SLHS 539 Exam 1

3 main components of eating

Feeding

Swallowing (mouth to stomach)

Digestion

Feeding involves…

Motivation and readiness for eating (saliva, movement, etc)

How food gets to correct place in mouth

The placement of food in the mouth

Interactions between feeder and patient/person who is eating

Swallowing is ….

A series of neurogenic sensorimotor events

* initiated by recognizing the presence (touch), taste, temperate, and viscosity of food/fluid in oral cavity
* Followed by the preparation to a consistency that can be swallowed
* Finalized by safe transportation through the oral, pharyngeal, and esophageal anatomic structures of the stomach

\
* Extremely fast, dynamic and complicated - 3 phases

Phases of swallowing

Oral (Prep and Transport)

Pharyngeal

Esophageal

* All phases controlled by the PNS and brain stem

What is dysphagia?

Any disruption in any of the 3 steps of swallowing (presence, preparation, and transportation

* always a symptom of another disorder or disease- what has **caused** the dysphagia

What does dysphagia mean for people who suffer?

Malnutrition

Dehydration

Aspiration pneumonia

Reduced quality of life

Decreased rehab potential

Increased hospital length stay

Increased healthcare cost

Social isolation

Death

Oral preparatory stage (Role & How)

ROLE: Food is accepted, contained, manipulated, and made ready to swallow

HOW? Placement of food in oral cavity, sensory awareness (receptors), movement patterns (labial seal, lingual seal)

* only time during swallowing able to breathe

\

Oral Prep Stage (movement patterns)

Liquids- tongue cups around liquids with sides sealed against lateral alveolus

Thicker soft foods- same plus some mastication. The soft palate is usually down, towards base of tongue

Solid foods- 1. **initial transport component**- tongue places food on back molars - lateralization. 2. **Reduction component stage (processing)**- segmentation of food into smaller pieces, mixture with saliva to become a bonus

Reduction component = initial chewing longer, rapid chewing as pieces get smaller

Volume of a single - great variation

Sensory information is very important

Piecemeal deglutition

* swallowing multiple times
* Could be normal a symptom depending on size/amount of food

Oral Transport Stage (Role & How)

\

ROLE: Movement of bolts front front of mouth to oropharynx

HOW? Movement patters-

Tongue top elevated towards superior alveolar ridge

Soft palace now up

Posterior tongue depresses

Sides and tip of tongue maintain good closure

Bonus propulsion - tongue forms a groove and pushes the bonus superiority and posterior lay (**most important part)**

Oral Transport (time & pressure)

Timing- starts when bolts propulsion posteriorly initiated (less than 1 second, but depends on viscosity)

Pressure- higher with higher viscosity

* Almost immediately after propulsion, hyoid bone initiates anterior movement, then right after, UES starts opening

Triggering the initiation of the pharyngeal stage

ROLE: start pharyngeal stage - as bolus movements backward, receptors will be **on fire** will send signals to brain stem — which triggers pharyngeal stage

Typical pharyngeal trigger …

Leading edge of bolus passes any point between the anterior faucial pillars and the site where the tongue base meets the lower rim of the mandible as viewed on the VFSS studies

Onset depends on viscosity, age, and how person is feeling

The control is both voluntary and automatic

Pharyngeal Stage (Role & How)

ROLE: Transport food through pharynx and into the esophagus

HOW? A programmed sequence of sensorimotor events, with an allowance for variability that is not understood

TIME: Pharyngeal transit time \~750 ms

5 phases of the pharyngeal swallow

1. Velopharyngeal Closure
2. Anterior and superior movement of the hyoid bone and larynx
3. Airway closure (laryngeal vestibule closure)
4. Base of Tongue and Pharyngeal walls movement


1. Cricopharyngeal / UES Opening

Velopharyngeal Closure

*Movement*

How?

* Velum elevates and moves posteriorly more tightly
* Posterior pharyngeal wall moves forwards
* Lateral pharyngeal walls move inward

Why?

* To enable buildup of pressure in pharynx

Anterior and Superior Movement of Hyoid Bone and Larynx

*Protection*

What Happens?

* Suprahyoid (primarily) muscles will pull hyoid bone upward and forward
* Thyrohyoid membrane connections and thyrohyoid muscles will bring larynx along
* Epiglottis will flip

Why?

