Face and oral Cavity Flashcards
What does the buccal cavity refer to
The mouth
What is the main sensory nerve of the head and neck
The trigeminal nerve- also has a motor function
How many quadrants of dent tissue do we have
4
Describe the potential impact of strokes and degenerative diseases on swallowing
Voluntary and involuntary component of swallowing- lots of cranial nerves involved- imparied brain function can greatly hinder swallowing
Which cranial nerve is involved in the gag response
CN9
Why we put a depressor on the tounge
Summarise the oral cavity
The oral cavity is inferior to the nasal cavities (Fig. 8.243A). It has a roof and floor and lateral walls, opens onto the face through the oral fissure, and is continuous with the cavity of the pharynx at the oropharyngeal isthmus.
Describe the boundaries of the oral cavity
The roof of the oral cavity consists of the hard and soft palates. The floor is formed mainly of soft tissues, which include a muscular diaphragm and the tongue. The lateral walls (cheeks) are muscular and merge anteriorly with the lips surrounding the oral fissure (the anterior opening of the oral cavity).
The posterior aperture of the oral cavity is the oropharyngeal isthmus, which opens into the oral part of the pharynx.
What separates the oral cavity into two different regions
The oral cavity is separated into two regions by the upper and lower dental arches consisting of the teeth and alveolar bone that supports them
Describe the two different regions of the oral cavity
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The outer oral vestibule, which is horseshoe shaped, is between the dental arches and the deep surfaces of the cheeks and lips—the oral fissure opens into it and can be opened and closed by muscles of facial expression, and by movements of the lower jaw.
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The inner oral cavity proper is enclosed by the dental arches.
How can we alter the displacement between the upper and lower dental arches
The degree of separation between the upper and lower arches is established by elevating or depressing the lower jaw (mandible) at the temporomandibular joint.
What can the oropharyngeal isthmus be opened by
The oropharyngeal isthmus at the back of the oral cavity proper can be opened and closed by surrounding soft tissues, which include the soft palate and tongue.
Describe the functions of the oral cavity
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It is the inlet for the digestive system involved with the initial processing of food, which is aided by secretions from salivary glands.
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It manipulates sounds produced by the larynx and one outcome of this is speech.
It can be used for breathing because it opens into the pharynx, which is a common pathway for food and air. For this reason, the oral cavity can be used by physicians to access the lower airway, and dentists use “rubber dams” to prevent debris such as tooth fragments from passing through the oropharyngeal isthmus and pharynx into either the esophagus or the lower airway.
Summarise the soft palate
The soft palate (Fig. 8.264) continues posteriorly from the hard palate and acts as a valve that can be:
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depressed to help close the oropharyngeal isthmus, and
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elevated to separate the nasopharynx from the oropharynx.
The soft palate is formed and moved by four muscles and is covered by mucosa that is continuous with the mucosa lining the pharynx and oral and nasal cavities.
What is the uvula
The small tear-shaped muscular projection that hangs from the posterior free margin of the soft palate is the uvula.
Summarise the muscles of the soft palate
Five muscles (Table 8.22) on each side contribute to the formation and movement of the soft palate. Two of these, the tensor veli palatini and levator veli palatini, descend into the palate from the base of the skull. Two others, the palatoglossus and palatopharyngeus, ascend into the palate from the tongue and pharynx, respectively. The last muscle, the musculus uvulae, is associated with the uvula.
Describe the anatomy and function of the tensor veli palatini
Origin- Scaphoid fossa of sphenoid bone; fibrous part of pharyngotympanic tube; spine of sphenoid
Insertion- palatine aponeurosis
Function- Tenses the soft palate; opens the pharyngotympanic tube (links nasopharynx to the middle ear)
Describe the anatomy and function of the levator veli palatini
origin- Petrous part of temporal bone anterior to opening for carotid canal
insertion- Superior surface of palatine aponeurosis
function- Only muscle to elevate the soft palate above the neutral position
Describe the anatomy and function of the palatoglossus
origin- Inferior surface of palatine aponeurosis
insertion- Lateral margin of tongue
Function- Depresses palate; moves palatoglossal arch toward midline; elevates back of the tongue
Describe the anatomy and function of the palatopharyngeus
origin- Superior surface of palatine aponeurosis
Insertion- Pharyngeal wall
Function- Depresses soft palate; moves palatopharyngeal arch toward midline; elevates pharynx
Describe the anatomy and function of the musculus uvulae
origin- Posterior nasal spine of hard palate
insertion- Connective tissue of uvula
function- Elevates and retracts uvula; thickens central region of soft palate
Summarise the innervation to the muscles of the soft palate
All muscles of the palate are innervated by the vagus nerve [X] (via pharyngeal branch to pharyngeal plexus), except for the tensor veli palatini, which is innervated by the mandibular nerve [V3] (via the nerve to the medial pterygoid).
List the three sets of tonsils found in the upper GI tract.
