**3.1 The phases of the swallow**

#### *3.1.1 Pre-oral phase*

Simply described, the swallowing process starts when we transfer food from the plate to the mouth (**Figure 2**). This phase is negatively affected when postural control or arm and hand motility are reduced, possibly after stroke [17].

### *3.1.2 Oral phase*

The oral phase (**Figure 2**) starts when we close our lips, chew, reduce the food to manageable pieces and mix it with saliva. As the food is formed into a bolus the tongue's backward and upwards movements propel it towards the pharynx, at the same time the floor of the mouth rises. And then immediately before the swallowing reflex is triggered we press our lips together creating a low pressure in the mouth. This activity normally takes up to 10 seconds [5]. The decrease in pressure in the mouth eases the transport of the food mixture from the mouth to the pharynx.

The phases employ a mixture of voluntary and involuntary commands*.*

**Figure 2.** *The four phases of the swallowing process.*

*Introducing IQoro: A Clinically Effective Oral Neuromuscular Treatment for Dysphagia DOI: http://dx.doi.org/10.5772/intechopen.101144*

### *3.1.3 Pharyngeal phase*

Once the bolus has passed the anterior palatal arch towards the pharynx, the swallow reflex takes over. This is controlled by the brain stem no longer consciously controlled as the pre-oral and oral phases were. The interplay between the voluntary and involuntary processes is described in the following section on the neurology of the swallow.

A normal swallow requires a balance between the infrahyoid and suprahyoid muscles to stimulate the swallowing reflex [20, 26].

In a later section "The neurology of the swallow" we will see that these muscles are triggered by the following nerves - Infrahyoidal muscles: CN XII hypoglossus.

– Suprahyoidal muscles: CN VII facialis, CN V trigeminus, CN XII hypoglossus.

**Middle illustration: A Functional swallow** is prepared when the hyoid bone is pulled backward and upwards (red arrow) by the styloid muscles (CN VII) and the posterior part of the digastric muscles (CN VII), at the same moment as the tongue base retracts.

The swallow reflex is then triggered when the hyoid bone is pulled forwards and upwards (blue arrow) by the digastricus anterior abdomen (CN V), m. mylohyoideus (CN V), and m. geniohyoideus (CN XII). At the same moment, a breathing suspension is caused as the epiglottis closes the laryngeal air pathway, and tongue forward movement is initiated. The chewing muscles are active throughout the swallow.

**Left illustration: A dysfunctional swallow.** If the chewing muscles are weak, the patient cannot lift his lower jaw and close his lips fully, which hinders swallowing. At the same time, the lower muscle groups of the tongue pull the hyoid bone downwards, which further degrades swallowing ability. The same thing happens when grinding the teeth.

**Right illustration: A dysfunctional swallow.** When the head falls backward, because of impaired head control, the mouth opens spontaneously and the equilibrium of the hyoid bone is completely upset, resulting in swallowing difficulties.

The pharyngeal phase (**Figures 2**–**4**) is a critical part of the swallow controlled purely reflexively and takes between 0.5 and 1 second. It requires a precise interplay between breathing and swallowing functions [5, 13]. When the bolus is to be swallowed, the tongue moves it back towards the anterior palatal arch and the

**Figure 3.** *Functional and dysfunctional swallow.*

#### **Figure 4.**

*The pharyngeal phase - a critical phase requiring coordination of swallowing and breathing.*

smooth palate which seals against the nasal passages. The larynx raises reflexively, and the tongue starts its forward movement.

The first of four security levels to prevent aspiration of food or drink is now activated. The constrictor muscles: *Constrictor pharyngeus superior*, *Constrictor pharyngeus middle*, *Constrictor pharyngeus inferior* contract [27]. The last of these is also known as the UES [28]. The second level is achieved when the epiglottis closes over the trachea or air pathway. The third and fourth levels are executed as first the false vocal cords close, and then the true vocal cords themselves.

There is perhaps more crossover in dysfunction in the different phases than is often thought. Misdiagnosis is a risk when healthcare professionals concentrate too much on their own specialities without considering a more holistic approach.

For example:


*Introducing IQoro: A Clinically Effective Oral Neuromuscular Treatment for Dysphagia DOI: http://dx.doi.org/10.5772/intechopen.101144*

in many cases to start treating for a Hiatal hernia as soon as stroke has been ruled out.

### *3.1.4 Esophageal phase*

The esophageal phase (**Figure 2**) concerns the movement of food and drink from the esophagus down to the stomach. The esophagus' longitudinal musculature is activated, forming a stiff pipe and allowing the entrance to the Upper Esophageal Sphincter (UES) to relax and open to allow the passage of the bolus into the esophagus. At the same time, the Lower Esophageal Sphincter (LES) opens to allow the entrance of the bolus to the stomach [5, 29]. This phase takes around 7 seconds to complete.

As well as the outer longitudinal layer of muscles, the esophagus also has an inner layer of circular muscles. To transport the food down to the stomach, these circular muscles produce coordinated peristaltic wave motions - this explains why we can swallow even if we were hanging upside down.
