SLHS 53900 Quiz 1

Somatosensory and motor pathway diagrams, test format: M.C., T or F, labeling, few fill-in-the blanks

Week 2: Introduction to Normal Deglutition and Swallowing

What is eating?

1. Feeding

2. Swallowing

3. Digestion (not our role)

Depends on

• Anatomy/physiology/skill

  • Sensory - motor

• Financial ability

• Ethnicity/culture

• Motivation

What does feeding involve?

• Motivation and readiness for eating

• The placement of the food in the mouth

• Interactions between feeder and patient/person who is eating

• Oral manipulation of the food or liquids

Swallowing is…

A series of neurogenic sensorimotor events that

• Are initiated by recognizing the presence (touch), taste, temperature, and viscosity of food or fluid in the oral cavity

• Followed by the preparation to a consistency that can be swallowed

• Finalized by its safe transportation through the oral, pharyngeal, and esophageal anatomic structures to the stomach

What are the 3 stages of swallowing?

• Pre-oral (feeding)

• Oral

  • Oral preparatory

  • Oral transport

• Pharyngeal

• Esophageal

The phases of swallowing are controlled by 3 areas, which are:

• PNS

• Supratentorial areas

• Brainstem

How can we define dysphagia?

• Difficulty in swallowing

• Any disruption in any of the 3 phases of swallowing

  • Identifying/recognizing presence or taste of food in mouth

  • Preparing into a bolus

  • Any disruption in safety, efficiency, or effectiveness through the oral pathway

• Symptom of underlying disorders or diseases

Complications for individuals that have dysphagia

• Malnutrition/failure to thrive

• Dehydration

• Aspiration pneumonia

• Reduced Quality of Life (QOL)

• Decreased rehabilitation potential

• Increased length of hospital stay

• Increased health care cost

• Social isolation

• Death

Know basic anatomy structure!

Oral preparatory: role and how does it work?

• Role: food is accepted, contained, manipulated and made ready to swallow in the oral cavity

• How?

  • Placement of food in oral cavity

  • Sensory awareness - receptors

• Movement patterns

  • Labial seal

  • Lingual seal

  • Breathing? How?

  • Different for various boluses

• Only time during the swallowing sequence that we continue to keep breathing normally

Movement patterns of the oral preparatory stage: liquids

Tongue cups around liquids with sides sealed against lateral alveolus

Movement patterns of the oral preparatory stage: thicker, soft foods

• Same plus some mastication (not necessary)

• Usually soft palate (toward the lower base of the tongue)

Movement patterns of the oral preparatory stage: solids

Slightly different events

As you are chewing, your velum goes up/down with solids - why is this risky?

When the velum is up, it’s risky because something can spill down while the airway is still open

Describe the two stages of mastication (very complex process) for solid foods

1. Initial transport component (Stage I - transport)

   1. Tongue places food between molars - lateralization

2. Reduction component (Stage II - processing)

   1. Segmentation of food into smaller pieces (longer)

   2. Mixture with saliva to become a bolus (shorter, rapid)

What’s the volume and duration of a single bolus?

Varies

What is the role of the oral transport stage?

To move the bolus from the front of the mouth to the oropharynx (back of the mouth)

Describe the movement patterns within the oral transport stage

• Tongue tip elevated toward superior alveolar ridge

• Soft palate now elevated high up, makes more space in the back of the mouth

• Posterior tongue depresses

• Sides and tip of tongue maintain good closure

• Bolus propulsion: tongue forms a groove and pushes the bolus superiorly and posteriorly

When does the oral transport stage start? What is the duration?

• Starts when bolus propulsion posteriorly is initiated

• Duration: ~1 second (but slightly longer with increased viscosity [thickness])

What is the pressure/viscosity ration in the oral transport stage?

Increased viscosity → increased pressure

What other important events are initiating while the oral transport stage is happening?

• ~150 ms are propulsion starts: hyoid bone initiates its anterior movement

• ~400 to 750 ms after propulsion starts: UES starts opening

How does the triggering of the pharyngeal stage happen?

