Swallowing

Mastication is the process of...

preparing food for swallowing

Deglutition (Swallowing) is the process of...

moving the bolus from the mouth to the stomach

What is a Bolus?

"A masticated morsel of food or another substance [e.g., liquid] ready to be swallowed

What is Laryngeal penetration?

The entry of material into the laryngeal vestibule, but not below the level of the vocal folds (Where is the laryngeal ventricle?)

What is Aspiration?

The entry of material into the airway below the level of the vocal folds

The Aerodigestive tract has...

Shared pathways for respiration and swallowing
a. includes oral cavity, pharynx, larynx, and upper esophagus

What are the structures of the Aerodigestive tract?

important structures include the lips; tongue; mandible; velum; pharyngeal walls; epiglottis, vocal folds, and ventricular folds; and upper esophageal sphincter

What is the esophagus? (Figure 7-2)

The tube-like structure of the digestive tract that connects the pharynx to the
stomach.

What is the upper end of the esophagus leveled with?

The upper end of the esophagus is leveled with the lower level of the cricoid cartilage of the larynx

What is the esophagus located behind?

The esophagus is located behind the trachea and the heart; it passes through an opening through the diaphragm and extends downward to the stomach.

What is a sphincter?

A set of muscle fibers that are arranged in a circular pattern to keep an opening, such as the esophagus, closed. There is a sphincter at the top and at the bottom of the esophagus.

The upper esophageal sphincter (UES) is also known as the...

pharyngoesophageal segment / PE segment

What is the UES thought to be composed of?

The cricopharyngeus muscle, which is part of the inferior pharyngeal constrictor.

What does the UES/ PE segment keep closed?

The upper esophageal sphincter (UES)/ pharyngoesophageal segment keeps the upper end of the esophagus closed; it opens, though, during swallowing.

What are the valleculae & pyriform sinuses and where are they located?

laryngopharynx?

Where is the lower esophageal sphincter is located?

At the lower end of the esophagus where it enters the stomach; remains closed, except when swallowing, to prevent stomach contents from flowing back into the esophagus.

Muscle fibers in the walls of the esophagus

Muscle fibers in the walls of the esophagus

From the upper end of the esophagus to the lower end, the muscle fibers change from...

striated (voluntary) muscles to smooth (involuntary) muscles.

What do muscle fibers in the walls of the esophagus contribute to?

They contribute to *peristalsis*, the sequential, wave-like contractions that push the bolus down to the stomach.

Note oral, pharyngeal, and laryngeal structures pertinent to mastication and swallowing (Figs. 4-3, 4-4, 4-5; 7-2, 7-4)

Lips, teeth, hard palate, velum tongue, mandible, pharynx, larynx (epiglottis, vocal folds, cricoid cartilage, valleculae, esophagus. Hard palate, velum, tongue, larynx, pyriform sinus, pharyngeal walls (especially the cricopharyngeal muscle), esophagus, valleculae, vocal folds, ventricular folds, epiglottis, aryepiglottic folds. Lips, teeth, hard palate, velum, fauces, faucial pillars, tongue

What are the four phases of swallowing?

1. Oral preparatory phase
2. Oral transport phase
3. Pharyngeal phase
4. Esophageal phase

What is the first phase of swallowing?

Oral preparatory phase: "The stage in which food is prepared for swallow."
Sennett's definition: Preparation for swallowing—food is chewed and mixed with saliva to prepare it to be swallowed and digested.

What keeps food in the oral cavity?

*Anterior and posterior seals*

During the oral preparatory phase, what does the *anterior seal (lip seal) involve closure of?

It involves *closure of the lips* during the oral
preparatory phase. Closure of the lips is maintained until the esophageal phase begins. (Lip seal begins just prior to the next phase in some people.)

What muscles of the lips maintain closure?

The *orbicularis oris muscle and mentalis muscle*

What is the cranial nerve innervation that controls facial movement?

Facial nerve (VII/7)

What does the *posterior seal* involve closure of?

Involves *closure of the fauces* by continuous contact of the *velum and the back of the tongue.*

The velum is lowered by the...

