Week 7 HUBS - Pharynx

Boundaries of the Pharynx

  • Nasopharynx: choanae to soft palate
  • Oropharynx: soft palate to epiglottis
  • Laryngopharynx: epiglottis to top of oesophagus

Muscles of the Pharynx

  • Constrictors (3): $3$ constrictor muscles – Superior, Middle, Inferior
    • Anterior attachments: pterygomandibular raphe, hyoid bone, thyroid cartilage
    • Posterior attachment: pharyngeal raphe (seam) to pharyngeal tubercle (occipital bone)
    • Innervation: all by CN X; function: constrict pharynx during swallowing
  • Longitudinal muscles (3): Salpingopharyngeus, Palatopharyngeus, Stylopharyngeus
    • Elevate pharynx; Palatopharyngeus also closes the oropharyngeal isthmus
    • Innervation: Salpingopharyngeus and Palatopharyngeus by CN X; Stylopharyngeus by CN IX

Pharyngeal Mucosa and Landmarks

  • Pharyngeal mucosa lines the pharynx; important landmarks include:
    • Valleculae: between root of tongue and epiglottis
    • Piriform recess: lateral to laryngeal inlet
    • Pharyngeal tonsil (adenoids) in nasopharynx
    • Palatine tonsil in oropharynx (can enlarge with infection)
    • Isthmus (fauces) between oral cavity and oropharynx

Blood Supply

  • Ascending pharyngeal artery
  • Facial artery
  • Maxillary artery
  • Inferior laryngeal artery (branch of thyrocervical trunk)
  • All are branches of the external carotid system

Venous Drainage

  • Pharyngeal venous plexus drains to the internal jugular vein

Innervation (Motor and Sensory)

  • Motor innervation (pharyngeal muscles): CN X (vagus) except:
    • Stylopharyngeus is CN IX
  • Sensory innervation by region:
    • Nasopharynx: CN V2 (trigeminal, maxillary division)
    • Oropharynx: CN IX (glossopharyngeal)
    • Laryngopharynx: CN X (vagus)

Regions for Food Lodgement in the Pharynx

  • Valleculae (between root of tongue and epiglottis)
  • Piriform recess (lateral to laryngeal inlet)

Swallowing (Deglutition) — Brief Sequence

  • Bolus prepared and propelled to oropharynx by tongue
  • Palatoglossus and Palatopharyngeus squeeze bolus further back
  • Tensor veli palatini and Levator veli palatini elevate soft palate to seal nasopharynx
  • Pharynx shortens and widens (via palatopharyngeus, stylopharyngeus, salpingopharyngeus)
  • Suprahyoid muscles elevate hyoid and larynx to close larynx
  • Sequential constrictor contractions propel bolus into oesophagus

Cricopharyngeus and Upper Esophageal Sphincter

  • Cricopharyngeus is part of the inferior pharyngeal constrictor
  • Forms the upper esophageal sphincter at the cricopharyngeal region
  • Connects pharynx to oesophagus

Additional Notes

  • Pharyngeal raphe and pharyngobasilar fascia are key fascial attachments
  • Pharyngobasilar fascia and pharyngeal tube boundaries relate to access during swallowing
  • The pharyngeal bands link to surrounding structures via the pharyngoepiglottic and aryepiglottic folds

Quick Reference (Key Terms)

  • Choanae, soft palate, epiglottis, piriform recess, valleculae, pharyngeal raphe, pharyngobasilar fascia, pharyngeal tubercle, cricopharyngeus, upper esophageal sphincter, CN X, CN IX