Normal Swallow

Question 1

What is the role of the Trigeminal Nerve in swallowing?

Answer 1

S: sensation to tongue, teeth, gums, palate, lip, cheek + proprioception of muscles of mastication

M: control muscles of mastication. Tenses velum, assists nerve IX to elevate larynx

Question 2

Which nerve is responsible for the muscles of mastication?

Answer 2

Trigeminal Nerve (V) proprioception (sensory) and motor innervation (mandibular branch only)

Question 3

What nerves are involved in elevating the larynx?

Answer 3

Trigeminal (V) and glossopharyngeal (IX)

Question 4

Which nerve provides sensation to the oro and nasopharynx?

Answer 4

Trigeminal (V) and Facial (VII)

Question 5

What is the role of the Facial Nerve (VII) in relation to swallowing?

Answer 5

S: tastebuds on anterior 2/3 tongue, nasal and palatal sensation + proprioception of facial expression muscles

M: muscles of facial expression Parasympathetic: submandibular and sublingual salivary glands

Question 6

How are the salivary glands innervated?

Answer 6

Facial Nerve (submandibular and sublingual) and Glossopharyngeal (parotid)

Question 7

How are the muscles of facial expression innervated?

Answer 7

Sensation to the face = Trigeminal nerve

Proprioception & motor innervation = Facial nerve

Question 8

What is the role of the glossopharyngeal nerve in relation to swallowing?

Answer 8

S: tastebuds posterior 1/3 tongue, sensation & proprioception of pharynx muscles

M: pharyngeal constriction with vagus nerve, elevation & anterior movement of larynx

Secretion saliva (parotid)

Question 9

which nerves are involved in pharyngeal constriction?

Answer 9

Glossopharyngeal and Vagus nerve

Question 10

What is the role of the vagus nerve in relation to swallowing?

Answer 10

S: proprioception of velum & larynx

M: raises velum, contraction of pharyngeal constrictors, VF adduction for laryngeal closure, innervation of cricopharyngeus muscle, oesophageal stage, muscles of respiration

Question 11

Which nerve adducts the VF for laryngeal closure?

Answer 11

Vagus nerve

Question 12

Which nerve does proprioception of velum and larynx?

Answer 12

Vagus nerve

Question 13

What is the innervation for tensing and raising the velum?

Answer 13

Vagus and Accessory nerve

Question 14

True or false: the accessory nerve is both sensory and motor

Answer 14

False: only motor

Question 15

Describe the role of the accessory nerve in swallowing

Answer 15

tenses & raises the velum with vagus, depresses velum, constricts pharynx, muscles for movement of head & neck

Question 16

Which nerve is responsible for movement of head and neck?

Answer 16

Accessory nerve

Question 17

What is the role of the hypoglossal nerve in swallowing?

Answer 17

Motor control of intrinsic and extrinsic tongue & infrahyoid muscle.

Question 18

What are the stages of the swallow?

Answer 18

Pre-oral anticipatory stage, oral prep, oral, pharyngeal, oesophageal

Question 19

Describe the pre-oral anticipatory stage of the swallow

Answer 19

Prior to food contacting oral cavity - it is the interaction of pre-oral motor, cognitive psychosocial and somatoesthetic elements of mealtime. It is thoughts, smell, mouth watering, stomach rumbling, recognition of food (idea of what it would feel like, taste like, smell like), appetite, etc.

Question 20

What are the structures involved in the oral prep stage?

Answer 20

• Lips = obicularis oris (innervaed by facial nerve)
• tongue = anterior 2/3 tongue, extrinsic (trigeminal except hypoglossal for geniohyoid) and instrinsic (hypoglossal innervation) muscles
• teeth & jaw
  
  • temporalis, masseter & medial pterygoid muscles (trigeminal) = mandibular closure & grinding
  • lateral pterygoid & anterior belly of digastric = jaw opening (CNV)
• cheek = buccinator (CNVII)
• salivary glands = facial & glossopharyngeal innervation

Question 21

What changes in the swallow when there is a larger volume of food/fluid in oral cavity?

Answer 21

Tongue subdivides the amount – either holding some back in tongue for liquids or moving to cheek for solids in order to work only part of mouthful into a bolus for swallowing

Question 22

How does oral prep for solids and liquids differ?

Answer 22

Solids

• tongue moves bolus to molars
• crushing, rotary movement of jaw masticates bolus
• chewing (plus cortical awareness) stimulates release of saliva from glands
• saliva mixed with bolus until correct wetness for swallow
• During chew = velum in normal resting position away from tongue (premature spillage normal)
• Bolus pulled together = velum pulled down and forward to approximate against base of tongue to seal off oral cavity from pharynx

Liquids

• momentary containement of bolus
  
  • tippers = fluid held in middle of tongue and hard palate with tongue tip elevated and against alveolar ridge
  • dippers = held in floor of mouth in front of tongue
• while held = base of tongue is raised and velum pulled down and forward towards base of tongue

Question 23

What is the sensory feedback from oral prep stage?

Answer 23

• info received from receptors in teeth, tongue, gums, palate
  
  • temp & mechanical = trigeminal
  • taste ant 2/3 = facial; post 1/3 - glossopharyngeal
• this info sent to brainstem –> integrated in nucelus tractus solitarius of medulla + cortical control = impacts duration of oral prep

Question 24

What are the key structures of the oral stage?

Answer 24

• Instrinsic muscles of tongue - change shape of tongue to form groove for bolus
• extrinsic muscles - digastric (CNV), mylohyoid (CNV), and geniohyoid (CNXII) –> allow tongue to propel bolus backwards & elevate hyoid superiorly & anteriorly

Question 25

What is the difference in liquids and solids for the oral phase?

Answer 25

Liquids = less pressure to propel into phaynx

Solids = thicker require increased pressure of tongue against hard palate to propel efficiently into pharynx. This is assisted by pressure contribution of buccal muscles (inwards & tensing)

Question 26

What happens in the oral phase of the swallow?

Answer 26

Begins after bolus is prepared and ends with “trigger” of swallow

• posterior propulsion of bolus by tongue into oropharynx and then into hypopharynx
  
  • bolus held in groove w. lateral sides of tongue against teeth
  • lips & buccal muscles contract + velum elevates to close off nasopharynx
  • posterior of tongue depresses and anterior tongue presses against hard palate to propel bolus backwards (stripping action)

Question 27

When is the commencement of the pharyngeal stage?

Answer 27

VFSS = bolus head reaches where tongue base crosses mandible

FEES = bolus passes around epiglottis or reaches the lateral channels