Lumbar Plexus & Innervation Of Abdomen & Pelvis-1/11/16

Question 1

This lumbar plexus n. Emerges lateral to psoas major , deep to the lateral arcuate ligament, just beneath the 12th rib.

It traverses quadratus lumborum and pierces transversus abdominis, running between it and the internal oblique.

Its provides sensory branches to skin on the anterior and lateral body wall and upper gluteal area

Answer 1

Subcostal n. (T12)

Question 2

This lumbar plexus n. Emerges from lateral side of psoas maj. To run within the musculature of the abdominal wall.

It traversesd quadratus lumborum, piercing transversus abdominis at its medial border and runs anteriorly between transversus abdominis and internal oblique.

It also pierces internal oblique a few cms. Inferomedial to ASIS and runs between internal and external oblique

It supplies skin of suprapubic region and skin of upper gluteal region

Answer 2

Iliohypogastrinc n. (L1)

Question 3

This lumbar plexus is located slightly inferior to iliohypogastric and often anastomoses with it.

It pierces the internal oblique near the deep inguinal ring and the terminal branch accompanies the spermatic cord (male) or round ligament (female) as it runs within the canal. It exits the canal through superficial inguinal ring where it lies on the superior aspect of the spermatic cord or round ligament.

It gives sensory fibers to root of penis and anterior scrotum in males and skin of mons pubis and labia majora in females.

Answer 3

Ilioinguinal n. (L1, L2)

Question 4

This lumbar plexus nerve emerges from the anterior surface of psoas major near the level of L3-L4 and descends on the anterior surface of psoas, deep to psoas fascia.

One branch enters the inguinal canal at deep inguinal ring and exits inguinal canal through superficial ring. It is motor to cremaster muscle and sensory to anterior scrotum or upper part of labia majora.

The other branch passes under the inguinal ligament on the surface of external iliac artery to enter femoral sheath and pierces femoral sheath and deep fascia of thigh to innervate skin of thigh.

Answer 4

Genitofemoral n. (L1, L2)

Genital branch is 2nd paragraph

Femoral branch is 3rd paragraph

Question 5

This lumbar plexus nerve emerges from the lateral border of psoas major, crosses iliac fossa deep to the iliacus fascia, passes beneath inguinal ligament near ASIS, and supplies sensory fibers to skin of anterolateral and posterolateral thigh.

Answer 5

Lateral femoral cutaneous n. (L2, L3)

Question 6

This lumbar plexus nerve is the largest of the plexus and emerges from the lateral border of psoas muscle just above inguinal ligament, in the angle between psoas major and iliacus. It passes beneath the inguinal ligament to enter the femoral triangle of the upper anterior thigh.

It supplies motor branches to iliacus, anterior thigh muscles and sensory branches to anterior and medial thigh and to medial leg.

Answer 6

Femoral n. (L2-L4, Posterior divisions)

Question 7

This lumbar plexus nerve emerges from the medial border of psoas major, entering the thigh through the obturator foramen. It crosses the sacroiliac joint and passes lateral to the internal iliac vessels.

It supplies motor fibers to the medial thigh muscles and sensory fibers to the hip joint, skin of medial thigh.

Answer 7

Obturator n. (L2-L4, anterior division)

Question 8

What neurotransmitters are used in the SNS?

What types of axons are in the SNS?

Answer 8

Ach

Axons are thick and myelinated=FAST CONDUCTION

Question 9

The ANS can excite or inhibit using these neurotransmitters:

What types of axons are found in the ANS?

Answer 9

Ach and Norepi

Axons are thin, some are myelinated, others are not=slower conduction

Question 10

This cranial nerve supplies parasympathetic fibers to foregut and midgut derivatives of the abdomen

Answer 10

Vagus n. (CN X)

Question 11

____ parasympathetics go to the hindgut derivatives: lower abdomen and pelvis

Answer 11

Sacral-Pelvic splanchnic nerves (S2-S4)

Question 12

The ____ plexus contains fibers from both left and right vagus n. And forms the anterior vagal trunk

Answer 12

Anterior esophageal plexus

Question 13

What does the anterior vagal trunk supply (preganglionic fibers)?

Answer 13

Stomach
Liver
Gallbladder
Duodenum
Pancreas

Question 14

The posterior vagal trunk supplies preganglionic fibers to:

Answer 14

Stomach

Intestines

Question 15

Cardiac plexus:

Increased sympathetic activity will ____

Increased parasympathetic activity will ____

Answer 15

Increase HR and BP

Decrease HR

Question 16

Pulmonary plexus:

Parasympathetic pathway causes ____

Sympathetic innervation causes ____

Answer 16

Bronchoconstriction and increased secretion from mucous glands of bronchial tree

Bronchodilation

Question 17

Esophageal plexus:

Parasympathetic axons control ____

Answer 17

Swallowing reflex

Question 18

Abdominal aortic plexus:

Consists of ____ plexi and have have autonomic control of _____

Answer 18

Celiac, superior mesenteric, inferior mesenteric

Digestion

Question 19

Hypogastric plexus:

Innervates ___ and has autonomic control of _____ function

Answer 19

Pelvic viscera

urinary and reproductive

Question 20

Sympathetic preganglionic neuron cell bodies are housed in the ____ regions of the spinal cord

Answer 20

Lateral horns of the T1-L2

Question 21

These preganglionic axons are myelinated and are similar to “entrance ramps” on a highway. They carry preganglionic sympathetic axons from the T1-L2 spinal nerves to the sympathetic trunk

Answer 21

White rami

Question 22

These carry postganglionc sympathetic axons from the sympathetic trunk to the spinal nerve. Their axons are unmyelinated and similar to “exit ramps” on a highway.