*palatoglossus muscle*

Cranial nerve innervation for most muscles of velum:

*vagus nerve (CN X/10)*

The muscles that bunch up the back of the tongue to contact the velum are...

Palatoglossus and styloglossus muscle

What is the cranial nerve innervation for most muscles of the tongue?

hypoglossal nerve (CN XII/12)

How can mandibular muscles move the mandible?

They can raise, lower, lateralize, protrude (underbite, crimson chin) and retract (overbite, no chin)

Mandibular muscles move the mandible to...

chew (masticate) the food.

What are the elevators (raise, lift up) of the mandible?

*masseter, temporalis, medial pterygoid.*

What are the depressors (lower, pull down) of the mandible?

*lateral ptyerygoid, anterior belly of digastric, mylohyoid, geniohyoid.*

What is the cranial nerve for most mandibular muscles?

Trigeminal nerve (Cranial nerve V/5)

What are the lingual muscles?

Intrinsic and extrinsic muscle.

Intrinsic muscle:

superior longitudinal, inferior longitudinal, transverse,
vertical muscles

Extrinsic muscle:

primarily the genioglossus muscle

These lingual muscles move food over grinding surfaces of the teeth.

Occlusal - the chewing or grinding surface of the bicuspid and molar teeth.

What is the cranial nerve innervation for most muscles of the tongue?

hypoglossal nerve (Cranial nerve XII/12)

What are the facial muscles in the buccal walls?

Buccinator & risorius muscle

Buccal (toward the cheek)

the tooth surface which is next to your cheeks.

These facial muscles in the buccal walls compress the cheeks against the teeth to...

prevent food from leaking into buccal cavity (lateral sulcus).

What is the cranial nerve innervation that controls facial movement?

Facial nerve (Cranial nerve VII/7)

What is saliva?

a mixture of serous fluid, mucous, and enzymes that helps to moisten the food and break down its starches, which is secreted into the mouth through salivary ducts.

What three pairs of salivary glands produce saliva?

the parotid glands, the submandibular glands, and the sublingual glands.

The parotid glands

superficial (closer to surface of the body) to the ramus of the mandible and the masseter muscle

The submandibular glands

deep to the mylohyoid muscle, along the inner surface of the mandible

The sublingual glands

along the inner surface of the mandible, above the submandibular glands.

*Saliva is secreted* into the mouth to

moisten the food and to begin the
breakdown of food starches (Fig. 7-5)

What is the second phase of swallowing?

Oral Transport Phase (Figure 7-7): "The stage of swallow in which the bolus is transmitted to the pharynx."

Several processes occur to move the bolus to the...

back of the oral cavity

a. Respiration ceases/stops (apneic interval begins)

i. Typically, inhalation occurs just prior to the beginning of this phase.
ii. Respiration stops before exhalation.

b. Mastication stops with the

*mandible elevated*(raised, lifted up)

c. The front of the tongue elevates to contact the hard palate;

the tongue progressively elevates to the palate from front to back to squeeze the bolus toward the pharynx.

d. The *base of the tongue lowers* as the

bolus moves back.

*Mandibular elevators* maintain mandible in an

elevated position.

Front of tongue is raised to contact the...

hard palate.

Mylohyoid muscle elevates the...

floor of the mouth & tongue

Superior longitudinal muscle elevates the...

tongue tip & rest of tongue sequentially.

Tongue then "squeezes" the bolus toward the...

oropharynx.

The *palatoglossus* which had kept the back of the tongue, and the velum together, begins to...

relax

The base of the tongue lowers,

It's depressors: *hyoglossus, genioglossus muscles*

During the Oral transport phase, *the lips are firmly closed* and the cheeks are...

pressed
inward to keep the food in the oral cavity proper.

What is the third phase of swallowing?

Pharyngeal Phase: "The stage of swallow in which the bolus is transmitted to the esophagus; involves numerous protective responses."

The pharyngeal phase *begins* when the bolus contacts the...

*anterior faucial pillars*

The pharyngeal phase *ends* when the bolus reaches the...

