Pharynx Flashcards
What are the muscles involved in swallowing?
Superior constrictor
Middle constrictor
Inferior constrictor
++++
note: open anteriorly, attach to the pharyngeal raphe posteriorly
What is the difference in the pharynx when swallowing and not swallowing?
Not swallowing:
- oesophageal sphincter contracted
- epiglottis up & glottis opened —> air flows through trachea into lungs
Swallowing:
- triggered when bolus of food reaches the pharynx
- larynx moves forward & tips the epiglottis over the glottis (preventing food from entering the trachea)
- oesophageal sphincter relaxes, allowing the bolus to enter the oesophagus
- after the food has entered the top of the oesophagus, the larynx moves downwards and opens the breathing passage
What is the blood and nerve supply to the pharynx?
Arterial = branches of lingual, facial, & maxillary arteries (branches of external carotid arteries)
Venous = pharyngeal venous plexus (IJV)
Motor:
- vagus nerve (CNX)
- glossopharyngeal nerve (CNIX)
- hypoglossal nerve (CNXII)
- facial nerve (CNVII)
Sensory:
Nasopharynx = maxillary division of trigeminal nerve (CNV2)
Oropharynx = glossopharyngeal nerve (CNIX)
Laryngopharynx = hypoglossal nerve (CNXII)
What is the level of the nasopharynx? What are the boundaries and contents of the nasopharynx?
C1 - above soft palate, lined with ciliated pseudostratified epithelium
Boundaries: SUPERIOR = skull base INFERIOR = level of soft palate ANTERIOR = posterior choane POSTERIOR = nasopharyngeal tonsils (adenoids) & C1 vertebra
Contents:
- adenoids
- orifice of Eustachian tube
What is the mechanism of swallowing?
- Pushing food from oral cavity to oropharynx
- tongue & suprahyoid muscles pull the hyoid and larynx up
- soft palate elevates (nasopharynx closed off)
- superior constrictors contract - Food bolus passes into laryngopharynx by aid of middle & inferior constrictors
- Larynx protected overhanging tongue, epiglottis, & vocal cords
- Cricopharyngeus relaxes
What is the level of the oropharynx? What are the boundaries and contents of the oropharynx?
C2-C3 - behind oral cavity & tongue, lined by stratified squamous epithelium
Boundaries: SUPERIOR = level of soft palate INFERIOR = superior edge of epiglottis ANTERIOR = oral cavity POSTERIOR = C2-C3 vertebrae
Contents:
- palatine tonsils (lymphoid tissue covered by squamous epithelium; atrophies after puberty), supplied by tonsillar branch of facial artery & drained by pharyngeal venous plexus; lymph drains to nodes along IJV to the jugulodigastric node (angle of mandible - C2)
- anterior/palatoglossal arch (boundary between buccal cavity & oropharynx —> lateral wall of tongue) & posterior/palatopharyngeal arch (palate —> wall of pharynx) tonsillar pillars
What is the level of the laryngopharynx? What are the boundaries and contents of the laryngopharynx?
C3-C6 - below epiglottis, lined by stratified squamous epithelium
Boundaries: SUPERIOR = superior edge of epiglottis INFERIOR = level of inferior edge of cricoid cartilage ANTERIOR = larynx POSTERIOR = C3-C6 vertebrae
Opens into larynx anteriorly & oesophagus posteriorly
What are the adenoid tonsils?
Mass of lymphoid tissue producing IgA, IgG, IgM
Maximal size at 3-8yrs, then regress
Enlarge with viral & bacterial infections (difficult to assess by imaging/examination - clinical diagnosis)
—> nasal obstruction (mouth breathing, hyponasal/high-pitched speech, feeding difficulty, snoring/obstructive sleep apnoea)
—> Eustachian tube obstruction (recurrent otitis media, chronic otitis media with effusion)
What are the complications of adenoidectomy?
Bleeding
Atlanto-occipital joint dislocation (due to infection)
Eustachian tube stenosis
What are the indications for tonsillectomy? What are the complications of tonsillectomy?
Indications:
- recurrent tonsillitis (5/yr for at least 2yrs)
- previous quinsy (peritonsillar abscess)
- suspected cancer (unilateral enlargement/ulceration)
- obstructive sleep apnoea
Complications:
- bleeding
- infection
What is a pharyngeal pouch?
Posterior herniation of pharyngeal mucosa between the inferior constrictor muscle (thyropharyngeus) and the cricopharyngeus (Killian’s dehiscence)
Can fill with food —> infection —> halitosis & enters the airways
note: pharyngeal pouch is a true diverticulum - all layers protrude out
(unlike diverticula of the colon - occur between layers at natural areas of weakness; therefore do not contain all layers of the intestine)
Contrast stridor & stertor.
STRIDOR = noisy breathing caused by partial obstruction of the airway at or BELOW the larynx
STERTOR = snoring sound caused by partial obstruction of the airway ABOVE the larynx
What are the anatomical and physiological differences between adult and paediatric airways?
ANATOMICAL:
- larger head:body ratio in children
- smaller face & mandible
- large tongue
- adenotonsillar hypertrophy
- short & soft trachea
- higher surface area:weight
PHYSIOLOGICAL:
- different baseline measurements
- smaller respiratory reserve
- compliant chest walls
- greater metabolic rate & rate of oxygen consumption
- can not always rely on specific commands (AVPU)
note: adult: cylindrical airway, child: funnel-shaped airway (due to underdeveloped cricoid cartilage)
What is different about the anaesthesia given during a laryngotracheobronchoscopy?
No muscle relaxant is given so patient is unconscious but still breathing spontaneously
What is acute epiglottitis?
Rare
Usually in 2-7yrs
Bacterial infections = Haemophilus influenzae, Staph., beta-haemolytic Strep., pneumococci
Septic/pyrexial + classic “tripod” position (leaning forward with hands on knees) + drooling
Management: EMERGENCY - secure the airway
- broad spectrum antibiotics (ceftriaxone)
note: Haemophilus influenzae B vaccine given
What is croup?
Laryngotracheobronchitis = acute inflammation & obstruction of the respiratory tract involving the larynx, trachea, and bronchi
Initial viral infection (+/- secondary bacterial infection) e.g. (para)influenza
Common cause of stridor (on inspiration & expiration as obstruction is just below the larynx —> no give when breathing)
Associated “barking” subglottic cough which is overly harsh (disproportionate to individual)
Infective oedema narrows the subglottis —> steeple sign on X-ray
What is the clinical presentation of foreign bodies in the airway?
Episode of coughing, choking, or playing with foreign body (or unwitnessed episode)
Radiology can show segmental/lobar collapse, localised emphysema (air trapping)
Remove via bronchoscopy
What is laryngomalacia?
Condition characterised by paroxysmal attacks of breathing difficulty and stridor caused by flaccidity of the structure of the larynx
Rare
Epiglottis partially covers the larynx on inspiration (stridor on inspiration)
Air pushes epiglottis out of the way during expiration (no stridor on expiration)
What is the purpose of the levator glandulae thyroideae?
Elevates the thyroid gland
Fibrous band which may contain muscle connects the isthmus of the thyroid gland to the hyoid bone
What is the difference between the actions of the suprahyoid and infrahyoid muscles during swallowing?
SUPRAHYOID = lift the larynx during swallowing to prevent aspiration of food
INFRAHYOID = stabilise the larynx by opposing the suprahyoids during swallowing
