Swallowing

The act of swallowing is a complex process which serves to transport food and saliva as from the oral cavity to the stomach that the airways remain protected while.

The act of swallowing is first prepared arbitrarily. By irritation of the tongue reason the swallowing reflex is triggered, which are beyond the subsequent processes of intentional influence. Act of swallowing impairments are referred to as dysphagia.

Anatomy and Physiology

Average occurs in humans daily 1000-3000 swallows ( in the sleep phase much less frequently than in the wax phase ).

On swallowing the anatomical structures of the oral cavity and their limitations, pharynx, and larynx, esophagus and stomach are involved. Is coordinated by the interaction of the involved 26 pairs of muscles by the swallowing center in the brainstem and higher cortical centers and suprabulbäre.

The five pairs of cranial nerves are involved

• Trigeminal nerve
• Facial nerve
• Glossopharyngeal
• Vagus nerve
• Hypoglossal nerve

The involved three cervical nerves originate from the segments C1 to C3.

The function of the swallowing process consists not only in the transport of the food bolus into the stomach, but also serves to clean the esophagus, in particular the eradication of got into the esophagus stomach acid. The increased nocturnal symptoms in reflux disease can thus be attributed to the decreased frequency of swallowing activity partly at night.

The sip size varies greatly and depends on the type of food. About 20 g of aqueous chyme or a maximum of 40 ml liquid ( hasty drinking ) can be added per sip. ( To provide a frame of reference: A soup spoon contains 10 ml )

Over dinner, sip duration depends on how well it is chewed and mixed with saliva to the bite. The time of passage through the esophagus is about 8-20 seconds.

Individual phases

The act of swallowing in the narrower sense consists of three transport phases. Equally important, however, is what happens before - especially in the solid feed intake. Thus, the following classification is made: one preparatory phase close to the mouth, the pharynx and the esophagus eventually phase:

Oral preparatory phase

With the oral preparatory phase, those operations are summarized, which precede the actual swallowing process and enable them only. A food morsels must first be sufficiently small to chew so that it can only sufficient. The crushed food is mixed with saliva and lubricated. Precondition thus the undisturbed function, among others, lips, teeth and periodontium, TMJ and masticatory muscles and the tongue and salivary glands.

Ultimately, creating a large bolus 5-20 ml.

Oral transport phase

This phase is subject only to the part of arbitrary control: While it may be chewed with his mouth open, his lips are now closed to avoid a loss of saliva and the swallowing of air ( aerophagia a ); the cheek muscle is tense. The tongue is pressed to start the swallowing process against the hard palate - this thus serves as an abutment - and the bolus with a rear-facing undulating movement (supported by Musculus styloglossus and muscle hyoglossus that pull the tongue like a punch to the back) on the throat tightness pushed into the throat.

The swallowing reflex is not triggered until the base of tongue or posterior pharyngeal wall can be touched by the bolus. From this point, the subsequent process can be influenced nurmehr partially or following a swallowing training.

Pharyngeal transport phase

In this phase, both the upper and the lower airways are sealed to prevent passage of the chyme into the nose or swallowing:

• The soft palate is tight and raised to prevent passage of the chyme in the upper airways. This is ensured by the " tensioner and lift the soft palate " ( tensor veli palatini and levator veli palatini ). Both muscles will also be expanding the Eustachian tube ( auditory tube ), which explains why there is an equalization of pressure between the middle ear and a different external pressure during swallowing. This can be deliberately exploited during rapid changes in the ambient pressure (aircraft takeoff, landing ).
• The upper pharynx (musculus pharyngeal constrictor superior, more precisely, its pars pterygopharyngea ) contracts and forms the so-called Passavant- torus, to which the velum port, so that the closure of the upper airway is now complete and get no more food in the nose can.

• It comes to the closing of the vocal folds
• The epiglottis ( epiglottis ) is lowered by the base of the tongue ( with the help of the musculus aryepiglotticus )
• The muscles of the floor of the mouth shrinks; Larynx and hyoid bone stand out to about 2 cm, which is keyed and well - at least in men - can also be seen clearly. These so-called " laryngeal elevation " is the Musculi mylohyoid, digastric and stylohyoid (these raise the hyoid bone ) and the thyrohyoid muscle (which the larynx ) are supported.

With the higher- stepping of the larynx, two things happen simultaneously:

• Epiglottis and larynx approaching - and so are the lower airways now 3 -fold protected
• The upper esophageal sphincter (the upper esophageal sphincter or esophageal sphincter ) opens. Thus, the food bolus is the way for further transport free.

By contraction of the middle and lower pharynx ( pharyngeal Musculi constrictores medius and inferior ) above the bite this direction esophagus is transported and injected into this.

Oesophageal transport phase

After entry of the bolus into the esophagus, the sphincter closes again. This represents a further airway closure is no longer useful and they are opened again. In the upright position of the bolus slips through the esophagus to the stomach, esophageal peristalsis can the bolus but also against gravity ( headstand ), or further promote lying down. The cardia opens; after entry of the bolus into the stomach, this closes again and the act of swallowing is completed.

Swallowing and age

During pregnancy, the amniotic fluid volume is regulated to a large extent by the fetus itself: After the 15th week of pregnancy, he can drink amniotic fluid - at the end of pregnancy approximately 400 ml daily. Thus, the amount of amniotic fluid is present next to an undisturbed micturition ( urination ), particularly of an undisturbed swallowing dependent.

In newborns, the larynx is much higher in the throat than later, so that the infant can breathe and drink even one time without choking. The epiglottis is higher than the base of the tongue and the food thus enters the recess pyriform both sides of the larynx into the esophagus. The infant may therefore breathe simultaneously through the nose and drink by mouth. However, this prevents the formation of complex sounds such as vowels, which are essential for learning a language, since the throat is too small .. Therefore, the larynx lowers after about three months, the throat is larger. From then on, the infant can not only learn to speak, but (in theory) also snore.

The healthy old man has no dysphagia. The ratios do not differ materially from those described here.

Diagnostics

The diagnosis of dysphagia has been significantly expanded with the Videokinematographie the act of swallowing. In a suspected presence of dysphagia is a comprehensive clinical swallowing examination by speech therapist / speech therapist done ( history, examination of the structures involved in swallowing including cranial nerve status, swallowing tests). The most important grading techniques for detection of cause, type and severity of dysphagia are the Videofluroskopie ( Videofluoroscopic Swallowing Study; VFSS ) and the video endoscopy of swallowing (Flexible Endoscopic Evaluation of Swallowing; FEES).