16-01-23 – Oral Cavity and Pharynx Flashcards
Learning outcomes
- Briefly list the functions of the digestive system
- Describe the bones and structures that form the boundaries of the oral cavity
- Briefly describe the functional anatomy of the 4 primary muscles of mastication
- Briefly describe the teeth
- Describe the functional anatomy and clinical implications of the cheeks, lips, floor of mouth, tongue, salivary glands and palate
- Describe the different parts of the pharynx, their internal features and functions
- Describe the functional anatomy and skeletal attachments of the pharyngeal fascia and muscles (constrictors and elevators)
- Describe the anatomy of the pharyngeal and lingual tonsils
- Describe the neural supply of the pharynx
- Describe, anatomically, the sequence of swallowing
- Describe the major differences in oral cavity, pharynx and larynx anatomy of infants and adults
What does the digestive system consist of?
What is the function of the digestive system?
What 8 processes are conducted in the digestive system?
- The digestive system consists of the GI tract (Oral cavity to the rectum and anal canal and the accessory organs (salivary glands, liver, gallbladder, pancreas)
- The function of the digestive system is preparation of food for cellular utilization
- 8 processes are conducted in the digestive system:
1) Ingestion
2) Mastication (chewing)
3) Deglutition (swallowing)
4) Propulsion (peristalsis and segmentation)
5) Mechanical digestion
6) Chemical digestion (primarily in the intestines)
7) Absorption
8) Defecation
What 2 things is the oral cavity (mouth) comprised of?
Where is the oral vestibule and oral cavity proper located?
Where are they both connected?
What is located at the oral cavity proper?
What is the oral cavity proper bound by posteriorly?
What are 5 functions of the oral cavity?
- The oral cavity (mouth) is comprised of the oral vestibule and the oral cavity proper
- The oral vestibule is the space between the teeth and gums internally and the space between the lips and cheek externally
- The oral cavity proper is deep to the teeth anteriorly and laterally
- The oral vestibule and oral cavity proper are connected behind the wisdom teeth at the retromolar triangle
- The anterior tongue is located at the oral cavity proper
- The oral cavity proper is posteriorly bound by the palatoglossal folds (aka palatoglossal arches, anterior pillars of the fauces), which is the boundary between the oral cavity and the oropharynx
- 5 functions of the oral cavity:
1) Mastication & initiate swallowing
2) Saliva production
3) Antimicrobial defence
4) Digestion
5) Lubrication of food bolus
Where is the vermillion border located?
What structures does the vermillion border lack?
Why are lips red?
What are the lips lined with internally?
What is the innervation of the lips like?
- The vermillion border is the area between the skin and the mucous membrane of the lips
- The vermillion border lacks sebaceous/sweat glands
- The Lips are red because they consist of poorly keratinized skin that is rich in blood vessels, which results in the reflection of the blood vessels giving off a red colour
- Lips are Internally lined with oral mucosa with small labial glands that open into the oral vestibule.
- There is dense innervation present in the lips, making the lips very sensitive to light touch
What are the 4 regions teeth are described in in adults?
What 4 things does each region contain?
How many teeth are there in total?
What are deciduous teeth?
Which teeth are deciduous teeth?
What can dental development be used for?
- The 4 regions of teeth are described in adults
1) Left
2) Right
3) Maxillary
4) Mandibular - Each region contains:
1) 2x Incisors
2) 1x Canine
3) 2x Premolars
4) 3x Molars - The are 32 teeth in total
- Deciduous teeth, or primary teeth, are the first set of teeth that humans and other mammals develop
- They are eventually replaced by permanent teeth, that begin to grow in throughout childhood
- Deciduous teeth - 2 incisors, 1 canine & 2 molars
- Dental development can be used to determine the age of a baby and can indicate signs of growth retardation
What cranial nerves come from the:
* Cerebrum (2)
* Midbrain (2)
* Pons (4)
* Medulla Oblongata (4)
- Cranial nerves that originate from the:
- Cerebrum
1) Olfactory nerve (CN I)
2) Optic nerve (CN II) - Midbrain
3) Oculomotor nerve (CN III)
4) Trochlear nerve (CN IV) - Pons
5) Trigeminal nerve (CN V)
6) Abducens nerve (CN VI)
7) Facial nerve (CN VII)
8) Vestibulocochlear nerve (CN VIII) - Medulla oblongata
9) Glossopharyngeal nerve (CN IX)
10) Vagus nerve (CN X)
11) Accessory nerve (CN XI)
12) Hypoglossal nerve (CN XII)
What is the primary mechanism for opening the mouth?