*upper esophageal sphincter* at the top of the esophagus.

The swallow becomes reflexive when the bolus reaches the...

faucial pillars and it continues being a reflexive process during the next phase, as well.

(Pharyngeal phase processes)
a. The *velopharyngeal port is sealed* as the velum elevates and a broad portion of the

upper lateral pharyngeal walls constrict to seal the velopharyngeal port.

b. Respiration must cease/stop

(this usually happens at the end of the oral preparatory phase and/or beginning of the oral transport phase)

The lower airway is protected by

(a) tight adduction of the vocal folds and the ventricular folds
(b) depression of the epiglottis, which is pulled down to close the laryngeal aditus.

c. Larynx is pulled up and forward — the result is:

i. to force the epiglottis downward to close over the additus (i.e., the passage into the larynx)

ii. To relax the

upper esophageal sphincter (the cricopharyngeus ms.)

d. As the bolus finishes moving past the fauces,

*the faucial pillars* constrict to close off the oral cavity from the pharynx

e. The *pharyngeal constrictors sequentially contract* to...

squeeze the bolus down to the esophagus (superior, middle, & inferior constrictors)

*Velum elevates* and tenses, and *the pharyngeal walls*

constrict to *direct bolus downward.*

a. What muscles are involved in elevating the velum and tensing the pharyngeal walls?

Levator palatini muscle & superior pharyngeal constrictor muscle

a. What is the cranial nerve innervation for most muscles of velum?

Vagus nerve. Cranial nerve 10/ X

b. Velopharyngeal closure is more forceful and extensive for

swallowing than for speech.

*Laryngeal valves close to...*

*prevent bolus from being aspirated into the lungs*

a. *Vocal folds tightly adduct & shorten*—

*thyroarytenoid, lateral cricoarytenoid & interarytenoids*

Cranial nerve innervation of vocal folds:

Vagus nerve. Cranial nerve 10/ X

b. *Ventricular folds (i.e., false vocal folds) adduct* as a result of...

the strong adduction force on the vocal folds

c. *Epiglottis lowers & inverts*—

(i) the *base of the tongue moves downward* at the same time the *larynx is pulled upward*, which forces the epiglottis downward into an inverted position
(ii) *aryepiglottic muscle also pulls downward on the epiglottis.

The *hyoid bone and larynx are pulled... (This action helps (a) to move the epiglottis downward and (b) to relax the components of the upper esophageal sphincter (UES) (including the cricopharyngeus ms.)

*upward and forward as a unit.*

What does this action help the epiglottis do?

This action helps to move the epiglottis downward.

What does this action help relax?

This action helps to relax the components of the *upper esophageal sphincter (UES)* (including the cricopharyngeus muscle)

What are the laryngeal elevators?

mylohyoid, geniohyoid, digastric

*Faucial pillars move medially to...*

prevent food from reentering oral cavity.

What muscles help the faucial pillars move medially?

Palatoglossus and palatopharyngeus muscle

*Pharyngeal constrictor muscles sequentially constrict the pharynx* and...

force the bolus downward into the esophagus.

What are the pharyngeal constrictor muscles?

superior, middle, and inferior pharyngeal constrictor muscles

What relaxes and opens to allow the passage of the bolus into the esophagus?

The upper esophageal sphincter (UES)

Exhalation continues (Fig. 7-10)

Exhalation continues (Fig. 7-10)

When the bolus reaches the level of the epiglottis, it tends to divide and flow to either side over the

*epiglottic valleculae* and slide down through the *pyriform sinuses* (spaces on either side of the larynx, between the aryepiglottic folds and the thyroid cartilage).

As people age, the reflexive onset for the pharyngeal swallow becomes...

delayed; the trigger moves further back toward the esophagus.

What is the fourth phase of swallowing?

Phase 4: Esophageal Phase (Fig. 7-7): "The stage of swallow in which food is transported from the upper esophageal region to the stomach."

1. The esophageal phase *begins* as the bolus is passing through the...

upper esophageal sphincter (UES)

The esophageal phase *ends* when it passes through the...

lower esophageal sphincter, into the stomach.