12 ANS and pelvic viscera

Question 1

what does the autonomic nervous system consist of?

Answer 1

visceral efferent motor fibres

visceral afferent pain fibres

Question 2

where is the ANS distrubuted?

Answer 2

CNS and PNS

Question 3

what are the differences in the two divisions of ANS?

Answer 3

sympathetic and payasympathetic nervous system

• anatomical
• neurotransmitters
• physiological effects

Question 4

function of sympathetic nervous system

Answer 4

prepare body for an emergency

• increase heart rate
• redistribution of blood- arterioles of skin and intestines constricted. arteriole of Skm dilated
• increased in BP

Question 5

sympathetic nervous system

Answer 5

thoracolumbar outflow

• efferent outflow from spinal cord, sympathetic trunk, branches, plexuses and ganglia
• Lateral horn (preganglionic cell bodies location) positioned from T1-L3
• Axons of preganglionic neurones leave lateral horn and enter into paravertebral ganglia of the sympathetic trunk

Question 6

SNS: Once pre-ganglionic fibres enter sympathetic trunk they can…

Answer 6

1. synapse at entry level
2. ascend and synapse- travel cranially
3. descend and synapse- travel caudally
4. no synpase with ganglia assocaited with sympathetic trunk- form splanchnic nerves

(synapse at ganglia some distance away)

Question 7

what type of fibres are splanchnic nerves?

Answer 7

pre-ganglionic sympathetic fibres

Question 8

what is the sympathetic chain/ paravertebral column?

Answer 8

two ganglionic nerve trunks that extend the whole length of vertebral column

• Superior cervical ganglion of each sympathetic trunk lies at base of cranium
• Ganglion impar forms inferiorly where two trunks unite at level of coccyx
• Associated with spinal cord

Question 9

how many sympathetic ganglia are associated with:

neck

thorax

abdomen

pelvis

Answer 9

3

11/12

4/5

4/5

Question 10

lower thoracic splanchnic nerve vertebrae

origin

Answer 10

greater- T5-T9 (T10)

lesser T10-11

Least T12

thoracic sympathetic trunk

Question 11

2

6

yellow arrows

12

13

Answer 11

azygous vein

SVC

sympathetic chain

lesser splanchnic nerves

greater splanchnic nerves

Question 12

which plexuses do the thoracic splanchnic nerves form

Answer 12

greater- pierces crura of diaphragm to synapse with coeliac plexus

lesser- pierces crura of diaphragm, descends with greater splanchnic nerves to join lower part of coeliac plexus

least- preganglionic fibres of excitatory neurones in ganglia of renal plexus

Question 13

function of parasympathetic nervous system

Answer 13

cranio-sacral outflow

Function to conserve and restore energy

• Decrease heart rate
• Peristalsis and glandular activity increased
• Sphincters are opened
• Bladder wall is contracted
• Pupils are constricted

Question 14

locations of nerve cells of PNS

Answer 14

CNIII oculomotor

CNVII facial

CNIX glossopharyngeal

CNX vagus

sacral segments of spinal cord- grey matter

S2-S4 anterior roots of spinal nerves

Efferent fibres of cranio-sacral outflow are pre-ganglionic and synapse in peripheral ganglia located close to viscera they innervate

Question 15

waht type of nervous system are pelvic splanchnic nerves

Answer 15

parasymapathetic S2-S4

Question 16

hypogastric nerve plexuses

Answer 16

superior hypogastric nerve plexus-> sympathetic

splits into R and L hypogastric nerves-> inferior hypogastric plexus -> mixed

Question 17

7

34

Answer 17

7 inf mesenteric artery

34 internal iliac artery

Question 18

Answer 18

Question 19

enteric nervous system:

what plexuses does it consist of

Answer 19

Two important plexuses of nerve cells and fibres extend along/around the GI tract

Meisser plexus (submucosal plexus)

auerbach plexus (myenteric plexus)

• Capable autonomous (coordination of reflexes)
• Operate independently of brain and spinal cord
• Does receive autonomic nervous innervation

Question 20

ENS: function of Meissner’s plexus and location

Answer 20

• Controls glandular secretion of mucosa
• Located between submucosa and circular muscle layer
• Also involved in local movement of muscle

Question 21

ENS: function and locaiton of Auerbach’s plexus

Answer 21

• Controls peristalsis
• Movement of gut wall
• Between circular and longitudinal muscle layers

Question 22

Answer 22

Question 23

myenteric

stimulation

inhibition

Answer 23

• Myenteric: longitudinal chains of neurones
  
  • Stimulated Plexus increases tone of gut and velocity and intensity of contractions
  • Motility through gut
  • Inhibition: relax sphincters, controls flow of digestive food/ waste
• Submucosal:
  
  • Local conditions and controls local secretions and local muscle movements
• Mucosa and epithelial tissue have sensory nerve endings that feed signals to both layers of enteric plexus
  
  • Tissues send info back to sympathetic prevertebral ganglia-> spinal cord-> brain stem

Question 24

role of sensory nerves in ENS

Answer 24

monitor tension and gut wall and conditions in lumen

feedback to assc nerves

Question 25

functions of ENS

Answer 25

Estimated more neurones associated with it than spinal cord * Second brain * Contains a variety of functional types of neurones and a plethora of neurotransmitters * Controls motility and secretory functions * Complete reflex circuit * Afferent sensory neurones, interneurons and efferent secretomotor neurones * Functions autonomously, but modified by sympathetic and parasympathetic nervous systems

Question 26

pathology of ENS

Answer 26

Hirschsprung’s disease * Congenital birth defect (1:5000) * Enteric neurones absent from variable lengths of the distal gut * Failure of neural crest cells to colonise region of gut (vs nerves not surviving) * Intestinal obstruction or severe constipation Descending colon: lacking enteric neurones (aganglionic) * Contracted and devoid of content * Region proximal to aganglionic zone is distended (megacolon) due to accumulation of fecal content Mutations in identified genes 50% of causes

Question 27

dorsal primary ramus

Answer 27

part of spinal nerve (contains motor, sensory and autonomic) innervating back.

Question 28

ventral primary ramus

Answer 28

part of spinal nerve innervating everything in front of spinal cord – hence larger than dorsal primary ramus.

Question 29

white ramus

Answer 29

preganglionic sympathetic fibres connecting ventral primary ramus with sympathetic chain. Myelinated nerves only found T1 – L2

Question 30

grey ramus

Answer 30

post ganglionic sympathetic fibres connecting sympathetic chain to dorsal and ventral primary ramus of spinal nerve. Unmyelinated nerves