Palatine, Pharyngeal, Lingual
Between which two folds do the palatine tonsils lie
Palatopharyngeal Fold
Palatoglossal Fold
Surface projections of their muscles
Describe the faucial pillars
Part of the palatine tonsil- can become swollen or infected in infection.
Describe the palatine aponeurosis
The palatine aponeurosis is attached anteriorly to the margin of the hard palate, but is unattached posteriorly where it ends in a free margin. This expansive aponeurosis is the major structural element of the soft palate to which the other muscles of the palate attach.
Where are the palatopharyngeal arches found relative to the palatoglossal arches
The palatopharyngeal arches lie posterior and medial to the palatoglossal arches when viewed anteriorly through the oral cavity
Describe the clinical relevance of the levator veli palatini
The levator veli palatini is innervated by the vagus nerve [X] through the pharyngeal branch to the pharyngeal plexus. Clinically, the levator veli palatini can be tested by asking a patient to say “ah.” If the muscle on each side is functioning normally, the palate elevates evenly in the midline. If one side is not functioning, the palate deviates away from the abnormal side.
It raises the soft palate and uvula and depresses the tongue, which are vagus-mediated effects. So the GP is testing the motor function of the vagus nerve.
To which side would the tongue move if a patient with a unilateral lesion in the hypoglossal nerve was asked to stick their tongue out?
Towards the side of the lesion because the genioglossus is used in protracting the tongue
What happens in swallowing
Larynx moves upwards
epiglottis- retroflects and covers airway to prevent food from entering- covers the laryngeal inlet
What is the hard palate useful for
Anteriorly the palate is bone- useful for demastacation- helps breakdown food by crushing it against the hard palate
Describe the borders of the hard palate
The palatine processes of the maxillae form the anterior three-quarters of the hard palate. The horizontal plates of the palatine bones form the posterior one-quarter. In the oral cavity, the upper alveolar arch borders the hard palate anteriorly and laterally. Posteriorly, the hard palate is continuous with the soft palate.
What are the 3 parts of the pharynx
Nasopharynx
Oropharynx
Laryngopharynx
What are the three parts of the pharynx and what are their borders?
Nasopharynx – down to the soft palate (pharyngeal isthmus)
Oropharynx – between the soft palate and the epiglottis
Laryngopharynx – between the epiglottis and the cricoid cartilage
Which structures open into each part of the pharynx
The posterior apertures (choanae) of the nasal cavities open into the nasopharynx.
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The posterior opening of the oral cavity (oropharyngeal isthmus) opens into the oropharynx.
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The superior aperture of the larynx (laryngeal inlet) opens into the laryngopharynx.
Describe how the soft palate can act as a flutter valve
Although the soft palate is generally considered as part of the roof of the oral cavity, it is also related to the pharynx. The soft palate is attached to the posterior margin of the hard palate and is a type of “flutter valve” that can:
▪ swing up (elevate) to close the pharyngeal isthmus, and seal off the nasopharynx from the oropharynx, and
▪ swing down (depress) to close the oropharyngeal isthmus and seal off the oral cavity from the oropharynx.
Ultimately, what is the pharynx
The pharynx is a musculofascial half-cylinder that links the oral and nasal cavities in the head to the larynx and esophagus in the neck (Fig. 8.194). The pharyngeal cavity is a common pathway for air and food.
Where does the pharynx run from
The pharynx is attached above to the base of the skull and is continuous below, approximately at the level of vertebra CVI, with the top of the esophagus.
What are the walls of the pharynx related to
The walls of the pharynx are attached anteriorly to the margins of the nasal cavities, oral cavity, and larynx.
What are the superior and anterior margins of the pharynx attached to
The superior and anterior margins of the pharyngeal wall are attached to bone and cartilage, and to ligaments. The two sides of the pharyngeal wall are welded together posteriorly in the midline by a vertically oriented cord-like ligament (the pharyngeal raphe). This connective tissue structure descends from the pharyngeal tubercle on the base of the skull to the level of cervical vertebra CVI where the raphe blends with connective tissue in the posterior wall of the esophagus.
Describe the irregular C-shaped line of attachment of the pharynx to the base of the skull
There is an irregular C-shaped line of pharyngeal wall attachment on the base of the skull (Fig. 8.196). The open part of the C faces the nasal cavities. Each arm of the C begins at the posterior margin of the medial plate of the pterygoid process of the sphenoid bone, just inferior to the cartilaginous part of the pharyngotympanic tube. The line crosses inferior to the pharyngotympanic tube and then passes onto the petrous part of the temporal bone where it is just medial to the roughening for the attachment of one of the muscles (levator veli palatini) of the soft palate. From here, the line swings medially onto the occipital bone and joins the line from the other side at a prominent elevation of bone in the midline (the pharyngeal tubercle).
What are the muscles of the pharynx organised according to
The muscles of the pharynx are organized into two groups based on the orientation of muscle fibers.
The constrictor muscles have fibers oriented in a circular direction relative to the pharyngeal wall, whereas the longitudinal muscles have fibers oriented vertically.