1. As the bolus moves backward, sensory receptors will be on fire

2. Receptors send signals to the brainstem to tell the pharynx and larynx that there’s food and to close off the airway

3. Then these will trigger the initiation of the pharyngeal stage

Describe the onset of “typical” triggering

When the leading edge of the 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 lateral-view video fluoroscopic studies

What are the variations seen in the triggering of the pharyngeal stage?

• Viscosity

• Age

• Even within person (ex: tiredness)

What is the role of the pharyngeal stage?

Safely transport the food through the pharynx into the esophagus

How is the pharyngeal stage done?

A programmed sequence of sensorimotor events, with an allowance for variability that has yet to be understood

Timing of the pharyngeal stage (PTT: Pharyngeal Transit Time)

~750 msec (very fast and very important)

What are the 5 stages within the pharyngeal stage?

1. Velopharyngeal closure

2. Anterior and superior movement of hyoid bone and larynx

3. Airway closure (laryngeal vestibule closure)

4. Base of tongue (BOT) and pharyngeal walls (PW) movements

5. Cricopharyngeal/UES opening

Pharyngeal stage: velopharyngeal closure

How?

• Velum elevates and moves posteriorly more tightly

• Posterior pharyngeal walls moves forward

• Lateral pharyngeal walls move inward

Why?

• To enable buildup of pressure in pharynx

Pharyngeal stage: anterior and superior movement of hyoid bone and larynx

What happens?

• Suprahyoid (primarily) muscles will pull hyoid bone upward and forward

• Thyrohyoid membrane connections and thyrohyoid muscles will bring larynx along

• Epiglottis will invert

Why?

• To better protect airway and help UES opening

Pharyngeal stage: airway closure (laryngeal vestibule closure)

• 3 levels

  • True VFs

  • False VFs

  • Arytenoids to epiglottis approximation

• Often in that order

• Duration: 250-750 ms → single swallows / >= 5 sec in sequential cup drinking

Why?

• To engalge airway protection

Pharyngeal stage: base of tongue (BOT) and pharyngeal walls (PW) movements

How?

• Retraction of BOT

• Forward and inward movement of PPW and LPWs

• Sequential contractions of pharyngeal constrictors

Why?

• Bolus passage through pressure

Pharyngeal stage: cricopharyngeal/UES opening

Depends on

• Relaxation of the CP segment/UES

• Anterior pull upon the CP and the entire UES resulting from the anterior movements of the hyoid bone

• Gravity and pressure of the oncoming bolus

Why?

• Emptying of pharynx and bolus passage to esophagus

What is the role of the esophageal stage?

Move the food through the esophagus into the stomach

What two sphincters are involved in the esophageal stage?

• UES

• LES

How long is the esophagus? How long (approximately) does it take a bolus to pass through this tube?

• 20-24 cm long

• Duration: 8-20 sec

What kind of muscles is the esophagus made of?

• UES: striated (voluntary)

• Middle: striated (voluntary) and smooth (involuntary)

• LES: smooth (involuntary)

What type of event is swallowing?

Pressure driven

What are the sets of tubes and valves involved in swallowing?

Tubes

• Oral cavity

• Pharynx

Valves

• Lips

• Tongue

• Velopharynx

• Larynx

• Pharynx

• UES

Bolus

Material ready to be swallowed

Penetration

Liquid or food goes to the level of the true VFs

Aspiration

Liquid or food goes below the true VFs and into the lungs (beyond)

Residue

Material left behind after your primary swallow

Week 3: Neurophysiology of Swallowing Part 1 - Sensory/Afferent Peripheral Controls

Why is learning the neurophysiology of swallowing important?

• Swallowing involves all levels on the nervous system

  • If we don’t know how the NS works, we don’t know how swallowing works

• Swallowing is a series of neurogenic events

  • Knowledge of the NS and its recovery/plasticity potential is essential in helping us to understand how to best rehabilitate this complex neurogenic function

What are the 3 systems that are involved in the neurophysiology of swallowing?