* To better protect airway and help UES open

\
* Hyoid going up- moves epiglottis to protect airway
* Cricoid attaches to UES - this goes up and starts to open UES

Airway Closure

*Protection*

3 levels of closure - true VF, false VF, arytenoids to epiglottis approximation (in the order) - very quickly

Why?

To protect airway

Base of Tongue (BOT) and Pharyngeal walls movement (PW)

*Movement*

How?

* Retraction of BOT
* Forward and inward movement of PPW and LPW
* Sequential contractions of pharyngeal constrictors

Why?

* Bolus passes through pressure

Esophageal Stage

ROLE: move food through esophagus to stomach

2 sphincters (UES and LES)

Muscular tubes

* Upper- striated muscles
* Middle- both
* Lower- smooth muscles

Swallowing mechanics- tubes and valves

Tubes

* oral cavity (horizontal)
* Pharynx (vertical)

Valves

* Lips
* Tongue
* Velopharynx
* Larynx
* Pharynx
* UES

\
* Swallowing is a pressure driven event - if pressure is interrupted at any stage, there’s a problem

Neural Control of swallowing

Peripheral neural control- sensory and motor

Central neural control

Swallowing is a series of …

Neurogenic events

Swallowing involves all levels of the nervous system

Parts of swallowing neurophysiology

Periphery (muscles and sensation)

PNS - cranial nerves and spinal nerves

CNS - brain and spinal cord

Functions of the lobes

Frontal: higher cog. Function (exec. Functioning), personality, primary motor cortex (motor demands), frontal operculum (important to speech and swallowing)

\
Parietal: somatosensory cortex (sensory information, all sensation), visuospatial skills

\
Temporal lobe: hearing ,speech/lang comprehension, cognition functions- memory (hippocampus)

\
Occipital: vision

PNS

Cranial and spinal nerves

Autonomic NS

* Sympathetic and parasympathetic

2 primary somatosensory pathways

Dorsal Column Pathway

Spinothalamic tract

Dorsal Column pathway

Dorsal root ganglia (1st order neuron), ipsilateral side up to the medulla (2nd order neuron), then signal decussates to contra lateral thalamus, information from thalamus to the somatosensory cortex (3rd order neuron)

Spinothalamic Tract

Dorsal root ganglia (1st order neuron), decussates right away (2nd order neuron), up through contra lateral spinal cord, then up to somatosensory cortex (3rd order neuron)

Important for spinal cord injuries-

Depending on level of injury, there could be lost sensation on ipsalateral and contra lateral sides of head and neck — some information may enter higher or lower in the brain stem and depending on the lesion — affects motor or sensory of swallow

Motor Pathways

Lateral corticospinal tract (LCT) = innervates peripheral areas (limbs, etc)

Anterior Corticospinal tract (ACT) = innervates more medial areas (trunk, etc)

Extrapyramidal controls

Tectospinal tract

Reticulospinal tract

Vestibulospinal tract

Rebrospinal tract (facilities communication between cerebellum and spinal cord -feedback loop)

Central pattern generators (CPG)

Collection of neural circuits that can generate rhythmic movements- even without direct input. EX: nuclei in spine for walking

*Modulated by the brain* - pharyngeal swallow is a CPG not a reflex

Reflex

Automatic - no brain input

Reflex arc - a response to stimuli

How are things different for the head and neck for sensation?

Cranial nerves are in charge

Sensory input travels to brain step (different levels of brain stem before crossing

*Most* sensory information travels…

*Bilaterally* (both sides)

Somatosensation (somatic)

Pressure, touch, pain, vibration

Visceral sensation

Taste

Types of receptors

Mechanoreceptors

Nociceptors

Proprioceptors

Thermoreceptors

Chemoreceptors

Multimodal (other receptors have to be activated)- Mechanoreceptors, thermoceptors, nociceptors

Mechanoreceptors

Touch, pressure, vibration

Function: Bolus texture (size, mouth feeling, and creaminess), Bolus size (large vs small volume)

Nociceptors

Pain

Function: Bolus burning sensation

Propioceptors

Position

Function: Bolus position on tongue

Thermoreceptors

Hot/cold bolus (soup/ice cream)

Chemoreceptors

Taste receptor cells (TRC) - gustation

Function: sweet, salt, sour, and meaty/savory (umami) bolus

Multimodal receptors

Chemesthesis (perceive or react to check chemical stimuli

Function: Astringency in bolus (chemical irritation), cooling affect from bolus (menthol in mint), carbonation from bolus (carbonation in soda)

