exam 4 - neuroanatomy

what are the 4 stages of a normal swallow?

oral prep, oral, pharyngeal, esophageal

what cranial nerves are involved in swallowing?

CN V (trigeminal), VII (facial), IX (glossopharyngeal), X (vagus), XI (accessory), XII (hypoglossal)

is the oral prep stage voluntary or involuntary?

voluntary

how long is the oral prep stage?

variable in length

what happens to solids during the oral prep stage?

they are masticated and mixed with saliva to form a bolus

what is the function of the labial seal in the oral prep stage?

it contains food in the oral cavity and creates suction for drinking

which cranial nerve innervates the muscles of mastication?

CN V (trigeminal)

what does saliva do for swallowing?

breaks down food

what is saliva made of?

water and enzymes

what are the 3 major salivary glands?

parotid, sublingual, submandibular

which cranial nerves are involved in the oral prep stage (besides CN V)?

CN IX (glossopharyngeal) and CN VII (facial)

is the oral stage voluntary or involuntary?

voluntary

how long does the oral stage last?

1 second

what does the tongue do during the oral stage?

the anterior tip rises and the posterior portion drops to act as a ramp for the bolus

what happens to the bolus during the oral stage?

it is squeezed posteriorly toward the pharynx through the oral cavity

what kind of motion does the tongue do during the oral stage?

rolling contact against the palate

is the labial seal still contained during the oral stage?

yes

does nasal breathing occur during the oral stage?

yes

which cranial nerves are involved in the oral stage?

CN V (trigeminal), CN VII (facial), and CN XII (hypoglossal)

is the pharyngeal stage voluntary or involuntary?

both involuntary and voluntary

how long does the pharyngeal stage last?

1 second

what does the bolus do during the pharyngeal stage?

it contacts the faucial pillars

what does the soft palate do during the pharyngeal stage?

it elevates

what do the vocal folds (both true and false) do during the pharyngeal stage?

they adduct

what happens to respiration during the pharyngeal stage?

it pauses (apnea)

what does the larynx do during the pharyngeal stage?

it elevates and moves forward

what does the epiglottis do during the pharyngeal stage?

it inverts

what does the cricopharyngeus do during the pharyngeal stage?

it relaxes and opens

why does the soft palate elevate (velopharyngeal closure) during the pharyngeal stage?

closes off passage to the nasal cavity preventing nasal regurgitation

what cranial nerves are involved in the pharyngeal stage?

CN V (trigeminal), CN X (vagus), and CN XI (accessory)

does the epiglottis close or elevate during the pharyngeal stage?

closure - it inverts to close off airway

do the false vocal folds/ventricular folds close or elevate during the pharyngeal stage?

closure - they adduct

do the true vocal folds close or elevate during the pharyngeal stage?

closure - they adduct

does the RLN (recurrent laryngeal nerve) of CN X (vagus) cause a closure or an elevation?

closure

does the larynx close or elevate during the pharyngeal stage?

elevation - it elevates

by what cranial nerves are the muscles that assist in elevation innervated?

CN V (trigeminal), CN VII (facial), CN XII (hypoglossal)

what does pharyngeal constriction do during the pharyngeal stage?

it squeezes the bolus through the pharynx to the esophagus

when is pharyngeal constriction initiated?

when the bolus meets sensory receptors near faucial pillars during pharyngeal stage

which cranial nerves are involved in pharyngeal constriction?

CN VII (facial), CN IX (glossopharyngeal), CN X (vagus), and CN XI (accessory)

is the esophageal stage voluntary or involuntary?

involuntary

how long does the esophageal stage last?

8-20 seconds

what happens when the bolus enters the esophagus?

peristaltic waves move bolus to stomach in conjunction with gravity

what does the cricopharyngeal muscle do during the esophageal stage?

it contracts to close the upper esophageal sphincter to prevent reflux

what happens to respiration during the esophageal stage?

it resumes

what coordinates peristalsis?

the medulla

which cranial nerve is involved in the esophageal stage?

CN X (vagus)

what are the 2 specialized nuclei in the brainstem?

nucleus tractus solitarius (NTS) and nucleus ambiguus (NA)

is the nucleus tractus solitarius made of efferent or afferent fibers?

afferent fibers

is the nucleus ambiguus made of efferent or afferent fibers?

efferent fibers

what path does the nucleus tractus solitarius (NTS) follow?

it ascends to the pons, hypothalamus, and thalamus and terminates in the primary sensory cortex of the parietal lobe

what path does the nucleus ambiguus (NA) follow?

it begins in the inferior motor cortex and descends to the substantia nigra and then to the reticular formation of the pons

list some areas involved in swallowing (8 of them):

inferior primary motor cortex, prefrontal cortex, cerebellum, basal ganglia, thalamus, right temporal lobe, primary motor cortex, primary sensory cortex

what is a cough?

a defense reflex

what does coughing do?

prevent aspiration and help clear secretions

what is the first component of the cough reflex arc?

afferent fibers from the vagus nerve (CN X) convey signals from cough receptors in the pharynx, larynx, and trachea

what is the second component of the cough reflex arc?

signals go to a cough center in the upper brainstem and pons

what is the third component of the cough reflex arc?

efferent signals are then sent from the cough center via the vagus (CN X), phrenic, and spinal nerves to the respiratory muscles, and via the vagus nerve (CN X) to the larynx

what can cause silent aspiration?

neurological damage that suppresses the cough reflex arc

how often does silent aspiration occur?