• Periphery (muscles and sensation)

• PNS

• CNS

PNS

• Cranial and spinal nerves

• Dorsal branch

• Ventral branch

CNS

• Brain

  • Lobes: frontal, parietal, occipital, temporal

• Spinal cord

  • Helps brain communicate with the brain (and vice versa)

What are the 4 lobes of the brain? Describe the function of each lobe

• Frontal: executive function, personality, primary motor cortex, sends body motor commands, premotor/plan (frontal operculum), Broca’s area (speech and swallowing)

• Parietal: primary somatosensory cortex (perceives sensations), secondary (help interpret reading and writing)

• Temporal: hearing, language, speech, comprehension, cognitive function (memory)

• Occipital: vision

Thalamus

Sensory relay station

Brainstem

• Midbrain, pons, medulla

• Bridge of information

Basal ganglia

Helps release desired movements and behaviors and inhibit undesired

Cerebellum

Helps coordinate movement (posture and balance)

Describe the differences between gray and white matter; ventral/dorsal horns of spinal cord

• Dorsal

  • Sensory information enters spinal cord

  • Gray matter

• Ventral

  • Motor information exits spinal cord and enters spinal nerves to innervate muscles

  • White matter

The autonomic nervous system is within the PNS; describe the two subsystems of the autonomic NS

Involuntary

• Sympathetic (fight/flight)

• Parasympathetic (rest/digest, come down from fight, swallowing)

What are the two somatosensory pathways? Create a somatosensory pathway diagram

• Dorsal column: fine or discriminatory touch, proprioception from one side of the body to the contra side of the brain

• Spinothalamic tract: pain and temperature from one side of the body to the contra side of the brain

• Both use 3-order neurons

  • 1st: dorsal root ganglia receives from nerve endings and transmits through ipsilateral spinal cord to medulla

  • 2nd: information crosses to the other side at the medulla then starts traveling to the thalamus

  • 3rd: Travel to primary somatosensory cortex

What are the two motor pathways? Create a motor pathway diagram

• Lateral corticospinal tract

• Anterior corticospinal tract

In addition to the primary motor pathways, there are shorter pathways that do not travel through the paramydial system but are still influential; what are the extrapyramdial pathways?

• Tectospinal tract

• Reticulospinal tract

• Vestibulospinal tract

• Rubrospinal tract

  • Communicate spinal cord

• Shorter tracts that help regulate balance, movement, and posture

What are Central Pattern Generators (CPGs)?

• Neural circuits (group of nuclei/gray matter) that can generate rhythmic and stereotypical movement even with the absence of brain input (can be modulated without input if needed)

• Pharyngeal swallow is regulated by a CPG in the brainstem and isn’t a pure reflex

What are reflexes? Do these require brain input?

• Automatic response to stimulus that’s generated by a pathway (reflex arc) that is able to generate impulses/responses as a response to the stimulus

• Doesn’t require brain input/modulation

How are things different for the head and neck in terms of sensations?

• Cranial nerves are in charge

• Sensory input travels to brainstem (different levels of brainstem before crossing)

• Most sensory information travels bilaterally - but still more on the contralateral side of the brain

• Somatosensation (somatic) and taste (visceral/autonomic) sensations

• Different brain areas perceive the sensations than for the body

How are things different for the head and neck for motor innervation?

• Cranial nerves and few spinal nerves

• Several types of muscles - different than limb muscles

• Most motor innervation is bilateral - but still more stemming from the contralateral side of the brain

  • Exceptions: CN VII (partially) and XII

• Somatic and visceral control

• Different and many brain areas in charge

What are the 6 pairs of cranial nerves directly involved in swallowing?

