L16: anatomy of oral cavity, tongue & pharynx Flashcards
Describe the oral cavity
Lies inferiorly to the nasal cavity & consists of two lateral walls, a floor and a roof
Lateral walls – buccinators (cheek muscle)
Roof – hard & soft palate
Floor – formed by several muscles of the tongue
Describe the functions of the oral cavity
Allows entry of food into the digestive tract
Following the process of mastication, food is broken down into a bolus ready for swallowing
Process is aided by salivary gland secretions -> lubricate the food & contain the enzymes that start the chemical digestion (parotid, submandibular & sublingual glands)
List the ducts of the salivary glands
Submandibular – Wharton duct
Parotid – Stensen duct
Sublingual – 8-20 excretory ducts per gland
Describe salivary glands stones (sialolithiasis)
Most stones are in the submandibular glands – twice the amount of calcium in the saliva produced by submandibular glands
Dehydration, reduced salivary flow – most are <1cm
Symptoms: pain in gland, swelling & infection (stimulated by eating)
Diagnosis: history, x-ray & sialogram
Describe the tongue
Entirely muscular tissue – covered in mucous membrane (squamous epithelium)
Muscles forming the tongue are broadly categorised as intrinsic and extrinsic
Describe the intrinsic muscles of the tongue
4 paired muscles lie entirely within the tongue and run longitudinally, vertically and transversely – named in according to the direction in which they travel
Act to alter the shape of the tongue
Blend with the extrinsic muscles
Innervated by the hypoglossal nerve
Describe the extrinsic muscles of the tongue
Act to change the position of the tongue – protrusion, retraction & side-to-side movement
Genioglossus – hypoglossal nerve (most important – protrudes the tongue -> test to determine hypoglossal nerve function)
Hyoglossus – hypoglossal nerve
Styloglossus – hypoglossal nerve
Palatoglossus – vagus nerve
Describe the sensory innervation of the tongue
Anterior 2/3 -sensation: trigeminal (V3) -taste: facial Posterior 1/3 -sensation and taste: glossopharyngeal
Describe tonsillitis
Inflammation of the palatine tonsils
Symptoms: fever, sore throat, pain/difficult swallowing, bad breath
Viral causes are the most common but can be bacterial – strep pyogenes
Describe a peritonsillar abscess (quinsy)
Symptoms: fever, bad breath, drooling, difficulty opening mouth
Can follow on from an untreated or partially treated tonsilitis
Can arise on its own – aerobic and anaerobic bacteria
Describe the nasopharynx
Base of skull to upper border of soft palate
Posterior: C1 & C2
Anterior: nasal cavity
Contains pharyngeal tonsil
Describe enlarged pharyngeal tonsils
Block the eustachian tube – recurrent/persistent middle ear infections Snoring/sleep apnoea Sleeping with mouth open Chronic sinusitis – sore throat Nasal tone to voice
Describe the oropharynx
Soft palate to epiglottis
Anterior: oral cavity
Posterior: C2 & C3
Contains palatine tonsils
Describe the laryngopharynx
Epiglottis to oesophagus at the level of the inferior border of the cricoid cartilage
Anterior: larynx
Posterior: C4, C5 & C6
Contains piriform fossa
Describe the piriform fossa
Small depression in the laryngopharynx
Potential site for foreign bodies entering the pharynx to become lodged
Also, site for pharyngeal cancers
Describe the muscles that elevate the pharynx and larynx during swallowing
Stylopharyngeus – styloid process to posterior border of thyroid cartilage
-glossopharyngeal nerve (CN IX)
Palatopharyngeus – hard palate to posterior border of thyroid cartilage
-pharyngeal branch of vagus (CN X)
Salpingopharyngeus – cartilaginous part of ET & merges with palatopharyngeus
-pharyngeal branch of vagus (CN X)
Describe the pharyngeal constrictors
3 circular muscles – constrict walls of pharynx when swallowing
Common midline tendinous insertion = pharyngeal raphe & innervation = vagus nerve
Superior pharyngeal constrictor – origin is pterygomandibular raphe
Middle pharyngeal constrictor – origin is hyoid bone
Inferior pharyngeal constrictor – has two parts
-thyropharyngeal: origin is thyroid cartilage
-cricopharyngeal: origin is cricoid cartilage
Describe a pharyngeal pouch
Between the two bellies of the inferior constrictor = point of weakness called Killian’s dehiscence
If there is incoordination of the pharynx during swallowing – pressure within the pharynx can rise & can cause part of the pharyngeal mucosa to herniate through Killian’s dehiscence = pharyngeal pouch
Symptoms: dysphagia, regurgitation of food, lump in the neck
Describe the motor and sensory supply of the pharynx
Pharyngeal plexus – located mainly on surface of middle constrictor muscles formed by branches of the vagus, glossopharyngeal and cervical sympathetic nerves
Motor – CN X innervates all muscles, except stylopharyngeus (CN IX)
Sensory:
-nasopharynx: maxillary branch of the trigeminal nerve
-oropharynx: glossopharyngeal nerve
-laryngopharynx: vagus nerve
Describe the clinical implication of the pharyngotympanic tube
Potential route for infection in the pharynx to the middle ear
Common for upper respiratory tract infections to be complicated by middle ear infections
Describe what happens if there are CN IX & X lesions
Absent gag
Uvular deviated away from lesion
Bit more subtle: dysphagia, taste impairment & loss of sensation in oropharynx
Can happen due to medullary infarct & jugular foramen issue (eg. fracture)
Describe what happens if there is a XII lesion
Wasted tongue Stick tongue – tongue may deviate -tongue points to side of lesion -muscle wasting -fasciculations
Describe the gag reflex
Afferent - glossopharyngeal nerve
Efferent - vagus nerve
