Lumbar Plexus & Innervation Of Abdomen & Pelvis-1/11/16 Flashcards
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
Subcostal n. (T12)
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
Iliohypogastrinc n. (L1)
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.
Ilioinguinal n. (L1, L2)
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.
Genitofemoral n. (L1, L2)
Genital branch is 2nd paragraph
Femoral branch is 3rd paragraph
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.
Lateral femoral cutaneous n. (L2, L3)
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.
Femoral n. (L2-L4, Posterior divisions)
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.
Obturator n. (L2-L4, anterior division)
What neurotransmitters are used in the SNS?
What types of axons are in the SNS?
Ach
Axons are thick and myelinated=FAST CONDUCTION
The ANS can excite or inhibit using these neurotransmitters:
What types of axons are found in the ANS?
Ach and Norepi
Axons are thin, some are myelinated, others are not=slower conduction
This cranial nerve supplies parasympathetic fibers to foregut and midgut derivatives of the abdomen
Vagus n. (CN X)
____ parasympathetics go to the hindgut derivatives: lower abdomen and pelvis
Sacral-Pelvic splanchnic nerves (S2-S4)
The ____ plexus contains fibers from both left and right vagus n. And forms the anterior vagal trunk
Anterior esophageal plexus
What does the anterior vagal trunk supply (preganglionic fibers)?
Stomach Liver Gallbladder Duodenum Pancreas
The posterior vagal trunk supplies preganglionic fibers to:
Stomach
Intestines
Cardiac plexus:
Increased sympathetic activity will ____
Increased parasympathetic activity will ____
Increase HR and BP
Decrease HR
Pulmonary plexus:
Parasympathetic pathway causes ____
Sympathetic innervation causes ____
Bronchoconstriction and increased secretion from mucous glands of bronchial tree
Bronchodilation
Esophageal plexus:
Parasympathetic axons control ____
Swallowing reflex
Abdominal aortic plexus:
Consists of ____ plexi and have have autonomic control of _____
Celiac, superior mesenteric, inferior mesenteric
Digestion
Hypogastric plexus:
Innervates ___ and has autonomic control of _____ function
Pelvic viscera
urinary and reproductive
Sympathetic preganglionic neuron cell bodies are housed in the ____ regions of the spinal cord
Lateral horns of the T1-L2
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
White rami
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
Gray rami
What are the 4 types of sympathetic pathways?
Spinal nerve
Postganglionic sympathetic nerve
Splanchnic nerve
Adrenal medulla
Outline a spinal nerve pathway
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
Diagram the postganglionic sympathetic nerve pathway to visceral effectors in the head (Salivary gland)
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
Diagram the postganglionic sympathetic nerve pathway to the heart and lungs
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
Diagram the adrenal medulla pathway
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
Diagram a thoracic splanchnic nerve pathway
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)
Diagram a pelvic splanchnic nerve pathway
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)
Splanchnic nerves are composed of ___ axons
What are the larger splanchnic nerves?
Preganglionc sympathetic
Greater thoracic splanchnic, lesser thoracic splanchnic, least thoracic splanchnic, lumbar splanchnic, sacral splanchnic
Splanchnic nerves terminate in ___ ganglia
Prevertebral (or collateral)
Where are prevertebral ganglia located?
Only in the abdominopelvic cavity
Include celiac, superior mesenteric, and inferior mesenteric ganglia
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
Parasympathetics–> Long pre-ganglionic, short post-ganglionic
Sympathetics –> Short pre-ganglionic, long post-ganglionic
Pelvic splanchnic nerves are associated with this ANS division:
Parasympathetic –> S2-S4
Preganglionic parasympathetic axons from neuron cells bodies in the lateral horn contribute to the formation of the ____ plexus
Superior and inferior hypogastric
Caudal contribution of parasympathetics via pelvic splanchnic nerves travel and synapse to these organs/effectors:
Distal portion of LI Rectum Most repro organgs Urinary bladder (contracts) Distal ureters Erection
Sympathetic fibers are accompanied by ___ fibers
general visceral afferent (GVA, pain) fiber
List the nerves of the Lumbar plexus:
- 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)
