1.3.1 Swallowing

Introduction

Swallowing is the process by which food moves from the mouth into the oesophagus and then towards the stomach. It is a complex action that involves several structures working together to ensure that food goes into the digestive tract and not into the airway. Swallowing begins as a voluntary action but quickly becomes involuntary once food reaches the back of the mouth.

Definition

Swallowing (also called deglutition) is the process by which food (in the form of a bolus) is moved from the mouth into the oesophagus and then down towards the stomach.

Main Idea

Swallowing involves a series of coordinated actions:

• The tongue pushes the bolus to the back of the mouth.
• The soft palate closes the nasal cavity.
• The larynx is pulled upward so that the glottis lies under the back of the tongue.
• The epiglottis prevents food from entering the glottis.
• The food is forced into and down the oesophagus by peristalsis.

The beginning of swallowing is voluntary, but once food reaches the back of the mouth, it becomes automatic (involuntary).

Core Concept

Why is swallowing important?

Swallowing serves two main purposes:

• Moves food from the mouth to the oesophagus — so that digestion can continue in the stomach.
• Prevents food from entering the airway — so that breathing is not blocked and food does not enter the lungs.

The body must coordinate breathing and swallowing to ensure that food and air go into their proper passages.

Detailed Explanation

The Process of Swallowing

In swallowing, the following actions take place:

(a) Tongue presses upward and back

The tongue presses upwards and back against the roof of the mouth, forcing the bolus to the back of the mouth.

Simple explanation: The tongue acts like a piston, pushing the food ball (bolus) towards the throat.

(b) Soft palate closes the nasal cavity

The soft palate (the fleshy part at the back of the roof of the mouth) closes the nasal cavity at the back.

Simple explanation: This prevents food from going up into the nose when you swallow.

Why this is important: Without this closure, food could enter the nasal cavity, causing choking and discomfort.

(c) Larynx is pulled upward

The larynx (voice box) cartilage around the top of the trachea is pulled upwards so that the glottis (opening of the trachea) lies under the back of the tongue.

Simple explanation: The larynx moves up to get out of the way and to allow the epiglottis to cover the airway.

(d) Epiglottis prevents food from entering the glottis

The epiglottis (a flap of cartilage) helps to prevent the food from entering the glottis instead of the oesophagus.

Simple explanation: The epiglottis acts like a lid that covers the opening of the trachea (windpipe) so that food goes into the oesophagus (food pipe) and not into the airway.

Why this is important: If food enters the glottis, it can block the airway and cause choking.

(e) Food is forced into and down the oesophagus by peristalsis

The beginning of the swallowing action is voluntary, but once the food reaches the back of the mouth, swallowing becomes an automatic or involuntary action. The food is forced into and down the oesophagus by peristalsis.

Simple explanation: Once the food reaches the back of the throat, you cannot stop the swallowing process. The muscles of the oesophagus automatically push the food down towards the stomach.

Intermediate Level

Swallowing is a coordinated process involving several structures:

The process begins as a voluntary action (you decide to swallow) but becomes involuntary once the food reaches the back of the mouth. This ensures that swallowing continues automatically and food does not get stuck.

Important Points

• - Swallowing is also called deglutition.
• - The bolus is the small, slippery, spherical mass of chewed food.
• - The tongue presses upward and back to force the bolus to the back of the mouth.
• - The soft palate closes the nasal cavity during swallowing.
• - The larynx is pulled upward so that the glottis lies under the back of the tongue.
• - The epiglottis prevents food from entering the glottis (trachea).
• - The beginning of swallowing is voluntary; once food reaches the back of the mouth, it becomes involuntary.
• - Food is forced into and down the oesophagus by peristalsis.
• - The pharynx is a common passage for food and air.
• - The epiglottis acts as a switch between the food pipe and the windpipe.

Remember

• - Swallowing = deglutition
• - Bolus = chewed food ball
• - Tongue pushes bolus back
• - Soft palate closes nasal cavity
• - Larynx pulled upward
• - Epiglottis covers glottis
• - Peristalsis moves food down oesophagus
• - Voluntary → Involuntary

Common Mistakes

• 1. Thinking swallowing is completely voluntary.
• - The beginning is voluntary, but once food reaches the back of the mouth, it becomes involuntary.
• 2. Confusing the glottis and epiglottis.
• - Glottis = opening of the trachea.
• - Epiglottis = flap of cartilage that covers the glottis during swallowing.
• 3. Forgetting the role of the soft palate.
• - The soft palate closes the nasal cavity to prevent food from entering the nose.
• 4. Believing food goes down the trachea.
• - Food goes down the oesophagus. The epiglottis prevents food from entering the trachea.
• 5. Thinking the larynx moves downward.
• - The larynx is pulled upward during swallowing.
• 6. Mixing up peristalsis and swallowing.
• - Swallowing is the act of moving food from mouth to oesophagus.
• - Peristalsis is the wave of muscular contraction that moves food down the oesophagus.

Quick Revision

60-Second Revision

• Swallowing = process of moving food from mouth to oesophagus
• Bolus = chewed food ball
• Tongue pushes bolus to back of mouth
• Soft palate closes nasal cavity
• Larynx pulled upward
• Epiglottis covers glottis (prevents food from entering trachea)
• Peristalsis moves food down oesophagus
• Voluntary → Involuntary (begins voluntary, becomes involuntary)
• Warning: Do not confuse glottis (opening of trachea) with epiglottis (flap that covers it).