Lumbar Plexus & Inn of the Abdomen and Pelvis Flashcards Preview

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Flashcards in Lumbar Plexus & Inn of the Abdomen and Pelvis Deck (41):

Lumbar Plexus

ventral primary rami
T12 to L4(L5)
branches also carry sympathetic fibers
L4-L5 from the lumbar plexus becomes the 1st branch of the sacral plexus
most branches associated w/ the psoas mm


Lumbar Plexus Components

Lateral femoral cutaneous
Lumbosacral trunk



voluntary or subconscious control single neuron pathway
no ganglia involved in pathway
sensory input from general and special senses motor output to skeletal m
excites using acetylcholine
axons are thick and myelinated = fast conduction



involuntary or unconscious control two neuron pathway
ganglia involved in pathway
sensory input from general and visceral senses motor output to cardiac, smooth m, and glands
can excite or inhibit function using acetylcholine and norepinephrine
axons are thin some are myelinated, other are not = slower conduction


autonomic plexuses

collections of sympathetic postganglionic axons and parasympatheitc preganglionic axons, as well as some visceral sensory axons
sympathetic and parasympatheitc plesuses are colose to one another, but they do not interact or synapse with one another
provide a complex innervation pattern to their target organs


cardiac plexus

increased sympathetic activity increases heart rate and blood pressure
increased parasympathetic activity decreases heart rate


pulmonary plexus

parasympathetic pathway causes bronchoconstriction and increased secretion from mucous glands of the bronchial tree
sympathetic innervation causes bronchodilation


esophageal plexus

parasympathetic axons control the swallowing reflex


abdominal aortic plexus

consists of the celiac plexus, superior mesenteric plexus, and inferior mesenteric plexus = autonomic control of digestion


hypogastric plexus

innervates pelvic visera = autonomic control of urinary and reproductive function


dual innervation

many visceral effector (ORGANS) are innervated by postganglionic axons from both ANS divisions
actions of the divisions usually oppose each other
opposing effects are also achieved by increasing or decreasing activity in one division (one division can up regulate or down regulate the other)


Parasympathetic Axons

long to Ach
short to Ach


Sympathetic Axons

short to Ach
Long to Nor


Sympathetics - Fight or Flight FXN of the ANS

may involve a single effector or many effectors
in mass activation, a large number of ganglionic neurons activate many effector organs
causes a heightened sense of alertness due to stimulation of the reticular activation system


organization and anatomy of the sympathetic division

much more complex than the parasympathetic division both anatomically and functionally
sypathetic preganglionic neurons cell bodies are housed in the lateral horn of the T1-L2 regions of the spinal cord
preganglionic sympathetic axons travel with somatic motor neurons axons to exit the spinal cord and 1st enter the anterior roots and then the T1-L2 spinal nerves
preganglionic sympathetic axons remain with the spinal nerve fro a short distance before they branch off and leave the spinal nerve


L and R sympathetic trunks

immediately anterior to the paired spinal nerves are the L and R sympathetic trunks
each is located immediately lateral to the vertebral column
a sympathetic trunk looks much like a string of beads
the string is composed of bundles of axons
the beads are the sympathetic trunk ganglia which house sympathetic ganglionic neuron cell bodies
once sypathetic trunk ganglion is approximately associated w/ each spinal n.
the cervical portion of each sympathetic trunk is partitioned into only three sympatheitc trunk ganglia, the superior, middle, and inferior cervical ganglia, as opposed to the 8 cervical spinal nerves


white rami

connecting 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 mylinated - the white ramus has a whitish appearance
similar to enterance ramps on a highway


grey rami

carry postganglionic sympathetic axons from the sympathetic trunk to the the spinal nerve
axons are unmylinated - 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
in this way sympathetic information that started out in the thoracolumbar region can be dispersed to all parts of the body


sympathetic pathways

spinal n pathway
postganglionic sympathetic n pathway
the splanchinic n pathway
the adrenal medulla pathway


splanchinic nerves

composed of preganglionic sympathetic axons
run anteriorly from the sympathetic trunk to most of the viscera
should not be confused w/ the pelvic splanchnic n associated with the parasympathetic divisions
terminate in prevertebral ganglia
called prevertebral because they are immediately anterior to the vertebral column on the anterolateral wall of the abdominal aorta
prevertebral ganglia typically cluster around the major abdominal a and are named for these arteries
sympathetic post ganglionic axons extend away from the ganglionic neurons cell bodies in these ganglia and innervate many of the abdominal organs


