H&N16 - Oral Cavity, Tongue, Pharynx

Question 1

3 features of the oropharyngeal isthmus

Location
Boundaries
Closure

Answer 1

1. ) Location - oral cavity begins anteriorly at the oral fissure and extends to the oropharyngeal isthmus
   - the oropharyngeal isthmus continues posteriorly into the oropharynx
2. ) Boundaries - isthmus is an arch formed by structures
   - soft palate above, upper surface of the tongue below
   - sides formed by anterior and posterior pillars (muscles)
   - anterior is palatoglossus, posterior is palatopharyngeal
   - between these muscles is the tonsillar fossa which contains the palatine tonsil
3. ) Closure of the Oropharyngeal Isthmus - occurs so that food remains in the oral cavity during chewing
   - caused by contraction of the of the palatoglossus and palatopharyngeal muscles

Question 2

6 features of the tongue

Epithelium
Intrinsic Muscles x4
Extrinsic Muscles
Papillae
Vasculature x3
Lymphatic Drainage

Answer 2

1. ) Epithelium - stratified squamous
   - entirely muscular tissue covered in mucous membrane
2. ) Intrinsic Muscles - change the shape of the tongue
   - 4: superior and inferior longitudinal, transvere, vertical
   - blends w/ the extrinsic muscles (dont attach to bone)
3. ) Extrinsic Muscles - changes the position of the tongue
   - anchor the tongue to structures above (styloid process and soft palate) and below (hyoid bone and mandible)
4. ) Papillae - sensory receptors for taste (‘taste buds’)
   - covers the dorsal surface of the tongue
5. ) Vasculature - mainly lingual artery (ECA)
   - tonsillary artery (facial) provides collateral circulation
   - venous drainage into the lingual vein
6. ) Lymphatic Drainage
   - anterior 2/3: submental and submandibular which then drain into the deep cervical lymph nodes
   - posterior 1/3: deep cervical lymph nodes

Question 3

4 extrinsic muscles of the tongue

Answer 3

1. ) Genioglossus - mandibular symphysis –> hyoid bone
   - protrusion (inferior fibres), depression (middle fibres)
   - superior fibres draws the tip back and down
   - protrusion is tested to determine CN XII function
2. ) Hyoglossus - hyoid bone –> side of the tongue
   - depresses and retracts the tongue
3. ) Styloglossus - styloid process –> side of the tongue
   - retracts and elevates the tongue
4. ) Palatoglossus - palatine aponeurosis –> broadly across the tongue
   - elevates the posterior aspect of the tongue
   - different motor innervation (X instead of XII)

Question 4

Innervation of the tongue (and salivary glands)

Motor
General Sensory
Special Sensory
Salivary Glands

Answer 4

1. ) Motor Innervation - hypoglossal nerve (CN XII)
   - innervates all the muscles of the tongue apart from palatoglossus which is innervated by the vagus nerve
2. ) General Sensory Innervation
   - anterior 2/3: trigeminal (lingual branch of Vc)
   - posterior 1/3: glossopharyngeal (IX)
3. ) Special Sensory (taste) Innervation
   - anterior 2/3: facial (chorda tympani, running w/ lingual)
   - posterior 1/3: glossopharyngeal (IX)
4. ) Salivary Glands
   - submandibular and sublingual: facial (chorda tympani)
   - parotid: glossopharyngeal (IX)

Question 5

3 divisions of the pharynx

Location
Relation to Vertebral Bodies
Contents
Sensory Innervation

Answer 5

1. ) Nasopharynx - posterior extension of the nasal cavity
   - lies superior to the soft palate and anteriorly to C1
   - contains the orifice of the Eustachian tube
   - also contains the pharyngeal tonsil (adenoids)
   - sensory innervation by maxillary branch of CN V(b) apart from the Eustachian tube (IX)
2. ) Oropharynx - level of soft palate –> epiglottis (superior border)
   - lies anteriorly to the vertebral bodies of C2 and C3
   - palatine tonsils lie in the oropharyngeal isthmus
   - sensory innervation by glossopharyngeal (IX)
3. ) Laryngopharynx - epiglottis –> oesophagus at the level of the inferior border of the cricoid cartilage
   - lies behind the larynx and anterior to C3-C6
   - on each side to the opening of the larynx, it has a small depression called the piriform fossa
   - sensory innervation by the vagus nerve (X)

Question 6

5 features of the pharyngeal constrictors

Function
Location
3 Types
Internal Pharynx Muscles
Innervation

Answer 6

1. ) Function - relax and contract sequentially from above to below to propel food bolus into the oesophagus
   - works collectively with the internal pharynx muscles
2. ) Location - externally, in the walls of the pharynx
   - posteriorly, all insert into the pharyngeal raphe
3. ) 3 Types - superior, middle, and inferior constrictors
   - all circular in shape
4. ) Internal Pharynx Muscles - three longitudinal muscles
   - stylopharyngeus, palatopharyngeus, salpingopharyngeus
   - shorten and widen the pharynx and also lifts the larynx during swallowing and speaking
5. ) Innervation - vagus nerve (X)
   - vagus nerve supplies all the muscles of the pharynx except for stylopharyngeus (IX)

Question 7

4 features of a pharyngeal pouch/diverticulum

What is it?
Killian’s Dehiscence
Cause
Effects

Answer 7

1.) What is It? - part of pharyngeal mucosa herniates through Killian’s dehiscence forming a pouch

2. ) Killian’s Dehiscence - area of weakness between the two muscles of the inferior pharyngeal constrictor
   - thyropharyngeus and cricopharyngeus

3.) Cause - rise in pressure caused by incoordination of the pharynx during swallowing e.g. thryopharyngeus contracts against a constricted cricopharyngeus

4. ) Effects - food may become trapped in the pouch
   - small pouches can be asymptomatic
   - others can cause dysphagia, regurgitation, or present as a lump in the neck

Question 8

3 phases of swallowing

Answer 8

1. ) Oral Preparatory Phase - voluntary
   - movements of the tongue pushes bolus towards the back of the oral cavity, towards the oropharynx
   - this triggers the pharyngeal phase
2. ) Pharyngeal Phase - involuntary
   - closing off the nasopharynx and epiglottis
   - food is pushed downwards into the oesophagus
3. ) Oesophageal Phase - involuntary
   - closure of the upper oesophageal sphincter
   - peristaltic wave carries bolus downwards into oesophagus

Question 9

5 steps in the pharyngeal phase of swallowing

Closing Off Nasopharynx
Closing the Epiglottis
Movement of Food Bolus
Protection of Airway
Upper Oesophageal Sphincter

Answer 9

1. ) Closing Off Nasopharynx - from the oropharynx
   - caused by elevation of the soft palate
2. ) Closing the Epiglottis - prevents aspiration of food
   - caused by elevation of the larynx:
   - contraction of the suprahyoid muscles and the internal/longitudinal pharyngeal muscles
3. ) Movement of Food Bolus - towards the oesophagus
   - action of the pharyngeal constrictors
4. ) Protection of Airway - vocal cords adduct
   - breathing temporarily ceases

5.) Upper Oesophageal Sphincter Opens

Question 10

Nerve innervation of the pharynx

Motor
Sensory x3

Answer 10

1. ) Motor Innervation - vagus nerve (X) supplies all the muscles of the pharynx and soft palate
   - except stylopharyngeus (CN IX)
2. ) Sensory Nasopharynx - maxillary branch of CN V(b)
3. ) Sensory Oropharynx - glossopharyngeal nerve
4. ) Sensory Laryngopharynx - vagus nerve