ANATOMY 03/25/26

Exam Information

  • Date: May 4
  • Time: 11:10 AM to 12:25 PM
  • Classroom: Same as before
  • Format: Non-cumulative exam (only materials discussed after spring break)
    • Students allowed to use a one-sided cheat sheet.
    • There will be a study guide to review before the exam.
    • Fill-in-the-blank questions will also be included.

Key Concepts in Voice Disorders

Jitter

  • Definition: Cycle-to-cycle variation in pitch during sustained phonation.
  • When a pitch is maintained, jitter reflects the instability, which may manifest as variations in frequency perceived as a wobble or shakiness.
  • Normal Jitter Values:
    • Less than 0.5%: Stable
    • 0.5% to 1%: Mild variation
    • Greater than 1%: Elevated jitter
    • Between 1.5% to 2%: Likely dysphonic (indicates issues in phonation)
    • Dysphonia: Refers to phonation issues where some sound is produced, but with complications.
    • Aphonia: Absence of sound (no phonation).

Shimmer

  • Definition: Cycle-to-cycle variation in loudness, indicated by inconsistent intensity during sustained phonation.
  • When asked to sustain a sound like "ah," any unexpected loudness changes indicate shimmer.
  • Normal Shimmer Values:
    • Similar categorization to jitter, with specific thresholds indicating stability or dysphonia.
  • Clinical Use: Values can be automatically measured in software like Pratt, without manual calculations.

Anatomy of Voice Production

Key Components

  • Focus on identifying the muscular and cartilaginous structures:
    • Must be familiar with shapes and sizes from anatomical images, as practical anatomy will lack color reference.
    • Recognize structures like the retinoids within unfamiliar diagrams.

Phases of Swallowing

Overview

  1. Oral Phase: Controlled phase, where the bolus is formed and manipulated voluntarily.
  2. Pharyngeal Phase: Partly automatic (semi-controlled) phase involving muscle reflexes. Cannot totally intervene once initiated.
  3. Esophageal Phase: Entirely automatic reflex action, where swallowing is no longer consciously controlled.

Oral Phase Details

  • Voluntary Control:
    • Initiated when food enters the mouth, control includes chewing and determining how to swallow.
    • Reflex pathways get activated as the bolus moves toward pharyngeal phase (e.g., epiglottis closure).

Pharyngeal Phase Details

  • Somatic Reflexes:
    • This phase is semi-controlled: involves both voluntary influence and automatic responses (e.g., before swallowing, airway must be protected).
    • Closure of the velopharyngeal gap and larynx, activation of peristalsis, and opening the upper esophageal sphincter.
    • Involvement of techniques for improving swallowing mechanics in patients with dysphagia, like altering bolus consistency and strength.

Esophageal Phase Details

  • Automatic Control: The final stage of swallowing, where further intervention is minimal.
    • Severe cases sometimes require alternative feeding methods, such as NG tubes or PEG.

Brainstem and Reflexes During Swallowing

Function

  • The brainstem is where the swallowing reflex is controlled through afferent and efferent nerve pathways, affecting swallowing reflexes and muscle responses.
  • Brainstem Reflexes: Triggered when the food stimulus is detected, leading to automatic muscle responses.

Nerve Functions

  • Afferent Nerve: Facial and trigeminal nerves (detecting input)
  • Efferent Nerve: Trigeminal nerve (motor control for mastication).
  • Important Receptors: Meissner's corpuscles (light touch detection), Merkel discs (sustained pressure), deep pressure detectors, and Ruffini endings.

Reflexes in Swallowing

Primary Reflexes

  1. Chewing Reflex: Involves mastication control, starting from tactile sensing from food.
  2. Sucking and Rooting Reflex: Present in infants, helps positioning to receive food.
  3. Uvula Reflex: Important for closing the nasal cavity during swallowing; it prevents food from entering the nasal passage.
  4. Gag Reflex: Protects against choking by triggering a muscle contraction response in the throat to expel harmful objects.

Repercussions of Reflex Failure

  • If reflexes such as the uvular reflex fail, risks include aspiration, choking, and overall compromised swallowing ability.

Glandular Secretions in Swallowing

Salivary Glands

  1. Parotid Glands: Secretes serous saliva; slippery texture facilitates movement of the bolus without forming it.
  2. Sublingual Glands: Produces mucoidal saliva; dense texture assists in forming and maintaining the bolus.
  3. Submandibular Glands: Provides a mixture of serous and mucoidal saliva, playing a crucial role against diverse bolus demands.

Importance of Glandular Secretions

  • Essential for the mechanical and chemical breakdown of food and forming the cohesive bolus.

Sensory Detection in Swallowing

Mechanoreceptors

  • Different types of mechanoreceptors respond to varied stimuli (e.g. pressure, stretch) within the oral cavity:
    • Meissner's