Describe how the pharyngeal constrictor muscles are arranges
The constrictor muscles overlap each other in a fashion resembling the walls of three flower pots stacked one on the other. The inferior constrictors overlap the lower margins of the middle constrictors and, in the same way, the middle constrictors overlap the superior constrictors.
Summarise the function and innervation of the pharyngeal constrictor muscles
Collectively, the muscles constrict or narrow the pharyngeal cavity.
When the constrictor muscles contract sequentially from top to bottom, as in swallowing, they move a bolus of food through the pharynx and into the esophagus.
All of the constrictors are innervated by the pharyngeal branch of the vagus nerve [X].
Describe the anatomy of the superior constrictors
Each muscle is attached anteriorly to the pterygoid hamulus, pterygomandibular raphe, and adjacent bone of the mandible. From these attachments, the muscle fans out posteriorly and joins with its partner muscle from the other side at the pharyngeal raphe.
Describe how the superior constrictor closes the pharyngeal isthmus
When the superior constrictor constricts during swallowing, it forms a prominent ridge on the deep aspect of the pharyngeal wall that catches the margin of the elevated soft palate, which then seals closed the pharyngeal isthmus between the nasopharynx and oropharynx.
Describe the anatomy of the middle constrictors
The middle constrictor muscles are attached to the lower aspect of the stylohyoid ligament, the lesser horn of the hyoid bone, and the entire upper surface of the greater horn of the hyoid (Fig. 8.198).
Like the superior constrictors, the middle constrictor muscles fan out posteriorly and attach to the pharyngeal raphe.
The posterior part of the middle constrictors overlaps the superior constrictors.
Describe the anatomy of the inferior constrictors
The inferior constrictor muscles attach anteriorly to the oblique line of the thyroid cartilage, the cricoid cartilage, and a ligament that spans between these two attachments to cartilage and crosses the cricothyroid muscle (Fig. 8.198).
Like the other constrictor muscles, the inferior constrictor muscles spread out posteriorly and attach to the pharyngeal raphe.
The posterior part of the inferior constrictors overlaps the middle constrictors. Inferiorly, the muscle fibers blend with and attach into the wall of the esophagus.
The parts of the inferior constrictors attached to the cricoid cartilage bracket the narrowest part of the pharyngeal cavity.
Summarise the anatomy of the pharyngeal longitudinal muscles
The three longitudinal muscles of the pharyngeal wall (Fig. 8.199 and Table 8.18) are named according to their origins—stylopharyngeus from the styloid process of the temporal bone, salpingopharyngeus from the cartilaginous part of the pharyngotympanic tube (salpinx is Greek for “tube”), and palatopharyngeus from the soft palate. From their sites of origin, these muscles descend and attach into the pharyngeal wall.
All innervated by vagus, except for the stylopharyngeus- - which is innervated by hypoglossal
Summarise the function of the pharyngeal longitudinal muscles
The longitudinal muscles elevate the pharyngeal wall, or during swallowing, pull the pharyngeal wall up and over a bolus of food being moved through the pharynx and into the esophagus.
The palatopharyngeal muscle also closes off the oropharyngeal isthmus
What is key to remember about motor and sensory innervation to the pharynx
Motor and most sensory innervation (except for the nasal region) of the pharynx is mainly through branches of the vagus [X] and glossopharyngeal [IX] nerves, which form a plexus in the outer fascia of the pharyngeal wall
What is the pharyngeal plexus formed by
The pharyngeal plexus is formed by:
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the pharyngeal branch of the vagus nerve [X],
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branches from the external laryngeal nerve from the superior laryngeal branch of the vagus nerve [X], and
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pharyngeal branches of the glossopharyngeal nerve [IX].
The pharyngeal branch of the vagus nerve [X] originates from the upper part of its inferior ganglion above the origin of the superior laryngeal nerve and is the major motor nerve of the pharynx.
What are all muscles of the pharynx innervated by
All muscles of the pharynx are innervated by the vagus nerve [X] mainly through the pharyngeal plexus, except for the stylopharyngeus, which is innervated directly by a branch of the glossopharyngeal nerve [IX] (
Describe the sensory innervation of the different parts of the pharynx
The nasopharynx is innervated by a pharyngeal branch of the maxillary nerve [V2] that originates in the pterygopalatine fossa and passes through the palatovaginal canal in the sphenoid bone to reach the roof of the pharynx.
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The oropharynx is innervated by the glossopharyngeal nerve [IX] via the pharyngeal plexus.
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The laryngopharynx is innervated by the vagus nerve [X] via the internal branch of the superior laryngeal artery.
Why is it important to close of the nasopharynx during swallowing
To prevent food entering the nose
Summarise the major steps in swallowing
Lift and retract tongue (styloglossus, intrinsic)
Bolus into oropharynx (palatoglossus)
Close off nasopharynx by raising soft palate
Raise the larynx, closed off by epiglottis
Peristaltic wave of constrictor muscles
Relax cricopharyngeus, open oesophagus