What are the 4 muscles of mastication?
Which 2 muscles are deep?
Where does each muscle attach?
What is unique about the mechanism of the lateral pterygoid?
How does this mechanism work?
What is the innervation of the muscles of mastication like?
- The primary mechanism for opening the mouth is gravity
- The 4 muscles of mastication:
1) Temporalis
* Located in the temporal fossa
* Attached to the coronary process of the mandible
2) Masseter
* Located lateral to the angle of the mandible
3) Medial pterygoid (deep)
* Attached to pterygoid process of the sphenoid
4) Lateral pterygoid (deep)
* Attached to pterygoid process of the sphenoid
- The mechanism of the lateral pterygoid is unique as it is the only muscle of mastication that ‘opens’ the mouth
- The lateral pterygoid is attached to the angle of the mandible via its joint cavity, so when it contracts, it pulls the head of the mandible anteriorly in a process known as protraction.
- This creates a gap between the upper and lower teeth
- This can be a useful mechanism in tetanus (small stimuli causing muscular contraction) in order to insert a nasogastric catheter
- All muscles of mastication are supplied by the mandibular division of the Trigeminal nerve (CN V)
What does Buccae mean?
What are the 6 layers of the cheek from superficial to deep?
What is the Buccal fat pad for?
Why is this a problem in malnourished babies?
- Buccae means cheek
- 6 layers of the cheek from superficial to deep:
1) Skin
2) Buccal (Bichat’s) fat pad
3) Buccopharyngeal fascia
4) Buccinator muscle
5) Buccal glands
6) Mucous membrane - The buccal fat pad is used by babies in order to created enough negative pressure in the oral cavity while breast feeding
- Malnourished babies may not have this fat pad, making it difficult for them to breast feed
What 4 things does the buccinator muscle attach to?
Where do the fibres of the buccinator muscle go?
What is the point of cross-over of fibres known as?
Where can it be felt?
What is the role of the buccinator muscle?
What is the buccinator muscle aided by?
What is the buccinator muscle innervated by?
- 4 things the buccinator muscle attaches to:
1) Maxilla (superior)
2) Mandible (inferior)
3) Pterygomandibular raphe (posterior)
* Where it fuses with the superior pharyngeal constrictor
4) Orbicularis oris (anteriorly)
* Fibres terminate in both lips, contributing to the orbicularis oris muscle
- The most superior fibres of the buccinator muscle go to the superior lip
- The most inferior fibres go to the lower lip
- The middle fibres cross over, which allows for us to purse our lips
- The point of cross-over is called modiolus and can be felt just lateral to the angle of the mouth
- The role of the buccinator muscle is to contract and keep food on the occlusal surfaces of the teeth, which are the surfaces used for chewing or grinding
- The buccinator muscle is aided by the tongue, which pushes the food laterally
- The buccinator muscle is innervated by CN VII (Cranial nerve 7 - facial nerve)
What is the role of the palate?
What are the 2 parts of the palate?
Where is the hard palate found?
What is it made from?
Where is the soft palate located?
Where does the soft palate attach?
What is the role of passage ways on the palate?
What are the 2 passage ways on the palate?
- The role of the palate is to the separate the nasal cavity and the oral cavity
- The palate can be broken down into the hard and soft palate
- The hard palate is located anteriorly and consists of bone – anterior 3/4s of the maxilla and the palatine bone posteriorly
- The soft palate is located posteriorly and is Musculomembranous
- The soft palate attaches to the posterior edge of the horizontal plate of palatine bone
- The role of passageways on the palate is to allow structures to move between the oral cavity and nasal cavity and vice versa
- The 2 passage ways on the palate:
2) Incisive foramen
* Transmits nasopalatine nerve
3) Greater palatine foramen
* Transmits greater palatine nerve
What 3 things does the soft palate consist of anteriorly to posteriorly?
How is the soft palate positioned?
Where is the uvula located?
What are Epstein’s pearls?
How do they resolve?
- 3 things the soft palate consists of anteriorly to posteriorly:
1) Palatine aponeurosis
* Contains the periosteum of the hard palate and the tendon of tensor veli palatini (tenses palate)
2) Glands
3) Mucous membrane
- The soft palate hangs like a drape from the posterior border of the hard palate
- The uvula is located at the posterior border of the soft palate in the midline
- Epstein’s pearls are clusters of white spots in the midline at the junction of hard and soft palates
- These resolve spontaneously
What 2 arches (aka folds) extend from the uvula to the lateral walls of the oropharynx?
What exists between these 2 folds?
What is the border between the oral cavity and oropharynx?
What are located deep to the palatine tonsils?
