OT103: Lec 5

• Feeding


  Setting up, arranging, and bringing food or fluid from the container to the mouth
• Eating


  Keeping or manipulating food or fluid in the mouth
• Swallowing


  Deglutition - Movement of solid or liquid bolus towards the esophagus. Moving food from the mouth to the stomach.

  
• Rate of swallowing solid food is 1-2 swallows per minute
• External Structures of the Oral Cavity

  • Orbicularis Oris - closes the mouth
  • Labial muscles - open the mouth
  • Buccinator - avoids pocketing of food
  • Temporalis, Masseter, Medial Pterygoid - close the jaw
  • Lateral Pterygoid - opens the jaw
  • Medial and Lateral Pterygoid - Mature pattern of diagonal, rotary chewing

  
• Internal Structures of the Oral Cavity

  • Hard Palate - helps in bolus formation
  • Soft Palate/Velum: Tensor veli palatini, levator veli palatini, & palatopharyngeous - elevates soft palate
  • Uvula - elevates soft palate
  • Faucial arches - passageway of bolus
• Muscles on the Floor of the Mouth

  • Digastric - lowers the mandible, raises the hyoid
  • Mylohyoid - raises the hyoid
  • Stylohyoid - raises the hyoid
  • Geniohyoid - raises the hyoid
  • Genioglossus - control the tongue
  • Hyoglossus - control the tongue
  • Styloglossus - control the tongue
  • Palatoglossus - control the tongue

  
• Pharynx


  Common space for nose, mouth, and throat. Serves as a passageway for both air and food.
• Divisions of the Pharynx

  • Nasopharynx -uppermost; between the soft palate and base of the skull
  • Oropharynx - behind the base of the tongue; between the soft palate and epiglottis
  • Hypopharynx - between the epiglottis and cricoid cartilage (ring-shaped cartilage in the larynx)
• Pharyngeal Muscles


  • Pharyngeal constrictors (Superior, Middle, Inferior) - narrows the lumen of the pharynx
  • Stylopharyngeus - raises and shortens the pharynx
  • Palatopharyngeus - raises the pharynx and larynx
  • Salpingopharyngeus - raises the pharynx and larynx
• Valleculae


  Space formed by the base of the tongue, epiglottis, and aryepiglottic folds. Space where the food goes before we swallow.

  
• Pyriform sinuses


  Space formed by the lateral insertion of inferior constrictor and lateral walls of the thyroid cartilage of the larynx. Resting areas for bolus prior to swallow reflex.

  
• Important Laryngeal Structures

  • Epiglottis - above the larynx; stops foreign entry into the airway
  • Aryepiglottic folds and cartilages - protects lower airways
  • False vocal cords (Ventricular folds) - Prevent egress of air; Prevent expectoration of air and phlegm
  • True vocal cords - prevents ingress of air
  • Arytenoid muscles - adduct the vocal cords
• Esophagus


  Carries food from the pharynx to stomach. Collapsed or thin at rest. Where peristalsis occurs.

  
• Esophageal Sphincters


  • Upper esophageal sphincter (Cricopharyngeal sphincter) - Prevents air from entering the esophagus; prevents regurgitation
  • Lower esophageal sphincter - Prevents regurgitation and acid reflux

  
• Sensory Cranial Nerves Involved in Swallowing

  • CN 5 - sensation from the anterior 2/3 of tongue; teeth, gums, soft & hard palate
  • CN 7 - taste from anterior 2/3 tongue
  • CN 9 - Sensation and taste from posterior 1⁄3 of tongue; Sensation from soft palate, posterior nasopharynx
  • CN 10 - Sensation from the lower pharynx

  
• Motor Cranial Nerves Involved in Swallowing

  • CN 5 - muscles for mastication
  • CN 7 - facial expressions; sublingual, submandibular, & salivary glands
  • CN 9 - Muscles involved in the upper lateral pharyngeal wall during swallow; Parotid salivary
  • CN 10 - muscles of palate and pharynx; elevates larynx
  • CN 12 - intrinsic and extrinsic muscles of the tongue
• Cranial Nerve Reflexes Involved in Swallowing

  • CN 9: Swallowing reflex, Gag reflex
  • CN 10: Swallowing reflex, Gag reflex, Cough reflex
• Swallowing Reflex


  Stimulated when food bolus is pushed into the oropharynx. Activated by receptors on posterior part of oral cavity and oropharynx. Protects respiratory tract.

