deglutition

Question 1

oral cavity boundaries

Answer 1

anterior - oral vestibule
posterior - palatoglossal arch

Question 2

mandibular depressor muscles

Answer 2

lateral pterygoid (CN V - third division)
digastric (ant. belly) (CN V - third division)
mylohyoid (CN V - third division)
geniohyoid (cervical plexus - C1)

Question 3

mandibular elevator muscles

Answer 3

masseter
temporalis
medial pterygoid
all innervated by trigeminal (CN V - third division)

Question 4

how do the muscles of the tongue help with swallowing of the bolus

Answer 4

intrinsic create a trough in the tongue
extrinsic elevate the tongue - tongue touches the palate
to create a downward slope

Question 5

main muscles of mastication

Answer 5

lateral pterygoid
medial pterygoid
masseter
temporalis

Question 6

how does salivation aid deglutition

Answer 6

chemical digestion
soften food forming bolus

Question 7

what nerve innervates the muscles of the tongue

Answer 7

hypoglossal (CN XII)

Question 8

what does activation of the glossopharyngeal nerve lead to

Answer 8

activation of vagus nerve (CN X)

Question 9

how do we prevent food entering the nasal cavity?

Answer 9

vagus nerve stimulates uvula to contract to block the nasopharynx
levator veli palatinei contracts to pull up the soft palate
trigeminal nerve innervates tensor veli palatinei, elevating the soft palate even more

Question 10

how do we prevent food entering the larynx?

Answer 10

lateral cricoarytenoids and transverse arytenoids contract, adducts the vocal cords
retroversion of epiglottis

Question 11

how do we make sure food goes into the pharynx?

Answer 11

palatoglossus contracts to squeeze bolus into next segment
palatopharyngeus contracts and squeezes bolus down into the pharynx
outer longitudinal layer elevated the pharynx and elevate the larynx (innervated by vagus nerve)
inner circular layer (pharyngeal constrictors) - muscles undergo peristalsis
larynx elevated and moves anterioly due to suprahyoid muscles

Question 12

what does the cricopharyngeus do?

Answer 12

innervated by CNX (vagus), relaxes due to peristaltic mechanism, allows bolus to move into oesophagus. main muscle in the upper oesophageal sphincter

Question 13

primary peristalsis is a continuation of ….

Answer 13

pharyngeal peristalsis

Question 14

what happens when food gets ‘stuck’?

Answer 14

stretches the walls of the eosophagus, activating stretch receptors
this stimulates secondary peristalsis through myenteric plexus