- 2 arches (aka folds) extend from the uvula to the lateral walls of the oropharynx
- Anteriorly, this is the palatoglossal arch (anterior pillar), which covers the palatoglossus muscle
- Posteriorly, this is palatopharyngeal arch (posterior pillar), which covers the palatopharyngeus muscle
- Between these 2 folds on the lateral walls of the oropharynx are palatine tonsils which are contained within the tonsillar fossa
- This is because the palatoglossal arch is the border between the oral cavity and oropharynx
- Deep to the palatine tonsils are tonsillar vessels, which can cause significant bleeding after a tonsillectomy
Which 2 muscles bring the soft palate down?
Which 2 muscle bring the soft palate up?
What is the tensor veli palatini attached to?
What is the action of the tensor vali palatini?
What is the innervation of 4 muscles of the soft palate?
- 2 muscles that bring the soft palate down:
1) Palatoglossus
2) Palatopharyngeus
- 2 muscle that bring the soft palate up:
1) Levator veli palatini
2) Tensor veli palatini
- The tensor veli palatini is attached to the pharyngotympanic tube
- When swallowing, the tensor vali palatini contracts and pulls the tube open, which allows pressure to be equalised between the nasopharynx and the middle ear cavity (e.g what happens on air planes)
- 3 of 4 of the muscles of the soft palate are innervated by the vagus nerve (cranial nerve 10) except for the tensor veli palatini, which is innervated by the trigeminal nerve
What does the tongue consist of?
What 4 things is the tongue used for?
What is the role of papillae on the tongue?
- The tongue consists of a ‘bag’ of striated muscle covered with a mucous membrane
- 4 things the tongue used for:
1) Mastication
2) Deglutition
3) Taste
4) Speech - Papillae on the tongue give the tongue a fuzzy appearance
- Papillae are used for gripping food and also house taste buds
What is the sulcus terminalis?
Where are the anterior and posterior sections of the tongue located?
How are they positioned?
What are they used for?
What are they each innervated by?
- The sulcus terminalis is a V-shaped groove on the tongue that separates the tongue into a posterior 1/3rd and an anterior 2/3rd, which is a separation from embryonic development
- The posterior 1/3rd of the tongue is located in the oropharynx and sits vertically
- The posterior 1/3rd of the tongue is responsible for taste and general sensation
- The posterior 1/3rd of the tongue is innervated by Cranial Nerve 9 (CNIX)
- The anterior 2/3rds of the tongue are located in the oral cavity and sit horizontally
- The anterior 2/3rds of the tongue are responsible for taste (CNVII) and general sensation (CNV – trigeminal nerve)
Where are taste buds located?
What are the 4 types of papillae?
Where are they each located?
Which ones have taste buds?
- Taste buds are located on the tongue, epiglottis, and lateral walls, usually on papillae
- 4 types of papillae:
1) Foliate papillae
* Located on the lateral/posterior tongue body
* Contains taste buds
2) Valliate papillae
* Largest papillae
* 8-12 papillae located parallel to the sulcus terminalis
* Contains taste buds
3) Fungiform papillae
* Located all throughout the tongue
* Contains taste buds
4) Filiform papillae
* Smallest papillae
* Don’t have taste buds
* Used for touch, temperature, and grip
What is the tongue suspended by?
What are the 2 types of skeletal muscle that suspend the tongue?
Where does each type extend between?
What is the function of each type?
Which extrinsic muscle is crucial to survival?
What is the innervation of the tongue muscles?
- The tongue is suspended in oral cavity by 4 pairs of skeletal muscles
- Extrinsic and intrinsic skeletal muscles suspend the tongue in the oral cavity
- The extrinsic muscles extend between various parts of the skull and insert on the tongue
- The extrinsic muscle’s function is to change the position of the tongue during mastication, swallowing and speech
- The genioglossus is an extrinsic muscle essential for survival, as its tone prevents our airway from being closed over when unconscious in the supine position
- Intrinsic muscles originate and insert on the tongue and are located posteriorly
- Intrinsic muscles modify the shape of the tongue during function
- All tongue muscles are innervated by CNXII (Hypoglossal nerve) except the palatoglossus, which is innervated by CNX (Vagus nerve) via the pharyngeal plexus
What are tonsils?
What is crypt?
Why can crypt cause problems?
Where can tonsils be found?
What do they form here?
What 4 things does Waldeyer’s ring consist of?
What is the vascularisation of the palatine tonsils like?
What can be a problem during surgical removal of palatine tonsils?