  
• Gag Reflex


  Contraction of pharynx muscles when they are stimulated. Prevents aspiration of food particles.

  
• Cough Reflex


  Last line of defense for the larynx, forcefully coughing out materials that manage to slip into the vocal folds and below.
• Aspiration


  Entry of material into the larynx and lower respiratory tract.
• Cortical Control of Swallowing

  • Medulla Oblongata (Primary deglutition and respiratory center)
  • Pons (Plays a small part in inhibiting respiration during swallowing)

  
• Phases of Swallowing


  • Oral Preparatory Phase
  • Oral Phase
  • Pharyngeal Phase
  • Esophageal Phase

  
• Swallowing Reflex


  • Stimulated when food bolus is pushed into the oropharynx
  • Activated by receptors on posterior part of oral cavity and oropharynx
  • Superior laryngeal nerves, CN 9 and 10
  • Protects respiratory tract by cleaning nasopharynx and oropharynx, and closing the larynx and nasopharynx

  
• Gag Reflex


  • Contraction of pharynx muscles when they are stimulated
  • Prevents aspiration of food particles

  
• Cough Reflex


  Last line of defense for the larynx is forcefully coughing out materials that manages to slip into the vocal folds and below
• Aspiration


  Entry of material into the larynx and lower respiratory tract
• Medulla Oblongata


  • Primary deglutition and respiratory center
• Pons


  • Plays a small part in inhibiting respiration during swallowing
• Oral Preparatory Phase


  1. Food is manipulated and masticated

  2. Bolus is formed by chewing, sucking, and coating food in saliva

  3. Bolus is held in oral cavity

  4. Larynx and pharynx are at rest

  5. Voluntary - we are controlling the movement

  
• Oral Phase


  1. 1 - 1.5 seconds

  2. Begins when the tongue initiates posterior movement of bolus

  3. Bolus push backward in the groove between tongue and palate

  4. Soft palate moves upward

  5. Passavant's ridge helps seal nasopharynx from oropharynx

  6. Tongue pushes bolus backward into oropharynx

  7. Voluntary

  
• Pharyngeal Phase


  1. 1 second

  2. Begins when pharyngeal or swallow reflex is triggered

  3. Bolus passes between the anterior faucial arches

  4. Receptors at the posterior wall is stimulated

  5. Swallow center receives signals

  6. Swallow reflex is triggered

  7. Reflex / involuntary

  • Velopharyngeal closure
  • Hyolaryngeal elevation
  • Pharyngeal contraction
  • Upper esophageal sphincter relaxation

  
• Esophageal Phase


  1. 5-6 seconds, 3-4 cm / second

  2. Structures return to resting position

  • Epiglottis, Hyoid & larynx, soft palate

  3. UES passively closes

  4. Esophageal peristalsis

  5. Lower esophageal sphincter relaxes
• Swallowing and Respiration

  • EXHALE - SWALLOW - EXHALE pattern
  • Impossible to breathe and swallow at the same time
• Drinking


  1. Pharyngeal response follows each swallow

  2. Esophagus is inhibited until the last swallow

  3. Peristalsis happens during exhalation
• Belching


  1. Prolonged drop in UES pressure

  2. Vocal folds and arytenoids adduct

  3. UES opens

  4. Small anterior hyoid movement
• Retching and Vomiting


  1. Pre-retch: Diaphragm tone increases, UES tone increases

  2. Retching: Phasic UES tone change, Retching to fill the lungs

  • Breathing: external intercostal muscles
  • UES opens

  1. After retching: Diaphragm relaxes; Glottis opens; UES strongly closes

  3. Vomit Expulsion: All UES muscles relax, UES is pulled open by hyoid muscles, Stomach contents expelled with contraction of the diaphragm
• Phases of Swallowing Dysfunction

  • Oral Preparatory: Poor bolus formation, Poor lip closure and drooling, Pocketing of food
  • Oral: Aspiration before swallow, Nasal regurgitation
  • Pharyngeal: Aspiration
  • Esophageal: Aspiration