Lumbosacral Plexus

Question 1

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

Answer 1

Iliohypogastric nerve
Ilioinguinal nerve
Genitofemoral nerve
Obturator nerve

Question 2

The lumbosacral plexus is composed of nerves from where

Answer 2

the anterior primary rami of spinal nerves L1 to S4

Question 3

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

Answer 3

anterior rami split into anterior and posterior divisions

the first lumbar and fourth sacral nerves

Question 4

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

Answer 4

anterior division

Question 5

What do the anterior and posterior divisions innervate

Answer 5

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

postaxial (behind the bone or posterior) musculature

Question 6

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

Answer 6

no

Question 7

how do postganglionic sympathetic fibers

join the spinal nerves

Answer 7

via gray rami communicantes

then distribute with branches of the lumbosacral plexus

Question 8

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

Answer 8

parasympathetic fibers

Question 9

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

Answer 9

within the psoas major muscle

Question 10

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

Answer 10

Quadratus Lumborum (L1-L4)
Psoas Major (L1-L2)

Question 11

What does quadratus lumborum do

Answer 11

extends and laterally flexes the vertebral

column

Question 12

What does the lumbar plexus supply innervation to

Answer 12

the muscles and skin of the anteromedial thigh

the skin of the medial leg and foot

Question 13

What does the iliohypogastric nerve pass across and then enter

Answer 13

passes inferolaterally across the quadratus lumborum muscle

and then pierces the transversus abdominis muscle

Question 14

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

Answer 14

L1

innervates abdominal musculature

supplies the skin of the suprapubic region and superior gluteal region

Question 15

What path does the Ilioinguinal nerve follow?

Answer 15

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

Question 16

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

Answer 16

L1

Supplies: abdominal musculature

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

Question 17

What path does the Genitofemoral nerve follow?

Answer 17

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

Femoral more lateral

Question 18

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

Answer 18

L1 L2

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

Femoral
Supplies skin over femoral triangle

Question 19

What path does the obturator nerve follow?

Answer 19

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

Question 20

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

Answer 20

Divides into anterior and posterior branches

Question 21

what seperates the anterior and posterior branches of the obturator nerve

Answer 21

Adductor brevis muscle

Question 22

What does the anterior branch of Obturator supply (6)

Answer 22

Adductor longus
adductor brevis
Gracilis
Sometimes pectineus

sensory to hip joint and skin of medial thigh

Question 23

What does the posterior branch of obturator supply

Answer 23

Obturator externus
adductor (horiz) portion of adductor magnus

provides an articular branch to knee joint

Question 24

What nerves form the posterior division of the lumbar plexus

Answer 24

Lateral femoral cutaneous

Femoral

Question 25

What is the path of the Lateral femoral cutaneous nerve

Answer 25

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

Question 26

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

Answer 26

L2 L3 skin over lateral thigh and buttock

Question 27

What is the largest nerve branch of the lumbar plexus

Answer 27

Femoral

Question 28

What supplies the iliacus muscle

Answer 28

Femoral as it crosses by it

Question 29

What is the path of the femoral nerve

Answer 29

- emerges from lat border of psoas major | - enters anterior thigh lateral to femoral artery

Question 30

What happens to the femoral nerve in the thigh and where

Answer 30

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

Question 31

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

Answer 31

L2 - L4 sartorious quadriceps femoris Pectineus articular branches to hip and knee joints

Question 32

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

Answer 32

Medial and intermediate femoral cutaneous nerves: -Skin of anteromedial thigh Saphenous nerve: - Anteromedial knee and leg - Medial side of foot

Question 33

What is the path of the saphenous nerve

Answer 33

Accompanies femoral vessels in the adductor canal

Question 34

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

Answer 34

Join L5 to form Lumbosacral trunk | NOT A PART OF THE LUMBAR PLEXUS

Question 35

What is the path of the lumbosacral trunk

Answer 35

- emerges from the medial border of psoas major | - Passes over sacral ala into pelvis

Question 36

What does the lumbosacral trunk contribute to the formation of

Answer 36

sacral plexus

Question 37

What forms the sacral plexus

Answer 37

Lumbosacral trunk | First 4 sacral nerves

Question 38

Where does the Sacral plexus lie

Answer 38

Posterior pelvic wall anterior to piriformis muscle

Question 39

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

Answer 39

leave from spinal nerves S2 S3 S4 Preganglionic parasympathetics

Question 40

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

Answer 40

no -Join inferior hypogastric plexus to distrubite to viscera via pelvic arterioal branches

Question 41

What does sacral plexus supply (in general)

Answer 41

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

Question 42

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

Answer 42

Sciatic nerve | L4 L5 S1-S3

Question 43

Which division of the sacral plexus forms the sciatic nerve

Answer 43

BOTH Anterior and posterior Sciatic is two nerves

Question 44

What encloses the sciatic nerve components

Answer 44

Connective tissue sheath

Question 45

What is the largest nerve in the body

Answer 45

Sciatic nerve

Question 46

What are the two components of the sciatic nerve

Answer 46

``` Tibial (anterior division) Common fibular (posterior division) ```

Question 47

When do the components of the sciatic nerve seperate

Answer 47

popliteal fossa

Question 48

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

Answer 48

Tibial

Question 49

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

Answer 49

Common fibular

Question 50

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

Answer 50

-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

Question 51

What is the path of the Tibial nerve

Answer 51

- 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

Question 52

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

Answer 52

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

Question 53

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

Answer 53

- passes through greater sciatic foramen | - gives articular branch to hip

Question 54

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

Answer 54

L4 L5 S1 - Quadratus femoris - Inferior Gamellus - articular branch to hip joint

Question 55

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

Answer 55

Passes through greater sciatic foramen

Question 56

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

Answer 56

L5 S1 S2 Obturator internus Superior Gemellus

Question 57

What is the path of the Posterior femoral cutaneous nerve

Answer 57

- passes though greater sciatic foramen | - and accompanies sciatic nerve

Question 58

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

Answer 58

Formed from anterior and posterior divisions Anterior: S2 S3 Posterior S1 S2 skin of: inferior buttock posterior scrotum posterior thigh

Question 59

What is the path of the Pudendal nerve

Answer 59

- through greater sciatic foramen - Over sacrospinous ligament - reenters pelvis through lesser sciatic foramen - enters pudendal canall

Question 60

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

Answer 60

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)

Question 61

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

Answer 61

S3 S4 levator ani coccygeus

Question 62

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

Answer 62

- Common Fibular - Superior Gluteal - Inferior Gluteal - Nerve to Piriformis - Posterior Femoral cutaneous

Question 63

What is the path of the Common Fibular nerve

Answer 63

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

Question 64

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

Answer 64

Branches into the superficial and deep fibular nerves

Question 65

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

Answer 65

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

Question 66

What is the path of the Superior gluteal nerve

Answer 66

- Through greater sciatic foramen - Superior to piriformis - gives off articular branch to hip joint

Question 67

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

Answer 67

L4 L5 S1 - Gluteus medius - Gluteus minimus - Tensor Fasciae Latae - aricular branch to hip joint

Question 68

What is the path of the Inferior gluteal nerve

Answer 68

Through Greater sciatic foramen (below pirformis?)

Question 69

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

Answer 69

L5, S1, S2 Gluteus Maximus

Question 70

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

Answer 70

S1 S2 Piriformis