• CN V (Trigeminal)

• CN VII (Facial)

• CN IX (Glossopharyngeal)

• CN X (Vagus)

• CN XI (Spinal-accessory)

• CN XII (Hypoglossal)

CN V (Trigeminal)

• General somatic afferent

• Mandibular branch

  • Mucosa of anterior 2/3s of tongue

  • Mucosa of soft palate

  • Lower teeth and gums

  • Temporomandibular joint

  • Skin of the lower lip and jaw

• Maxillary branch

  • Mucosa of nasopharynx

  • Mucosa of soft palate

  • Mucosa of hard palate

  • Upper teeth and gums

CN VII (Facial)

• Special visceral afferent (taste)

  • Anterior 2/3s of tongue

CN IX (Glossopharyngeal)

• Special visceral afferent (taste)

  • Posterior 1/3 of tongue

• General somatic afferent

  • Posterior 1/3 of tongue

  • Mucosa of oropharynx

  • Mucosa of palatine tonsils

  • Mucosa of fauces (anterior and posterior)

CN X (Vagus)

Many branches

• Pharyngeal

• Superior laryngeal (nerve)

  • Internal branch (sensory branch)

• Recurrent laryngeal nerve

• Esophageal

CN X (Vagus): pharyngeal branch

• General somatic afferent

• Mucosa of the pharynx

CN X (Vagus): internal branch of superior laryngeal nerve

• General somatic and visceral afferent

• Mucosa of the laryngopharynx

• Mucosa of the epiglottis

• Mucosa above the VFs

• Joint receptors in the larynx

• Aryepiglottic folds

• Posterior tongue (small area)

CN X (Vagus): recurrent laryngeal nerve

• General somatic and visceral afferent

• Mucosa of larynx below the VFs

• Inferior pharyngeal constrictor

• Esophagus (upper)

CN X (Vagus): esophageal branch

• General somatic and visceral afferent

• Mucosa and striated muscle of the esophagus

Week 4: Neurophysiology of Swallowing Part 2 - Motor/Efferent Peripheral Controls

CN V (trigeminal)

• Mandibular branch (main muscle of mastication)

• Tensor veli palatini

• Anterior belly of digastric

• Mylohyoid muscle

CN V (trigeminal): mandibular

Closers

• Temporalis

  • Elevates, closes, retracts the mandible

• Masseter

  • Elevates, closes the mandible

• Medial pterygoid

  • Elevates, closes and protrudes the mandible

Main opener

• Lateral pterygoid

  • Depresses, opens, protrudes the mandible

  • Permits side-to-side chewing motion

CN V (trigeminal): mandibular (other)

• Tensor veli palatini

  • Unilaterally: pulsl the soft palate to the same side

  • Bilaterally: closes off the nasopharynx and oropharynx

• Mylohyoid

  • Elevates the hyoid bone during the swallow

  • Helps in depressing the kaw

• Anterior belly of the digastric

  • Elevates hyoid if jaw is fixed during the swallow

  • Helps in depressing the jaw

CN VII (facial): buccinator

• Provides tone

• Flattens the cheek

• Holds food in contact with the cheek/press cheek against teeth

CN VII (facial): orbicularis oris (sphincter)

• Helps with closing, opening, protrusion, and twisting of the lips

• Puckering

CN VII (facial): levator labii superioris

Elevate upper lip and raise angle of mouth

CN VII (facial): zygomaticus major

Smiling

CN VII (facial): depressor labii inferiorus

Depress the lower lip/frown

CN VII (facial): stylohyoid

• A suprahyoid muscle that elevates the hyoid

• Helps to retract the tongue

CN IX (glossopharyngeal)

Stylopharyngeus

• Elevates and dilates the pharynx

• Only portion of CN IX that is motor

CN X (vagus): pharyngeal

• Palatoglossus (anterior faucial pillar)

  • Either lowers the soft palate or raises the tongue

• Palatopharyngeus (posterior faucial pillar)