*Most* motor innervation is

bilateral - stemming from the contra lateral side of the brain

Exception - facial and hypoglossal (only contra lateral)

Somatic and visceral

Soccer example of swallowing

Soccer ball: food or liquid

Sensory players - defense- cranial nerves and sensors

Motor players - offense - cranial nerves and muscles

Center line fields - motor field/sensory field - nuclei in brain

Coaches - brain areas (control it all)

Cranial nerves directly involved in swallow

Trigeminal (CN V)

Facial (CN VII)

Glossopharyngeal (CN IX)

Vagus (CN X)

Spinal- Accessory (CN XI)

Hypoglossal (CN XII)

Pharyngeal Plexus and Cervical Plexus

Groups of nerve fibers that travel together

Trigeminal Nerve Branches

Opthalamic (eyes)

Maxillary (maxilla)

Mandibular (mandible)

Sensory innervation of CN V

General Somatic Afferent

CN V- sensory areas innervated

* Mandibular branch
* Mucosa of anterior 2/3 of tongue
* Mucosa of soft palate
* Lower teeth and gums
* Temporomandibular joint
* Skin of lower lip and jaw
* Maxillary branch
* Mucosa of soft palate
* Mucosa of nasopharynx
* Mucosa of hard palate

Trigeminal- swallowing stages

Oral - Prep and Transport

Facial Nerver (CN VII) - types of Sensory innervation

Special Visceral afferent - **taste**

Facial Nerver (CN VII) - sensory areas innervated

Anterior 2/3 of tongue to brain - Taste

(Different than somatosensory information from Mandibular branch of CN V)

Facial Nerver (CN VII) - swallowing stages

Oral - Prep and Transport

Glossopharyngeal Nerve (CN IX) - type of sensory innervation

Special visceral afferent

AND general somatic afferent

*Know what each innervation does*

Glossopharyngeal Nerve (CN IX) - sensory areas innervated

Special Visceral afferent - posterior 1/3 of tongue (taste)

General somatic afferent-

* posterior 1/3 of tongue
* Mucosa of pharynx mucosa of palatine tonsils
* Mucosa of fauces (anterior and posterior)

\

Why is CN IX important for swallowing?

It helps sense the food or liquid reaching the back of the mouth, which triggers the pharyngeal swallow— this is important for protection of the airway

Vagus Nerve (X) - Branches

* Pharyngeal Branch
* Internal Superior Laryngeal Nerve (Int. SLN)
* Recurrent Laryngeal Nerve (RLN)
* Esophageal Branch

Vagus Nerve (X) - Types of Sensory Innvervation

General Somatic Afferent - Pharyngeal, int. SLN, RLN, Esophageal

Visceral Afferent- Int. SLN, RLN, Esophogeal

Special Visceral Afferent- epiglottis

Vagus Nerve (X)- Sensory Areas Innervated

**Pharyngeal branch-** Mucosa of the pharynx (also through CN 9 due to pharyngeal plexus)

**Int. SLN**-

* mucosa of laryngopharynx
* Mucosa of epiglottis
* Mucosa above VF
* Aryepiglottic folds
* Posterior tongue (small part)

**RLN-**

* mucosa of larynx Below VF
* Inferior laryngeal constrictor
* Upper esophagus

**Esophageal branch** - mucosa and striated muscle of esophagus

Vagus Nerve (X)- Swallowing stages

* Part of pharyngeal stage (causes cough and protects airway)
* Esophageal Stage

Important sensory information to know for swallowing

4 nerves - how and what they innervate

CN V: upper and lower mouth

CN VII: taste information

CN IX: sensory for protection (pharyngeal stage) and taste

CN X: many branches= many jobs → Int. SLN, RLN, pharyngeal and esophageal

Example of what to watch for in VFSS?

The swallow: As the liquid goes down, we see the airway still open meaning the pharyngeal swallow is not activated properly —> the sensory fibers of CN IX did not work very well and respond to stimuli

Difference between dorsal column and Spinothalamic tract

Carrying different information.

DC is proprioception

STT is pain and temperature

Trigeminal Nerve- Muscles controlled

**Medial Pterygoid, Masseter, Temporalis** (closers)

**Lateral Pterygoid** (opener)

T**ensor Veli Palatini**

**Anterior belly of diagastic, Mylohyoid** (movement of hyoid)

Temporalis m.

CN V

Elevates, closes, retracts mandible

Masseter m.