1/3 dysphagia patients

what are the other indicators of silent aspiration?

dysphonia, dysarthria, abnormal gag reflex, abnormal volitional cough, cough after swallow, voice change after swallow

what should happen to the patient if they show any indicators of silent aspiration?

they should be assessed via diagnostic imaging

what is dysphonia?

a voice disturbance in the parameters of vocal quality, pitch, or intensity

what is dysarthria?

a speech disorder resulting from disturbances in muscular control affecting the areas of respiration, articulation, phonation, resonance, or prosody

what is an abnormal gag reflex?

either absent or weakened velar or pharyngeal wall contraction, unilaterally or bilaterally, in response to tactile stimulation of the posterior pharyngeal wall

what is an abnormal volitional cough?

a weak response, verbalized response, or no response when given the command to cough

what is a cough after swallow?

cough immediate or within 1 minute of ingestion of calibrated volumes of water (5, 10, and 20 mL presented in duplicate)

what is a voice change after swallow?

alteration in vocal quality following ingestion of calibrated volumes of water

what are some causes of neurological swallowing disorders/conditions?

CVA, stroke, TBI, tumors, multiple sclerosis, Parkinson’s disease, Huntington’s disease, ALS (amyotrophic lateral sclerosis), Guillain-Barre syndrome, myasthenia gravis, spinal cord injuries

what percentage of stroke patients end up having dysphagia?

70%

list some things that neurological injury can lead to in the oral prep and oral stages of the swallow (4 of them):

weakness in facial musculature leading to poor mastication and bolus control, poor labial seal which causes anterior spillage, pocketing, poor bolus propulsion and difficulting forming bolus (will see lingual pumping)

list some things that neurological injury can lead to in the pharyngeal stage of the swallow (3 of them):

it can be delayed, weak, or absent; damage to brainstem, NTS and/or NA can result in absent swallow; weakness in muscles can cause decreased pharyngeal constriction, weak laryngeal elevation, and impaired velopharyngeal (VP) closure

what is a neurological exam?

systemic examination of the nervous system

what is the neurological exam used for?

tool used to explore and identify any pathology affecting the proper functioning of nervous system organs

who typically performs a neurological exam?

usually neurologist, but SLP can also

what is step 1 of the neurological exam?

the interview - interview of patient and/or family to understand signs/symptoms and circumstances of illness

what is the purpose of the questions during the interview of a neurological exam?

meant to elicit patient’s “chief complaint”

list some questions that could be asked during the interview of a neurological exam (7 of them):

history of present illness, when did symptoms start?, how long do they last?, do they get better or worse?, past medical history, social and environmental history, review of systems - problems with lungs, heart, etc?

what is step 2 of the neurological exam?

the physical exam

list some things assessed during the physical exam of a neurological exam (6 of them):

patient awake and alert? responsive?, hygiene and dress are examined to determine ability for self-care, heart and lungs are assessed via stethoscope, body posture and motor activity observed, height and weight, HEENT exam

what is a HEENT exam?

exam of head, eyes, ears, nose, and throat

what is step 3 of the neurological exam?

neurological exam proper - more formal assessment of mental status, motor activity, reflexes, senses, and equilibrium

list some components of the neurological exam proper (4 of them):

briefly asses their expressive and receptive language abilities; assess cognition briefly - orientation, long and short-term memory, attention, etc; cranial nerve evaluation; motor testing - posture and movement of limbs

what is step 4 of the neurological exam?

lab tests

what kind of lab tests are needed for the neurological exam?

blood tests - CBC and metabolic panel, and neuroimaging if needed

what is a complete blood count (CBC)?

measures platelets, red and white blood cells, hemoglobin, and provides and insight into overall heath

what is a metabolic panel?

measures chemical balance and metabolism

what can damage to CN I (olfactory) cause?

anosmia (inability to smell), hyperosmia (abnormally sensitive smell), hyposmia (decreased sense of smell)

what can damage to CN II-IV, VI (optic, oculomotor, trochlear, abducens) cause?

decreased vision and blindness: hemianopsia (one-sided visual loss), loss of pupillary light reflex, deviation of gaze, diplopia (double vision), nystagmus (involuntary eye movements)

what can damage to CN V (trigeminal) cause?

difficulty moving mandible; impaired sensation to the forehead, cheek, upper and lower lips

what can damage to CN VII (facial) cause?

facial plegia or paresis (ask patient to smile), loss of taste

what can damage to CN VIII (auditory/vestibulocochlear) cause?

loss of equilibrium (balance issues and/or dizziness), hearing loss, tinnitus

what can damage to CN IX (glossopharyngeal) cause?

absent gag response, absent swallow

what can damage to CN X (vagus) cause?

absent swallow, impaired voice, silent aspiration, absent/impaired velar elevation (which may also happen with damage to CN V)

what can damage to CN XII (hypoglossal) cause?

impaired lingual lateralization, impaired lingual elevation and retraction, lingual atrophy (fasciculations)