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
