Physiology of Pharynx/Esophagus

Question 1

Swallowing

Answer 1

Process by which food and water is transported from the mouth to the stomach
- entire process is about half the length of the body

Question 2

Anatomic phases of swallowing

Answer 2

Oral phase
- oral stage (voluntary control)
- pharyngeal stage (autonomic)
- cricopharyngeal stage (seals top of esophagus)
Esophageal phase
- primary peristalsis (triggered by swallowing)
- secondary peristalsis
Gastroesophagel phase

Question 3

Pharynx

Answer 3

• nasopharynx
• oropharynx
• laryngopharynx

Question 4

What two portions of the pharynx are divided by the soft palate

Answer 4

Nasopharynx and oropharynx

Question 5

What are the 4 pathways food can take?

Answer 5

• nasopharynx (bad)
• reguritating
• laryngopharynx (bad)
• oropharynx (good)

Question 6

Functional phases of swallowing

Answer 6

Preparatory phase: licking, chewing (voluntary)
- oral cavity
Transfer phase: getting food from oral cavity to pharynx (fast)
- oral cavity and pharynx (40 cm/sec)
Transport phase (transport food from esophagus to stomach)
- esophagus (3-4 cm/sec)

Question 7

Masticatory and facial muscles

Answer 7

• muscles of mastication: trigeminal nerve (5)

- muscles of facial expression: facial nerve (7)

Question 8

Muscles of the tongue

Answer 8

Hypoglossal nerve (12)

Question 9

Muscles of the pharynx

Answer 9

Cranial nerves (9, 10, 11)

• 9 and 11 only serve the pharynx
• 10 serves all phases of swallowing

Question 10

Muscles of the larynx

Answer 10

Recurrant laryngeal nerve, a branch of vagus (10)

Question 11

Adduction

Answer 11

Closing of the larynx during swallowing

• vagus supplies the pharynx, larynx, and esophagus and both sphincters
• vagus is predominantly involuntary

Question 12

What functional phases of swallowing involve the involuntary swallowing reflex

Answer 12

Transfer and transport phase

Question 13

What nerves are involved in the preparatory phase

Answer 13

5, 7, 12

Question 14

Upper esophageal sphincter

Answer 14

Cricopharyngeal muscle

• striated skeletal muscle
• is a highly tight sphincter, only opens when you need it

Question 15

Lower esophageal sphincter

Answer 15

Not a true sphincter in dogs and cats

• considered a physiological sphincter
• gravity alone will drop food into stomach in dogs and cats due to lateral positioning

Question 16

Species differences of the esophagus

Answer 16

Canine
- straited muscle along entire length
- Ach as neurotransmitter and nicotinic receptors
Feline
- proximal 2/3 striated muscle
- distal 1/3 smooth muscle
- muscarinic and parasympathetic nerve supply, Ach is still receptor

Question 17

Primary peristalsis

Answer 17

Reflex peristaltic contraction wave associated with pharygeal phase of swallowing

Question 18

Secondary peristalsis

Answer 18

Reflex peristaltic contraction wave triggered by residual food in the esophagus