Chewing, tasting and swallowing. Flashcards
What are the main muscles of mastication?
Temporalis
Masseter
Lateral pterygoid
Medial pterygoid
Name the muscles involved in closing the mouth.
Temporalis
Masseter
Medial pterygoid (minor role)
What is the main role of the medial pterygoid?
Swinging the mandible from side to side
What is the function of the lateral pterygoid?
Opening the mouth (assisted by the digastric muscle)
At which joint do the mandible and cranium articulate?
The temporomandibular joint.
At rest where does the head of the mandible lie?
The glenoid fossa.
With which muscle is the disc of fibrocartilage found in the glenoid fossa continuous?
The lateral pterygoid.
Describe the movement of the mandibular head in the glenoid fossa. Why is this important?
The mandibular head rotates anteriorly and slides out of the fossa as the mouth opens. This freedom within the joint allows the mandibular head to move from side to side.
How many heads does the lateral pterygoid muscle have and where do they insert?
Two, upper and lower. They insert into the neck of the mandible and part of the TMJ.
What is the origin of the upper head of lateral pterygoid?
Sphenoid bone.
What is the origin of the lower head of lateral pterygoid?
Lateral pterygoid plate.
How does the lateral pterygoid open the mouth?
It pulls the neck of the mandible and parts of the TMJ forward, which protrudes the mandible but does not rotate it.
Which muscle is responsible for the rotation of the mandibular head?
The digastric.
What is the origin of the digastric muscle?
The mastoid process.
What is unusual about the digastric muscle?
Is has two bellies - connected by a tendon.
What is the origin of the temporalis?
The lateral surface of the skull.
What is the insertion of the temporalis?
The choronoid process of the mandible.
How does temporalis both elevate and retract the mandible?
The anterior fibres run in the verticle plane - elevating the mandible, while the posterior fibres run in the verticle plane - pulling temporalis back.
What is the origin of the masseter?
The zygomatic arch.
What is the insertion of the masseter ?
The choronoid process and the ramus of the mandible.
What is the origin of the medial pterygoid?
The medial surface of the lateral pterygoid plate and the maxilla.
What is the insertion of the medial pterygoid?
The inner aspect of the ramus of the mandible.
What happens when the medial pterygoid contracts?
The mandible is pulled upwards and medially.
Why does the lateral pterygoid also contract when the mouth is closing?
Confers extra control.
Describe the innervation of the muscles of mastication.
They are all innervated by the mandibular branch of the trigeminal nerve (CNIII).
Which nerve supplies the posterior belly of the digastric muscle?
The facial (CNVII).
What is the name of the junction between the two parts of the tongue?
Sulcus terminalis
What name is given to the structures of the posterior portion of the tongue located on the anterior surface?
Circumvallate pipillae
What is the nerve supply to the posterior surface of the tongue.
General sensation, special sensation and taste are provided by lingual branches of the glossopharyngeal nerve (CNIX).
Describe the nerve supply to the anterior surface of the tongue.
Taste sensation is provided by the facial nerve (CNVII)
General sensation is provided by the lingual nerve.
What is the role of the tongue in swallowing?
The tongue is then raised against the hard palate progressively from anterior to posterior, thereby squeezing the bolus of food increasingly towards the back.
What is the role of the soft palate in swallowing?
The soft palate is now tensed and elevated to close off the connection between the oropharynx and the nasopharynx, thereby preventing food being pushed upwards and into the nasal cavity.
What is the role of the epiglottis during swallowing?
During the process of swallowing, as the tongue is elevated towards the hard palate, the larynx is drawn upwards. This brings the larynx up under the cover of the epiglottis. At the same time, the epiglottis is being bent backwards and downwards by the posterior bulging of the tongue and by the bolus of food itself.
What is the role of the pharynx during swallowing?
The circular muscles of the pharynx contract successively from above downwards, generating a peristaltic wave that propels the bolus down through the pharynx and into the oesophagus.
