Anatomy of the Swallow

Anatomy and Swallowing


Cranium
    Sutures=movable joints
    
     Temporal Bones-
        Lateral sides of the cranium
        TMJ
   
     Mastoid Process-
         Just below the earlobe
         Sternocleidomastoid
         Digastric (floor of mouth)
    
     Styloid Process
          Hook like projection
          Styloglossus
          Stylopharyngeus
          Stylohyoid

     Zygomatic Process
          Forms with zygomatic bone
          Attachment site for various muscles of facial exp.

    Maxillae
         Upper Face
         Alvoelar ridge
         Initial portion hard palate
         Orbital and nasal cavity

    Zygomatic Bones
         Cheekbones
         Masseter

    Mandible
          U-shaped bone with a ramus on each side
          Mental symphysis-anterior midline where fuses
          Coronoid process-ramus anterior projection
          Condylar process-ramus posterior projection (TMJ)

     TMJ
          Condylar process at the mandibular fossa of the temporal bone 
                (depression, elevation, protrusion, retraction, lateralization)

Lips
      Vermillion border (bottom border of upper and lower lip)

      Cupid's Bow-dipped part of upper lip

      Columellae-2 columns from top lip to nose

      Philtrum-the groove between the columellae

Anterior and Posterior Faucial Pillars

      Formed by palatoglossus and palatopharyngeus muscles

      Between the palatine tonsils

Palate

     Median raphe-midline groove

     Torus palatinus-anterior midline raphe-appears as bulge or pad

         Alvoelar Ridge

True Vocal Cords     

         Believed to occur with elevation of hyolarygneal complex.

         Contraction of lateral cricoarytenoid, interarytenoids, vocalis (thyroarytenoid or 
         thyrovocalis) and thyromuscularis.

          CN X

          Adduction of vocal cords for phonation with increased pressure for swallowing.

Valleculae

          Made of base of tongue and epiglottis.
          
         On the side of the hyoepiglottic ligament, between the tongue base and epiglottis.

Pyriform Sinuses

          Either side of the thyroid cartilage at the bottom of the pharynx.

          Created as fibers of the inferior constrictor wrap to attach to the anterior 
          thyroid cartilage.

Soft Palate

          It's the velum's lack of action that assists in oral phase of the swallow.

          Rests low to help contain the bolus.

Passavant's Pad

          Simultaneous contraction of the horizontal fibers of the palatopharyngeus and 
          superior constrictor creating a bulge on the posterior pharyngeal wall.

Tongue

      Circumvallate Papillae-V-shaped region of bumps on the anterior tongue  

      Most important structure of  the oral swallow.

      Holds and manipulates bolus and transports. 

Salivary Glands

      Innervated by the autonomic nervous system

      Both sympathetic and parasympathetic fibers   

      Parotic Glands

             Largest gland

             Posterior and inferior cheeks

             Can stimulate by massage just below the ear lobe

             CN IX from inferior salivary nucleus in the pons of the brainstem

      Sublingual Glands

              Located immediately beneath the mucousal surface of the floor of 
                  the mouth along the internal surface of the jaw

              Rests on mylohyoid between genioglossus and mandible

              CN VII-superior salivary nucleus in the pons

        Submandibular Glands

               Under mandible

               Deep to mylohyoid
     
                CN VII, superior salivary nucleus

Cheeks

       Lateral boundary for bolus containment and manipulation

       Cheek tension-minimize pocketing

       Cheek tension=buccinator and risorius (CN VII)

       Buccinator-pterygomandibular ligament (raphe) runs horizontal muscle splits 
          and inserts into orbicularis oris.

Sensory Receptors

      Mechanoreceptors:
           Fire when mechanically deformed, mucosal contact with bolus or with other 
           oral structures during mastication.
        
     Proprioceptors:
          allow us to know the position of our articulators in space relative to one 
          another; located in the muscle fibers and tendons; help to maintain muscle 
          tone and facilitate controlled movement; stretch reflex; found in 
          muscles of tongue, jaw and velum and in TMJ.

     Thermoreceptors:
          responds to changes in temperature (in oral mucosa).

     Nociceptors: 
           mediate sensation of pain in response to tissue damage.

    Chemoreception:
            (taste is a form of); taste buds; salty, sweet, sour and bitter; CN VII, IX 
            through brainstem and thalamus; chemical characteristics of food 
            stimulate the automatic nervous system, modifying salivary flow 
            and critical in bolus preparation.

Neurotransmitters

             Acetylcholine

             Epinephrine
     
             Norepinephrine
   
             Serotonin

             Dopamine

             Amino Acids

             Nitric Oxide

Esophagus

            18-25 cm tube.

             At rest, collapsed or flattened.

             Can stretch 3 cm lateraland 2 cm A-P

             Top 1/3 is skeletal muscle.

             Peristalsis (primary, secondary, tertiary)

                   Primary-initiated by the pharyngeal swallow.

                   Secondary-normal, not initiated by a swallow.

                   Tertiary-Mostly in older adults, contractions at the same time as 
                   primary and secondary peristalsis (may be painful)

               CN X (recurrent laryngeal)

               Carries material to stomach and allows for retrograde movement 
               when vomit and burp.

               Liquids require decreased peristalsis.

Nucleus Tractus Solitarius (NTS)

               When the NTS receives appropriate intensity of sensory input, efferent  
               response is triggered atthe nucleus ambiguus. 
               Probably the overall pattern of stimulation that triggers the swallow.

               Bolus stimulates CN IX, X, XI in the medullary reticular formation (NTS).

               IncorporatesNTS input from V, VII, XII.

               NTS signals motor nuclei in nucleus ambiguus to help fire IX, X, XI.

               Nucleus Ambiguus innervates muscles of velum, pharynx, larynx 
               and upper esophagus (IX, X, XI) producing thepharyngeal swallow 
               response.

               Strongest oral ties to NTS=anterior faucial arches, posterior tongue
               at the lower edge of the mandible, valleculae, pyriform sinuses and 
               laryngeal aditus.



No comments:

Post a Comment