Lumbar Plexus and Innervation of the Abdomen and Pelvis Flashcards
lumbar plexus
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
subcostal N
T12
iliohypogastric N
T12-L1
ilioinguinal N
L1
lateral femoral cutaneous N
L2-3
genitofemoral N
L1-3
femoral N
L2-4
lumbosacral trunk
L4-5
obturator N
L2-4
cardiac plexus
a. Inc sympathetic activity increases HR and BP
b. Inc PS activity dec HR
pulmonary plexus
a. PS pathway causes bronchoconstriction and increased secretion from mucous glands of the bronchial tree
b. Sympathetic innervation causes bronchodilation
esophageal plexus
a. PS axons control swallowing
abdominal aortic plexus
a. Consists of the celiac plexus, superior mesenteric plexus, and inferior mesenteric plexus—control of digestion
hypogastric plexus
a. Innervates pelvic viscera—autonomic control of urinary and reproductive fcn
where are Sympathetic preganglionic neuron cell bodies housed?
lateral horn of T1-L2
white rami
- Connect the spinal nerves to each sympathetic trunk are rami communicantes
- They carry preganglionic sympathetic axons from the T1-L2 spinal nerves to the sympathetic trunk
- They are associated only with the T1-L2 spinal nerves
- Preganglionic axons are myelinated
a. The white ramus has a whitish appearance - Similar to entrance ramps on a highway
gray rami
- Carry postganglionic sympathetic axons from sympathetic trunk to the spinal nerve
- Axons are unmyelinated—gray rami have a grayish appearance
- Similar to exit ramps on a highway
- connect to all spinal nerves, including the cervical, sacral, and coccygeal spinal nerves
- sympathetic information that started out in the thoracolumbar region can be dispersed to all parts of the body
splanchnic N pathway
lateral horn–>ventral ramus–>spinal N proper–>white ramus–>traveling as a myelinated fiber in the thoracic spinal nerve to the prevertebral ganglion
splanchnic N
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
Craniosacral division of PNS
- Primarily concerned with conserving energy and replenishing nutrient stores
- Most active when the body is at rest or digesting a meal
- Participates along with the sympathetic division in maintaining homeostasis (a constant internal environment)
oculomotor nerve
CN III
facial nerve
CN VII
glossopharyngeal N
CN IX
vagus N
CN X
what is the source of PS stimulation for the thoracic and abdominal organs?
vagus nerve
Caudal contribution of PS
pelvic splanchnic N
- 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
- 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
referred pain for gallbladder
T6 right
referred pain for cecum and appendix
T10-12 righ
referred pain for stomach
T5-9 left