These connect to all spinal nerves, including the cervical, sacral, and coccygeal spinal nerves

Answer 22

Gray rami

Question 23

What are the 4 types of sympathetic pathways?

Answer 23

Spinal nerve
Postganglionic sympathetic nerve
Splanchnic nerve
Adrenal medulla

Question 24

Outline a spinal nerve pathway

Answer 24

Preganglionic fiber travels out of the ventral root –> though the spinal nerve –> through the white rami –> synapses at the ganglion –> post-ganglionic exits through gray rami –> exits spinal nerve at same level –> provides innervation to blood vessel, hair, or arrector pili and sweat glands of skin (example)

Same pathway as above but can enter white rami, not synapse at that level but ascend to next ganglion and synapse –> exit gray rami –> go to target

Question 25

Diagram the postganglionic sympathetic nerve pathway to visceral effectors in the head (Salivary gland)

Answer 25

Pre-ganglionic exits through ventral root (T1-T4) –> to spinal nerve –> through white ramus –> pre-ganglionic ascends to next level –> synapses in superior cervical neck ganglion –> post-ganglionic axon hops on arteries to target –> post-ganglionic axon synapses on salivary gland

Question 26

Diagram the postganglionic sympathetic nerve pathway to the heart and lungs

Answer 26

Lung:
Pre-ganglionic axon exits ventral root (T1-T6) –> travels through spinal nerve –> travels through white ramus –> pre-ganglionic synapses in ganglion of same level –> post-ganglionic axon travels and synapses on the lung

Heart:
Pre-ganglionic axon leaves ventral root (T1-T6) –> travels through spinal nerve –> travels through white ramus, doesn’t synapse at same level ganglion –> pre-ganglionic axon ascends and synapses at cervical ganglion of sympathetic trunk, in neck –> travels to heart and synapses

Question 27

Diagram the adrenal medulla pathway

Answer 27

Pre-ganglionic axon leaves SC at T8-L1 and travels through ventral root –> through spinal nerve –> through white ramus –> hops on thoracic splanchnic nerves –> synapses on the adrenal medulla cells

Question 28

Diagram a thoracic splanchnic nerve pathway

Answer 28

Pre-ganglionic axon exits spinal cord at T5-L2 –> goes through spinal nerve –> goes through white ramus –> pre-ganglionic hops on thoracic splanchnic n. –> synapses at pre-vertebral ganglion –> post-ganglionic axon travels on nerves in superior mesenteric plexus or celiac plexus –> synapses on visceral effectors (i.e., small intestine)

Question 29

Diagram a pelvic splanchnic nerve pathway

Answer 29

Pre-ganglionic axon exits SC at T10-L2 –> travels through spina nerve –> travels through white ramus –> descends down trunk –> synapses on lower lumbar or sacral trunk ganglion –> post-ganglionic axon travels through splanchnic nerve –> hops on nerves in inferior mesenteric, aortic, or hypogastric plexuses –> synapses on visceral effectors (i.e., bladder)

Same as above but instead of synapsing in lower lumbar or sacral trunk ganglion, the pre-ganglionic axon will pass through it, hop on a splanchnic nerve –> synapse at pre-vertebral ganglion –> hop on nerves in inferior mesenteric, aortic, or hypogastric plexuses –> synapse on visceral effectors (i.e., bladder)

Question 30

Splanchnic nerves are composed of ___ axons

What are the larger splanchnic nerves?

Answer 30

Preganglionc sympathetic

Greater thoracic splanchnic, lesser thoracic splanchnic, least thoracic splanchnic, lumbar splanchnic, sacral splanchnic

Question 31

Splanchnic nerves terminate in ___ ganglia

Answer 31

Prevertebral (or collateral)

Question 32

Where are prevertebral ganglia located?

Answer 32

Only in the abdominopelvic cavity

Include celiac, superior mesenteric, and inferior mesenteric ganglia

Question 33

Describe the lengths of the pre-ganglionic and post-ganglionic fibers of the Parasympathetics

Describe the lengths of the pre-ganglionic and post-ganglionic fibers of the Sympathetics

Answer 33

Parasympathetics–> Long pre-ganglionic, short post-ganglionic

Sympathetics –> Short pre-ganglionic, long post-ganglionic

Question 34

Pelvic splanchnic nerves are associated with this ANS division:

Answer 34

Parasympathetic –> S2-S4

Question 35

Preganglionic parasympathetic axons from neuron cells bodies in the lateral horn contribute to the formation of the ____ plexus

Answer 35

Superior and inferior hypogastric

Question 36

Caudal contribution of parasympathetics via pelvic splanchnic nerves travel and synapse to these organs/effectors:

Answer 36

Distal portion of LI
Rectum
Most repro organgs
Urinary bladder (contracts)
Distal ureters
Erection

Question 37

Sympathetic fibers are accompanied by ___ fibers

Answer 37

general visceral afferent (GVA, pain) fiber

Question 38

List the nerves of the Lumbar plexus:

Answer 38

• Subcostal n. (T12)
• Iliohypogastric n. (L1. Sometimes T12)
• Ilioinguinal n. (L1)
• Genitofemoral n. (L1, L2)
• Lateral femoral cutaneous n. (L2, L3)
• Obturator n. (L2-L4, Anterior divisions)
• Femoral n. (L2-L4, Posterior divisions)
• Lumbosacral trunk (L4-L5)