward foot
52
Q

What is the nerve source of the Tibial nerve and what does it innervate (10)

A

L4 L5 S1-S3

  • Semimembranosus
  • Semitendinosus
  • Long head of biceps femoris
  • Vertical portion of adductor magnus
  • articular branches to hip
  • articular branches to knee
  • all muscles of posterior leg
  • all muscles of plantar foot
  • all skin of posterior leg
  • all skin of plantar foot
53
Q

What is the path of the Nerve to the quadratus femoris and inferior gemellus

A
  • passes through greater sciatic foramen

- gives articular branch to hip

54
Q

What is the nerve source of the Nerve to the quadratus femoris and inferior gemellus and what does it innervate

A

L4 L5 S1

  • Quadratus femoris
  • Inferior Gamellus
  • articular branch to hip joint
55
Q

What is the path of the Nerve to obturator internus and superior gemellus

A

Passes through greater sciatic foramen

56
Q

What is the nerve source of the Nerve to obturator internus and superior gemellus and what does it innervate

A

L5 S1 S2

Obturator internus
Superior Gemellus

57
Q

What is the path of the Posterior femoral cutaneous nerve

A
  • passes though greater sciatic foramen

- and accompanies sciatic nerve

58
Q

What is the nerve source of the Posterior femoral cutaneous nerve and what does it innervate

A

Formed from anterior and posterior divisions
Anterior: S2 S3
Posterior S1 S2

skin of:
inferior buttock
posterior scrotum
posterior thigh

59
Q

What is the path of the Pudendal nerve

A
  • through greater sciatic foramen
  • Over sacrospinous ligament
  • reenters pelvis through lesser sciatic foramen
  • enters pudendal canall
60
Q

What is the nerve source of the Pudendal nerve and what does it innervate (6)

A

S2 S3 S4

  • External anal sphincter
  • Muscles of urogenital triangle
  • Perianal skin
  • Inferior anal canal
  • Skin of posterior scrotum
  • Skin and erectile tissues of penis(clit)
61
Q

What is the nerve source of the Nerve to levator ani and coccygeus and what does it innervate

A

S3 S4

levator ani
coccygeus

62
Q

What are the nerves of the posterior division of the Sacral plexus (5)

A
  • Common Fibular
  • Superior Gluteal
  • Inferior Gluteal
  • Nerve to Piriformis
  • Posterior Femoral cutaneous
63
Q

What is the path of the Common Fibular nerve

A
  • through greater sciatic with tibial (as sciatic)
  • descends posterior thigh
  • gives off articular branches to knee and then passes over head of fibula
64
Q

What happens as the common fibular passes over the head of the fibula

A

Branches into the superficial and deep fibular nerves

65
Q

What is the nerve source of the Common fibular nerve and what does it innervate (8)

A

L4 L5 S1 S2
Common:
-Short head of biceps femoris

Deep:

  • Muscles of anterior leg
  • Skin of anterior leg
  • Muscles of dorsum of foot
  • Skin between 1st and 2nd toes

Superficial:

  • Muscles of lateral leg
  • Skin of lateral leg
  • most of skin on dorsum of the foot
66
Q

What is the path of the Superior gluteal nerve

A
  • Through greater sciatic foramen
  • Superior to piriformis
  • gives off articular branch to hip joint
67
Q

What is the nerve source of the Superior gluteal nerve and what does it innervate

A

L4 L5 S1

  • Gluteus medius
  • Gluteus minimus
  • Tensor Fasciae Latae
  • aricular branch to hip joint
68
Q

What is the path of the Inferior gluteal nerve

A

Through Greater sciatic foramen (below pirformis?)

69
Q

What is the nerve source of the Inferior gluteal nerve and what does it innervate

A

L5, S1, S2

Gluteus Maximus

70
Q

What is the nerve source of the Nerve to the piriformis and what does it innervate

A

S1 S2

Piriformis

Anatomy Block 4 (16 decks)

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