- Tonsils are collections of lymphoid tissue located in the mucosa of the pharynx
- Crypt are pockets of folds that occur naturally in the tonsils
- Crypt can cause problems as food and bacteria can become trapped here, leading to infection, which can cause cryptic tonsilitis
- Tonsils can be found around the openings of the respiratory and gastro-intestinal tracts in the nasal and oral cavity where they form the Waldeyer’s ring
- 4 things Waldeyer’s ring consist of:
1) 1 Pharyngeal tonsil in the midline of the nasal cavity
2) 2 tubal tonsils around the opening of the pharyngotympanic tube
3) 2 palatine tonsils in the oral cavity
4) 1 Lingual tonsil deep to the tongue in the oral cavity
- The bed of the palatine tonsils in the tonsillar fossa is highly vascular
- Bleeding from the tonsillar branches of palatine artery may be a problem during surgical removal
What 4 things does saliva consist of?
What are the 4 functions of saliva?
What is the parasympathetic supply to salivary glands?
What do sympathetic supply in relation to salivary glands?
- Saliva consists of water, mucus, electrolytes and enzymes
- 4 functions of the saliva:
1) Lubrication and binding of the masticated food
2) Solubilization of dry food
3) Digestion of carbohydrates (α-amylase)
4) Oral hygiene - Parasympathetic supply to salivary glands are secretomotor fibres from the facial (CN-VII) & glossopharyngeal (CN-IX)
- Sympathetic go to vessels supplying salivary glands
What is the parotid gland?
Where is the parotid gland found?
What is the function of parotid duct?
How does it open into the oral cavity?
What is the blood supply and innervation of the parotid gland?
What are Koplik spots?
What are they a sign of?
- The parotid gland is a serous gland enclosed within a tough, unyielding capsule
- The parotid gland can be found in the retromandibular fossa below the external acoustic meatus, behind the ramus of the mandible (anterior and inferior to the ear)
- The parotid duct (Stensen’s duct) carries saliva from the parotid gland to the oral cavity
- It opens into the oral cavity by crossing the masseter superficially, piercing the buccinator and opening into oral vestibule opposite the second maxillary molar tooth
- The blood supply and innervation of the parotid gland is the terminal branching of the external carotid artery and facial nerve (CN VII)
- Koplik spots are white spots that can appear around the parotid duct and are a sign of measles
What is the pharynx?
Where does it extend between?
What is the pharynx responsible for?
What 3 regions is the pharynx divided into?
Where are they located?
What structures divide these regions?
- The pharynx is a Muscular and fibrous tube
- The pharynx extends between the base of skull and lower border of the Cricoid cartilage (upper margin of C6 vertebra)
- The pharynx is responsible for properly conducting food to the oesophagus and air to the lungs
- 3 regions is the pharynx divided into:
1) The nasopharynx (epipharynx), posterior to the nasal cavity
2) The oropharynx, posterior to the oral cavity
3) The laryngopharynx, at the level of the larynx
- The choana separates the nasopharynx and oropharynx
- The Oropharyngeal isthmus separates the oropharynx and laryngopharynx
- The laryngeal inlet separates the laryngopharynx from the larynx
Where do the Salpingopharyngeus and Salpingopalatine muscles run between?
What do they form?
- Salpingopharyngeus and Salpingopalatine muscles run between torus tubarius and pharynx and palate, respectively
- They form the Salpingopharyngeal and Salpingopalatine folds
Label these structures on the pharynx
How do the pharyngeal constrictor muscles fit together posteriorly?
How do they fit together anteriorly and laterally?
How do they fit together anteriorly?
Where do they each attach?
- The pharyngeal constrictor muscles fit together like cups posteriorly
- Anteriorly and laterally, there are gaps between the muscles that are filled by other structures
- Superior pharyngeal constrictor originates the pterygoid hamulus and pterygomandibular raphe with the buccinator
- Middle pharyngeal constrictor originates from the hyoid bone and stylohyoid ligament
- Inferior pharyngeal constrictor originates from the oblique line of the thyroid cartilage and the cricoid cartilage
Pharyngeal constrictor muscle diagrams
Where do all constrictor muscles insert?
What does the Pharyngobasilar fascia close over?
What is Killian’s dehiscence?
What is more likely to occur in this region?
- All pharyngeal constrictor muscles insert on Pharyngeal raphe, which attaches superiorly to the Pharyngeal tubercle on the occipital bone (doesn’t attach anywhere inferiorly)
- The gap between occipital bone and superior constrictor is closed by Pharyngobasilar fascia
- Killian’s dehiscence is the inferior-most region of the inferior constrictor muscle, where the superior pharyngeal constrictor ends
- It is a weak area
- Pharyngoesophageal diverticulum (Zenker’s diverticulum) is more likely to occur here due to an excessive increase in infrapharyngeal/infraoesopheageal pressure
- Zenkers diverticulum is pharyngeal pouch that forms where the lower part of the throat and the upper part of the esophagus meet
What is the sinus of Morgagni?
