Lumbar Plexus and Innervation of the Abdomen and Pelvis

Question 1

lumbar plexus

Answer 1

a. Ventral primary rami
b. T12-L4 or 5
c. These branches also carry sympathetic fibers
d. L4-L5 from the lumbar plexus becomes the first branch of the sacral plexus
e. Most branches associated with the psoas muscle

Question 2

subcostal N

Answer 2

T12

Question 3

iliohypogastric N

Answer 3

T12-L1

Question 4

ilioinguinal N

Answer 4

L1

Question 5

lateral femoral cutaneous N

Answer 5

L2-3

Question 6

genitofemoral N

Answer 6

L1-3

Question 7

femoral N

Answer 7

L2-4

Question 8

lumbosacral trunk

Answer 8

L4-5

Question 9

obturator N

Answer 9

L2-4

Question 10

cardiac plexus

Answer 10

a. Inc sympathetic activity increases HR and BP

b. Inc PS activity dec HR

Question 11

pulmonary plexus

Answer 11

a. PS pathway causes bronchoconstriction and increased secretion from mucous glands of the bronchial tree
b. Sympathetic innervation causes bronchodilation

Question 12

esophageal plexus

Answer 12

a. PS axons control swallowing

Question 13

abdominal aortic plexus

Answer 13

a. Consists of the celiac plexus, superior mesenteric plexus, and inferior mesenteric plexus—control of digestion

Question 14

hypogastric plexus

Answer 14

a. Innervates pelvic viscera—autonomic control of urinary and reproductive fcn

Question 15

where are Sympathetic preganglionic neuron cell bodies housed?

Answer 15

lateral horn of T1-L2

Question 16

white rami

Answer 16

1. Connect the spinal nerves to each sympathetic trunk are rami communicantes
2. They carry preganglionic sympathetic axons from the T1-L2 spinal nerves to the sympathetic trunk
3. They are associated only with the T1-L2 spinal nerves
4. Preganglionic axons are myelinated
   a. The white ramus has a whitish appearance
5. Similar to entrance ramps on a highway

Question 17

gray rami

Answer 17

1. Carry postganglionic sympathetic axons from sympathetic trunk to the spinal nerve
2. Axons are unmyelinated—gray rami have a grayish appearance
3. Similar to exit ramps on a highway
4. connect to all spinal nerves, including the cervical, sacral, and coccygeal spinal nerves
5. sympathetic information that started out in the thoracolumbar region can be dispersed to all parts of the body

Question 18

splanchnic N pathway

Answer 18

lateral horn–>ventral ramus–>spinal N proper–>white ramus–>traveling as a myelinated fiber in the thoracic spinal nerve to the prevertebral ganglion

Question 19

splanchnic N

Answer 19

a. Composed of preganglionic sympathetic axons
b. Run anteriorly from the sympathetic trunk to most of the viscera
c. Not the same as pelvic splanchnic Ns assoc with the PS division
d. Larger splanchnic Ns (all sympathetic)
e. Terminate in prevertebral ganglia
f. Called “prevertebral” b/c they are immediately anterior to the vertebral column on the anterolateral wall of the abdominal aorta
g. Prevertebral ganglia typically cluster around the major abdominal arteries and are named for these arteries
i. Celiac ganglia cluster around celiac trunk
h. Sympathetic postganglionic axons extend away from the ganglionic cell bodies in these ganglia and innervate many abdominal organs

Question 20

Craniosacral division of PNS

Answer 20

1. Primarily concerned with conserving energy and replenishing nutrient stores
2. Most active when the body is at rest or digesting a meal
3. Participates along with the sympathetic division in maintaining homeostasis (a constant internal environment)

Question 21

oculomotor nerve

Answer 21

CN III

Question 22

facial nerve

Answer 22

CN VII

Question 23

glossopharyngeal N

Answer 23

CN IX

Question 24

vagus N

Answer 24

CN X

Question 25

what is the source of PS stimulation for the thoracic and abdominal organs?

Answer 25

vagus nerve

Question 26

Caudal contribution of PS

Answer 26

pelvic splanchnic N

1. Apart from the cranial N components, the rest of the PS innervation in the body comes from sacral region of the spinal cord at S2-4
2. Preganglionic PS axons from neuron cell bodies in the lateral horn contribute to the formation of the superior and inferior hypogastric plexus
   a. From here, preganglionic axons travel to organs and synapse with ganglia close to or in the walls of the organs

Question 27

referred pain for gallbladder

Answer 27

T6 right

Question 28

referred pain for cecum and appendix

Answer 28

T10-12 righ

Question 29

referred pain for stomach

Answer 29

T5-9 left