  • Elevates the pharynx

• Salpingopharyngeus

  • Elevates upper lateral pharyngeal walls, nasopharynx

  • Blends with the palatopharyngeus

• Levator veli palatini

  • Elevates the soft palate

  • Seals the nasopharynx from the oropharynx

• Superior pharyngeal constrictor

• Medial pharyngeal constrictor

• Inferior pharyngeal constrictor

  • Circular contraction of the pharynx

• Cricopharyngeal muscle

CN X (vagus): superior laryngeal branch

• Cricothyroid

Closers

• Thyroarytenoid

  • Shorterns the VFs

• Oblique arytenoids

  • Adducts the arytenoids

• Transverse arytenoid

• Lateral cricoarytenoids

  • Adducts the arytenoids

Only opener

• Posterior cricoarytenoid

  • Only laryngeal muscle that opens the glottis

CN XII (hypoglossal): intrinsic muscles

• Superior longitudinal

  • Shortens the tongue

  • Turns the apex and sides upward which makes the dorsum concave

• Inferior longitudinal

  • Shortens the tongue

  • Turns the apex and side downward which makes the dorsum convex

• Transverse lingual

  • Narrows and elongates the tongue

• Vertical lingualis

CN XII (hypoglossal): extrinsic muscles

• Hypoglossus

  • Depresses and retracts the tongue

• Genioglossus

  • Protrudes apex from the mouth

  • Depresses the medial portion making it concave from side to side

• Styloglossus

  • Draws the tongue up and bakc

Cervical plexus: elevators

• Geniohyoid

  • Elevation and anterior movement of the hyoid

• Thyrohyoid

  • Approximates thyroid and hyoid

  • With hyoid fixed it raises the thryhyoid

    • During the swallow

  • With larynx fixed it lowers the hyoid

Cervical plexus: depressors

• Sternohyoid

  • Depresses hyoid

• Omohyoid

  • Lowers hyoid after it has been elevated

What is saliva? What is the function of it?

• Clear liquid we find in the oropharynx

• Helps make more solid foods more moist and easier to chew and swallow

• Cleansing properties (oral health)

• Need to have enough salvia to make sure our gums and teeth are healthy

• Digestion of carbohydrates

Which two nerves involve salivary glands?

• CN VII (facial)

• CN IX (glossopharyngeal)

What are some clinical issues associated with saliva?

• Xerostomia: very dry mouth

• Sialorrhea: drooling or excessive saliva production

Where in the brainstem are the nuclei of the sensory fibers/nerves?

• “Houses” in medulla and pons

• Trigeminal sensory nuclei

• Nucleus tractus solitarius (NTS - most important)

Where in the brainstem are the nuclei of the motor nerves (LMN’s)?

• Trigeminal motor nuclei

• Facial nucleus

• Nucleus ambiguous (NA - most important)

Which brain areas are associated with certain tasks (week 4 slide 38)?

Tasks → targeted function → brain activations

• Tongue tapping → oral components → sensorimotor cortex

• Throat clearing → laryngeal closure → insula and subcortex

• Swallowing (water) → swallowing → cortex and subcortex

• Plan swallow → praxis - cognitive preparation → premotor cortex

Misc. Class Questions

What are the two main sensory nuclei in the brainstem we are about? And why are they important?

• Trigeminal sensory nuclei

• Nucleus tractus solitarius (NTS)

  • Facial, glossopharyngeal, vagus

  • All sensory information travels through the NTS

What are the two main nuclei in the brainstem we are about? And why are they important?

• Trigeminal motor

• Facial nucleus

• Nucleus ambiguous (NA)

  • Innervates a lot of the muscles of the larynx and pharynx

• Hypoglossal nucleus

Which are the two main somatosensory pathways and what are their main differences?

• Dorsal column system

  • Fine touch, proprioception

  • Contralateral because it crosses later in the medulla

• Spinothalamic tract

  • Pain, temperature

  • Ipsilateral because it crosses in the spinal cord right away

What are the two primary motor pathways? Do we have any additional motor pathways? What are these collectively called?

• Lateral corticospinal tract: about 80% travels through this tract, gibers cross in medulla

• Anterior corticospinal tract: innervates trunk muscles, fibers cross in spinal cord

• Extra: extrapyramdial tract

What are some of the most important differences between somatosensation perception from the body and somatosensation perception from the head and neck area/

• Body

  • Perceived by one area only

  • Dorsal and spinothalamic

  • Spinal nerves get sensory information

  • Sensory information travels to the spinal cord before it crosses

  • Sensory information from your right hand is perceived from left cortices

• Head and neck

  • Perceived by multiple areas

  • Most information crosses contralaterally and bilaterally

  • Cranial nerves mostly get sensory information

  • Sensory information travels to the brainstem before it crosses