L16: anatomy of oral cavity, tongue & pharynx

Question 1

Describe the oral cavity

Answer 1

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

Question 2

Describe the functions of the oral cavity

Answer 2

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)

Question 3

List the ducts of the salivary glands

Answer 3

Submandibular – Wharton duct
Parotid – Stensen duct
Sublingual – 8-20 excretory ducts per gland

Question 4

Describe salivary glands stones (sialolithiasis)

Answer 4

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

Question 5

Describe the tongue

Answer 5

Entirely muscular tissue – covered in mucous membrane (squamous epithelium)
Muscles forming the tongue are broadly categorised as intrinsic and extrinsic

Question 6

Describe the intrinsic muscles of the tongue

Answer 6

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

Question 7

Describe the extrinsic muscles of the tongue

Answer 7

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

Question 8

Describe the sensory innervation of the tongue

Answer 8

Anterior 2/3 
-sensation: trigeminal (V3)
-taste: facial
Posterior 1/3 
-sensation and taste: glossopharyngeal

Question 9

Describe tonsillitis

Answer 9

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

Question 10

Describe a peritonsillar abscess (quinsy)

Answer 10

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

Question 11

Describe the nasopharynx

Answer 11

Base of skull to upper border of soft palate
Posterior: C1 & C2
Anterior: nasal cavity
Contains pharyngeal tonsil

Question 12

Describe enlarged pharyngeal tonsils

Answer 12

Block the eustachian tube – recurrent/persistent middle ear infections 
Snoring/sleep apnoea 
Sleeping with mouth open 
Chronic sinusitis – sore throat 
Nasal tone to voice

Question 13

Describe the oropharynx

Answer 13

Soft palate to epiglottis
Anterior: oral cavity
Posterior: C2 & C3
Contains palatine tonsils

Question 14

Describe the laryngopharynx

Answer 14

Epiglottis to oesophagus at the level of the inferior border of the cricoid cartilage
Anterior: larynx
Posterior: C4, C5 & C6
Contains piriform fossa

Question 15

Describe the piriform fossa

Answer 15

Small depression in the laryngopharynx
Potential site for foreign bodies entering the pharynx to become lodged
Also, site for pharyngeal cancers

Question 16

Describe the muscles that elevate the pharynx and larynx during swallowing

Answer 16

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)

Question 17

Describe the pharyngeal constrictors

Answer 17

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

Question 18

Describe a pharyngeal pouch

Answer 18

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

Question 19

Describe the motor and sensory supply of the pharynx

Answer 19

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

Question 20

Describe the clinical implication of the pharyngotympanic tube

Answer 20

Potential route for infection in the pharynx to the middle ear
Common for upper respiratory tract infections to be complicated by middle ear infections

Question 21

Describe what happens if there are CN IX & X lesions

Answer 21

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)

Question 22

Describe what happens if there is a XII lesion

Answer 22

Wasted tongue 
Stick tongue – tongue may deviate 
-tongue points to side of lesion
-muscle wasting
-fasciculations

Question 23

Describe the gag reflex

Answer 23

Afferent - glossopharyngeal nerve

Efferent - vagus nerve