L19: Brachial and lumbosacral plexuses

Question 1

central nervous system

Answer 1

brain, spinal chord

Question 2

peripheral nervous system

Answer 2

nerves outside brain and spinal cord
e.g. upper and lower limb

Question 3

anterior (ventral) root:

Answer 3

motor

Question 4

posterior (dorsal) root:

Answer 4

sensory

Question 5

each spinal nerve is formed by the union of:

Answer 5

anterior [ventral] root
posterior [dorsal] root

Question 6

where does spinal nerves leave the vertebral column

Answer 6

intervertebral foramina

Question 7

outside the vertebral column, spinal nerves divide into:

Answer 7

posterior [dorsal] ramus
anterior [ventral] ramus

Question 8

what plexus innervates upperlimb

Answer 8

brachial plexus

Question 9

what plexus innervates lower limb

Answer 9

lumbar and sacral plexuses

Question 10

structure of a nerve

Answer 10

signals travel in both directions
consist of many axons, each axon carries its own signal

Question 11

motor axons

Answer 11

[efferent]
carry signal to a muscle

Question 12

sensory axons

Answer 12

[afferent]
carry signals back to the spinal cord

Question 13

brachial plexus location

Answer 13

brachial plexus formed by C5-T1 spinal nerves

Question 14

structure - brachial plexus

Answer 14

5 roots
3 trunks
6 divisions
3 cords

Question 15

cords

Answer 15

cords named due to relationship to axillary artery
axillary artery lies between the medial and lateral cords, and anterior to the posterior cord

Question 16

trunks and divisions

Answer 16

each trunk splits into anterior and posterior divisions

Question 17

divisions and cords

Answer 17

3 posterior divisions: unite to form the posterior cord
3 anterior divisions: upper 2 unite to form the lateral cord, lower trunk forms the medial cord

Question 18

branches root level

Answer 18

dorsal scapular nerve
phrenic nerve
long thoracic nerve

Question 19

branches trunk level

Answer 19

only in superior trunk
suprascapular nerve
subclavian

Question 20

branches: cords - lateral cord

Answer 20

lateral pectoral nerve
musculocutaneous nerve
median nerve contribution

Question 21

branches: cords - posterior cord [STARS]

Answer 21

subscapular [upper] nerve
thoracodorsal nerve
axillary nerve
radial nerve
subscapular [lower] nerve

Question 22

branches: cords - medial cord

Answer 22

medial pectoral nerve
medial cutaneous nerve of arm
medial cutaneous nerve of forearm
median nerve contribution
ulnar nerve

Question 23

Lumber plexus

Answer 23

T12-L5
passes laterally through psoas major
passes anterior to hip joint

Question 24

what does lumbar plexus innervate

Answer 24

innervates pelvis muscles, anterior and medial thigh

Question 25

lumbar plexus nerves:

Answer 25

iliohypogastric nerve
ilioinguinal nerve
genitofemoral nerve
lateral cutaneous nerve
femoral nerve
obturator nerve

Question 26

lumbosacral trunk

Answer 26

contributions from L4 and L5 spinal nerves converge at sacral ala to form lumbosacral trunk

lumbosacral trunk joints sacral plexus and allows axons to pass between lumbar and sacral plexuses

Question 27

Sacral plexus

Answer 27

formed by S1-S4 spinal nerves
nerves unite on anterior surface of piriformis

Question 28

what does sacral plexus innervate

Answer 28

terminal branches descend posterior to hip joint and innervate: posterior thigh, leg and foot

Question 29

sacral plexus terminal branches

Answer 29

superior gluteal nerve
inferior gluteal nerve
sciatic nerve
posterior cutaneous nerve of thigh
pudendal nerve