Larger splanchinc nerves

greater thoracic splanchnic n
lesser thoracic splanchnic n
least thoracic splanchnic n
lumbar splanchnic n
sacral splanchnic n


prevertebral ganglia

differ from the sympathetic trunk ganglia
are single structures rather than paired
are anterior to the vertebral column on the anterior surface of the aorta
located only in the abdominopelvic cavity
prevertebral ganglia include the celiac, superior mesenteric, and inferior mesenteric ganglia


Parasympathetic division - rest and digest

parasympathetic division is most active during times when the body must process nutrients and conserve energy
lack of extensive divergence in preganglionic axons prevents the mass activation seen in the sympathetic division
effects of the parasympatheitc nervous system tend to be discrete and localized
parasympathetic activity can affect one group of organs w/o necessarily having to turn on all other organs


The parasympathetic division

also termed craniosacral division
primarily concerned with conserving energy and replenishing nutrient stores
in most active when the boy is at rest or digesting a meal
participates along with the sympathetic division in maintaining homeostasis


cranial nerves

associated with the parasympathetic division are: the oculomotor nerve (CN III) facial nerve (CNVII), glossopharyngeal nerve (CN IX), vaugus nerve (CN X)


Vagus nerve

parasympathetic stimulation for the thoracic and most abdominal organs
multiple terminal and inramural ganglia
heart rate decrease
decrease respiration
constrict excites mucous production
promotes swallowing and peristalsis
promotes digestion


caudal contribution of parasympathetic

apart from the cranial nerve components the rest of the parasypatheic innervations in the body comes from the sacral region of the spinal cord
preganglionic parasympathetic axons from neuron cell bodies in the lateral horn contributes to the formation of the superior and inferior hypogstac plexus
preganglionic axons travel to the organs and synapse with ganglia close to or in the walls of the organs


Parasympathetic via pelvic splanchnic n

distal portions of large intestine
most reproductive organs
urinary blader
distal ureters


segmental innervation of abdominal visera

approximate spinal cord segments and spinal sensory ganglia involved in sympathetic and visceral afferent pain innervation of abdominal viscera are shown


gallbladder visceral pain

T6 right


cecum and appendix visceral pain

T10-T12 right


stomach visceral pain

T5-T9 left


subcostal n

T 12
motor to - recutus bodominis, pyramidalis, transversus abdominis, internal oblique, external oblique
sensory - skin of the anterior and lateral body wall and to the upper gluteal area


iliohypogastic n

transversus abdominis, internal oblique, external oblique
skin of suprapubic region
skin of upper gluteal region


ilioinguinal n

motor - transversus abdominins and internal oblique
sensory - root of penis and anterior scrotum in males, skin of the mons pubis and labia majora in females, skin of the medial and upper thigh in males where it constitutes the afferent limb of the cremasteric reflex


genitofemoral n

L1 and L2
genital - motor to cremaster sensory to anterior scrotum or upper part of the labia majora
femoral - innervate the skin of the thigh


lateral femoral cutaneous n

L2 and L3
sensory fibers to the skin of the anterolateral and posterolateral thigh


femoral n

L2,L3, and L4
motor branches to iliacus, anterior thigh m
sensory branches to anterior and medial thigh and medail leg
afferent and efferent limbs of the knee jerk reflex


obturator n

L2, L3, L4
motor fibers to the medial thigh m
sensory fibers to hip joint, skin of medial thigh


accessory obturator n

L3 and L4
pectineus m


lumbosacral trunk

L4 and L5
joins sacral plexus