Lecture 04 Visceral Afferent Pathways

Question 1

Describe the laryngeal expiration reflex

Answer 1

Stimulus: laryngeal mucosa
Internal br of SLN->nucleus tractus solitarius and adjacent LER pattern generator and associated brainstem and spinal cord nuclei ->reticular formation (LRST) and LVST

Two pathways:
Nucleus ambiguus->recurrent laryngeal n->glottal control->expiratory cough epoch airway cleaering
Medial motor cell column->thoracoabdominal n->External abs->closure of abdominal and pelvic sphincters ->expiratory coughs

Question 2

What is a cough defined as?

Answer 2

an inhalation followed by an expiratory cough - like a voluntary cough

Question 3

What is the pattern for an airway protective cough?

Answer 3

3-5 expiratory cough without inhalation

Contraction of external abdominal oblique mm squeeze tot help clear airway

Question 4

What must be synchronized with the increase in intra-abdominal pressure during the LER cough epoch?

Answer 4

closure of the lower esophageal sphincter, internal urethral sphincter, external urethral sphincter, anal sphincter, and inguinal canal

Question 5

What is the muscle in the wall of the bladder primarrily under the control of?

Answer 5

parasympathetics - sacral spinal cord segments 2-4

Some sympathetic fibers may relax the bladder

Question 6

What is the bladder reflex?

Answer 6

Stimulus: increased volume
Stretch receptors in bladder wall->afferent n sacral->visceral afferent nucleus ->sacral autonomic nucleus->efferent n -> either increase bladder tone or void

Question 7

What does atonic bladder result in?

Answer 7

due to lesions of the dorsal roots of S2-4 or dorsal funiculi, it results in flaccid bladder and increased bladder capacity
voluntary voiding is possible but incomplete

Question 8

What is reflex bladder?

Answer 8

Transection of the spinal cord above S2 interrupts the lateral reticulospinal tracts to the sacral autonomic nucleus, and the pt is unable to voluntarily void his bladder

Question 9

What happens to the bladder after spinal shock?

Answer 9

The bladder reflex may return w/o voluntary control and the pt will have automatic reflex voiding or a reflex bladder

Question 10

What is the pathway for slow pain of the body?

Answer 10

spinal ganglion->dorsolateral fasiculus->nucleus proprius->fasiculus proprius->centromedian hypothalamus

Question 11

What is the visceral pain pathway for the body?

Answer 11

spinal ganglion->dorsolateral fasiculus->visceral afferent nucleus->reticular formation->centromedian hypothalamus

Question 12

What is the slow pain pathway for the head?

Answer 12

Trigeminal or sensory ganglia->descending tract of V->subnucleus caudalis->trigemino-reticular fibers->centromedian hypothalamus

Question 13

What is the visceral pain pathway for the head/

Answer 13

GVA sensory ganglia->solitary tract->solitary nucleus ->solitaro-hypothalamic fibers->centromedian hypothalamus

Question 14

Describe the Gag reflex

Answer 14

Stimulus: touching pharyngeal mucosa

CN IX->nucleus tractus solitarius ->Reticular formation ->nucleus ambiguus->pharyngeal br of vagus->gagging