008 anatomy and relations of the pharynx Flashcards
what and where is the pharynx?
muscular tube that connects the nasal cavities to larynx and oesophagus
- both respiratory and gastrointestinal
- behind the nose, mouth and larynx and just above oesophagus
- between the trachea and vertebral column, continuous with oesophagus
what is the function of the pharynx?
- passes food safetly across airway during swallowing (prevent choking)
- helps direct air flow via oral cavity
- closes the nasal cavity from the oral cavity during chewing and swallowing
what is the overall anatomy of the pharynx?
- muscular tube, fastened to the pharyngeal tubercle of the basi-occipital bone and anterior attachments to the:
- occipital bone (pharyngeal tubercle),
- sphenoid (medial pterygoid plates)
- mandivular body and ramus,
- greater horn of hyoid and thyroid/cricoid cartilages
posterior attachments to the pharyngeal raphe (midline) - 3 anterior openings
what are the 3 anterior openings of the pharynx?
- nasal cavity, oral cavity, larynx opening
what are the 3 regions of the pharynx?
- nasopharynx
- oropharynx
- laryngopharynx
what is in the nasopharynx?
- located above the palate, behind the nasal cavity
- covered by the sphenoid body and rostrum
- lined with respiratory epithelium
- contains adenoid tonsils and opening of auditory tube
what is the clinical relevance of the nasopharynx/adenoid tonsils?
- adenoid tonsils can enlarge due to infection/inflammation
- when enlarged it can obstruct the opening of the eustachian tube which equalisies the pressure in the middle ear by draining fluids
- so can lead to chronic ottis media with effusion = middle ear infection
what is in the oropharynx?
- behind oral cavity
- floor is formed by the posterior part of tongue and space between tongue and epiglottis
- roof formed by soft palate
- contains posterior 1/3 of tongue, lingual tonsils, palatine tonsils, valleculae and super constrictor muscles
what is the clinical relevance of the oropharynx/palatine tonsils?
- palatine tonsils can be enlarged/inflamed due to infection (tonsilitis)
- chronic infection = tonsillectomy
- If infection spreads to peritonsillar tissue, can cause abscess formation, causes deviation of uvula and can obstruct pharynx/airway = drain and antibiotics
what is in the laryngopharynx?
- located between the epiglottis and inferior border of cricoid cartilage
- posterior to larynx
- contains the piriform fossae
- contains middle, inferior pharyngeal constrictors
what is the clinical relevance of the laryngopharynx/pharyngeal diverticulum?
- area between 2 parts of inferior constricter muscle is weak mucosa
- if cricopharyngeus doesn’t relax during swallowing, a midline diverticulum forms between the thyropharyngeus and cricopharyngeus and food can accumulate here
= cause dysphagia
what is the auditory/pharyngotypmpanic tube?
- connects the anterior wall of the tympanic cavity to the nasopharynx
- the anterior 2/3 is cartilaginous and posterior 1/3 is bony (so that front can grow with face from child to adult)
- opening of cartilaginous part is close to tonsillar tissue
- closely associated with soft palate muscles and tensor tympani muscle which help to close the tube
what is the clinical relevance of the pharyngotympanic/auditory tube?
- canal from nose to ear
- lots of respiratory infections are in the nose = easily spread to ear and get an ear infection
what is the piriform fossae?
- depressions in the mucous membrane on each side of the laryngeal inlet
- together with the valleculae at the base of the tongue, they channel the food and water around the laryngeal inlet to prevent choking
what are the 3 main functions of the muscles of the pharynx?
- assist movements of the soft palate (superior constrictor, palatopharyngeus)
- constrict diameter of pharynx and push food along (constrictors)
- lift the pharynx as a functional unit (palatopharyngeus, stylopharyngeus and superior constrictor)
what are the constrictor muscles of pharynx?
- superior, middle and inferior pharyngeal constrictors
- constrict lumen to push food down into the oesophagus
- circular muscles, all innervated by the vagus nerve
(note inferior constrictor has 2 parts = thyropharyngeus (superior part) and cricopharyngeus (inferior part)
what are the muscles of the soft palate?
- tensor veli palatini (tenses/stretches/lifts)
- levator veli palatini (elevates palate)
- palatoglossus (moves palate to tongue (anteirorly))
- palatopharyngeus (moves palate down (posteriorly))
- superior pharyngeal constrictor (lifts palate and closes soft palate)
- stylopharyngeal
what is the innervation of the soft palate muscles?
- all vagus nerve except
- tensor veli palantini = mandibular division of trigeminal nerve
- stylopharyngeus = glossopharyngeal
what is the sensory innervation of the soft palate?
maxillary division of the trigeminal nerve
what muscle in the soft palate does 1?
tensor veli palatini
what muscle in the soft palate does 2?
palatoglossusa
what muscle in the soft palate does 3?
levator veli palatini
what muscle in the soft palate does 4?
superior constrictor
what muscle in the soft palate does 5?
palatopharyngeus
what are the structures of the soft palate?
- soft palate is posterior to hard palate
- palatoglossal arch (fold of mucosa between tongue and soft palate)
- palatopharyngeal arch = posterior to palatoglossal arch and merges with pharyngeal wall
- uvula (dangles down in middle)
- pharyngeal tonsil in the walls of the palatopharyngeal arch
what is the sensory innervation to the different divisions of the pharynx?
- nasopharynx = maxillary division of trigeminal
- oropharynx = glossopharyngeal
- laryngopharynx = vagus
what is the blood supply of the pharynx?
- branches of external carotid artery =
- ascending pharyngeal artery
- maxillary artery ( oro and nasopharynx)
- facial artery –> ascending palatine arteries and tonsillar arteries
- lingual artery (tongue and pharynx)
describe the lymphatics of the pharynx
- lots of tonsils around the pharynx (adenoids, tubar, palatine, lingual) which are collections of lymphoid tissue covered by mucous membrane
- drain into retropharyngeal nodes, submandibular nodes, and deep cervical nodes
what is the pharyngeal plexus?
contains branches of vagus and glossopharyngeal nerves and sympathetic fibres from the superior cervical ganglion
what is the oral preparatory phase of swallowing?
- lips closed (facial expression muscles)
- food is squeezed from oral vestibule between teeth (lips and buccinator muscles)
- oral cavity is sealed posteriorly by depressing the soft palate against the back of tongue
what is the oral phase of swallowing?
- tongue is raised against hard palate to push the bolus backwards
- assisted by elevating mandible and raising hyoid bone
- soft palate is elevated to close off the nasopharynx and to direct the bolus into the oropharynx
what is the pharyngeal phase of swallowing?
- food contacts the posterior wall of the pharynx (mucosa, glossopharyngeal nerve)
- this contact initiates contraction of pharyngeal constrictor muscles from superior to inferior (vagus nerve)
- the bolus then contacts the epiglottis and folds it backwards over the laryngeal inlet (vagus nerve)
- respiration stops and vestibular and vocal cords are abducted (shut off larynx) by the arytenoid muscles to prevent inhalation of food (vagus)
what is the oesophageal phase of swallowing?
- contractions of the cricopharyngeus (inferior part of the inferior pharyngeal muscle) initiate the movement of the bolus through the oesophagus
- a wave of contractions of circular muscles moves the food down, coordinated by vagal nuclei in brainstem (peristalsis)
