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

**Figure 7.** *The sensory-motor reflex arc (level 1).*

In the brain stem (**Figure 7**) we find the Nucleus Tractus Solitarius (NTS): the afferent nucleus. The NTS is the core that gathers all incoming sensory signals via the afferent nerve pathways as described (**Figure 7**). The NTS then transmits the signals onwards either to the brain's cortex or directly to the network-like system in the brainstem called the Formatio Reticularis (FR). These efferent motor signals are transmitted to the musculature of the face, mouth, esophagus, diaphragm, down to the stomach, the intestines, and the rectum. The process by which the incoming sensory signals trigger afferent commands is known as the sensory-motoric reflex arc (**Figure 7**) [5, 25, 26, 29].

The three swallowing centers' interactions - from the brain stem to muscles. In the FR, the afferent signals from the NTS and the cortex (**Figure 7**) are first interpreted and then passed through various distribution nodes to the efferent nuclei: the Nucleus Ambiguus (NA), and the Nucleus Dorsalis Nervi Vagi (NDNV).

The NA (**Figure 7**) sends impulses to the skeletally striated musculature in the oral and pharyngeal regions; and the NDNV (**Figure 7**) to the smooth musculature of the esophagus and beyond. How these function during swallowing we will explain in more detail below.

In the FR there are three distribution nodes (swallowing centers) that are key to the swallowing process; as well as a number of other centers that control breathing, speech, chewing, coughing, vomiting, evacuation of the bowels and bladder, and those muscles that control the body's posture (**Figure 8**). [5, 25, 26, 29].

**Figure 8.** *The Formatio Reticularis (FR) is the control centre for a variety of vital functions.*

#### *Dysphagia - New Advances*

The Formatio Reticularis is the control centre for several vital functions including breathing, speech, chewing, coughing, vomiting, evacuation of the bowels and bladder, and those muscles that control the body's posture.

The incoming information is routed by the Nucleus Tractus Solitarius (NTS) in two pathways: some directly to the first of the three swallowing centers in the brain stem, whilst the remainder of the information continues upwards to the cortex to be processed before being also directed to the first swallowing center (**Figure 7**).

#### **4.3 The swallowing centers**

#### *4.3.1 First swallowing center*

If the combination of information received by the first swallowing center (**Figure 9**) from the NTS and from the cortex is interpreted as that something is to be swallowed, this instruction is sent to the second swallowing center.

#### *4.3.2 Second swallowing center*

The second swallowing center (**Figure 9**) transmits signals to the muscles via the motor nerves – the downward-transmitting efferent nerve pathways. Here, there is a pre-programmed "swallow / don't swallow" stereotypical muscle response.

If the food is to be swallowed, a command is sent to the NA, which in its turn sends the instruction via the efferent nerve pathways to the striated musculature in the oral and pharyngeal regions of the swallowing chain. Concurrently, impulses are also sent to the third swallowing center.

#### *4.3.3 Third swallowing center*

The third swallowing center (**Figure 9**) transmits information to the NDNV - an efferent nucleus and then onwards to the esophagus'smooth musculature to complete the swallowing action and to transport the bolus downwards to the stomach.

The three swallowing centers' interactions from the 2nd center to the striated muscles, and the 3rd center to the smooth muscles is illustrated here.

**Figure 9.**

*The sensory-motoric reflex arc (level 1–3).*

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

The 3rd swallowing center transmits information to the Nucleus Dorsalis Nervi Vagi (NDNV), and then onwards to the smooth muscles including those in the esophagus (**Figures 9** and **10**).
