HFA 213 Week 11 the Pharynx 1 2 PARTS OF THE PHARYNX THE PHARYNX Nasopharynx Skeleton Above the level of the soft palate
Choanae (posterior nasal openings) Auditory tube (Eustachian tube) Medial pterygoid plates Adenoid tonsils Pterygomandibular raphe Levator palati Mandibular tuberosity Salpingopharyngeus muscle Hyoid bone Greater and lesser Oropharynx horns Below the soft palate Stylohyoid ligament Uvula Thyroid cartilage Behind the palatoglossus muscle Cricoid cartilage Palatine tonsil (fauces) Palatopharyngeus muscle Posterior 1/3 of tongue Median and lateral glossoepiglotic folds Valleculae
Laryngopharynx Behind the opening of the larynx Epiglottis Aryepiglottic folds Arytenoid cartilages Piriform recesses Posterior edge of thyroid laminae Posterior aspect of the cricoid lamina Pharynx ends at the level of the cricoid ring
HFA 213 Week 11 the Pharynx 3 4 THE PHARYNX THE PHARYNX Constrictor muscles Longitudinal muscles ALL Origin from the pharyngeal skeleton Lie inside the circular coat -- unlike the rest of the GIT Insert into a midline raphe posteriorly (meets the one from the opposite side) Three longitudinal muscles take origin from the base of the skull
Superior constrictor Stylopharyngeus From the pterygomandibular from the styloid process raphe Palatopharyngeus (and the bone at either end) from the soft palate Salpingopharyngeus Middle constrictor from the auditory tube From the hyoid bone (salpinx = tube) (greater and lesser horns)
Inferior constrictor From the thyroid and cricoid cartilages Cricopharyngeus at the junction of pharynx and oesophagus.
“Flower pots” - the lower constrictors overlap the one Palatopharyngeus and above Salpingopharyngeus are inside the pharynx from the origin All the nerves and vessels that supply the pharynx (and larynx) must enter in the gaps above or Stylopharyngeus takes origin outside the pharynx, and has to pass between the superior below the constrictors and middle constrictors to get inside the pharynx HFA 213 Week 11 the Pharynx 5 6 DEGLUTITION = SWALLOWING THE PHARYNX 3 Phases Nerve supply
Things to avoid Sensory supply: Food must not go into the nose Glossopharyngeal nerve Food must not be forced back into the mouth Food must not go into the larynx Motor supply: 1. Vagus nerve supplies the muscles of pharynx, larynx and palate Oral phase Voluntary - duration variable ie. constrictors, palato and salpingopharyngeus Tongue gathers bolus - to roof of mouth, then backwards 2. Glossopharyngeal nerve supplies one muscle => stylopharyngeus Soft palate contracts to seal off nasopharynx from oropharynx At the end of the oral phase the bolus is thrown into the pharynx The pharyngeal plexus lies in the loose connective tissue coat And palatoglossus contracts to seal off the oropharynx from the mouth surrounding the pharynx (buccopharyngeal fascia). It receives pharyngeal branches of the vagus and glossopharyngeal nerves Pharyngeal phase Reflex - fraction of a second Reflex is triggered when the bolus touches the oropharynx (CN IX) The gag reflex: when you touch the back of your throat (oropharynx) it The longitudinal muscles contract triggers a reflex contraction of the pharyngeal muscles Raising the larynx (helping to fold the epiglottis and seal off the airway) Sensory limb = glossopharyngeal nerve Pulling the pharynx up over the bolus Processsing centre = Medulla of brain Then circular/constrictor muscles contract and the longitudinal ones relax Motor limb = vagus nerve and pharyngeal muscles Carrying the bolus down Peristaltic contractions then take over Like any reflex test this reflex tests all these components
Oesophageal phase Involuntary - slow - may take up to a minute The upper part of the Oesophagus is voluntary muscle Middle part is mixed smooth and voluntary muscle Lower part is smooth muscle
HFA 213 Week 11 the Pharynx 7 8 STRUCTURES ENTERING THE PHARYNX The Pharynx
Above superior constrictor
Salpingopharyngeus Auditory tube Levator palati Ascending palatine artery
Between superior constrictor and middle constrictor Lingual nerve Lingual artery Hypoglossal nerve Stylopharyngeus Glossopharyngeal nerve Submandibular duct
Between middle constrictor and inferior constrictor Internal laryngeal nerve and superior laryngeal artery
Below inferior constrictor
Recurrent laryngeal nerve and inferior laryngeal artery