Components of Swallow, Impairments, Causes, Observations, and Therapy

Abstract

Please check the hierarchy of the section headings and confirm if correct.

Introduction

This chapter will summarize in a tabular form the chief components of the swallow, the impairments, the causes and conditions of such swallowing dysfunction, the observations and findings on evaluation, and the suggested therapy strategies. The components of the swallow which are relevant in the dysphagia associated with head and neck cancers and its management, are lip closure, lingual control, mastication, tongue base retraction, velopharyngeal closure, hyolaryngeal excursion, laryngeal closure, pharyngeal contraction, and pharyngoesophageal segment (PES) opening (Fig. 31.1).

Fig. 31.1

Components of normal swallow. Schematic representation

Videos 31.1 and 31.2 (slow motion) and Fig. 31.2a–d show normal swallow on a lateral view VFS.

Fig. 31.2

(a–d) Steps of normal swallow

Lip Closure (Table 31.1)

This component is essential for the oral bolus containment and the generation of intraoral pressure to transport the bolus. The orbicularis oris seals the lips.

Table 31.1 Lip closure

Video 31.3 and Fig. 31.3 show poor lip seal.

Fig. 31.3

Poor lip seal

Lingual Control (Table 31.2)

This component is essential for shaping, holding, and manipulation of the bolus in the oral cavity. This is also essential for the anteroposterior bolus propulsion. The muscles of the tongue, both intrinsic and extrinsic, help in this function.

Table 31.2 Lingual control

Video 31.4 and Fig. 31.4 show poor lingual control in a total glossectomy.

Fig. 31.4

Poor lingual control in total glossectomy

Mastication (Table 31.3)

This component is essential for the preparation and manipulation of the bolus in the mouth so that it can be propelled back through the pharynx and esophagus. The masticator muscles, the temporalis, the masseter, and the medial pterygoids, help in elevating the mandible. The lateral pterygoids assist in the movement of the mandible side to side and a rotary pattern.

Table 31.3 Mastication

Video 31.5 and Fig. 31.5 show poor mastication in a segmental mandibulectomy.

Fig. 31.5

Poor mastication, segmental mandibulectomy

Tongue Base Retraction (Table 31.4)

This component primarily generates the positive pressure against the bolus and helps in the pharyngeal clearance and airway protection. The extrinsic muscles of the tongue help in the retraction of the tongue to get the tongue in contact with the posterior pharyngeal wall.

Table 31.4 Tongue base retraction

Video 31.6 and Fig. 31.6 show poor tongue base retraction and total glossectomy.

Fig. 31.6

Poor tongue base retraction, total glossectomy

Velopharyngeal Closure (Table 31.5)

This component is essential for the flow of the bolus retrograde into the nasopharynx. It is also needed for the generation of the pressure to drive the bolus downward. The levator veli palatini assisted by the tensor veli palatini and the musculus uvulae tenses, elevates, and retracts the soft palate against the posterior pharyngeal wall. This will separate the oral and nasal cavities.

Table 31.5 Velopharyngeal closure

Video 31.7 and Fig. 31.7 show poor velopharyngeal closure with nasal regurgitation.

Fig. 31.7

Poor velopharyngeal closure, nasal regurgitation

Hyolaryngeal Excursion (Table 31.6)

Hyolaryngeal excursion is necessary for the protection of the airway by facilitating epiglottic inversion over the laryngeal vestibule. It also helps in the upper esophageal sphincter opening that allows the bolus to enter the next stage. The suprahyoid musculature moves the hyoid anteriorly when the longitudinal pharyngeal muscles shorten and widen the pharynx. The thyrohyoid elevates the larynx to displace the epiglottis to a horizontal position.

Table 31.6 Hyolaryngeal excursion

Video 31.8 and Fig. 31.8 show infrequent hyolaryngeal excursion.

Fig. 31.8

Reduced hyolaryngeal excursion and poor opening of upper esophageal sphincter

Laryngeal Closure (Table 31.7)

Laryngeal closure happens at three levels (aryepiglottic, ventricular fold, and true cord). This closure is critical for the protection of the airway, respiration regulation, effective cough reflex, and voice production. The thyroarytenoid, the lateral cricoarytenoid, and the interarytenoid muscles approximate the arytenoid cartilages to close the true cords and approximate the ventricular folds. The styloglossus and the palatoglossus retract the base of the tongue to protect the vestibule.

Table 31.7 Laryngeal closure

Video 31.9 and Fig. 31.9 show penetration.

Fig. 31.9

Penetration

Video 31.10 and Fig. 31.10 show aspiration.

Fig. 31.10

Aspiration

Pharyngeal Contraction (Table 31.8)

This is required for pushing the bolus down through the pharyngeal cavity, into the esophagus. This occurs by squeezing the walls of the pharynx along with a stripping wave effect. The superior, middle, and inferior constrictors contract sequentially and cranio-caudally to create a positive pressure on the bolus.

Table 31.8 Pharyngeal contraction

Pharyngoesophageal Segment (PES) Opening (Table 31.9)

PES is also the upper esophageal sphincter (UES). It relaxes at the end of the pharyngeal phase of the swallow and allows the bolus to enter the esophagus. It then closes, preventing the reflux of the contents back into the pharynx and airway. The cricopharyngeus relaxes aided by the inferior pharyngeal constrictor. The suprahyoid and infrahyoid muscles and the longitudinal pharyngeal muscles elevate the hyolaryngeal complex to produce a traction.

Table 31.9 Pharyngoesophageal segment (PES) opening