Lumbar and Sacral Plexus

Question 1

lower extremity receives innervation from

Answer 1

the ventral rami of spinal n.

Question 2

the ventral rami of spinal n. are organized into

Answer 2

the lumbar and sacral plexuses (“lumbosacral plexus”)

Question 3

where do the lumbar and sacral plexuses emerge from?

Answer 3

the lumbar enlargement of the spinal cord

Question 4

what is the lumbar plexus comprised of?

Answer 4

the ventral rami of L1-L4

Question 5

what is the sacral plexus comprised of?

Answer 5

ventral rami of L4-S4

Question 6

what are the lumbar and sacral plexuses connected by?

Answer 6

the distal portion of the lumbar plexus

Question 7

what is the distal portion of the lumbar plexus?

Answer 7

the lumbosacral trunk

Question 8

what is the lumbosacral trunk?

Answer 8

L4 and L5

Question 9

Cauda equina

Answer 9

L2-S5, most of the lumbar and sacral plexuses make up this

Question 10

the peripheral nerves that originate from the lumbar and sacral plexuses course along

Answer 10

the inner abdominal and pelvic walls, and down to the lower extremity

Question 11

the peripheral nerves carry

Answer 11

general sensory information from the body wall and lower limb, as well as somatomotor to muscles in these regions

Question 12

gluteal region nerves

Answer 12

superior and inferior gluteal nerves and nerves to small rotators of the hip joint

Question 13

thigh nerves

Answer 13

lateral femoral cutaneous, femoral, obturator and sciatic nerves

Question 14

leg nerves

Answer 14

sciatic nerve- common fibular and tibial nerves

Question 15

ankle and foot nerves

Answer 15

sciatic nerve- common fibular and tibial nerves

Question 16

cutaneous innervation to the thigh includes which nerves?

Answer 16

lateral femoral cutaneous n., posterior femoral cutaneous n., genitofemoral n. (groin), ilioinguinal n. (groin)

Question 17

innervation of the thigh’s deep structures includes which nerves?

Answer 17

anterior compartment: femoral n.
medial compartment: obturator n.
posterior compartment: sciatic n.

Question 18

cutaneous innervation of the leg includes which nerves?

Answer 18

saphenous n. (terminal femoral branch), lateral sural cutaneous n., sural n.

Question 19

innervation of the leg’s deep structures includes which nerves?

Answer 19

sciatic n.: anterior and lateral compartments: common fibular n. (deep and superficial branch)
posterior compartment: tibial n.

Question 20

innervation of the foot includes which nerves?

Answer 20

medial and lateral plantar nn., from tibial n.

Question 21

what is a dermatome?

Answer 21

an area of cutaneous innervation on the skin that can be traced back to a single spinal nerve

Question 22

what are the dermatomes of the lower extremity?

Answer 22

spinal nerve roots L1-S5, includes the groin and gluteal region

Question 23

cutaneous nerves of the peripheral nerves of the lumbar and sacral plexuses, and/or branches of these peripheral nerves distribute…

Answer 23

over the limb in a different pattern, since nerves typically carry axons from more than one spinal nerve

Question 24

what are myotomes?

Answer 24

the segmental innervation of muscle groups, they tend to correspond to movements

Question 25

myotomes ______, such that...

Answer 25

overlap, such that a given movement will involve more than one myotome, also because motor fibers from more than one spinal nerve segment

Question 26

what are the 2 deep tendon reflexes and what spinal cord segments/tendons do they correspond with?

Answer 26

quadriceps (knee jerk): L3/L4, patellar tendon, tests function of the femoral nerve and spinal cord segments L3-L4, absence is called Westphal's sign calcaneal (ankle jerk): S1/S2, achilles tendon

Question 27

what are the major nerves of the lumbar and sacral plexuses?

Answer 27

``` femoral obturator sciatic (fibular division= common fibular, tibial division= tibial) lateral femoral cutaneous posterior femoral cutaneous ```

Question 28

femoral n. roots

Answer 28

L2-L4

Question 29

obturator n. roots

Answer 29

L2-L4

Question 30

Sciatic n. roots

Answer 30

L4-S3, F: L4-S2, T: L4-S3

Question 31

lateral femoral cutaneous n. roots

Answer 31

L2-L3

Question 32

posterior femoral cutaneous n. roots

Answer 32

S1-S3

Question 33

Iliohypogastric n.

Answer 33

provides sensory innervation to the lateral gluteal region and motor innervation to abdominal musculature (L1)

Question 34

Iliolinguinal n.

Answer 34

provides sensory innervation to the superior medial thigh and regions of the perineum, as well as motor innervation to abdominal musculature (L1)

Question 35

Genitofemoral n.

Answer 35

provides sensation to the superior thigh region (femoral portion) and the perineum (genital portion) (L1 and L2)

Question 36

Lateral femoral cutaneous n.

Answer 36

provides innervation to the skin of the lateral thigh region (L2 and L3)

Question 37

Femoral n.

Answer 37

the nerve of the anterior compartment of the thigh (L2, L3, L4)

Question 38

Obturator n.

Answer 38

the nerve of the medial compartment of the thigh (L1-L4), provides cutaneous innervation of the medial region of the thigh

Question 39

Lumbosacral trunk

Answer 39

unites the lumbar plexus with the sacral plexus

Question 40

femoral nerve (which innervates the _____ compartment of the ____) innervates muscles that do

Answer 40

anterior, thigh, flexion of hip, extension of knee

Question 41

obturator nerve (which innervates the ____ compartment of the ____) innervates muscles that do

Answer 41

medial, thigh, adduction of thigh, some extension of hip

Question 42

femoral nerve branches into nerves that innervate

Answer 42

iliacus, sartorius, rectus femoris, vastus lateralis, vastus medialis, vastus intermedius, pectineus

Question 43

obturator nerve branches into nerves that innervate

Answer 43

pectineus, adductor brevis, adductor longus, gracilis, adductor magnus, obturator externis

Question 44

the sacral plexus is made of which nerves?

Answer 44

superior and inferior gluteal nerves, nerve to piriformis, sciatic nerve (common fibular and tibial divisions), posterior femoral cutaneous nerve, pudendal nerve

Question 45

superior and inferior gluteal nerves

Answer 45

provide motor to the three gluteal muscles

Question 46

nerve to piriformis

Answer 46

provide motor innervation to the small rotators of the hip

Question 47

sciatic nerve provides innervation to

Answer 47

to the posterior thigh and leg

Question 48

posterior femoral cutaneous nerve

Answer 48

innervates the skin of the posterior thigh

Question 49

pudendal nerve

Answer 49

sensation to the perineum

Question 50

sciatic nerve is composed of nerves _____ and innervates

Answer 50

L4 and L4, lumbosacral trunk, hamstring muscles in the thigh, which function to flex the knee; and branches into the tibial nerve (for plantar flexion of the foot and toes, inversion of foot, posterior leg) and the common fibular nerve (for dorsiflexion of foot and toe extension, foot eversion, anterior and lateral leg)