How strong is this area?
- The Sinus of Morgagni is the space between the base of the skull at the occipital bone and upper free border of superior constrictor muscle
- This is a weak area that isn’t as strong as the muscle
What is Passavant’s ridge (palatopharyngeal sphincter)?
What does it encircle?
What is its action when swallowing?
What happens if you try to speak at this point?
- Passavant’s ridge (palatopharyngeal sphincter) is a mucosal ridge caused by superior pharyngeal constrictor or the palatopharyngeus
- It encircles the posterior and lateral walls of the nasopharynx
- During swallowing, Passavant’s ridge touches to the soft palate and separates the oropharynx from nasopharynx, closing off the airway
- If you try to speak at this point, the food can be pushed into the nose
Label these pharynx muscles
What is the role of pharyngeal elevator muscles?
What is the role of pharyngeal constrictor muscles?
How do they contract?
What is the cricopharyngeal sphincter?
What is its role?
How can lack of coordination between certain muscles lead to Killian’s dehiscence?
- Pharyngeal elevator muscles pull pharynx superiorly and receive bolus
- Pharyngeal constrictors compress the lumen of the pharynx and push bolus towards the oesophagus
- They contract involuntarily from superior to inferior
- The inferior pharyngeal constrictor has a lower circular part around the upper oesophagus that is known as cricopharyngeal sphincter
- The cricopharyngeal sphincter prevents air being drawn into the stomach during inhalation
- Lack of coordination between pharyngeal constrictors and cricopharyngeal sphincter can cause Pharyngoesophageal diverticulum through Killian’s dehiscence
What is the motor innervation of pharyngeal elevators and constrictors?
What is the exception?
- The motor innervation of all pharyngeal elevators and constrictors is the the vagus (CN-X) except 1
- Stylopharyngeus is the only pharyngeal muscle supplied by the glossopharyngeal nerve (CN-IX)
What is the sensory supply of the nasopharynx?
What 4 things receive their sensory supply from the Glossopharyngeus (CNIX)?
Where can pain from the Glossopharyngeus (CNIX) be referred to?
What 3 things receive their sensory supply from the vagus nerve?
- Nasopharynx receives its sensory supply from the Maxillary (CN-V2) division of trigeminal nerve (CN-V)
- 4 things that receive their sensory supply from the Glossopharyngeus (CNIX):
1) Oropharynx
2) Palatine tonsils
3) Inferior surface of soft palate
4) Posterior 1/3 of the tongue
- Pain from the Glossopharyngeus (CNIX) can be referred to the middle ear
- 3 things that receive their sensory supply from the vagus nerve:
1) Laryngopharynx
2) Vallecula
3) Epiglottis
How is food kept between the occlusal surfaces of the molar teeth?
Describe the 3 mechanisms in the closure of the oropharyngeal isthmus.
What is each mechanism carried out by?
- Buccinator muscle, together with the tongue keeps food between the occlusal surfaces of the molar teeth
- 3 mechanisms in the closure of the oropharyngeal isthmus:
1) Soft palate is pulled down: Palatoglossus & palatopharyngeus
2) Tongue is drawn slightly upwards: Palatoglossus & palatopharyngeus
3) Palatoglossal & palatopharyngeal arches move medially like curtains
Describe the 8 stages of deglutition (swallowing) and which structure carries out each phase
- 8 stages of deglutition (swallowing):
1) The bolus is pushed towards the back of the oral cavity by raising the tip & body of the tongue upwards towards the palate: mylohyoid & tongue muscles
2) The palatoglossal & palatopharyngeal arches relax and move laterally
3) The tongue is pulled upwards & backwards to tip the bolus through the oropharyngeal isthmus & into the pharynx: Styloglossus
4) The soft palate is stretched and elevated: Tensor veli palatini, levator veli palatini
5) Elevated soft palate and Passavant’s ridge separate the nasopharynx from the oropharynx: Superior pharyngeal constrictor
6) The pharynx (and larynx) is elevated by the pharyngeal elevators: stylopharyngeus, salpingopharyngeus & palatopharyngeus as well as stylohyoid & digastric
7) Laryngeal inlet is closed: Tongue, Aryepiglottic and thyroepiglottic muscles
8) Bolus is pushed towards the oesophagus: Pharyngeal constrictors