CN V

Elevates and closes mandible

Medial Pterygoid m.

CN V

Elevates, closes and protrudes the mandible

Lateral Pterygoid m.

CN V

Depresses, opens, protrudes mandible and permits side to side chewing

\

Tensor Veli Palatini

CN V

Unilaterally pills soft palate to side

Bilaterally closes off nasopharynx and oropharynx

Anterior Belly of Digastric m.

CN V

*Movement of hyoid*

Elevated hyoid in jaw is fixed during swallow and helps depress the jaw

Mylohyoid m

CN V

*Movement of hyoid*

Elevates the hyoid bone during the swallow and helps depressing the jaw

Facial Nerve- Muscles Controlled

**Buccinator**

**Orbicularis Oris (sphincter)**

**Levator Labii Superioris**

**Zygomati major**

**Depressor Labii inferiorus**

**Stylohyoid** (movement of hyoid bone)

Buccinator m.

CN VII

Provides tone, flattens cheek, holds food in contact with cheek/press cheek against teeth

Orbucularis Oris (Sphinctor) m.

CN VII

Helps with closing, opening, protrusion, and twisting of lips, puckering

\

Levator Labii Superioris m.

CN VII

Elevates upper lip and raise angle of mouth

Zygomatic major m .

CN VII

Smiling

Depressor Labii Inferiorus

CN VII

Depress lower lip/ frown

\

Stylohyoid m.

CN VII

*movement of hyoid bone*

Suprahyoid m. that elevates the hyoid, helps retract the tongue

Glossopharyngeal Nerve- muscles controlled

**Stylopharyngeous**

Stylopharyngeous m.

CN IX

Elevates and dilates the pharynx

Only portion of CN IX that is motor

Vagus Nerve- Muscles controlled - Pharyngeal branch

Pharyngeal Branch

* **Paltoglossus**
* **Palatopharyngeus**
* **Salpingopharyngeus**
* **Levator Veli Palatini**
* **Superior Pharyngeal Constrictor (hugger)**
* **Medial Pharyngeal Constrictor (hugger)**
* **Inferior Pharyngeal Constrictor (hugger)**
* **Cricopharyngeal**

Vagus Nerve- Muscles controlled - External SLN

**Cricothyroid**

Vagus Nerve- Muscles controlled - RLN

Closers:

**Thryoarytenoid**

**Oblique arytenoids**

**Transverse arytenoids**

**Lateral arytenoids**

Opener:

**Posterior cricoarytenoids**

Palatoglossus m.

CN X - Pharyngeal Branch

(Anterior faucial pillar)

Either lowers soft palate or raises tongue

Palatopharyngeus m.

CN X- Pharyngeal branch

(Posterior faucial pillar)

Elevates pharynx

Salpingopharyngeus m.

CN X- Pharyngeal Branch

Elevates upper lateral pharyngeal walls and nasopharynx, blends with the Palatopharyngeus

Levator Veli Palatini m.

CN X- Pharyngeal branch

Elevates soft palate, seals the nasopharynx from the oropharynx

What muscles cause the contraction of the pharynx?

Superior, medial, and inferior pharyngeal constrictors

Circular contraction of the pharynx - Huggers

Cricopharyngal m.

CN X- Pharyngeal branch

Portion also controlled by fibers of the RLN and Ext. SLN

Cricothyroid m.

CN X- Ext. SLN branch

No role in swallowing BUT assessing its function can give information o the inferior pharyngeal constrictor AND sensation in the larynx — motor deficits if no sensation

Thyroarytenoid m.

CN X- RLN branch

Shortens VF — once VF are addicted via arytenoids addiction, TA shortening = glottal closure

*Closers*

Oblique arytenoids m.

CN X- RLN branch

Adducts arytenoids

*Closers*

Transverse arytenoids m. & lateral cricoarytenoid m.

CN X- RLN branch

Adducts arytenoids

*closers*

Posterior cricoarytenoids m.

CN X- RLN branch

Only laryngeal muscle that opens the glottis — important for phonation but also closing VF when swallowing

*opener*

Hypoglossal Nerve- Extrinsic muscles

*change tongue placement in oral cavity*

**Hypoglossus**

**Genioglossus**

**Styloglossus**

Hypoglossus m.

CN XII

Depresses retracts tongue

Genioglossus m.

CN XII

Protrudes apex from mouth, depresses medial portion making it concave from side to side