N24 - swallowing

Question 1

what is the definition of a anatomical sphincter?

Answer 1

circular muscle closing and opening

Question 2

what is a physiological sphincter?

Answer 2

muscle which binds on opening tightly (may not be visible post mortem (when relaxed)

Question 3

name the 2 oesophageal sphincters

Answer 3

upper
- cricopharyngeus

lower
- slight thickening of wall

Question 4

describe the obligate muscles in swallowing

Answer 4

• same action every time
• all or none action
  eg
• mylohyoid
• palatopharyngeus,
• pharyngeal constrictors
• oesophageal muscles

Question 5

describe the facultative muscles in swallowing

Answer 5

• roles variable from one swallow to another
• roles variable from individual to another
• eg
• lip muscles, facial muscles, jaw closing muscles
  extrinsic tongue muscles

Question 6

describe an adult swallow compared to infant

Answer 6

adult
- jaw/tongue stabilised by jaw closing muscles
- teeth together
tip of tongue stable behind incisors

infant

• jaw/tongue stabilised by facial muscles
• gum pads apart
• tongue thrust

Question 7

describe the neural control of swallowing

Answer 7

• dorsal centre (pattern generator)
• ventral centre (relay)
• swallowing muscle motor -
  neurones and autonomic nerves
• swallowing muscles

Question 8

where does the initiating signal for swallowing come from?

Answer 8

peripheral nervous system

Question 9

describe reflex swallowing

Answer 9

peripheral nerves

• receptors at back of mouth and pharynx
• synapses mainly in nucleus of solitary tracts (dorsal swallowing centre)

Question 10

describe voluntary swallowing

Answer 10

• cerebral cortex
• related to sensory perception of bolus :

food particles small enough
bolus cohesive
enough taste extracted

Question 11

where is the swallowing center located?

Answer 11

medulla

• dorsal part; nucleus of the solitary tract
• ventral part: medial reticular formation

Question 12

what must the swallowing centre do?

Answer 12

• identify initiating signal as correct one for swallowing

- generates and send out appropriate signals to motor neurones to produce all or nothing swallow

Question 13

which cranial nerves are involved in the gag reflex?

Answer 13

IX
X
(Vth)

Question 14

what is the stimuli for GAG reflex?

Answer 14

mechanical at back of mouth/oropharynx

• soft palate
• tonsillar pillars
• base of tongue

Question 15

what does the CNS determine?

Answer 15

swallowing or gagging

and suppresses the other