The Pharynx

The Pharynx

1. Lymph Drainage

   • from tonsil passes through superior constrictor to nodes along inernal jugular vein
     • epecially jugulodigastric node at angle of jaw
       • in TONSILITIS its the first nodes to enlarge
         • TONSILLECTOMY
           • lymphoid tissue of tonsil and tonsillar capsule are removed
             • usually superior constrictor lies separate from tonsils and its capsule by areolar tissue
               • so not damaged during operation
         • infection in peritonsilar tissue secondary to tonsillitis
           • abcess so formed can bulge into pharynx
             • can compromis swallowing and breathing
               • treatment - incising and draining
         • childrens tonsilis are normally larger than adults
     • QUINSY
     • constrictor muscles constric pharynx involuntarily
       • so their action propels food onwards during swallowing
       • pharyngeal wall is weakest between constrictors
         • important where oesophagus loses support of inferior constrictor
           • before it acquires a full longitudinal coat of muscle
           • here diverticular of oesophagus can occur
           • as pharnyx tapers to oesophagus, carotid cartilage prevents the oesophagus expanding anterioly
             • swallowed objects can lodge here
               • oesophageal lumen is narrow ant and post, widest from side to side
                 • = can see stuck objects on x-ray

2. Lateral Relations of Pharyngeal Constrictors

   • CN exiting skull via jugular foramen, IX, X and XI pass close to pharyngeal constrictors
     • IXth nerve enters neck lying with X, XI and XII between the internal carotid artery and internal jugular vein
       • opposite the styloid process it winds around stylopharyngeus and runs along lat side of this to pass into the gap
         • between sup and middle constrictor
         • supplies innervation to stylopharyngeus as it crosses it
       • IX - glossopharyngeal - mainly sensory to tongue and pharynx
         • supplies mucosa of posterior 1/3 of tongue with fibres for general sensation and tase
           • on the SA of middle constrictor it joins with pharyngeal branch of vagus to form pharyngeal plexus
             • thought that his plexus IX supplies tonsils and pharyngeal mucosa
               • and with X supplies carotid body and carotid sinus
       • internal and common carotid arteries are, with jugular vein, closely applied to constrictors
         • no. of structures lying between the internal and external carotid
           • styloid process
           • stylopharyngeus
           • IX nerve
           • pharyngeal branches of vagus
           • styloglossus
           • parotid gland

3. 12-14cm long muscular membraneous tube

   • from cranial base to lower border of carcoid cartilage at C6 level
     • becomes continuous with oesophagus
   • 3 regions
     • Nasopharynx
       • posterior to nose and superior to soft palate
       • has pharyngeal tonsil, pharyngotympanic membrane and pharyngeal isthmus
     • Oropharynx
       • posterior to mouth
       • contains palatine tonsils and oropharyngeal isthmus
     • Laryngopharynx
       • posterior to larynx
       • contains epiglottis and laryngeal inlet

4. X-Ray

   • Retropharyngeal interspace normal -
     • C1 - 10mm, C2 - 5mm C3 - 7mm C4 - 7mm C5-7 - 20mm
       • inc - neoplasm, post traumatic haematoma, abcesses

5. Muscles of Pharynx

   • External layer
     • 3 constrictor muscles (sup, inf, middle)
       • contract involunarily during swallowing, constricting walls of pharynx
       • Superior Pharyngeal Constrictor
         • O - pterygoid hamulus, pterygomandibular raphe, post end of myloid line of mandible and side of tongue
         • I - pharyngeal tubercle on basilar part of occipital
         • I - Pharyngeal branch of vagus and pharyngegal plexus
       • Middle
         • O - stylohyoid lig and greater and lesser horns of hyoid
       • I - Parhyngeal raphe
       • Inferior
         • O - thyroid cartilage and side of cricoid cartilage
       • N- pharyngeal branch of vagus and pharyngeal plexus plus branches of external and recurrent laryngeal nerves of vagus
   • Longitudinal Muscles
     • inner layer of pharynx is made of up 3 mucles
       • all descend and insert into wall of pharynx
         • elevate larynx and shortes pharynx during swallowing and speaking
       • Palatopharyngeus
         • O - hard palate and palatine aponeurosis
         • I - post border of lamina of thyroid cartilage and side of pharynx and oesophagus
       • Salpingopharyngeus
         • O - cartilaginous part of pharyngotympanic tube
         • I - blends with palatopharyngeus
       • Stylopharyngeus
         • O - styloid process of temporal bone
         • I - post and sup borders of thryoid cartilage with palatopharyngeus
         • N - glossopharyngeal nerve
       • N - Pharyngeal branch of vaus and pharyngeal pleuxs
   • Fascia
     • Muscles of pharyngeal wall are between 2 layers of fascia
       • THIN BUCCOPHARYNGEAL FASCIA
         • coats external layer of pharynx and is continuous post with prevertebral fascia
           • anteriorly passes over buccinator
       • retropharyngeal space exists between prevertebral and buccopharyngeal fascia
     • much thicker pharyngobasilar fascia exists between skull base and sup constrictor which passes inf, and eventually disappears
   • Holes in the Wall
     • Gaps between muscles in pharyngeal wall exist and act as route for muscles and neurovascular tissue to pass
       • one large one is between sup and middle constrictors
         • allows stylopharyngeus, IX and stylohyoid lig to pass to pharyngeal wall
     • gap between middle and inf constrictors allows internal branch of superior laryngeal nerve and accompanying vessels to enter larynx
       • recurrent laryngeal nerve and accompanying vessels enter larynx post to lesser horn of hyoid deep to inferior constrictor
         • KILLIAN'S DEHISCENCE
           • pathological space - posteiror midline of wall of laryngopharynx within inferior constrictor
           • = weakness here
             • = food/ liquid escapes, and can collect in a pharyngeal pouch

6. Nerve supply

   • motor and most sensory innervation is via branchs of IX and X
     • forms pharyngeal plexus
       • motor fibres are from vagus nerve and innervate all mscles of pharynx and soft palate except
         • STYLOPHARYNGEUS - IX
         • TENSOR VELI PALATINI - V3
   • sensory fibres in plexus are from IX and supply most of mucosa of entire pharynx
     • sensory supply for ant and sup. nasopharynx is via V2

7. Hard palate

   • concave, allowing space for tongue to rest
     • formed by palatine processes of maxillae and horizontal plates of palatine bones
       • no. of foramen within hard palate allowing transmission of nerves

8. Soft Palate

   • forms mobile posterior 2/3 of palate suspended form hard palate
     • no skeletal framework but is supported by palatine aponeurosis extending from hard palate
       • has a curved free margin from which hangs the uvula